Turquoise Energy Newsletter #140 - January 2020
Turquoise Energy News #140
covering January 2020 (Posted February 8th 2020)
Lawnhill BC Canada - by Craig Carmichael


www.TurquoiseEnergy.com = www.ElectricCaik.com = www.ElectricHubcap.com

Features:
* Open Loop, Free Air Heat Pumping: COP > 10? - or: How to Heat a Building Really, Really Cheap! (see: Month in Brief, Other Projects)
* 12 Years of Green Energy Projects in Review (see "In Passing")

Month In "Brief" (Project Summaries etc.)
 - Brr! - Free Air Heat Pumping - Theory - Heat Pumping Experiments - Meanwhile in Other News - Bringing a Dead NiMH Battery Back to Life

In Passing (Miscellaneous topics, editorial comments & opinionated rants)
  - Von Braun and the Apollo Moon Landing Project - 12 Years of Energy Projects in Review - Reversing Desertification - Small Thots: Columnating out-of-line binoculars, Hair mites, Earth heat... - ESD

- Detailed Project Reports -
Electric Transport - Electric Hubcap Motor Systems (No Reports)

Other "Green" Electric Equipment Projects
* HAT & CAT Plugs & Sockets
* Very High COP Open Air Heat Pumping
  - Cooling - Heat Pump Heating - Some Simple Tests - Experiments - Copper Pipe, Soldered Copper Fins - A Test - More Compressed Air Piping and Test 2 - Outer Ducting and Test 3 - Building-to-Outdoor Heat Exchanger and Tests #4 - Michelin Air Compressor Tests - Air Compressor Noise Solutions? - Custom Air Pumps? - Refrigerator Air Pump

Electricity Generation
* My Solar Power System: - Monthly Solar Production log et cetera - Notes. (December & January: trivial power output!)
* "Carmichael's Woodstove Engine" (& generator) -- Called off for now for greener pastures & easier projects.
* An Experiment: Woodstove Electricity with Thermoelectric Generators (TEGs)

Electricity Storage
* Turquoise Battery Project (Mn-Zn or Ni-Zn in Mixed Alkaline Salt electrolyte)
 - Thinner copper current collector - nickel electrode - pure zinc electrode - Nickel-manganates Again - Low Currents - Back to Graphite Felt? - Chemistry seems fine but Mushy Electrodes Don't Conduct Well




January in Brief


House with some snowed-over solar panels on the roof.
Some snow had melted or slid off the bottoms, but
they don't produce unless the whole panel is clear.

Best Laid Plans and all that: It's the Weather


   After returning from my Christmas holiday I had intended to carry on with the model of the ground effect vehicle, but I came back with a nasty chest cold. I put heat and steam on in my bedroom at night for some days. (yet more electricity!) I sat down and looked into the Stirling engine heat pumping idea. This led to thinking of an exciting way to refrigerate, followed by an even more exciting way to heat a building, for exceptionally low cost. These dominated my creative thoughts.

   And the weather was cold, varying from -5 to -10°C for a couple of weeks. I could hear 2 or 3 chainsaws in the neighborhood, I thought to cut more firewood in the unexpected cold. Luckily I was already short of it and I had bought a cord of fairly dry firewood just before Christmas. (On the night of the 13th-14th it dropped to -10.2. That's the coldest I've ever been in in 47 years on the west coast - if only by a degree or so and I'm farther north now.) I left the kitchen sink running a bit to make sure the pipes coming in from the well through the unheated garage didn't freeze. (Some other peoples' water did freeze.)
   ACK! My potatoes! Since it doesn't usually get so cold I had left them in the ground, digging them up as needed. Now they were in danger of freezing! I went outside for a couple of short sessions, throwing off big slabs of frozen dirt about 3-4 inches thick and then digging through the soft sandy soil underneath. There were too many in the frozen top layer, and I sliced through too many with the shovel, and doubtless I missed too many. (Weapon of choice for potatoes is normally a pitchfork: you'll skewer a few, but you'll turn them up without slicing a bunch of them in half.) I wasn't a day too soon as there was thick snow the nest day. It would have gone better in December - if I had guessed what was coming. I only got the main patch - there were still others. Oh well, 6 Kg of potatoes is 6 Kg of potatoes. Some had been frozen and went mushy, but most were good.
   Sitting anywhere but the livingroom where the woodstove was - and preferably next to it - wasn't comfortable. So I dabbled at things that didn't require going outside or into the workshop much... or even into the kitchen. Especially things for which I could sit near the stove to do some of the work. On the 13th I noticed that electricity consumption had gone WAY up that day, from 40 KWH to 90. I finally realized the house baseboard heaters, set to 10°, must have come on at night when the fire was low. They were using far, far more electricity, to keep the house less warm, than my new plan for heat pumping would have if it had been already working instead of just a concept.
   On the 15th I checked my "root cellar" storage room. It usually maintains a nice, cool temperature but now the thermometer said 35°f... 2°! I put a 425 watt heater down there to keep the room with its many gallons of paint and some food from freezing. I can only be glad I'm not on the prairies. Edmonton where I grew up was almost -40°c (= -40°f), even colder than the coldest day when I was going to school in the 1960s, -30°f or -34°c --  "-90 [°f] with wind chill". (I remember it well. That was before Canada went metric)

   We have by no means seen the end of unprecedented weather and broken all-time records. It's global. IMHO there are three main forces at work: Unnatural high stratospheric cloud cover being caused by jet aircraft which are heavily disrupting the global wind circulations and precipitation patterns (TE News #109 etc), global warming, and the grand solar minimum ("GSM") with the sun being slightly dimmer than usual for a period of (hopefully only) 2 or 3 decades. It seems to me that the first of these is the most disruptive.

   Things improved for some days in the later part of the month, but there was just one sunny day where it was nice to be outside, and on the night of the 31st it snowed again, with the temperature around freezing.

Free Air Heat Pumping: How to Heat a Building Really, Really Cheap

   Reading in a paper that Stirling engines might potentially get a Coefficient Of Performance (COP) of 8 to 10, that is, pump 8 to 10 times as much heat from a cool place to a warm place as the electricity being used to pump it with a 30° temperature rise or fall, was really exciting. Why didn't we already have such equipment, then? I just couldn't drop the subject in my mind. Then I thought, why a Stirling engine? When powered by a motor, all it did was shuffle air around, and perhaps not even as effectively as it might. One could shuffle air around in simpler ways. What about just a plain air compressor using open air?

   On the 6th I started writing ideas down, and the more I looked into it, and the more thought I gave to it, the more exciting it seemed. I started thinking of refrigeration, but soon turned to building heating. It was so much simpler than a refrigerant gas/liquid heat pump system that even if the COP wasn't higher, it should be cheaper and so would have broader application. And the COP looked like it could be substantially higher. If a 'regular' heat pump had a COP of 2 to 4 depending on temperature differentials, might free air (at this point based solely on the Stirling engine paper and expecting similar) be 6 to 12, using 1/2 or 1/3 as much energy to do just as much heating of cooling? But it turned out the Stirling engine paper seemed to have been quoting almost theoretical maximum COP, not what was likely to be attained by actual heat pumping equipment, especially pumping air and with amateur homemade equipment.


In a typical closed-loop heat pump, a refrigerant
is pumped between outdoors and the building.
The cooled refrigerant must be reheated from
below the outdoor temperature to above
room temperature to heat the building.

   By the time I realized that, I had also realized that by using open loop heat pumping with air instead of a closed loop refrigerant based system, one might actually get a real COP above 10 - even 15 to 20 or more by further heating indoor air instead of heating air from outdoor temperature! The lower the temperature rise, the higher the COP. So one might perhaps get (eg) 1200 watts of heat from each 100 watts used to run the compressor. This was the essential conceptual breakthrough. Soon a few more bits fell into place to enable that to work well.

   In northern latitudes heating is the great energy consumer, in winter exceeding all other energy uses combined including transport. The possibility of attaining "unheard of" COPs by doing just a small temperature rise seemed unbelievable at first, but I didn't see a flaw in it. It seemed like such an exciting idea, to be achieved with such potential simplicity, as to be a game changer for home energy use - the energy equivalent of going from incandescent light bulbs to LEDs, but for the much larger energy use of space heating. How could I not look into it? I learned more. (What a fantastic resource the internet is, and accessible from home!)

The Theory

  I finally found the essential, simple formula for theoretical maximum COP. Temperature units must be in absolute temperature (°Kelvin, °K = °C+273):

             Thot
COP = ----------
         (Thot Tcold )

   The denominator is known as the "lift", the number of degrees (here °K or °C are the same) by which one wishes to raise a temperature. To pick a simple round number for Thot, Earth's temperature is around 300°K. (That's 27°C.)

Graph showing COP potential for heat pumping at various temperature "lifts",
   assuming 50% efficient heat pumping. But: "Infeasible" looks feasible!
   So if one wants to heat ("lift") outdoor air by 30°K (= 30°C), eg, to heat from freezing air temperature up to 30°C to be warm enough to radiate heat into the building to get a comfortable 23°C or so room temperature, 300 / 30 = 10 theoretical COP. Inefficiencies in closed loop, refrigerant based heat pumping apparently reduce the actual COP to around 2 if it's below freezing outside, to 3, or often 4 or higher if it's not very cold outside. (When the most heat is needed the COP is lowest. Note: Could newer equipment do a little better than my old statistics?)

   If instead we can merely heat the indoor air from 23 to 30 at the radiators, that's only a 7° "lift".   300 / 7 = 43 theoretical COP. Given even just 25% equipment efficiency overall, we still get an actual COP of 11: eg, 1100 watts of heat for 100 watts of electricity. If the equipment is more efficient, it may go up from there. With a fabulous radiator system one might need a lift of just 3°, giving a theoretical maximum COP of 100: 10,000 watts of heat from 100 watts of electricity!

   The questions arose, and then the answers. How can one just heat pump the indoor air? Doesn't the air finally come out of the system at room pressure, chilled as it decompresses? The heat pumped is chilled again! That's where the open loop system has the advantage: it can discharge the cooled air to the outdoors. So overall heat from the outdoors is transferred into the building.
   That is the essential, but there's still another improvement to be had. Since outside air is drawn into the building to replace what the compressor uses, one can add a building-to-outdoor heat exchanger (or just "outdoor heat exchanger") instead of just letting it suck cold air through the cracks. The outgoing air warms the incoming air, while the incoming air cools the outgoing air. Then when the outgoing air, now cooled to almost outdoor temperature, is decompressed to the outdoors, it will be colder than the outdoor air. But the heat exchanger passively raises the temperature, and the heat pump only heats room temperature air up a little warmer.


   So the open loop, free air heat pump system has three main components.

1. The prime mover is an air compressor. It is (at least thermally speaking) inside the building being heated. As air is compressed, it contains the same thermal energy but in a smaller and smaller space. If it's compressed into half the space at double the pressure, it theoretically doubles in absolute temperature. But the much denser solid materials of the compressor cylinder, piston and pressure tank quickly absorb this excess thermal energy and warm up, so it takes a lot of air to warm things a little. But it is heat that came from the already warm building air, not from the electricity running the compressor.

2. The second component is the radiator - a heat exchanger between the warmed, compressed air and the room air. This (at least in my prototype) is copper pipe with copper fins, all inside a thin walled aluminized flexible dryer hose. The compressed (and hence a little warmed) air flows continually from the compressor through the pipe, under full pressure all the way. Its warmth is transferred from the pipe via the fins into the dryer hose around it. The dryer hose is thin walled and not insulated, and a small fan also blows the air through the hose/duct and out the end. Moving air transfers heat to the room air much better than just passive convection and radiation from the pipes, minimizing the "lift" needed to heat the radiator enough to heat the indoor air, and hence maximizing the COP.

3. The third component is the building-to-outdoor heat exchanger. The workings of these are long and well known since the 1970s(?). (Thanks ASHRAE trade shows!) Inch by inch as the air comes in, it gets a little warmer until it's (almost) room temperature, and inch by inch the outgoing air gets cooler until it's (almost) outdoor temperature as the two exchange their heat. (I've seen manufacturer's claims of 90% efficiency.)
   The unit should work without an outdoor heat exchanger, but cold air being sucked in from outside would add to the heating load. "Portable" single duct air conditioners also work, but similarly the outside air they draw in as the duct expels building air, adds to the cooling load and they lose efficiency.

   The unit in this case is like the radiator pipes except its outer duct is insulated. The compressed air, having heated the living space, is down (almost) to room temperature. The pipe is now routed through the outdoor heat exchanger, where it is cooled to (almost) outdoor temperature. The pipe ends outdoors and pointed away from the incoming air. The compressor is using air from inside the building and exhausting it outside, and so air is drawn in from outdoors through the outdoor heat exchanger's outer duct. So as the compressed air is exiting the building, it is warming the incoming air to (about) room temperature while itself being cooled.
   At the very end of the long compressed air pipe, outdoors, is a nozzle where the air is decompressed, which further cools it, and released. Thus the air actually exits the system below the surrounding outdoor air temperature. So the building is heated while the outdoors is cooled just like with other heat pumps. But here the pump itself only heats indoor air. The outdoor heat exchanger has pre-warmed the air to help make an extreme COP possible - regardless of outdoor temperature.

   (I used square aluminum fin pipes I had already made. Probably not optimum. And the outer duct ended up being a bit narrower than I had intended.)


Heat Pumping Experiments

   I ordered a "highest flow capacity" plug-in 120 volt air compressor: over 4 CFM at 90 PSI. (MORE money going out, ahrg!) I had hoped for a quieter one than the piston type, but the quieter and supposedly more efficient (now I have my doubts) helical screw, scroll and centrifugal types seem to be made only in very large sizes.
   And I made a short "stegosaur" finned radiator pipe with diagonally oriented, soldered-on copper fins to catch the air going along in the duct outside the pipe, about 2 feet long. This proved very tedious and they had less than an optimum grip (a few fell off) and thermal connection, so I decided I had to make a jig(s) to simplify and improve the process before I did any more.


"Stegosaur" finned pipe

The "Star Wars Cannon" setup. It doesn't much
 matter whether the body of the outdoor heat
  exchanger is inside or outside, so I just set
 the end up against the window, opened a bit.
    Later in the month I thought of my small lab vacuum/pressure pump. I bought various pipe fittings, and made a mini heat pump unit with it, making and testing one component at a time. The heart was a plywood box with the compressor and a fan to blow air through the duct. (I plugged the 36 volt fan into my DC solar power system outlet.) On the 26th I completed the last one, the building to outdoor heat exchanger, and in the evening I tried it out in the kitchen/dining area with no other heat on and both doors closed so it wasn't just being heated from other areas through the doors.
   It was hard to tell what the effect was. The air coming out the indoor radiator hose hose was only 2-3 degrees above the air going in, but it was a fair amount of air being moved. The room temperature wasn't rising. But then it was cold out, 4°C, and the space was mostly exterior walls/floor/ceiling. How effective was it really? I ended up by running several tests measuring only the room temperature, one after another, with each test for one hour:

Test
Start Temp.
(degrees C)
End Temp.
(after 1 hour)
Rise/-Drop
Heat Pump
17.1
17.0
-.1
No Heat
17.0
16.0
-1.0
Heat Pump
16.0
15.9
-.1
425W Radiant heater
15.9
16.1
+.2
No Heat
16.1
15.5
-.6

   It can be seen that without heat, room temperature dropped. The heat pump almost kept it steady, so it was obviously having some effect. The 425 watt radiant heater managed to bring it up slightly. By comparing it with the radiant heater result, I conclude that the heat pump with the 75 watt compressor must have been pumping in around 300 to 375 watts of heat. That's a COP of 4 to 5. That's just a prototype with a compressor that works but is probably not very efficient. (It keeps running but won't rise above 25 PSI. I was using 17 PSI to get some flow and still have some pressure. A substantially higher pressure would probably be more ideal.)


   The next evening I tried again with my big compressor, but I only found a thin tube (~1/8 inch ID?) to connect it to the piping. The compressor got hot instead of the piping, and the pipe was substantially warmer than the air it was supposed to be heating so it didn't transfer even that heat to the air very well, and the result was unsatisfactory. The 800 watt compressor seemed to heat the room less than 900 watts worth of radiant heaters. A second experiment connecting straight to the compressor tank with 1/2 inch copper pipe wasn't noticably better. If I hadn't tried the previous experiment, I might have concluded the whole thing didn't really work. But it was pretty obvious that most of the heat was somehow trapped inside the compressor, from which it simply radiated. (Now I think the pressure inside the compressor cylinder was much higher than what I was allowing in the pipe, and so there was far too much flow. I should have run with much higher pressure to match the compressor, with less flow.)

   The next step will be to make a jig for making copper finned radiator pipes, and then to try again with much more radiator pipe and duct.

   What about compressor noise? That will have to be dealt with before the system is commercially acceptable. (I discuss it a bit in the 'detailed report'.) On February 1st I got an 80 watt fridge compressor at the scrapyard. It's quiet enough to use. If I can really get 800 watts or more of heat from it, that will be great! (It should work, but it's still hard to imagine!)


   As a side note, in doing a little further investigation I found where someone suggested on a discussion list that instead of just venting compressed air to the outdoors to decompress it, it could be decompressed through a turbine to generate electricityas it goes! I don't know how worthwhile this would be with a small home system, but it would recover even some of the little energy used to compress the air. Factoring this in would further raise the overall effective COP - could it really hit 100?

Meanwhile in Other News

   On the 10th I noticed that nearly 1/3 of the month was already gone on heat pumping theory and I turned to other projects, starting with trying out the higher temperature nylon printing filament for CAT and HAT electrical sockets. That went well. Mike pointed out that if I 3D printed a few plugs and sockets, they could be mass produced by making a silicone rubber mold and casting them in epoxy. And that epoxy was probably high temperature enough, or perhaps could be with an additive. Now we're talking real, low cost production! Perhaps for battery cases, too?
   What didn't go very well was putting in and connecting the pins. The crimp rings bulged out too far to the sides after crimping the wires to the pins. I widened the recesses a bit to make more room. This was however making the whole socket thicker and wider.


   Later in the month I did a plug. It still didn't go together so easily, so I further adjusted the design for next time. And another adjustment in the cap - a larger hole for the exit for heavier wire. They're getting better. But fatter. The earlier plugs and sockets for soldered-on wires (green, above) are considerably smaller.


   On the 12th I decided that funding rejection or not, I should put together another battery cell with the gold plated copper and the new pure zinc sheets and try it out. This zinc behaved quite differently in hydrochloric acid, which showed what impure crap the old stuff I'd been using was. I had trouble with the cell leaking - again! Sigh! That's disheartening and I set it aside.
   But I planned a new 106 x 106 mm flat battery case. The new Cura slicer would doubtless make cases that wouldn't leak. The pure zinc sheets came in 100x100 and 140x140mm. (4"x4", ~5.5"x5.5") So (counting outer walls) 106x106 should be a good small production size. The zinc sheets would be on the bottom, so if graphite felt was used it could be on top and wouldn't have to bend up much to make a terminal. They should turn out about 7mm (just over 1/4") thick/tall.
    Then I tried a copper oxide electrode in the plus side, then two of nickel manganates again. In all cases conductivity was poor. Under load the voltages were low and it didn't last long. The last one with the powder in graphite felt, wasn't much better than the others. But with it if I put weights on the cell, everything improved, and it improved markedly if I leaned on it. It supplied load for much longer at higher voltages. It seemed the chemistry was fine in each case. It was the mechanical aspect that needed something.

   I looked at some old issues of TE News and found that I had been getting much better results in 2013-2014, probably from torching the positive electrodes before I put them in. That presumably "sintered" many of the particles together so the whole piece (even if it stayed crumbly and fragile when handling) didn't just swell up and everything lose connectivity once it was immersed in the electrolyte. How easy it is to forget things after enough time goes by. If that works I should finally be able to put together real, working batteries now. I suppose if I had stuck solely or at least more heavily to battery development I might have had it all working years ago and not had time to neglect and then forget various details between experiments sometimes months apart. But I hadn't really "connected all the dots" and I confess I got rather discouraged for quite a while.


   Having put the woodstove closed cycle steam engine generator on hold in favor of the heap pump project, I decided to (at long last) try a thermo-electric generator (TEG) on the woodstove idea, little promise tho it seemed to have. I could make four modules with four TEGs each, wire them in series, use a DC to DC voltage boost converter to get a regulated output, and feed that into the solar power system through the 36 volt HAT receptacle near the woodstove.
   But I put one together and found that it was much harder than expected to keep the upper heatsink cool. The TEGs passed a lot of heat through from the stove. And anyway the output seemed pretty dismal - 3 or 4 watts, so it would have been under 20 watts with all four. I was hoping for 50 and I gave up on the idea again.


Bringing a Dead NiMH "D" Cell Back to Life

   I was ready to post this newsletter on the night of February 2nd, but the internet was down, apparently to the whole of northern BC owing to landlides in the Fraser canyon and or high winds and blizzard conditions and or damaged equipment that was hard to replace - for over a week. (Without internet I only hear rumors of what happened! I suppose the landslides will be on Nared King on Youtube!) And everybody just in the last couple of months has canceled their satellite internet accounts since the fiber optic system was hooked up. Satellite internet may be slow and glitchy, but it would be a good backup.
   Okay, someone tells me that the microwave link on a mountain on the mainland was hit by high winds and a blizzard. It broke off the two dish antennas (one was never found) and wrecked the equipment shack. To get internet back, on the 6th one of the two dishes on the island side was taken to the mainland and a half-speed link was restored. It will be months before new dishes are built and installed. It may be a bit slow, but it's better than satellite and at least we're on line again.

  So here is another tidbit, February 3rd: I had been virtually certain that the nickel-metal hydride dry cells lost capacity and finally quit working not due to any fault of the chemistry, but rather because they dried out inside. After all, lots of the flooded NiMH batteries used in the 1997-2001(?) EVs like the GM EV1 and the Toyota RAV4-EV were still working after 20 years and much hard EV use.

   I had previously tried dumping some of the dead "D" cells into a 200 liter barrel of water, but none of them revived. Now I cut the top button off one with the angle grinder. (It was a very dead cell with the plastic label melted off the outside in the Swift fire in 2017.) Under the button was a rubber sealing piece. Under the rubber piece, dead center, was a small hole into the cell. That must be where the water hisses out if there's much pressure in the cell, for example if it was being overcharged, pressing the rubber seal out of the way. Or seemingly it eventually came out anyway.
   I found that if I dripped distilled water onto it, it just sat there on top. But if I put the eyedropper against the hole and squeezed, the water went in. I squirted in 2 or 3 CC, and then hooked it to the power supply at 1.4 volts overnight to charge it. It took a charge and held it!
   It put out half the short circuit current of a good cell I grabbed for comparison, but still over 5 amps. I squirted in another 1/2 a cc. That's all for now. More tests in February to see how 'restored' they can really be.
   If it works I could in theory drill through the center of each cap and use a sharp syringe to poke through the rubber and add a measured optimum amount of water, and restore my NiMH solar power batteries that have so little capacity left in them. (I would want to set the tubes of cells on end so the holes then faced up.)



New Hybrid Ferries being delivered to BC Ferries on a huge semi-submersible cargo ship, the Sun Rise.
It is a bit disappointing after seeing pure electric ferries in service in Europe since 2015.
It is said there isn't any charging infrastructure for them yet where they're to be put
into service, on the Port McNeil-Alert Bay-Sointula (Malcolm Island) run and um... where
was that again... Campbell River to Quadra Island? Anyway it's a step in the right direction.
Hopefully the infrastructure will be upgraded soon so they don't need to run the diesels.





In Passing
(Miscellaneous topics, editorial comments & opinionated rants)

Werner Von Braun and the Apollo Moon Landing Project

   Of course, the idea of going to the moon had always intrigued people, especially after Jules Verne's early science fiction story From the Earth to the Moon well before such a flight was really conceivable. The young Werner Von Braun probably read it.

   I watched a documentary on Von Braun. In judging him morally on his early days in Nazi Germany one must remember he was still pretty young. He and his group were trying to build rockets on the usual sort of shoestring research and development budget, and suddenly (before the war) the government came along and pressed on his group virtually unlimited funds to do so. The alternative was probably to be drafted into the army. Even then his great talents both scientific and for managing other creative workers were definitely manifested. His privately expressing regret that they weren't building a spaceship, and thinking the war wasn't going well, in early 1944, was reported to the authorities, which "defeatism" led his arrest. But he was indispensable and had to be released ("unpalatable though it is" said Hitler) for the V2 rocketry program to continue.
   There was footage of him in early flights of fancy (1948-1955?) even before the Soviet Union had actually launched the first satellite into Earth orbit, showing how space exploration could be done, and I was surprised to see pretty much the same designs I'd seen in magazines when I was young. I hadn't realized they were mostly his conceptions. I was unaware of just how much it was Von Braun that had primed everyone for taking the dream and turning it into an actual program.

   In the actual Apollo project, Von Braun showed what a master manager he was, with thousands of talented people enthusiastically and effectively working under him. In 1977 he died of kidney cancer at my present age, 65. (The vitamin D, Luke! Use the vitamin D!) He never got to fly in space himself, but he and his vision, with Kennedy's presidential backing and vision, did get men to the moon.

   There was a point to this narration: Few will ever have both the inspiration and ability to inspire others plus the scientific/technical and the managerial talent of Von Braun. Visiting the moon might still be a dream without him. Myself I have uncovered and pursued some very exciting technologies, but I haven't managed to inspire anyone with major resources and I haven't had the experience of supervising more than a person or two for single work sessions. But if somehow Turquoise Energy had a real budget to commercialize the various products I've developed or half developed, I think I could hold my own.
   But I think of the Avro Arrow, and I think of the Apollo project, and even Glen Clarke's catamaran ferries, and think that in Canada today, about the most effective way to really pursue a large project that needs some research in the course of product development would be with the prime minister or provincial premier actively on your side, brushing away red tape and doubting naysayers and helping with funds. Or maybe some very wealthy philanthropist. But perhaps that's an exaggeration - getting these things started would be a far smaller project than those, and soon there should be revenues. Elon Musk got SpaceX and Tesla EV companies going without such backing... didn't he?
   What would this need? Tens of millions of dollars, or maybe hundreds if it was to be scaled up fairly rapidly. Not billions. Not thousands of employees. Not to start with.



12 Years of Green Energy Projects in Review

Here is a quick recap of some of the perhaps more significant projects I've undertaken since January 2008. Most of the unfinished/unproven ones would surely be done/proven by now except one person can only do one thing at a time and there are only so many hours in a year.

* Electric Hubcap & Electric Caik 95% efficient BLDC motors for electric transport - these work well (I converted an outboard motor to electric with Electric Caik motor.)
* Motor controllers for above - haven't been very reliable. (Electric Hubcap motor ran great with a Kelly 300A/36V BLDC controller.)
* Switched reluctance motors - I got enthused about these, and made one that ran, but finally I decided BLDC is better - it will surely give the longest range in an EV.
* Concept for unipolar BLDC motors (potentially with permanent magnet assist for ultimate performance) - should be pretty simple to go from the above motors to these since the construction techniques are the same.
* Motor controllers for above would be inherently more reliable. (I made one for the reluctance motor. It worked.)

* Infinitely variable automotive torque converters - after long stumbling about I finally have a complete design of what should be a fabulous unit - now 3/4 built. 100% efficiency (once vehicle is moving at driving speeds all the converter's parts rotate together in unison 1:1 - no friction or losses).

* Ground Effect Vehicle: A rather radical design of ground effect craft with many new features, for riding a cushion of air just over the waves at aircraft speeds with very low fuel consumption. This project expects to make such a craft practical: much more seaworthy than any previous and easy to 'drive'. In personal transport or "sea bus" sizes it would really open up islands and isolated rugged coastlines. - Radio Controlled model almost completed.

* New Chemistry Batteries. Found a lot of good chemical and construction techniques. (I think I can now at long last make working, very long life nickel manganate + zinc cells.)

* Peltier module refrigerator - worked well. Used a lot of power for the amount of cooling. (There are some somewhat improved Peltier modules now available.)
* Magnetic refrigeration - Had a novel concept that probably would have worked well. I started but didn't go very far. Decided other means of refrigeration were better regardless of whether it worked or not. (Air heat pumping may prove more effective.)

* Have worked out the theory for getting "free" electricity from High Energy (HE) rays, which come from all directions but especially from the plane of the Milky Way and seem to be by far the most abundant radiant "background" energy in the electromagnetic spectrum. - Theory has not yet been demonstrated.

* Have (in this very issue!) conceived of and demonstrated open loop air heat pumping for space heating. It works - potential for incredible coefficients of performance and very cheap electric space heating.

* Solar power system components:
   * Made LED lighting before it was available to buy.
   * Made various good plugs, sockets and wall plates for house wiring of DC power systems, 12 volt and 36 volt. These should be commercialized.
   * Various battery/solar power infrastructure components - mostly unbuilt conceptions.

* A fine handheld bandsaw mill for milling lumber (use similarly to alaska mill). It incorporates several features including self correcting band guides to make it simple, easy to use, and low power. (It cuts lumber from smaller logs or cants with just a plug-in skillsaw motor: the least power, thinnest kerf and least sawdust of any mill.) - prototype works great!

   Somehow many of these projects seem ripe or almost ripe to explode into commercial activity to produce fabulous new products that have never been available before. Will it ever happen?



Reversing Desertification

   It has been said that the amount of arable land in the world is actually dropping. More and more turns to desert. People have various ideas on causes and cures.

"Around the planet, you see the same pattern -- People cleared the land to farm, then they raise sheep and/or goats, the grazers eliminate every vestige of vegetation, the soil erodes, and a desert results.  You see this in Scotland, Ireland, Spain, Greece, the fringes of the Sahara, the Loess plateau of China, Australia, ... the list is endless." -- Kevin Byrne (Youtube Video Comment)

===

Restoring the ancient Caledonian Forest Alan Watson Featherstone: TEDxFindhorn

"The most predominant feature in the picture of the planet from space is desertified areas."

https://www.youtube.com/watch?v=nAGHUkby2Is





How Peter Andrews rejuvenates drought-struck land | Australian Story

https://www.youtube.com/watch?v=-4OBcRHX1Bc


   Then Allan Savory has a completely different idea: have herds of grazing animals, but keep them moving so they can't overgraze one spot before moving on.

How to green the world's deserts and reverse climate change | Allan Savory

https://www.youtube.com/watch?v=vpTHi7O66pI


   Of course it is known that the migratory cattle ranchers in the USA of the old west (1800s I suppose?) hated the sheep farmers because while cattle left some grass stubble to grow back, the sheep would eat it to the ground and wreck the land. (I think it was some teacher in grade school who told us that. Probably Mrs. Husby.)



Small Thots

Columnating out-of-line binoculars  Ever had binoculars where the two images didn't line up? I just had a problem with one pair (dropped them) and discovered something new. The objective lenses screw in. If you loosen the threads on one or both and rotate them a bit, the alignment changes. I got two pairs lined up, including a 12x70mm pair that had never been in line.

   In theory this should have no effect, but apparently the lenses are not entirely straight and centered, and it worked for me.

* Gold and silver used to be used as currency. Until 1933 gold was 20 $US/ozt, and there were coins to that effect, even in circulation, until 1933. So a 1 oz gold coin actually said 20 $ on it and could be spent in a store. (Not in a grocery store unless you were stocking up on food for several months.) Now the 20 $US coin costs over 2000 $C to buy, and the 1/4 oz, 5$ coin is now over 500 $C. (One expects that soon they'll be over that in $US too, as the demand for actual physical gold has become unprecedented in the last 2-3 years. There is enough printed money in circulation to buy all the gold in the world hundreds of times over if not thousands.)

* Last month (TE News #139) I was hopeful that lost hair could be restored (as well as further loss prevented) if one could eliminate or greatly curtail the activity of the widespread demodex mites the majority of people have, with the techniques mentioned. But I'm not confident my thin hair areas are getting thicker, that full normal growth has immediately returned. It may well be that these supposedly harmless mites permanently damage the hair follicles, or that they take a very long time to recover after a sufficient infestation. I suppose I'll just be thankful I caught it and found good tools to deal with them before it got any thinner or I became bald.

* I also showered and put shampoo in my hair to be left to soak in for a couple of minutes... and then (my eyes already being closed) I shampooed my eyebrows and eyelashes and let them soak for a bit too. Why give the [choice of expletive] things a free ride and a free lunch?

* I should also note that I read that the older a person is the more likely they are to have the mites, and to have greater concentrations of them. Every 90 year old tested had them. That supports my idea that parts of our immune systems probably weaken as we get older, and explains why more older people have thinning hair or are bald. (I can still hardly believe people don't seem to have connected these common mites with hair loss as being a cause-effect relationship.)

* I expect that some day people will recognize these critters are in fact a problem and sooner or later will deal with them and, rather like lice of past generations, they will plague people no more.

* Where is the heat inside the Earth coming from to activate so many volcanoes, and to make so many earthquakes all at the same time? Could rising ocean temperatures have anything to do with it? Could cutting down the cooling forest canopies have anything to do with it? Could thousands of square miles of dark asphalt road surfaces absorbing sunlight have anything to do with it?
   The Earth's core is so hot compared to the surface, how could dark roads cause volcanoes? But there is a continual outward flow of heat. Hotter ground surfaces will reduce that flow and make it even hotter inside. So could it be that even these seemingly most natural and unfathomable of cataclysms are mainly of our own making?

* Alberta's highways are a much lighter color than most others. They would absorb much less sunlight. How do they do that?



ESD
(Eccentric Silliness Department)

* Why is an "outside the box" solution more innovative than an "out of the box" solution?

* Which drugs are cheaper, over the counter or under the counter?

* Chimneys weep for a chimney sweep. (must be some "woodchuck chuck" line in there somewhere.)

* Daylight Savings Date: US congress has just passed the new "Daylight Savings Date" bill. Canada, as we are a sovereign nation, will follow suit automatically. On the first Sunday in March, from now on the date will be moved ahead one week. Just think, school will get out a week earlier, and there'll be a whole week with more daylight in the fall just when the farmers need it to bring in the crops! On the last Sunday in December dates will revert to normal calendar time (NCT), making an extra week of Christmas holidays. It's a win-win for most everyone. I'm sure. except for calendar makers, future historians, people with the wrong birthdays, the easily confused, ordinary people...




   "in depth reports" for each project are below. I hope they may be useful to anyone who wants to get into a similar project, to glean ideas for how something might be done, as well as things that might have been tried, or just thought of and not tried... and even of how not to do something - why it didn't work or proved impractical. Sometimes they set out inventive thoughts almost as they occur - and are the actual organization and elaboration in writing of those thoughts. They are thus partly a diary and are not extensively proof-read for literary perfection, consistency, completeness and elimination of duplications before publication. I hope they add to the body of wisdom for other researchers and developers to help them find more productive paths and avoid potential pitfalls and dead ends.





Electric Transport
no reports




Other "Green" Electric Equipment Projects


Easier CAT Plugs and Sockets

(10th) I removed the ABS filament from the 3D printer and inserted the 6/66 nylon higher temperature, which should be high enough "temperature resistant" to use for electrical sockets. Then I printed another of the HAT 36V/15A sockets designed last month. Oddly bed temperature is just 60°C where ABS is 100°, but the extrusion temperature was a little higher: 245 where I had been using 230 for ABS. (ABS just slides the bed off below about 95° but the nylon stuck well at 60.)

   Did it need the heat gun on it while printing, like the ABS? I decided to try with the same g-code file, which set the temperature to 230°, and gave it a try. After a few layers, the print shrank and one end pulled away from the bed. Then of course the whole thing came loose. But it didn't seem as bad as ABS. I tried again with the heat gun on it, and got a good socket.

   Then I made small modifications and made a CAT 12V/15A socket. This time I edited the file to read "245" and I tried again without the heat gun. This time it worked - no unsticking, a good socket! If that result proves consistent (next two worked fine too), it will make printing them a heck of a lot easier. It could be told to print, eg, 4 rows x 4 columns, 16 sockets or plugs at a time and just left alone for hours to do it and who cares how long it takes. (It would have to be somewhere safe if left unattended - eg, in a shed away from the house, in case of the worst. Or, a smoke detector might be an alternative idea as long as someone was in the house. Or maybe place the printer well back on the woodstove hearth bricks so that even if it somehow made a fire it couldn't spread. Yes, I think I like that.)

   Next I cut two strips of cupro-nickel and made the "Z-fold" connection sockets. Then I cut pieces of the 6 mm copper pipe with 1 mm walls for crimp rings. One was a bit long for the socket height, so I made the fold shorter on the other one and the ring shorter too. That one fit in.
   If I made the socket longer, the longer one would have fit, but the shorter one would have been sloppy. Obviously some sort of jigs or automated processes are needed to be made to get consistent part sizes for consistent results.

   But using nylon for socket shells instead of having to make them of porcelain was a big improvement. I might say needing to use porcelain would have been almost a show stopper.

(25th) I took a day off from the heat pump. Having good internet again, I downloaded a new version of OpenSCad to replace my ancient 2012 version. It was night and day simpler to create many common 3D shapes. I designed a CAT 12V plug with rounded corners and a taper to the shape, and an opposite taper on the cap.
   For the first time I used the Cura slicer. In spite of selecting "Generic Nylon", just like the "Skeinforge" it picked 200° (PLA) print temperature and I had to edit the file to say 245°. It printed pretty well.


   I shaped some copper for the blades and cut two crimp rings from the 6mm copper pipe with 1 mm thick walls. I wired and crimped them. Things didn't fit readily (even the screws were too tight) and I adjusted some dimensions (yet again) so the next one would be easier.

   Just for the sake of doing something with it I attached a flat "COB" ("Chip on Board") LED light board through a resistor and plugged it into 12 volts so the light came on. Now the light just needs a housing... 3D printed... and a heatsink... NO! Get back! Not another project.





Simple Air Compression Heat Pumping
- or -
How to Heat a Building Almost for Free

Warning: long, convoluted article

(6th) If, as the paper Coefficient of Performance of Stirling Refrigerators had seemed to indicate, Stirling engines could get a coefficient of performance ("COP") for heating or cooling as high as 8 or 10 at a 30°c temperature differential with simple gas expansion and contraction, I wondered what society has overlooked that we are still using ozone depleting, refrigerant phase change gas/liquid that gets (as best I understand) COP under 4 or 5. Certainly house heat pumps are only around 3, and less in freezing weather.

   Even having far more than enough projects, my mind just couldn't let this rest. (Especially in the cold weather!) What coefficient of performance was really possible - and practical, by compressing and expanding air? If a Stirling engine works doing nothing but sort of churning air inside a closed cylinder, what was the ultimate? What COP could simple open loop air compression and expansion give? And how simple could such systems be made? Could they also be far more practical and economical to install than refrigerant based systems? Could they simple enough to be practical for hot water heaters, clothes dryers and maybe even cooking ovens?

   I began to think that if it really worked, such high COP heat pumping could be central to answering energy problems by greatly reducing the demand side of the equation. If one only needs (say) 1/4 as much energy to live just as well as before or better, the need for energy supply is greatly reduced. Not only grid-tied solar panels (supply side) but low energy light emitting diode ("LED") lighting (demand side) has already reduced the loads on many utility power grids. High COP heat pumping would do much more.

   Heating and cooling are the greatest energy consumers in most lives. Dwelling heating and cooling, followed by heating for hot water are the greatest energy uses in a house.
   Consider the effects if 5000 watts of dwelling heat could be pumped in from outdoors using just 500 watts of electricity. I could perhaps heat my whole house electrically with that - the amount of energy now being used in one small electric heater to keep mold out of my travel trailer. Or that trailer with 50 watts. Or heat (or cool) the bedroom with 175 watts instead of 1750. Or run a fridge needing 300 watts of cooling from a 30 watt supply. Or in a hot water tank get perhaps 3000 watts of heating from say 400 watts of electricity.
   These things would make a tremendous difference - a "game changing" difference! And is 10 the ultimate COP attainable? Ground source heat pumping reduces the temperature differential, which would further and substantially increase the COP from whatever was being got from cold air in winter. Suddenly the potential for drastically, and probably easily, reducing the total energy needs of a home - and a whole society - comes into focus.
   The load of a refrigerator and freezer might be thought not very significant, but they run so much over each day that they use enough that it's hard to keep them supplied from solar power, and most every home has at least a fridge.

   And new uses come into view as well. Perhaps it would become practical to heat a greenhouse enough (as well as lit enough with LED lighting) to grow things all winter? Perhaps the separate home workshop can be properly heated to make working in it more comfortable in the winter without incurring major expense?

   A big advantage of an open air system in home heat pumping is obvious: In closed system heat pumps, refrigerant sent to the outdoor unit has been greatly cooled to heat the indoors, and must be reheated back up toward the outdoor temperature before it is recirculated. There is a big heat exchange pipe with radiator fins in it, and a big fan blowing outside air onto it to try to heat it up again. And it is still a bit colder than the outdoor air when it is sent back into the house to again extract heat from, increasing the thermal gradient that the compressor must pump it against. And the cold refrigerant is subject to creating frost on the radiator fins, so it loses efficacy when the weather get down near freezing, let alone when it is even colder. A simple COP 1 "auxiliary" electric heater takes over in the colder weather when heating costs the most - ouch!

   The air expansion system would merely draw in outdoor air at the temperature it is, and blow it out again, colder, somewhere else. There is no outdoor unit needed at all, and it suffers nothing from very cool or below freezing weather. (It gets better - read on!)

(9th) On the 6th and 7th I started writing a bunch of stuff, but I was confused by the unfamiliar subject area abetted by a misleading statement in Wikipedia -- in fact I edited the Wikipedia article.
   A graph indicated that a COP of about 10 at 30° 'lift' (to create a 30° temperature rise or fall) was the theoretical maximum. (Later I found there's a simple formula for maximum COP which the graph was based on. (it's below)) Typical COP might be half of that, 50% efficiency as indicated. I suspect it's likely 8 or above for the Stirling was a theoretical rather than a realistic figure. (Unfortunately, having failed to copy the page or a link to it (Coefficient of Performance of Stirling Refrigerators) I couldn't find it again except at a site that wanted a ransom for permission to read it, so I didn't.)



   What might the simple open loop compressed air system really achieve? Before I got far enough to be disillusioned, I had hit on another aspect: because it was open loop instead of closed cycle, it could be made so that instead of heating outdoor air, the heat pump could further heat indoor air, just a little. Theoretical COP limit for say a 10° lift was 30, and for 15°, 20. At just 7.5° it could hit 40. Now THOSE figures left a lot of room for actually achieving a COP of around 10 - or even higher.

   The more I looked, the more I found that the whole thing was a lot more complex than simple 'ideal gas' laws. Something that especially struck me was "isothermal" versus "adiabatic". In an isothermal demo a piston in a poorly insulated cylinder slowly compresses the gas to higher pressure in a smaller volume. The gas hardly changes temperature (eg, <1°) because the heat gain is lost into the environment. That would demonstrate "the ideal gas law" equation perfectly - and shows why it is misleading. But the gas DID gain heat - it merely wasn't retained! In an adiabatic demo, a piston in a well insulated cylinder (a "fire syringe") is suddenly plunged (hammered) down, compressing the gas so fast and with so little heat loss that the air temperature obtained and retained for a moment can ignite cotton in the cylinder.

[Now back to the 6th, re-edited on 9th to correct for Wikipedia error and other misconceptions...  The reader could probably skip or skim quite a lot of the following without missing much - especially if familiar with the subject.]

(6th) Now, what about trying to make it work? I looked up Boyle's Law which I had heard of and ended up at the ideal gas law:

P * V = n * R * T

where:

P = pressure in Pascals
V = volume in cubic meters
n = is the number of moles of the gas
R = 8.314  Joules/(°K*n)
T = Temperature in degrees Kelvin

There was nothing in that to suggest that when the pressure is doubled, the temperature will double too, because if a cylinder is compressed to double, obviously the amount of gas "n" will also double and the two sides will cancel with temperature "T" remaining the same.

Then there was the combined gas law, which doesn't specify the number of moles but shows relationships:

P * V
------  = k
   T

Where k = an arbitrary constant, and the others are as above. (This was stated in a mistaken or at least misleading form on Wikipedia, saying "'k' is a constant (for a given amount of gas)". [My italics] This caused me to double "k" when I doubled pressure, since there was now twice as much gas. That fit with what the "ideal gas law" said. Then temperature would remain the same no matter how much the gas was compressed or rarified. How then did one change the temperature of a gas by heat pumping? One could change the pressure by changing the temperature, but not the temperature by changing the pressure? It made no sense and caused me further confusion.
   Finally I realized that the temperature simply must double if the pressure is doubled regardless of what the formulas seemed to say, and if the gas is doubled the pressure must double. "k" can NOT describe the amount of gas. (It's not very often I see need to edit Wikipedia, but I removed those words. I also rewrote several equations & text below.)

Solving for "T", replace all values with "1" in arbitrary units.

1(P) * 1(V)
-------------  = 1(T)
   1(k)

If we compress air into a fixed size tank until the pressure is doubled, the temperature is doubled.

2(P) * 1(V)
-------------  = 2(T)
      1(k)

   Of course the gas soon heats the pressure vessel walls and cools, and the pressure vessel walls eventually cool to ambient. Then if we open a valve and let out the extra air, the pressure is halved (back to "1" again) and "k" is halved:
     
      .5(P) * 1(V)
T = --------------  = .5 (half temperature)
          1(k)

 Since the solid pressure vessel quickly absorbs the temperature of the gas and since it is far more massive than the air, the actual temperature rise and fall are only a little. Thus to attain significant heating or cooling the process must be (a) far higher pressures, (b) incrementally repetitive or (c) continuous. Or of course a combination of these.

   Then I thought that compressed gas hissing out through a valve would rapidly cool. It was said that it doesn't. Again this appeared to be misinformation, but the cooling isn't really perceptible because the decompressing air is so quickly dispersed into the surrounding air. But I got a good cooling result from air hissing out through the water drain spigot. Why? I could feel moisture there when I did that test. The water was vaporizing into the thinning, moving air, causing evaporative cooling.


Cooling

   Maybe the project should be separated into its two halves: the compression of the air and the decompression. I could use the air compressor to fill a tank with compressed air, then consider just the cooling half of the cycle, the refrigeration.
   What about taking a compressed air tank and feeding that compressed air through a thin pipe that runs through a fridge? It might hiss through a narrow valve into the pipe (both inside the fridge), and then the coldness would radiate through the pipe walls.
   For using air compression and decompression, which as seen in the Stirling heat pumping figures can give a very high COP, would completely decompressing the compressed air within the fridge not give the ultimate cooling COP? The expanding air should continuously cool the pipe with the utmost efficacy possible from compressed air, however efficiently or inefficiently it was compressed, right? Proving (or disproving) that should be an easy experiment!

   Then the overall COP would be directly proportional to the efficiency with which the compressor compressed the air. And with "ultimate" COP on the cooling side, if a Stirling engine could manage a COP of 8 or 10, it should be possible to attain an even higher COP. Is there anything wrong with this picture?

   That reminded me of the Tata Motors compressed air vans: they have free air conditioning from the cooling of the expanding air coming out of the engine cylinders. Great thing for hot climes, I'm sure! Of course, they are unconcerned with the COP because the main purpose of the compressed air is to move the vehicle. (It was well over 100 Km range from a carbon fiber compressed air tank under the van (that would rip, not explode); I don't remember - Was it even 200 or 300 Km? Wow!)

   If the "hissing valve" released depressurized cold air into the pipe, a length of pipe could radiate that coldness into the fridge. I looked for and found three 1/2 inch copper pipes with aluminum fins that I made some years back in connection with peltier modules and low pressure boiling water heat transfer. (I was amazed I found them all quickly and easily in the first 3 different places I looked - they had been carelessly tossed here and there when I moved.)
   I also had a 120(?) liter brass water tank. (Had it for almost 40 years, originally intending to make a solar hot water system that would last.) Surely it would take at least 60 pounds of pressure. Refrigeration shouldn't need 1/2 that much, and such a large tank would probably run a fridge for many hours before refilling it.

Let's see, how much pressure would it take?: If we want (eg) 40°c cooling for a freezer (from +20 to -20 or in real scale terms from 293° to 253°K) we have to have at least that much gas expansion, so we have to compress it that much.

293 / 253 = "x" PSI / 14.7 PSI

or

x = (293/253) * 14.7 = 17.0 PSI

So we need at least 2.3 PSI (above regular atmospheric pressure) to get 40° cooling.

   Gosh, that seems like nothing! It doesn't take much to compress air that much. Of course it'll need to be considerably higher than that (or an awful lot of actual air) to cool a real freezer with finite insulation, but the potential for very high COP seems to be there.

(7th) Can everyone really have missed something this simple that sounds this good for this long? I can't believe I'm the first to come up with it. One thing I could potentially believe is it just isn't as good in real life as it sounds before calculating or testing it out - but not without trying it out! Another is that someone invented it and patented it long ago, and a company making 'conventional' refrigerators bought the patent and threw it in a drawer, just like the car companies have always done with better car inventions. Since someone held the patent, no one was able to build them and eventually the whole technology was forgotten. Western civilization is replete with examples of this practice.

   I didn't see how to easily calculate exactly what to expect in advance, but checking it out just looked easier and easier...

   I could connect the three 1/2 inch copper radiator pipes together in series and to a valve, and mount the assembly to the underside of the lid of the shallow chest fridge, with an inlet and an outlet to the outside air.

   Then I could just connect the air compressor to the fridge inlet pipe, and set its output to (say) 10 PSI.

   Initial testing would be a matter of cracking open the valve until air was hissing through it and seeing how fast the fridge got cold and what temperature it got down to, and connecting a power monitor to see how much power the air compressor used.
   To get the roughest of ideas:
1. My fridge-freezer is around 150 watts and runs 60%(?) of the time. Call that 2.16 KWH/day. (Well, less in winter when the kitchen is cold.) I should monitor that and record it, too.
2. My shallow chest fridge is maybe 1/3 the size and has no freezer. Energy parity then might be around .5 KWH/day. If over some days it used substantially less than that, it would doubtless be owing to a higher COP. If it was around parity, it might be compressor inefficiency compensated for by higher COP, or it might be just similar COP.

   It all depends how far open the valve has to be cracked to get the requisite cooling to keep the small fridge cold. That air flow will determine how often the compressor has to come on. And that will determine how much energy is used. An important point is that the compressor runs until it hits 120 PSI or so. If it only hit (eg) 20 and shut off, it might run more efficiently and use a lot less energy, even while running much more often to supply the same amount of air overall. Air compressors are probably not designed to maximize efficiency in the first place. People are simply happy if they work. (Perhaps at some point I could try opening the control box and adjusting it to have it shut off at a much lower pressure?)

   If it proves worthwhile, the next step would be thermostatic control. This could be on-off, or analog with an air valve that can be minutely adjusted to pass more or less air, depending on the temperature and heat loading. Then one has a real fridge or freezer. (In the 1980s doing computerized controls for Victoria schools I had an electrically activated variable pneumatic valve. Where did I get it? Accutemp? Are they still available?)
   There would be a second advantage to such a fridge: The compressor could be somewhere else besides in or at the fridge, connected by a single pipe. It could be in the basement underneath. And it would only run occasionally. Kitchens - and many cafes - could be quiet places again!

   By evening of the 7th I had convinced myself that this project was more worth pursuing than the woodstove electricity generator. Furthermore, the first experiments with the fridge were so simple to set up (given that I had an air compressor and most of the parts) it seemed foolish not to do so.

Heat Pump Heating

   But what about the heating side of the equation? Soon this replaced cooling in my thoughts because a fantastic potential came into view. Logic said that if a Stirling engine could manage COP up to 10, that unless the compressor was very inefficient, the heat being put into the air tank - the thermal energy of the air going into the tank - must be much greater than the amount of electricity it took to pump it in. In the tank was the thermal energy to heat a house, if radiated out through pipes and probably with a fan. Once the heat radiates out along the air pipe, it is routed outside the house and decompressed at a spigot to cool the great outdoors. More air has to be compressed from the inlet side to keep pressure in the pipe and pumping in thermal energy from outdoors. Once again the pressure doesn't have to be very high to gain a 30, 40 or 50 degree differential from the outside air to the radiator pipe.

   I had no idea how efficient or inefficient my compressor was. It was 99 $ at Rona with a plethora of attachments. It's a light duty unit intended to be used once in a while to blow off dust or pump up a car tire. Okay for limited testing, but not much more.
   For house heating one would want a unit designed for continuous service in a building, and optimized for efficiency. and as quiet as they come. And it needs to move air volume, but not with a high pressure buildup. But! such units are doubtless already available. I started off thinking that if it became a project, I would have to build some pumping unit from scratch, but (excluding controls) really there are only three components: compressor, radiaators and decompressor valve. Only the compressor is complex and uses power. Unlike with most new inventions, I wouldn't need to build/create any major component, to create a new type of high COP open air home heat pump system! This makes it an incredibly tempting project for someone much too busy to start yet another new project.

Some Simple Tests

(8th) I brought the air compressor into the livingroom. (At -2°c outside that was the only place warm enough to work in - and by no means warm as the stove had gone out in the early AM, and once out it is hard to get a good fire going in it again.) I plugged it in and turned it on. I connected the hose with the dust blower attachment. I stuck a plastic tube over the blower end and inserted a thermocouple into the tube. It was about 15°. I pressed the lever lightly and air started hissing out into the tube. But instead of dropping the temperature rose to 18°.
   This was a puzzle. Why didn't it drop? How warm was the air in the tank in the compressor? I had brought it in from the unheated workshop and it was about freezing outside. I cursed that there was a plastic enclosure over the whole compressor. (I liked it until now!) I unscrewed some screws and took the top off. The thermistor said the tank was about 18°.

   So on the compression side of the equation, filling the tank with compressed air had probably raised it from around 0 degrees to 18? That seemed like a lot. How long had the compressor run - a minute? But then, the livingroom air was 15° and most of the actual air it was filled with came from indoors. So more like 14(?) to 18. Subsequent releases and refillings with air showed that it rose almost 1° with each 15 second refilling burst. After a few tests it was up to 23. It used about 780 watts whenever it was running: .004167 hours * 780 W = 3.25 watt-hours to raise the tank almost a degree. (I was surprised the compressor used so much power. That's half of what's allowed in a regular 120 V plug-in for what I thought of as a pretty minimal compressor.)

   Next I tried tipping the compressor sideways and I stuck the thermocouple in the hole in the water drain spigot. I turned that on and the temperature dropped with the hissing air, this time as expected. Depending on how far it was opened and how fast the air was hissing out, it dropped down as low as 4°c. And this of course also cooled the brass spigot as well, probably to about the air temperature, which would also cool the tank wall in the area. When the tank was empty (or at least lower pressure) I checked it and found the tank itself had dropped a few degrees with the decreasing air pressure. (At least, in the area near the spigot - I had closed the case again and that was the only accessible surface of the tank.)

   3.25 watt-hours is about the amount of heat from running a 20 watt soldering iron inside it for 9.75 minutes. Would that do it, or were we getting a COP of over 1?
   Now I cursed that the thermocouple temperature reading was unit degrees only. Still, if I put the soldering iron in for 30 minutes, it should be 3°. And the wires pulling on the compressor's flimsy push-button power switch broke it, in preference to pulling the slip-on connectors off the switch. I tried to fix it, but now it only worked while I held it on.
   I found a 25 watt iron that the hot end fit in the hole. In about 8-9 minutes it raised the air temperature in the tank by about 5°. (It said 6 near the upper side and 4 near the lower. So how much had the tank walls heated?) I certainly hadn't proved anything good there! But the conditions of the tests and measurements, and the seemingly low efficiency of the compressor, were such that I thought I hadn't disproved much, either. (From store product pages it seemed compressors of no more than twice the power probably moved as much as ten times as much air. Again just a guess since I don't have the specs for my own.)

   Then I took off the spigot and connected the air hose to its hole in the tank, as the threads were the same. Then I tried again to have the air hiss out through the dust blower, this time direct from the tank, and blowing into a copper pipe. But once again the temperature seemed about the same as the tank. With the thermocouple stuck right into the dust blower opening and no pipe, the temperature dropped only slightly. Either the dust blower or the long hose was causing some sort of trouble, while the drain spigot worked great. I couldn't try the spigot with the hose or the blower without it owing ending up with M to M or F to F threaded holes. I did try the spigot on a different short hose. Again the temperature didn't change much. It dropped a few degrees if I opened it wide enough, but nothing like when connected straight onto the tank. This still seemed like a puzzle to me.
   I put the spigot back on the bottom of the tank and tried again. Good temperature drop. The more the airflow, the more the drop as before but I didn't get it below 9°. I held a 3/8" copper pipe against it and put the thermocouple inside the pipe. I didn't see such large temperature drops (12°), but the air blowing out the end was cold.

   I decided that was about all I could do without connecting up the radiator pipes. That meant buying fittings and I still had a bad cold. But I got on line and looked for a better air compressor. It seemed that in addition to noisy piston compressors there were rotary screw, scroll and centrifugal compressors. But they were all big and costly. Piston was the only realistic option.
   Little compressors such as mine are under .5 cubic feet per minute (CFM) capacity. I ordered a bigger one at KMS Tools, a 1.5 HP Makita (it claimed 2 HP but the voltage and current figures said that was a lie) and 4.1 CFM capacity at 90 PSI. It was also 79 dB of noise and 77 pounds shipping - too big for the post office. Second best seemed to be a cheaper one from Princess Auto, but it used a little more power and added 5 dB to get about the same airflow. The idea here was to use the least power to get highest COP, whatever it would be.

   I also came up with the idea to have the air intake inside the house instead of outside. Then the unit would be adding heat to the indoor temperature instead of the outdoor. That would surely make for highest COP! But the cooling (decompressing) air would vent to the outside. The trick then would be to use a heat exchanger so that as the house sucked in air, that air would automatically be warmed to indoor temperature. Unfortunately there seems to be a flaw in there: If the expanding/cooling air is venting to the outside, the house will be sucking in through the heat exchanger but not blowing out. That won't work. I must think about that one!

(9th) Okay, I have it! The air in the pipes is warmer as long as it is compressed, but it is losing heat as it radiates it into the house until it is house temperature. Instead of discharging the compressed air outside somewhere else away from the intake, the compressed air pipes would extend through, would be, the cooling side of the heat exchanger. Only after they exit that would the air be allowed to decompress and cool from gas expansion. This will of course require some quite different type of heat exchanger from the usual diagonal coroplast sheets, since those can't be expected to hold compressed air (or even be made not to leak it out).
   But once we have that configured, there is tremendous potential for ultimate COP. The air to the compressor is warmed coming through the heat exchanger almost to indoor temperature. Thus it is compressing room temperature air to an even warmer level, not outdoor temperature air. This means it doesn't have to pump across much "lift", much temperature rise. If the radiators were 40°c and the house 23°, it's only 17°, regardless of the outdoor temperature. And that would be for passive pipe radiators. With forced air the radiators might be 35° (or less) and so the difference would be just 12.
when the air has gone through the radiators to the exit, it should be almost down to room temperature. From there it goes through the exit side of the heat exchanger, losing heat presumably almost to outdoor temperature as it heats the incoming air from outdoor to almost house temperature. Only then is it decompressed, hissing out a valve, and discharged pointing away from the air intake. Thus owing to having the open air system instead of a closed loop we can gain the following benefits (here we will ignore incidental losses, the "almosts" and "nearlys"):

* The air is heated from outdoor to indoor temperature as it enters the house through the heat exchanger.
* The compressor compresses and heats this room temperature air instead of cold outdoor air,
     giving it a very low lift with very high COP. Colder weather increases heating load, but it doesn't affect the COP.
* The flowing air heat radiator pipes inside the house (with or without forced air blowing over them) are nothing special:
     they impart the heat of the compressed air into the dwelling.
* The spent heating air in the radiator pipes, now only at house temperature, goes through the heat exchanger,
     warming the air to the compressor from outdoor to indoor temperature and itself cooling to outdoor temperature.
* This cold air is then exhausted through an appropriate size slit/valve exit, aimed away from the intake.
     Up to this exit point, all the air piping is at the pressure of the compressed air tank.
* The compressor doesn't have to be directly connected to the incoming heat exchanger air:
     The air being 'consumed' by the compressor and then going out will create a vacuum that will cause fresh
     air to come in through the heat exchanger. Thus instead of having a stuffy house to keep the cold out,
     ample free ventilation with fresh outdoor air, preheated to room temperature, is obtained.
* The machine heat from inefficiencies in the compressor is added to the indoor temperature too.

   As I see it, the chief downside - and it's a big one - is having a noisy air compressor running somewhere in the house. (That's why I was investigating quieter other-than-piston compressor types.) If noise can be kept from being a show stopper, this project and its potential to heat buildings almost for free just looks more and more exciting!
   For cooling a building, one would want reverse the heat exchanger and have the compressor outside - a much more appealing configuration but not of much use where I live.

-----

On the 9th I also finally found the actual theoretical parameter of heat pumping, the formula for "ideal COP":
                       Thot
Cop[ideal] = ----------  (temperatures T-hot and T-cold of course must be in °K)
                    Thot - Tcold

So for say a 30 degree 'lift' from 270°K (-3°C) to 300°K (27°C), we would get:

300
---- = 10
 30

Sure enough, just what the graph indicated!

And then if we can reduce that by heating indoor temperature air by just 10° from (eg) 290 to 300, we get:

300
---- = 30
 10

Even at 40% efficiency that's actual COP=12 - huge! That's 82 watts electricity to get 1000 watts of heat!

(11th) And if with sufficient radiator pipes and fans we got the differential down to 5°, ideal COP would be 60 and 'actual' target of about 25: 40 watts to make 1000 watts of heat.
   Since air compressors themselves are more like 1500 watts than 25, one gets the idea they won't have to run a high percentage of the time to keep the radiators filled with moving compressed air, and the house warm.


   One may ask, "But where does the inevitable cooling occur that goes along with the heating in heat pump systems?"

   Here again is where the open loop system is so different from the usual closed loop. When air is compressed into the air compressor tank, it is taken from the house. Rarifying the house air would cause cooling. What will actually happen is that air will leak or flow into the house to prevent any notable vacuum from developing. And the amount of air taken from Earth's atmosphere is to say the least negligible. Therefore the cooling of bringing in the air to compress is negligible.
   Of course if one is heating the house because it's cold out, the air coming into the house would be cold air. That's where the heat exchanger comes into play. Over a sufficient length of dual entry-exit duct, the temperature if the incoming air is gradually raised to near room temperature by conduction with that going out, while the exhausting air is gradually lowered to near outdoor temperatures by the air going the opposite direction in the contacting pipe.
   For a bit I thought I here was an 'invention' where I wouldn't have to make anything special. But the outgoing air from the radiator pipes must be kept compressed until it is through the heat exchanger, so radiator pipes with fins inside an outer duct must replace the usual 32 diagonally alternately arranged one foot by one foot squares of coroplast. Since the compressor will be drawing the air into the house, and then the compressed air will be released outside after passing through it, it can be a simple passive unit.
   If the compressor can move 4 cubic feet of air per minute, what does the capacity of the heat exchanger need to be? I don't know, but I have a feeling it'll be pretty large.

   Still, the whole thing seems so simple as to be worthwhile trying out for the rest of this winter, this heating season. My next electricity bill is looking like 250$. Even with the woodstove the majority is for heat - the trailer to prevent mold (85$ for 2 months), and the bedroom at at night (similar?). A few more finned radiator pipes and the heat exchanger, and the air compressor I'm ordering, should be mostly all I need. That and an immensely sound insulating box. (Now I need some thin aluminum sheet, perhaps #20-24 gauge, to make more pipe radiator fins. I don't have it, and I don't know where to buy it on this island. Mail order from ??? To heat from a low temperature will take a lot of radiator pipe. Or, surely someone somewhere sells finned radiator pipe?)

(12th) I looked it up on line, and I became convinced that making my own was not a good way to go. There were machines winding spiral fins onto pipes that had several fins per inch instead of just two, and they probably made better contact with the pipe. And there were heat exchanger assemblies of pipes that might be just about what I needed, too. But I had a hunch that such things would be costly, as well as not available locally. Then it occurred to me that I might try the refuse transfer station and or the landfill. Perhaps someone might have thrown away some suitable pipes or heat exchangers that hadn't been mashed up yet? It was worth trying.

   On the 13th I visited Mike, and noticed a piece of dryer duct hose on the floor of his shop. Hmm... I went to the hardware store and found some with an aluminized skin. I bought a piece. My finned tubes just fit inside. That was it: indoor heat exchanger! The pressurized warm air would be in the finned pipes, and air would blow through this outer duct. That would pick up the heat best in the least amount of finned pipe and blow it out to the house.

   Then I decided I probably couldn't afford the nice finned pipes I really wanted, and (not expecting to find much at the dump) I asked one company if they could supply me with 2000 square aluminum fins made to push onto regular copper plumbing pipes that I already had. I got no reply and on the 15th I asked a neighbour if he knew where I might get sheet aluminum. He said there was nowhere on the island, but another neighbour often ordered it from a place in Prince Rupert. I phoned that one and got a name and phone number. I asked for two 4 foot by 8 foot sheets. That could make 1600 fins. Then I called back and said "pure aluminum if you can get it." Pure aluminum is a substantially better conductor of heat and electricity than any alloy. I found a site that said it was "238" where most alloys were "160" or less, tho a couple were "190". (Pure aluminum is 4th best; gold is better, copper is 2nd best, and silver is a few percent better than copper, which was "420". I didn't note what the units were. Although it would be ideal, I'm not buying silver - or even copper for that matter - just for fins!) I got no return call from the store, either.

Copper Pipe, Soldered Copper Fins

(19th) I changed my mind. I already had lots of copper pipes, both scrapyard and new from a plumbing wholesaler. Not only is it better heat transfer through the metal, but pieces of copper can be soldered to the outside of copper pipes - a better thermal connection than friction-fit aluminum fins. For no evident reason I just felt a powerful urge to buy all this copper pipe about 5 years ago and I spent some time collecting it. Now I realized it'd be the best for this project, and I wouldn't be able to buy them at a reasonable price on this island. What luck that I had them! "All things work together for the progress of men and angels" - the Urantia Book

   So I decided to cut up scrap pipes to make solder-on fins for new pipes. Perhaps I would run them through the jewelers rolling mill and stretch them longer and thinner? They'd go farther that way. I was also wondering about airflow. If the pipes were inside dryer duct and the fins were crossways like my aluminum fins, would air flowing along the pipe really get in there? But if they were longitudinal, would the air again flow alongside with much less heat transfer? I decided I would solder them on diagonally. That should optimally capture air passing by making maximum turbulence, without blocking the flow.
   The better the heat transfer, the shorter the pipes and ducts could be. or the higher the COP.

   I first slit a piece of pipe and then cut it off with a hacksaw. It was about 1-3/4" square. That was slow. I found the only practical way to cut off the pipe pieces was with the angle grinder, and I also used it to slit them. But after a while I found I could slit them with tinsnips. Next I cut some only ~3/4" long (x ~1-3/4"). I could 'unroll' these with two pairs of pliers instead of prying them open with successively larger wedges. Then I decided 1-3/4" long was too long anyway and started cutting them in half, ending up with varying sizes really averaging around 5/8" x 7/8". I realized the copper was tempered, so to roll it thinner I'd have to heat it red hot and let it cool. I didn't bother. They seemed like a good thickness anyway.
   I was worried about trying to solder them to the pipe. If I used a torch it would melt solder out to the ones already done and they would fall off. The soldering iron couldn't heat that much copper. I but I ended up turning it up to 750°(F - from 550°) and using it. At that temperature it could quickly melt solder in the immediate area of the join without the heat spreading too far and before it itself cooled below soldering temperature. (It didn't always bond well. I had to wait sometimes for the iron to heat back up between tries. Luckily the temperature is shown on its display.)

   Between that technique and soldering flat edges onto round pipe, the joins weren't the strongest, but they would transfer heat to the fins. At first I put them sticking straight out. Then I got more creative and started trying various angles, which put more fin surface in contact with the solder and pipe, while still trying to have them diagonal to the air flow.
   After working at it quite a while, I had 15" of "stegosaurus pipe" and another 30 fins to stick on. How much pipe did I need? Maybe 10 meters? (20th) In a short morning session I had put on the rest of these fins and extended it to 24". Just 8% done! And I had got pretty good at it, so barring finding some way to speed it up or automate it, it was going to be tedious.



   The slowest parts were cleaning off the copper (with a wire brush on the grinder and stationary belt sander) and soldering them on. I could speed up the cleaning by using only the 'new' pipes. I probably had enough. It seemed like a waste cutting them up into bits when I had the old ones, but I wanted to get on with it. (Of course, having flat copper sheet metal to start with, cleaning it as one piece and then cutting it up with a sheet metal shear would be far simpler.)
   I didn't see how to speed up the soldering. Perhaps some pencil flame to melt the solder rapidly, with a jig to hold the pipe and fin(s) aligned? Was that worth doing for one heater? 25 feet of stegosaurus pipe... hmm! Well, I had 5 feet of the old aluminum finned pipe, too. Should I use that? Then "only" 20 feet - 18 more - to cut and solder up.

   Let's see... a jig. Say 3 feet long. It would hold each end of the pipe in place. A thing with a diagonal slot in it every two inches would be directly above along the whole length. The fins would slip through the slots and sit vertical on top of the pipe even without solder or if the solder was melted. Then one could run a propane torch and solder along the pipe from one end to the other and solder the 3 feet of fins on in one operation. Then the pipe could be rotated 90° and the process repeated for all four 'quadrants'. (Uh-oh! How do we prevent the side and bottom fins from coming un-soldered? Aha! Fill the pipe half full of water and plug the ends! Then the solder can only melt on the top of the pipe. Or set the pipe in a tray of water half way up the sides - that would wet the bottom and side fins, too.)
   If one could figure out how to make the diagonal slots, perhaps in a piece of wood - or aluminum - that would sure speed up the soldering. Perhaps it would have to be made in two pieces with one edge of each shaped so that when put together they would form the slots.

A Test

   Since I had the little vacuum-pressure pump (75 watts), and a few finned radiators, I realized I could run a test if I just found a few pipe fittings (new and old) and a pressure gauge (kicking around for years - I'd never used it before. What luck I still had it!) and did some soldering to get things to fit together. I mounted the pump on a piece of plywood. (I also cut some more pieces to make it into a box.) With a compression fitting I attached the stegosaur pipe to its air outlet, pointing straight up. On the top end of that I put a 90° elbow with a 1/2 inch "National Pipe Thread" (NPT) female threaded output, to which various things could be easily attached and removed.
   First I tried a garden hose faucet. It leaked through the handle when it was opened and the pressure gauge (it had a garden hose fitting) didn't read. I took the garden hose piece off the pressure gauge, which left it with its original 1/4 inch NPT. Using two fittings and a pipe between I made up an adapter to fit the gauge onto the 1/2" NPT threads.
   So I had the compressor, the finned pipe sticking up, and a gauge on the top end. To allow air to flow, I had to partly unscrew the gauge. (That would have worked better if it didn't start rattling and turning by itself with the compressor vibration, but it sufficed.) I taped a temperature sensor to the pipe just above the compressor. (I wished I had a better one - this one was a big blob that only changed its reading very slowly.)
   But when I noticed it, I wasn't impressed with the tiny holes in the outlet pipe opening of the pump. It seemed to me that with air flowing, pressure might drop significantly between the piston/cylinder and the pipe owing to the resistance. It might not be a very good pump for this purpose.

   At the start the temperature was 18.7°. With the gauge tightened the pressure went up to about 25 PSI. Having no shutoff the pump kept pumping but the pressure didn't go up further. I loosened the gauge off to allow air to flow. The temperature gradually started to rise. I didn't think to time it because I wasn't sure what to expect. In maybe 15 minutes it climbed to 29.0° and then pretty much stayed there. It seemed to climb fastest with lower pressures and higher air flows. But the heat didn't extend very far up the pipe. The upper end felt cool throughout. (I really needed 3 or 4 temperature sensors.) I couldn't tell whether the temperature rise was owing to the heat pumping effect, or was just heat from the motor and pump itself. presumably much of the 75 watts was turning the motor and pump rather than making heat, and the air was moving through, so the temperature rise might indicate that there was more heat entering the pipe than just from electrical and mechanical inefficiencies in the pump. But it was disappointing that only the lower section, perhaps the bottom 10 inches, of the pipe warmed up noticeably above room temperature.


More Compressed Air Piping and Test 2

   Of course since the air was venting and decompressing indoors, there would have been no net heat pumping. For that it would have to vent outdoors. I decided to try that. I put together some more fittings and did some more soldering, and added a horizontal pipe with aluminum fins, one of my old ones. I put that out a window (opened it 2mm) and put the pressure meter on the end, outside the window. Again it seemed to work best at around 10 PSI, as best I could tell, which wasn't very well. I could hear air hissing through, especially where the bend was.
   After 1/2 an hour I took temperature readings, one at a time. It was painfully slow because the temperature sensor took a painfully long time to move and settle in. It was the only one I had that would give .1° increments instead of just clunky unit °C readings. I worked from the top to the bottom of the stegosaur tube. By then headed for 1/2 an hour had gone by. Then I did it again (right column) and got slightly different results. I couldn't measure the air temperature itself. These were the temperatures of the outside of the pipe or a fin right next to the pipe, in degrees C:

17.2     16.6   Room temperature (Kitchen was cooler than livingroom)


18.2     20.0      At top of fins
19.3                 2/3 up toward top of fins
            20.9     1/2 up fins
21.6                 1/3 of the way up the fins
            23.2     1/4 of the way up
24.5                 Near bottom fins
27.0                 Very bottom fins
34.6                 Fitting on pump.

Conclusions 2:

* First, it didn't seem like a lot of heat. 75 watts is expected to pump 750+ watts of heat. This didn't feel like anything like that much heat. More like 75 watts.

* From the bottom two measurements, the heat conduction from the pump into the pipe must be poor. Perhaps there is an immediate pressure drop from the cylinder to the output of the pump. I suspect there's a very severe drop in efficiency at this point. (Probable, and from the tiny openings in the pump output.)

* From 16.6° (room) to 34.6° (pump) is 18°. If it counts, that is about double the "lift" we are hoping for, much reducing the potential COP. And I didn't measure the body of the pump itself - it might be even worse. (Is the teflon tape on the pump-to-pipe-fitting join a thermal barrier?)

* Most of the apparent warmth was radiated off in the bottom section of the pipe, notwithstanding the significant air flow through the pipe and the weaker passive radiation. There wasn't much heat to be felt toward the top of the fins - but they were still warmer than the room.


   If I was going to continue (with this apparently low efficiency pump), the next thing to try would be to box the unit up and add the outer heat exchanger tube around the radiator pipe with a fan to forcibly blow the heat out from the compressor and the pipe. That might improve the overall performance.


(24th) Outer Ducting and Test 3:

I made and assembled the rest of the box. I found a fan labelled "48 volts" and mounted it on one end blowing into the box. I made a long cable to plug it into a 36 volt HAT socket. It blew plenty of air and made lots of noise at that voltage. The solar meter said it was using 3.3 watts. (Half audio output, I'm sure - but almost nothing compared to the compressor.) The "stegosaur" finned pipe now fit inside the dryer hose, and the air from the fan ended up blowing air out the top hole of the dryer hose. Thus there was forced air blowing around the pump and along the finned pipe. I couldn't attach the temperature sensor to the inside pipe, so I just lowered it down the dryer hose. I turned it on and let it run a while to stabilize.

The air pressure was about 14 PSI. I got these temperature readings:

Room near floor where the air was being drawn in from: 17.1°.

Inside tube near bottom, just above the box: 20.1°.

Inside tube a few inches below the top opening: 19.6°.

The room air temperature at the height of the output of the unit was about 18.3.

On opening the box I and feeling the pump and the bottom of the pipe, I had the impression they were a little cooler than in test 2. However, I had removed the fan to reach in, and that fact armd them up, so this proved difficult to measure.

---

   Instead of shutting it off I reduced the air pressure in the pipe to 8 PSI and took some more measurements.

Air entering at fan (at floor level): 16.2°

Air at top of duct below exit: 18.8°

Top of box just below bottom of duct: 19.6°

I finally unplugged the compressor but left the fan running. I thought the temperature at the bottom of the duct would drop quickly, but it took a couple of minutes to register even .1° down. Then it started falling, but I was surprised it took several minutes. The pump motor body must have stored substantial heat. When it was down to 18.0 I unplugged the fan. After that the temperature went up and after a few more minutes passed 20° - the warmth of the motor was no longer being blown out the top of the box.

Conclusions 3:

* The unit was blowing a considerable amount of air out the hose at 2.5-2.6° warmer than it was going in by the floor, and 1.3° warmer than the room air around the exit. On the face of it, this seems promising.

* So it had to be heating, and I'm guessing the performance was substantially better than test 2 and more than just the 75 watts of the pump. Unfortunately the way I had put the box et al together, I couldn't measure the temperature of the pump body or the actual copper tube temperature. One expects that with the air blowing by them, they would be kept cooler than they were in test 2.

* With the pump sucking in room air and blowing its exhaust through the pipe out the window, cold air was being pulled in through the window to replace it, largely preventing the room from warming up. (In fact it was probably drawing in far more than the pump was using. It was definitely a considerable cold draft.)

* After couple of hours my ears were ringing and I finally put on hearing protectors. With this little pump. Compressor noise will definitely be an issue.

   It would seem that to actually heat the room with this "low grade" warmth, one would need to make the building to outdoors heat exchanger that uses the warm air going out to heat the cool air coming in. As usual with modern equipment, it only works if all the parts are working.


(25th) Building-to-Outdoor Heat Exchanger and Tests #4:

  With the indoor heat exchanger the objective is to disperse the heat of the compressed air into the room a well as possible with the equipment and piping rising in temperature as little as possible. With the building to outdoor heat exchanger, once the outdoor air has entered, it is to be heated more and more as it flows through the duct until it is almost at room temperature as it enters the room. In doing so it has taken all the heat from the air going out and reduced it, by the time it exits to the outside, almost to outdoor temperature. Thus the outside of the outdoor duct is insulated to hold the increasing temperature instead of being thin, heat transferring aluminum like the dryer air hose.
   Again, on the other side, the air from indoors having transferred its heat until it is almost outdoor temperature, is allowed to decompress and vent (away from the intake of course), finally cooling below outdoor temperature as it is released. The heat pumped indoors does in the last analysis come from equally cooling the outdoors. (Then of course the heat leaks out of the house like always and equally heats the outdoors back up again, so there is equilibrium except for the electricity used.)

(26th) I put a few more fins on the second pipe and soldered fittings on the ends. I made one of them a "pipe union" fitting so I wouldn't have to turn the pipe - and the whole output heat exchanger box - in order to connect it.
   And I made the output heat exchanger outer duct and insulated box. In order to have it stand up yet without being at an exact height I put a couple of legs in the middle. I stood it up at the window and connected it to the compressor/indoor section -- and the "star wars cannon" was ready to fire!


   At around 15:30 PM the room temperature started about 17.5° (using a different, glass thermometer) and outdoors it was around 6°. I closed the doors so ithe kitchen/diningroom space wasn't being heated from the woodstove in the livingroom. I plugged in the compressor and the fan. The valve I used on the output turned out to be tricky to set and there was only about 3-4 PSI. That meant maximum air through the pipes, but at very low pressure. The air being drawn in at the floor was about 16.3°. After a while the air coming out the top was about 19.0°. I checked at the bottom again and it was 16.5. Back at the top, 19.1. By this time it was 18:00.
   The air wafting in through the outdoor heat exchanger (what little there was to feel) felt slightly cool; nothing like 6°. The room temperature (except at the floor) hadn't changed.

   I decided to try more pressure but it wouldn't go up much. The output valve was leaking. It took quite a while to find the problem and deal with it (outside, standing on a chair). I had wanted to replace the leaky valve, but every other one had some other problem and I finally just used lots of teflon tape instead of a little, tightened hard, and by 7 PM I had it on again, no leak. I set the pressure to 17 PSI. With all the going in and out and the door open, the room was down to ~16.8°. The fan intake at the floor was 15.6°. Soon the air was coming out at 18.5°.
   If that was heating beyond the 75 watt draw of the pump, it certainly was "low grade energy", just a couple of degrees above the room - but definitely there was some airflow at that temperature. How much heat was needed to raise the temperature? There was already about 200 watts of LED lights on in the LED indoor garden in the corner. To see a noticeable effect then and warm the room perceptibly might take an equivalent 400 watts or more. If it really was COP 10 it'd be putting out 750 watts worth. But I wasn't expecting this was a very efficient little pump. What if it was only pumping 25 watts worth of compressed air?
   By 7:20 the floor was up to about 16.1° and by 7:25 the "warm" air was at 19.0°. The room at counter height stayed stuck on 16.8... or was it up just a tiny bit? Would the room get warmer, or was even 750 effective watts doing well to keep it from cooling? By 7:45 the room was up - but less than 1/2 a degree and still not back to 17.5 where it had started before I had been leaving the door open. The "warm" air was up to 19.3°. I turned off the LED lights for the night. Any heat being made now was from the heat pump.
   By 8:30 PM it was under 5° outside, the room was down to ~16.7 (according to the glass thermometer), the warm air was down to 19.0, and the floor air was down to 16.1°. It wasn't warming, but it seemed to be cooling quite slowly. At 8:40 I turned the system off to see how fast the room temperature would drop if it wasn't running, still with the doors closed. First I put the digital thermometer to measure the room at counter height, for better precision than the glass one. It read 17.0°. Fifteen minutes later it was 16.7 and in 40 minutes, by 9:20 PM, it was 16.3. It had also dropped to 3° outside. Too many variables! At the one hour off mark, the room read 16.1° -- a .9° drop. I felt the air coming in the outdoor heat exchanger. It seemed very slight - as it should be since there was no air going out.

   I decided to turn it on again for one more hour, and see if that did anything about the dropping room temperature. The air pressure said 20 PSI so I went out and cracked the valve open a bit wider. It dropped to 16. So did the temperature. It occasionally flicked to 16.1 or 15.9° during the hour from 9:40 to 10:40 PM, but didn't drop further.
   So in the hour it was off, the room air temperature dropped about 1°, and in the next hour when it was on again, it hardly changed. And that was with the outdoor temperature down to 2° by 10:40. So it was heating the room, and surely by more than 75 watts!
   For a final test, I turned the unit off again and turned on a 425 watt electric radiant heater. (It said 400W, but the power meter said 425.) The room temperature read 15.9°. After an hour, it was 16.1. So 425 watts very gradually raised the temperature a bit.
   Then it occurred to me to repeat the "no heat on" test for an hour. The room temperature dropped from 16.1 to 15.5 - only a .6° drop (for whatever reason). Outdoors it was still 2°.

* In both one hour tests with the heat pump on, the temperature stayed almost stable, dropping by about .1°.
* In the first "no heat" test, the temperature dropped by almost a full degree. In the second one, it only dropped by .6°.
* In the 425W radiant heater test, room temperature went up by .2°.

Conclusions 4

   We may tentatively conclude from the reduced drop of the second "no heat" test that the earlier higher temperatures lost heat more quickly. As they dropped, the room had less tendency to cool: even with the doors closed, they got more into balance with the interior walls transmitting some heat. And perhaps earlier there was a wind that died down by the last tests. (Awk! Another variable?)
   Thus we may also suspect that the 425W radiant heater, run just before the second "no heat" test, had an easier time keeping the room from cooling than earlier on when the heat pump was running. However, it managed to raise the temperature where the heat pump didn't quite manage that in either test. Here is a table of the results:

Test
Start Temp.
(degrees C)
End Temp.
(after 1 hour)
Rise/-Drop
Heat Pump
17.1
17.0
-.1
No Heat
17.0
16.0
-1.0
Heat Pump
16.0
15.9
-.1
425W Radiant heater
15.9
16.1
+.2
No Heat
16.1
15.5
-.6

   Thus a rough estimate of the effective heat being put out by the 75 watt heat pump might be 300-375 watts. That would give it a COP of 4 to 5. But my suspicion is that the pump is way under 100% effective. If it was for example compressing at only 33% of realizable efficiency, that would mean there was only 25 watts of actual heat pumping, making 300 to 375 watts output a realistic potential COP of 12 to 15.
   The room temperatures indicate that the method works: the room stayed warmer with the heat pump running than with it off, and by an amount substantially above what a 75 watt heater would provide by itself and more similar to what the 425 watt heater provided. I expect a highly efficient compressor would give better results, and of course a more powerful compressor would provide more heat. And with the more powerful compressor will be the need for more heat exchange pipes and ducts.
   And some way to deal with the noise. I suspect in lieu of truly quiet air compressors, it may be necessary to locate them outside of the living space but connected with insulated ducts as if they were inside the space. Or perhaps in a utility or storage room where people don't linger.

Michelin Air Compressor Tests

(28th) I decided to try it out with my Michelin compressor (~800 W). I set it to 48 PSI. I figured it wasn't really enough radiator pipe, but in the previous test the pipe had mostly cooled in the first foot or so if not the first 6 inches. The room started at 15.6° on the digital thermometer, maybe 15.3 on the glass one. At the floor it was 14.3. In about 10 minutes the warm air was 15.8 and slowly rising.
   With this compressor running one could feel the air blowing in from the outdoor heat exchanger instead of just wafting. And it didn't feel cold. After an hour or so I checked it with a glass thermometer, which said it was ~16° - approximately the room temperature. And outdoors it was 5°, and there was wind, getting stronger and blowing heat away. Apparently the heat exchanger actually worked.
   The output fitting of the compressor was hot to touch even for a moment. The thin air hose I had used was the only one with two "F" ends that would connect the compressor to the pipes. One could feel the temperature drop along its 2 foot length. And I thought I could hear a leak somewhere, but I couldn't pin down where. Apparently a lot of pressure was being lost because it was too thin and its resistance to air flow was too high - and maybe there was a leak, too. And the whole kitchen soon stank with the heat of the compressor. Hot oil maybe? Well, all in the cause! (When I disassembled it the next day, this little tube had a lot of water in it, indicating the loss of pressure within. It may have been the water spitting around that I was hearing as being a "leak".)
   I set the outside valve at the end of the piping to give it 55 PSI, to have more pressure with less airflow. By 35 minutes the thermometer on the counter hadn't moved, but the air at the floor feeding the radiator was up to 15.0. Perhaps the warm air was filling from the counter height down to the floor before more warmth would appear higher up? Then (after an hour) I found I neglected to close the far door and was heating almost twice as much space as I thought.
   Ten minutes later the digital thermometer said the room was 16.7°. That was ~1° rise.
   Then I got the temperature probe clamped to the pipe between where it came out of the house radiator and went into the outdoor exchanger. The pipe was 19.5°. That explained why the incoming air was right at room temperature: the outgoing radiator was warmer than the room. It also said there wasn't enough house radiator for the compressor. The closer to room temperature the warm air was, the higher the COP could be.
   After 1-1/2 hours the room was at 16.8°. It wasn't warm, but discernibly warmer. Was it warmer - or the temperature dropping less - than 800 watts of compressor motor by itself? By the 2 hour mark it seemed to have gone down, to 16.4° But the air pressure had kept creeping up. I suspected higher pressure (over the meter scale's 60 PSI max) was meaning less air flow. I went outside and adjusted the valve to get 38 PSI. It sounded like way more air hissing out. In 20 minutes the warm air (radiator) temperature hit its highest yet, 18.1°, the air coming in through the outdoor heat exchanger was at ~14°, and the room crept up to 16.6°.

   In the last tests the 425 watt radiant heater had raised the room only .2° in an hour. I decided to bring in another heater that would make it 925 watts, and see what happened to the room temperature in another hour. What a relief to turn that compressor off! Somehow I looked after I turned them on and the room said 16.3°, just a couple of minutes after it had said 16.6. ???
   I thought the heat pumping hadn't been very effective and that the temperature would start to rise with 900 watts of radiant heat. It only went up .3° in an hour, back to 16.6. It seemed the wind was making the windward side of the house a lot harder to heat than the day before.
   I turned the heat off for an hour (during which the power quit - another tree across the power poles?) and the temperature dropped to 15.3, a 1.3° drop. (Compare with pervious night: -.9° and -.6° in two like tests.)

The Michelin compressor connected with a copper pipe from the tank's 
drain spigot, with a gratuitous  picture of the "LED indoor garden":  
Coffee, lettuce, spinach, scraggly cherry tomato, carrots, all on rollers 

(29th) I tried out the system again with not dissimilar unsatisfactory results. This time I replaced the thin hose with 1/2" copper pipe. It came as straight out as possible: 1/4" to 3/8" adapter; 3/8" threaded elbow; 3/8" to 1/2" copper pipe clamp fitting; 2 foot copper pipe to fan box; copper elbow (soldered); "stegosaur" finned pipe going up; elbow to pressure meter "T" and ouside heat exchanger. In spite of the solid copper pipe attached to the compressor, The fittings on the bottom of the compressor were burning hot, the 2 foot pipe cooled to "just hot" going into the fan box, and the finned pipe at the box exit was just warm.
   It would seem that most of the heat wasn't being transferred from the compressor to the air, or from there through the pipes. What seemed to be needed was to start the radiators right at the compressor so that it didn't itself get hot. And not go through some constricted 1/4 inch fitting - that was probably where the heat was being lost! And not even have a pressure tank - that could be replaced by all that radiator and heat exchanger piping.
   It had worked best in the first test where the small compressor was right inside the fan box. How could that be done with a large compressor -- especially if the compressor was to be kept out of the living space?

Later: I think the pressure inside the compressor cylinder was much higher than what I was allowing in the pipe, and so there was far too much flow and high pressure drop inside the compressor. I should have run with much higher pressure to match the compressor, with less flow. I limited it to 60 PSI simply because my pressure gauge only went that high. Duh! How about a new gauge, then?


Inside the Michelin Compressor.
Typical cheap piston with no pin tilts back and
forth as it goes in and out of open bottom cylinder.

Compressor Noise  Solutions?

(27th) Here is what may be the most practical answer to the compressor noise problem. It is similar to "conventional" heat pumps: have the compressor outside the living space.

* Put the compressor outdoors in an insulated box. Unlike the "conventional" system the box is insulated instead of ventilated, and stays at indoor temperature.

* Two pressurized air pipes go through the wall from the box into the space to be heated: supply to and return from the space heating radiators/indoor heat exchangers.

* The indoor-outdoor heat exchanger now has its inner end in the box instead of in the house. As the compressor moves the air, it is warmed from outside to (almost) room temperature coming in this heat exchanger, is compressed and thus heated by the compressor, flows through and heats the house, returns at (just above) room temperature to the box, is cooled (almost) to outdoor temperature by going out this heat exchanger, then is further cooled (colder than outdoor temperature) as it decompresses to the outdoors. Because the air is returned from the house at room temperature, the incoming air is heated to room temperature, and so the heat pump still draws (roughly) room temperature air for the fantastic COPs that result from the small "lift".

   On behalf of the neighbors, the "sealed" box enclosure with insulation will hopefully make it quieter than "conventional" heat pump equipment where a big fan and the compressor are in the open air. The most sound is likely to be compressor noise coming out the open end of the indoor-outdoor heat exchanger. The nature of the insulation in it could have a considerable effect, and a 180° bend or two might also dampen sound.
   The one negative to the arrangement is that if the indoor-outdoor heat exchanger was in the house, it would supply fresh air, at room temperature.
   I suppose it would be possible to still do this if the outer tube of the radiators went into the house from the box and ended indoors, and then a return tube went through the wall back to the box. But the ducts would transmit the compressor noise.

Custom Air Pumps?

(29th) With the tests of the large air compressor showing highly unsatisfactory transfer of the heat from the compressor to the output, and yet with the first little compressor located inside the fan box at least showing that air heat pumping worked with a fair COP, it would seem that a better configuration - probably including a better air pump/compressor - was the key.

   I had been contacted by one Peter of ReliableSteam.com . Since that business used lots of pistons I asked for his thoughts on how one might get a quiet compressor. He said the way to make them quieter was with long cylinders and long piston stroke. That made sense since probably much of the noise is the valves opening and closing at the ends of the stroke. And slower strokes moving more air per stroke would be quieter. Peter suggested a hydraulic cylinder with a piston.

   At this point we're talking about making a custom air pump. That would doubtless be far more ideal than a stock air compressor... but how far do I want to get into this? OTOH, I have spent a fortune on electric house heating over the years (mitigated by a lot of firewood cutting, splitting, hauling and stacking), and so has everyone else in cold climates. Having a way to do it cheap with very low electricity use would be more than a little appealing - and something to commercialize. Considering they would be relatively low cost, not very hard to install, and far lower cost to run than anything else, tens of millions of them would be bound to be made and installed!

Okay, how about this? A long cylinder with copper heatsink vanes on the outside:

* Wide open air entry (with filter) at the input end
* a large one-way flap at the compress end
* The entire cylinder (or at least the compression end) and a large copper output pipe has heatsink vanes
* a large one-way flap in the top of the piston

1. In the compression stroke, as soon as the pressure in the cylinder is higher than that in the output piping (which replaces having a pressure tank), the clyinder flap will open and for the rest of the compression stroke, until the piston reaches the top, the air will enter smoothly through the flap.
2. In the back stroke, the pressure in the piping pushes the output flap closed. As soon as the pressure in the cylinder is less than the outside air, the piston flap opens, allowing fresh air to enter for the rest of the stroke until the cylinder is full when the piston is at bottom. Then the next compression stroke starts.

   The entire unit is enclosed by house heating duct (it's "in the box") with air blowing past it as part of the radiator system. The heatsink vanes around the cylinder and output pipe are the start of the radiator system. The compressed air then feeds into the rest of the finned piping and finally to the outdoor heat exchanger.

   Now... how should we drive the piston? Typically one would use a motor and have a crankshaft, giving a sinusoidal motion. But what about simply using a solenoid? Instead of just having the piston just switch on and off, a microcontroller could give it a soft start and end both to optimize the effectiveness and to keep it quiet.

===

(30th) It occurred to me there was another option, by itself or in conjunction with quieter compression: I could put a variable frequency drive (VFD) on the compressor motor. If one cut the speed down (eg in half, 30 Hz) not only would the compressor noise level drop but the output air could be adjusted to match the piping and the heating load. It seemed to me Jim Harrington had told me he gets VFDs for not so much more than 100$. This seems like a simpler plan!
   (Oh, wait... The motor in this compressor has brushes. I may need a PWM control instead of VFD. I'll have to see what's in the new compressor when it arrives. PS: Brushed motors with field coils aren't the most efficient type of motors, either!)

   At this point I decided I had done more than enough on this project for January. But I took the air compressor apart and had a look. The piston was driven by a toothed belt - good. But the air from the cylinder went through a skinny little hose to the tank - probably under 1/4" diameter inside. I had bypassed most of the other restrictions in the last test by attaching to the tank's drain cock hole instead going through the output regulator. But it seemed pretty clear that the air was being forced through some narrow spaces inside the compressor and probably most of the heat was being generated within it instead of going to the piping - as evidenced by the high temperatures at the compressor.
   The next choice would have been to disconnect the tank entirely and go straight from the cylinder to the piping. That probably would have helped, but a bigger exit hole in the cylinder would have been better. I decided to reassemble my compressor as I needed it for typical compressor tasks, and await the larger one that I had ordered. (It arrived February 2nd)

Refrigerator Air Pump

   On February 1st I went to the refuse transfer station and picked up a refrigerator type compressor from a discarded office water cooler. I found it quickly pinned the needle on my 0 to 60 PSI pressure gauge. But it pumped a low volume. By putting a balloon over the output and measuring its size after 90 seconds (Volume = 1/6 pi D^3), I concluded that it only pumped around 0.17 cubic feet per minute even at low pressure. It also only drew only 80 watts of power. Perhaps I'll try this one in place of my lab pump, at a fairly high pressure.
   I complain about refrigerator compressor noise, but they're much quieter than any other compressors. This one I could actually tolerate to leave running if it was heating a room almost for free. At least if I wasn't in the room much. Or how about in my travel trailer? I could eliminate the continual 500 watt portable heater drain and (hopefully) have it warmer in there with 80 watts, and I wouldn't hear it at all from the house.




Electricity Generation

My Solar Power System

Month of January Log of Solar Power Generated [and grid power consumed]

(All times are in PST: clock 48 minutes ahead of sun, not PDT which is an hour and 48 minutes ahead. DC power output readings - mostly the kitchen hot water heater for some months, then just lights - are reset to zero daily (for just lights, occasionally), while the others are cumulative.)

Solar: House+DC, Trailer  => total KWH [grid power meter reading(s)@time] Sky conditions

Dec. 23rd 08.31.(.53), 926.71 =  0.42 [[email protected]:00] dull.

(I was away Dec 24th until Jan 2nd)

Jan 02 08.31,(0), 926.71 =  0000  [[email protected]:30] sleet, rain, dull. OUCH! Over 41 KWH per day keeping the house at 12°c over the holidays. That's a main reason I have a woodstove. I couldn't afford the power bill to keep it at livable temperature full time electrically. With everything so cold to start (and the woodstove being no great performer), it took a good bundle of wood and 3 or 4 hours to get the livingroom tolerably warm when I got home. The rest of the house stayed pretty chilly.
3rd ?
04th --- [Car 72 Km, chj, 55 Km, chj; [email protected]:00] Cloudy 3rd & 4th. Snow on 4th early AM, then sleet, misty drizzle. Bit of sun. The solar equipment is still shut off.
05th --- [[email protected]:30] Snow. Clouds

   I turned on the grid tie inverters on January 6th (@ 11 AM PST - 2 hours before actual noon), but the solar panels were covered in an inch of snow. I tried to sweep it off the two panels on the lawn, but it had become crusty and hard, and wouldn't come off. Furthermore, there were tree shadows on all the house panels. Only the trailer roof ones were in full sunlight. So 3440 watts of panels were making only a few watts.
   At 12 "PM" (really AM - still almost an hour before noon) I got the snow off one panel on the ground and it was making 200 watts. A while later the snow had softened on the other and I swept it off. A very light cloud I hadn't even noticed brought production down to 100 watts instead of up. But not so long after it was up to 300.
   By noon those panels were in tree shade. The panels on the roofs started melting from the top down, but the bottom lip of the frames kept it from all sliding off, and panels are only as good as their darkest cell, so there was still almost no production on the first sunny day in January.

06th 00.66, - , 926.84 => 0.79 KWH [[email protected]:30] Mostly Sunny
07th 01.57, - , 927.02 => 1.10  [55Km,car charging; [email protected] 16:30] Sunny. 10 panels still have snow (@end of day)
08th 02.33, .11, 927.23 = 1.08  [[email protected]:00] clouds AM sunny later PM. 9 panels still have snow, only one completely cleared.
09th 02.53, .12, 927.24 = 0.34  [[email protected]:30] Cloudy. +3°. Egads, I'm not even driving anywhere, and the woodstove is on! That's an awful lot of power for bedroom heat, even in the cold weather. Besides the trailer (500W) do I have some heater on I'm unaware of? 9 panels still have some snow. A wind came up after dark and melted the snow.
10th 02.99, - , 927.54 => 0.76  [[email protected]:00; 95Km,chj] Clouds. (But panels clear of snow)
11th 02.03, - , 927.56 => 0.06  [55Km,chj; [email protected]:30] snow. dreary. dark. dim. dismal. Turned off 3 of 4 inverters at dusk. Snow after dark covered the solar panels again.
12th 02.04, - , - => 0.01 [[email protected]:00] Overcast. -7°. In early PM I tried to sweep off the panels on the ground, but the snow was too icy and crusted. (I did thin it.) There is of course no point comparing 4 snowed-over panels on one inverter with electricity consumed. Yes, there are electric heaters I haven't been thinking of: In the garage near the kitchen. At -7 outside, they are working hard to keep the garage at +7°. The 240V/60A double breaker to the shop blew. I reset it. It was okay. ??? (The open loop heat pump described in this issue should use less electricity to heat the whole house nicely than I am presently using for the bedroom at night and to keep that garage from freezing!)
13th 03.40, - , - => 1.36 [60Km,chj; [email protected]:00] light snow, light overcast. Low: -8.2° I went into town, and when I got back, I noticed the snow had melted off the 2 panels on the lawn. Even more surprising, they made over 1 KWH of electricity. (sun msut have come out?) EGADS, WHAT could possibly have used 90 KWH of electricity in ONE DAY?!? Double every other day?!? Hmm, I guess in this extreme cold, some of the house baseboard heaters (set to 10°) are coming on at night when the fire is low. OMG the next electric bill will be murder! Must keep the stove going higher at night!
14th 03.62, - , - => 0.22 [[email protected]:30] Mostly overcast (sun glowed a bit a one point). Still just 2 panels clear of snow.
15th 03.73, - , - => 0.11 [[email protected]:00] About same as yesterday, periods of light snow, -6 to -9. Snow accumulated at the bottom of the two solar panels that had been clear.
16th 03.86, - , - => 0.13 [[email protected]:30; 45Km,chjng] slightly sunny then overcast, then snow, then blizzard. -3°.
17th 00.01,~2,- => 2.01 [71078 (Est.)] More snow. Around 0°. Wind. Power went out in evening before I took readings so everything is an estimate. Windplant was very active. It charged the batteries and then some, and I put on a 500 W heater directly on the rectifier output, before the charge controller. All solar panels covered with snow.
18th - solar production off - [[email protected]:00] Windplant was overcharging - the voltage even with the heater on was a little too high for the charge controller (ie, above battery voltage -- it only boosts, not reduces voltage. Heater: 40 V = 1/3 voltage, 1/3 current, so 500 W / 9 = 56 W. The heat was quite perceptible. I turned the kitchen hot water heater on to provide more load. Then of course the wind dropped off, and I turned it off again. Soon the wind died completely) AM Overcast, +3° - the snow is getting wet, heavy and slushy. Evening (20:00), +1°.
19th 00.25, - , 928.08 => 0.77  [[email protected]:30] A bit of sun but not much. (Lots of jet trails.) +4° in PM. The snow had melted off the 4 trailer roof solar panels, and I swept it off the 2 on the lawn. So I turned on their 2 inverters and 6 of 12 panels were working. Whoopee, 3/4 KWH for the day!
20th 00.70,.35*,928.81 => 1.53 [[email protected]:30; 55Km,charging] AM SUNNY! +2°. Not for long - PM overcast. A lot but not all of it looked like high altitude jet trails again, back and forth, back and forth, almost from one end of the sky to the other. The snow slid to the bottom then almost disappeared off the four top solar panels on the house. The bottom two were still not wholly uncovered. I turned on the other two grid ties. *From windplant
21st 01.69,  -  , 929.44 => 1.62 [[email protected]:30; 55Km,charging] Overcast. (The snow musta come off the other panels.)
22nd 01.87, - , 929.56 => 0.34 [55Km,charging; 71241(?)@17:30] Heavy overcast & rain. +5°. Snow is reduced to patches.
23rd 03.28, - , 930.52  => 2.97 [[email protected]:00] Overcast AFAIK. I don't get it.
24th 04.52, - , 931.32  => 2.04 [85Km,charged; [email protected]:00] AM started sunny with normal tropospheric scattered clouds 7°, then it got largely overcast.
25th 06.05, .3*,932.77 => 2.88 [55Km,charging; [email protected]:30] Sunny AM, then jet trails, clouds - overcast.
26th 07.02, .1*,933.48 => 1.78 [[email protected]:30] Uniform gray overcast.
27th 09.22,  - , 934.96 => 3.68 [[email protected]:00] Wow, a mostly sunny day!
28th 09.90,  - , 935.36 => 1.08 [55Km,charging; [email protected]:00] Overcast again, 2 to 5°; Power fail at night.
29th 01.35, -  , 936.14 => 2.13 [[email protected]:30] Mainly Overcast. 5°,
30th 03.67, - ,  937.24 => 2.42 [[email protected]:00] AM overcast, PM mostly sunny, 4-7° (morning was warmer).
31th 03.76, - ,  937.32 => 0.17 [85Km,charging; [email protected]:00] dull. dreary. dim. rain. 3°.

February 1th 04.02,-, 937.33=>0.27 [55Km,charging; [email protected]:00] Mostly dull, snow 0°. Collectors covered with snow except the two on the lawn, which are set at a steep angle.
Feb. 2th 05.06, - , 937.55 => 1.26 [[email protected]:30] Sunny. 10 panels still covered in snow. 1 was clear by late afternoon.
Feb. 3th 05.39, - , 937.78 => 0.56 [[email protected]:00] overcast & rain, 3°. Solar panels were clear of snow (at end of day).





Daily-
KWH-  # of Days (January)
Made
0.xx  - 17
1.xx  - 7
2.xx  - 6 (1 day it was from the *windplant) - otherwise all near end of month.
3.xx  - 1 (near end of month)
4.xx  -
5.xx  -
6.xx  -
7.xx  -
8.xx  -
9.xx  -
10.xx-
11.xx-
12.xx-
13.xx-
14.xx-
15.xx-
16.xx-

Monthly Tallies: Solar Generated KWH [Power used from grid KWH]

March 1-31: 116.19 + ------ + 105.93 = 222.12 KWH - solar [786 KWH - used from grid]
April - 1-30: 136.87 + ------ + 121.97 = 258.84 KWH [608 KWH]
May  - 1-31: 156.23 + ------ + 147.47 = 303.70 KWH [543 KWH] (11th solar panel connected on lawn on 26th)
June - 1-30: 146.63 + 15.65 + 115.26 = 277.54 KWH [374 KWH] (36V, 250W Hot Water Heater installed on 7th)
July  - 1-31: 134.06 + 19.06 + 120.86 = 273.98 KWH [342 KWH]
August 1-31:127.47 + 11.44+91.82+(8/10)*96.29 = 307.76 KWH [334 KWH] (12th panel connected on lawn Aug. 1)
Sept.- 1-30: 110.72 + 15.30 + 84.91 = 210.93 KWH   [408 KWH] (solar includes 2/10 of 96.29)
Oct.  - 1-31:  55.67 + 13.03 + 51.82 = 120.52 KWH, solar [635 KWH - from grid]
Nov. - 1-30:  36.51 +   6.31 + 26.29 =   69.11 KWH, solar [653 KWH - from grid]
Dec. - 1-23**: 18.98 +   .84 + 11.70 =   31.52 KWH, solar + wind [711 KWH + 414** = 1125 from grid]
Jan. - 2**-31: 17.52 + ----- + 10.61  =  28.13 KWH, solar+ wind [1111 KWH from grid]

11  month total March 1 to January 31: 2104.15 KWH made; [6964 KWH consumed from grid]

** On December 24th I went away for Christmas until January 2nd, and I left the solar equipment turned off for safety. (And I kept it off until January 6th, there being power bumps and flickering lights.)

Things Noted

* Solar panels don't work covered in snow.

* December and January solar collection was only around 10% of that of the spring and summer months. The days are short, the angle of the solar panels is poor for the low winter sun and occasionally snow covered the panels.

* Tons of grid power was used in heating, especially in December when I was away, and in the very cold weather in January. Next winter (I hope) we'll see what changes with free air heat pumping!

* If I get the open loop air heat pumping installed and working, if it proves makable by an amateur such as myself and practical, winter electricity consumption will drop dramatically and annual totals by perhaps 25 to 35%. (It must be remembered that a significant portion of the total consumption is for driving - recharging the car. The "ultra efficient" EV if I ever get it going could drop that portion of the usage by maybe 1/3 as well.)



Woodstove Electrical Generator with Closed Cycle Steam Engine?

Pressure Release Cycle Valve?

(6th) I had the idea a couple of times that it would be nice to open a valve to prevent pressure buildup while the piston was descending. But how would it be activated? It almost seemed like it would need a second rod to the flywheel, activated at at different angle than the piston - a la the Stirling engine.
   Now I came up with an at least somewhat easier plan:

* Have the valve on the underside of the chamber separator. Up is closed, Down is open.
* Give it some weight so that if there's no pressure underneath it falls down into the "open" position.
* Have the piston operate a lever so that just before the bottom of its stroke it pushes the valve closed and holds it there until the piston is moving up again.
* The pressure building up holds the valve closed  as well as pushing the piston back up.
* When the piston reaches the top of its stroke the pressure is relieved and the valve falls open again.
* Again as the piston descends the valve is open.

   I'm not saying I'm going to build this, and certainly not for the first rendition. It would mean pressure is escaping while the piston is going down. If the pressure is building with heat from the stove while the piston is descending, it pushes against the descent. (Note: the vacuum is also building in the top compartment as it cools.) But that built up pressure is still there as the piston rises again, helping to push it up just as much as it hindered the fall. So overall it has no net effect. The pressure building as the piston is at the bottom and on the way back up is what drives the engine either way.
   The offset cycle with the piston descending rapidly and rising slowly is surely the way to maximize use of the pressure buildup, because then most of it assists the power stroke. The main effect of the valve would probably be a potential to reduce noise, as there will be less total pressure in the "pop" when the piston hits the top of its stroke and the compartment pressures equalize.

   BUT with the new house open loop heat pumping idea, I decided to put the generator on hold for now. One can only work on so many things. (And I would have LOVED to have had some cheap heat this month!)



Woodstove Electrical Generator with Thermoelectric Generators (TEGs)

   I used to think that a TEG sitting on the woodstove would need overtemperature protection. Now I've seen that with my present stove, the top never gets hot enough to burn out TEG modules. That simplifies it immensely.

   One other reason I have been reluctant to start an otherwise simple project was that I would have to build a unit with enough TEG modules to make say 14 volts in order to at least be able to charge a 12 volt battery, and 3 times larger to charge the 36 volt solar system. And there's an uncertainty factor of just how many TEG units it would take to do either of those.
   It also didn't seem it would make a lot of power. For 100 watts they might be worth it. For 20 to 50, not so much. So the complications and uncertainties seemed like to much bother.
   Another complication was that it seemed to me that for best effect the heatsinks for the TEG cold sides should be over the edge of the stove to catch cool air, rather than on top. But the TEG powered air fan I already use could draw cool air across the top of the stove and blow it across the heatsinks. That again simplifies it.

   But I do have all the parts. They've sitting around for quite a while now - most of them for some years.

   It has occurred to me that I now have DC to DC up converters. I can take even a very low voltage and convert it to a regulated higher DC output voltage. That changes the picture. As long as the TEG puts out enough voltage it can have any desired output level, and there's a 36 volt plug near the woodstove, so the output can easily be used to charge the solar power system batteries - by feeding into the plug instead of drawing out from it, like the Chinese grid tie inverters. That makes it simpler; more practical.

   I decided to make separate sets of four modules, each set using one heatsink and aluminum stovetop plate. The plates would be larger to gather heat from the surrounding area, not just the stovetop right under the heatsink. These units would be wired in series, 2 or 3 or 4 of them perhaps. First one for a test, then two, then more if it seemed worthwhile. (5 would be about all that would fit. I have 3 good heatsinks and 2 acceptable.) Since the stove top isn't really flat, multiple smaller plates will sit closer to the surface with 3 contact points each instead of 3 total. and allow buildup in small modular sections.


Module 1: Aluminum plate, aluminum
finned heatsink and four TEG modules

(15th) I drilled out bolt holes in a 6" x 7" x 1/4" thick aluminum plate I had on hand and put one unit together. I put it on the stove and soon got 3.6 volts. I shorted the leeds and got 1.5 amps. Without measuring an actual proper load, one might perhaps get 3 volts at 1 amp: 3 watts or so. Two units would then be a whopping 6 watts. If I recall correctly the DC to DC boost converters need at least 4 volts input. Well, I had figured it'd take at least two (8 TEGs) to do anything useful.


Testing on the woodstove

   But to my surprise the TEG powered woodstove fan proved wholly inadequate to cool the heatsink. The voltage started dropping as the TEG top sides and heatsink warmed up. I set it down on the hearth before it got too hot to pick up. I hadn't counted on the high conduction of heat across the TEGs. Some better system of cooling the tops would be required. That took me back to a previous design idea: one with circulating water for cooling.

   That sounded a lot more complicated. For how many watts, again? Under 20? I decided I had better things to do.





Electricity Storage (Batteries)

Turquoise Battery Project: Long lasting, low cost, high energy batteries

Current Collectors: Sheet Metal or Thinner Metal Foil?

   The copper sheet I bought was called "copper foil" (~.10 mm thick), but it's a lot thicker than typical aluminum foil (~.02 mm). It occurs to me it doesn't really need to be. Gold plating may be costly, but copper itself isn't cheap either. And having anything any thicker than it needs to be is just extra weight per unit of energy storage. It's no problem sticking with .1 mm for test cells, but I should probably look for .05 mm or less for production.
   And maybe the zinc doesn't need to be more than electroplated foil either. After all, most of the surface area and hence available reaction energy must be in the fluffy zinc electroplating, not the sheet. But since the surface of the zinc sheet does take part in the reactions, there is probably a minimum thickness for it to maintain cohesiveness. Well, to be determined in testing I suppose!

   With foil, thin, flat "sheet of paper" size batteries may be the most practical form. (Think "sheet of corrugated cardboard" maybe, for an actual size and thickness?)

Next Zinc Electrode: Pure Zinc

(12th) Having obtained some supposedly pure zinc on AliExpress, I cut a piece for the electrode for the flat cell. I dipped it hydrochloric acid to etch it, and was amazed: It didn't turn black like the roof moss killer zinc! It kept its zinc color except for looking duller. It was like a different metal! I should have tried this much earlier, but I didn't know where to order any from. Perhaps my main problem with the other zinc was impurities?
   I put it in the electroplating tank at 400 mA for an hour. Presumably that would give it almost 400 mA-H of capacity in the plating, plus whatever little the surface of the sheet zinc itself had. It didn't plate very evenly. But the back was the worst, so I decided to use it even if it had less than 400 mA-H.

   As usual I forgot to weigh the zinc before I plated it, so we must rely on a left over piece of the same sheet and some mathematical contortions:

Leftover piece: 99x33mm, 4.75g = .00145 g/sq.mm

Measured/calculated area of actual piece: 64x31+34x9mm = 2290 sq.mm
Weight of actual piece before plating:  .00145 * 2290 = 3.3g

3.70g(plated) - 3.3g(unplated) = .4 g of plating

.4 g * 820 mAH/g = 328 mAH (Pfew!)

Cell Cover

   Along with making the zinc electrode I cut two pieces for the removable cover over the cell. I got them to fit pretty tightly (to minimize air leakage) and I was afraid the small piece might be hard to pull off, so I put a nylon pan head bolt into it for a handle.
   On doing this I realized that if I simply put the water reservoir at the other end it could just have one longer cover over everything. Putting it at that end was just a hangover from cells that stood on end, when that was the top. Oh well - for the next one.

Nickel Trode

(13th) I painted a little calcium hydroxide onto the gold plated copper current collector sheet. But the immediate goal was to see how well the pure zinc worked in the negative side.
   I took a second NiMH D cell out of its can some time back. Seeing my last NiOOH electrode hadn't worked well, I decided for the moment to just use pieces from the commercial one. That I can easily reopen the cell and swap out electrodes has its advantages. I cut pieces and as it was so thin (.7mm) I put in 3 layers. No doubt with the salt electrolytes and under pH 14 the nickel mesh will oxidize. Let's see how well it works after that. (And let's hope I haven't scratched the gold plating on the copper! I'm really not fussy about trusting a plating. Oh well.)
   I also painted a little samarium oxide onto the pieces, hoping it will soak in and raise the oxygen overvoltage of the whole electrode, with the (sulfonates) Sunlight dishsoap to make it a gel.


Zinc - Again

(14th) I opened the fridge and took out my agar gel with zircon additive. The cover had shifted and it was completely dried out. From now on I'll make a new tiny batch for each new electrode and not try to save any. It would have to be painted onto the electrode instead of just dipping the whole electrode into the "vat". At least I had the lab heater now instead of just the microwave or a stove burner.

   But I started having second thoughts about the electroplating. The new zinc was pure, but the electroplating solution had been made from the old zinc. A layer of black crud had to be fished out of the bottom after making it. What impurities might be lurking still in the solution and making the zinc plating impure, perhaps in some deleterious way?
   I had the powdered zinc electrodes from disassembled alkaline cells. I decided to make a whole new batch of zinc chloride from some of those, and redo the solution and the whole electrode. I put some of them in a beaker of distilled water to dissolve out at least most of the potassium hydroxide. Then I put them in the same jar (cleaned) and added distilled water, then hydrochloric acid. There wasn't a lot of reaction compared to the previous time. A lot of the zinc stayed on the bottom and the acidity stayed at pH 1. Probably much of the zinc was zinc oxide.
   I filled the jar with more water and put in the new electrode and a piece of the new zinc for an anode. I plated 1/2 an amp-hour or so. The coating in the acidic solution was very different than in the neutral pH zinc chloride, not 'fluffy' but solid "mountain ranges" on a seemingly almost unplated background instead of "towering trees with many branches". I can't think but that these must have far less surface area - but they also don't crumble off. Perhaps I can find a pH that will give some "optimal" result, a more solid yet still somewhat fluffy coating, perhaps at pH 3 or 4. Or perhaps a higher or lower current would give a more uniform as well as more desirable result.
   That last would be easy. I decided to try it: instead of 400 mA I would try 800 and then 200 and see what happened. Next time!

    
The odd patterns of plating attained with the acidic plating solution

   And how much plating was there actually? As usual I forgot to weigh the plate between etching it and plating it. Well, it would have been about the same as the last one. Hmm... a bit shorter; perhaps a bit less. Plated it weighed 3.75g.
3.75 - 3.2 = .55g
.55g * 820 mAH/g = 451 mAH. In theory. Depending on how much surface area of the rather solid looking plating is actually in contact with the electrolyte.

   I got out the osmium doped acetal ester and painted the surface. Later I did the agar with zircon, just a thin mix.

Testing

   I filled the cell with nothing but potassium chloride solution, full 35g/100cc strength, about 3:30 PM. On charge at 1.9 volts it drew 60-70mA, which dropped to 20 over an hour or more. A little gold-orange color appeared in the electrolyte in the reservoir area. I don't much like that!
   After a while I checked the pH: 6-7. I had expected it to be more alkaline. That's almost metal dissolving territory. I guess I rinsed the KOH out of the NiMH electrode pretty well. I added a few flakes of KOH and it rose to around 11-12.
   As the day went on the cell held higher voltages longer until by night it stayed up over 1.8 volts for half a minute. )Later for many minutes.) The nickel side obviously wasn't anything like fully charged yet. Overnight it dropped to just over 1.3 volts. Instantaneous short circuit current went up from 1/2 an amp to 3/4, but it still dropped to 1/4 amp after 10 seconds.

(16th) In running a few cycle tests, it appeared that the voltage descended to around 1.5 volts in just a few minutes, then very rapidly dropped down below 1.2. But after that it would run for quite a while under 1.2 volts.
   The zinc was either around -1 to -1.2 volts or it wasn't. I came to the tentative conclusion that the nickel was only holding its +.5 to +.6 volt charge where it was in the best contact with the trace of samarium oxide oxygen overvoltage raising substance, and so when I tried to discharge the cell, that rapidly dropped off... to something else. (Or the gold could have been oxidizing at the higher voltage level.) Was there a NiOH level not mentioned in the literature? Was it dropping to Ni(0) metallic? But that should have been an even lower voltage.
   What I really wanted was the lower manganese dioxide voltage which was easy to keep charged. But manganese didn't recharge properly. That led back to the nickel manganese oxides, AKA nickel manganates, as being a form of manganese that probably would recharge.

   I took the cell apart. The zinc looked okay. so far. The copper tab had almost ozidized off right where the gold plating ended. That was still being wetted with electrolyte that frothed up and left slat crystals on the surfaces. The gold plating had also come off and left exposed copper in three patches on the front and seemingly more on the bottom. I knew I didn't like depending on a plating to protect a metal! And the plastic bottom of the cell was very colorful with various oxides - nickel, copper... and ???
   I suppose the other option is to go back to graphite current collectors.

But the exposed copper could well explain the discharge voltages. It was around the voltage of a copper-zinc cell. (Maybe that's what I should make! At least it should work well, even if it's a little under a volt.)


Copper Oxides Electrode

   Hmm... Maybe not a joke. After all, what I was doing wasn't working well. And copper-zinc was used in some early batteries. Where was that copper Pourbaix diagram?
   Let's see... at pH 7 to 12 it oxidized to Cu2O - a solid, around 0 volts. At another +.15 volts, it further oxidized to CuO - still solid... Or was it to Cu(OH)4-- ? What was that printed, off to the right, for? That seeming a little ambiguous, I looked up some more Pourbaix diagrams of copper. They conflicted with each other. One of them called the products of interest "cuprite" and "tenerite", the mineral names, and I had ot look them up to make sure they were Cu2O and CuO. One said "insoluble in water" the other said "soluble in ammonium chloride" but mentioned no other chlorides. Ammonium chloride is slightly acidic and it probably depended on the acidity. This was to be a "mildly alkaline" battery all along.

    I decided to assume the products would be insoluble around pH 12 unless trying it showed otherwise.

   I checked on line for the resistance. No point looking at it if it was an insulator... but then it had been used for batteries before, so it couldn't be. One reference said it was, but others gave "electron-volt bandgap" figures and wildly varying resistivity figures. I stuck ohmmeter probes into the bag and got no reading, but some black oxide stuck to them and if I pressed them together I got readings, depending how hard I pressed, of megohms down to ten of kilohms. Good enough, if mixed with conductive graphite.

Now... was it in the pottery supply catalog?

"Red copper oxide (cuprous)" and
"Black iron oxide (cupric)".

   I thought copper compounds were green? Copper sulfate is quite blue, copper II carbonate-hydroxide is cyan, and copper chloride is cyan-green (IIRC). My gold plated copper current collector had developed some green and some black - but some red underneath on the case.
   My copper sheet was disintegrating at the tab where the gold plating ended - the tab was almost ready to fall off. I would assume the green and black were the oxidized copper.

   Next, how to get some. Of course I had lots of sheet copper. Metallic copper was the discharged state. And I had a piece of copper sulfate. Anything else? I went down to my storage and looked in the box. Sure enough! A small paper bag, "1/2 lb BLACK COPPER OXIDE" from the pottery supply. I don't remember buying it or why.
   "Black oxide" would be the fully charged state, valence +2, -- assuming it would charge electrically from cuprous to cupric (unlike Mn2O3 refusing to charge to MnO2). And if it did, the charge and discharge reactions would move two electrons instead of one, which would be a big advantage in amp-hours per kilogram in spite of the lower cell voltage. And there was some black on the back of the current collector (as well as on the front) - promising! I was assuming that both these oxides were at least somewhat conductive and not insulators that would passivate the electrode.
   So there were a few "ifs", and I've had my problems with impure materials, but I thought this was worth a try. Here was the plan:

* Use a graphite foil sheet for the current collector.
* Mix the CuO with some graphite powder - just like with MnO2.
* Add some gell and compact it into a briquette.

* Try it out.

   If it worked but had too low current capacity I could try some of the fancier things like graphite fibers and gold plated current collectors. The voltage is so low it shouldn't need any oxygen overvoltage raising additive.

   If it worked and barring more of the unforeseen problems that seem to plague all my battery designs and plans, I could apparently (and at last) make working batteries. I could experiment with nickel manganates later as a higher voltage alternative.

How much? If again I wanted 1/2 an amp-hour in the test cell, and if it moved 2 electrons in charge and discharge:

820 AH/Kg (Zn) * 65.4 / 63.55 = 843.74 (Cu)
But accounting for the oxygen: 63.55 / (63.55 + 16*2) = 665 AH/KG

   The voltage may be low, but actually the amp-hours per kilogram capacity makes nickel hydroxide (at 289 WH/Kg, IIRC) look pretty feeble.

So for 1/2 amp-hour, a little under a gram:  .5 AH / .665 mAH/g = .75 g

I had a feeling this was going to make a very thin electrode! To hedge my bets I decided to use 1.5 g. To this I added .3 g of fluffy conductive carbon black (or acetylene black, or "incredibly fine graphite" or whatever it's really called). Then I decided to double that and added another similar spoonful, so around .6 g, and a little of the sufonates soap for liquid. I pressed this to 5 tons. It made a very thin electrode, which crumbled.


Test

   It started out with 1.002 volts. Being that it should be 'fully charged' to start, and not seeing that there should be any impediments, I expected that in spite of the low voltage it would give solid performance. In fact, with a 56 ohm load, the voltage dropped rapidly, each minute 25 mV lower than the minute before. In 10 minutes it was hardly above half a volt. Most disappointing!

   Thus, still the only cell I can claim worked really well was the well known nickel oxides + zinc in potassium hydroxide. (And yet we know from 'standard' dry cells that salt electrolytes do work!) At least by gelling them they should last and last. Have I accomplished nothing more interesting in all this time?
   I went over TE News 135 where I had last tried hopefully forming nickel manganates. It seemed to have worked, albeit again with low current drive. What if I tried again with the new layout and ABS plastic that wouldn't disintegrate, maybe with more KOH or even wholly KOH solution?

Back to Nickel Manganates

   Aside from disintegrating PLA plastic, the chief complaint from the TE News #135 manganates was that it wasn't conductive enough. I got out the jar containing the rest of it and added 5 more grams of conductive carbon black to the remainder of the 5 original grams. ...Then I read further down in #135 and found I had already added 10 after that test back back then. Now it should be up to 20. Any lack of performance now could hardly be attributable to any shortage of conductive powder!

   The flat cell seemed to be leaking. It had a pool of liquid around it and kept needing a refill. I am getting SO tired of leaking cells! Next thing to try would be a similar cell made with the Cura slicer and finer printing instead of the old coarse Skeinforge intended for the old RepRap printer.

   Then I got into trying out the heat pumping idea (somewhere above) and left project this for some days.

(29th) The internet was down - to the whole island (Still down Feb. 2nd!) - and in the evening when I'm usually doing e-mails and web research, in OpenSCad I designed my 100x100mm flat case to fit the zinc sheets of that size. But I didn't 3D print it.

(30th) Having fixed the leaking, and having been contacted about potential collaboration in battery making, I thought it would be good to confirm, if possible, that this was good electrode material. I mixed 10 grams of the "extra graphited" powder with 1.6 grams of dishsoap/sulfonates gel. I put some in the compactor die and pressed it to 6 tons. It weighed 5.3 grams and still looked a bit dry, in fact spotty with some parts looking drier than others. I put it on top of the graphite current collector in the bottom of the cell. I re-agared the zinc 'trode, which had become dried out. I filled the cell with about 7 cc of 20% KOH + 20% KCl.
   When I filled the cell, it was a minute or two before I got a meter on it. I found it slowly rising at 1.45 volts. Just before it looked like it would hit 1.5, instead it suddenly (a few seconds) climbed to 1.68, and then inched its way up (minutes) to 1.705. Hopefully the potassium permanganate and the nickel hydroxide were reacting together to make nickel manganates.

   I really have no certain idea of what voltage to expect. Nickel oxyhydroxide voltage? Manganese dioxide? Something else?

   A brief short circuit gave 450 mA, after which the voltage quickly (seconds) returned to 1.69 more gradually to 1.701. Considering it was a graphite current collector and that there had been no charging, that seemed promising.
   pH was about 13. The electrolyte turned transparent green - no doubt nickel chloride. or maybe nickel sulfate with sulfate from the gel? (Later: Wait, isn't potassium manganate green too? No internet to look it up.) Maybe not enough gel, or the gel needed more time to 'set'? I decided to let it rest for a while.
   In an hour the voltage dropped to 1.691. Too bad the other piece of lid didn't fit to keep air out. I tried another short short circuit and got just 320mA, after which the voltage rose quickly back to 1.67, and then crept up to 1.691 again. I had a weight on the main cover. I removed it to no apparent effect, but when I put it back on zillions of little bubbles frothed up where the terminals poked out. Since it hadn't been charging, I assume those were oxygen coming off the permanganate as it reacted. I also surmise the bubbles (under the zinc) made for less electrolyte contact and hence the lower current.

   In the evening, without charging, I ran a load test with 60 ohms. This started at 1.678 volts but within one minute it was down to 1.2 volts. It ran for 11 minutes before the voltage dropped under 0.9 . After a 1/2 hour recovery to 1.645 volts, still without recharging, I ran it again and was surprised to get similar voltages for 8 minutes. Then a third time... and a fourth time... each for another 7 minutes. It was all just 10 milliamp-hours of current, but it ran. But how many times could it be done, and why didn't it just run much longer, once? A brief short circuit now gave about 250mA. The electrolyte was now a very dark green.
   Just because I was tired of doing it, I put it on charge. With almost 1.9 volts in, it was soon taking only 8mA - half of what it had been discharging at. I left it on a few hours, then off and in the morning it was around 1.44 V.

(31st) Thinking back afew years that the nickel-manganate/manganese cells had charged up to 2.6 or 2.7 volts, and that Zn was only supposed to be about .3 volts less negative than Mn, I wondered why I shouldn't be charging to higher voltage (Somehow 2.7 volts seems absurdly high now, but it drove a load at 2.3 or 2.4 volts!) I turned up the power supply to 2.5 volts. When I took off the charge, it quickly dropped back to about 1.9 volts - the voltage of nickel-zinc - and from there its fall slowed. But surely I needed to charge at a higher voltage than 1.8 or 1.9 for it to stay at 1.8. I set it to 2.3 volts and left it a while. It still drew only 10mA. But the voltages started rising.

Low Currents - Back to Graphite Felt?

   It seemed to me absurdly low currents might be the biggest problem. Looking back at some TE News issues in #67 to #73, it seemed I was getting far higher currents then than most tests recently from similar electrode compositions in fairly similar electrolytes. What was different? I was using not only graphite powder, but an electrode with the active powder filling a piece of graphite felt and then the works compressed into a brick. Apparently that gave much higher conductivity than just powder, and higher than with the bits of graphite fiber mixed into the electrode. Why does simple graphite powder work so well for MnO2 in dry cells? Well, it would seem the thing to do is to go back to what was working well in 2013.
   As I recall, I put pieces of the the felt in with the powder and shook the container. That wouldn't have done the best job. What it really needs tho is a vibrator system: put the felt in the bottom of a box (wall to wall foam), put powder on top, and vibrate it. The powder should fall through into the spaces in the felt. And maybe a square something over the top to add just a bit of weight (don't compress the foam!) to push the maximum amount of powder in.
   What did I have that vibrated? The air compressor was pretty bad, but I didn't want to take it apart again and the outer plastic case was quite damped. Some power tool? Too bad I don't have an orbital sander!

   I cludjed together a graphite felt electrode with some of the same powder mix as the last one. I tried a similar discharge test, but found a poor connection to the plus side. Probably it was because the the current collector, which I had had to bend up for connections, was slightly folded. It was by reconnecting below that fold that I got good contact. This one ran for 28 minutes before it was down below 1.0 volts. BUT, did the last one, even with all that graphite powder, perform poorly because its internal conductivity was poor, or because of the same bad connection? Was the graphite felt superfluous?

   I seem to have the most frustrating of problems with salt electrolyte, throwing everything off. No wonder everyone has so far gone for pH 14 alkaline where nickel metal doesn't oxidize, avoiding the need for graphite current collectors.

Chemistry Seems Fine But Mushy Electrodes Don't Conduct Well

   I did some charging and then hooked up the 60 ohm load. Voltage started dropping as usual. I put another spacer under the lid so pressing down on it pushed the electrodes together, and pressed down. Voltage came up substantially. So I added more weights. I think it came up by over 100 mV. Then on top of this assemblage I leaned, adding something like 50 pounds. It came up another 125 mV and was dropping much more slowly. Practically a whole 1/4 of a volt more! (I wondered how far I could go before powder oozed through the separator grille and shorted the cell. Somehow it didn't happen.)
   I ran another discharge test. The more weight I put on, up to maybe 70 or 80 pounds, the higher the discharge voltage. The test ran for 25 minutes, ending at 1.125 volts where it would have dropped below .9 volts in half that time with no pressure. (I could have run it much longer - an hour?) Then I hooked up the charge (2.2 volts) and likewise found I could increase the charge current from 70mA to 90mA (a ~30% gain) by leaning on it.
   On the morning of February 1st I tried another 60 ohm load test, this time pressing heavily on the top the whole time. Results were far better. In the previous tests, it was 1.112 volts after 5 minutes. In this one it never went below 1.3 .

   There was the problem with all my plus electrodes, of any chemistry, right in front of me. It was that the powders weren't being held compacted. They absorbed water and expanded, losing conductivity. I seem to keep learning this lesson over and over. What was needed was either pressure in the cell holding it together (probably what makes regular dry cells work) or else some construction of electrode that would hold together by itself including when immersed in liquid (as with lead-acid batteries). Chemically the electrodes were probably fine. Mechanically they needed.... something. I'm sure still better - much better - results than from just putting my weight on a mushy electrode are possible.
   That was what was appealing about the electrode shells type of construction. Drying and very briefly torching them seemed to help make them more internally solid too. In going over the old newsletters it seemed I was getting better results in 2013-2014, probably from that, so I'll try it again.



http://www.TurquoiseEnergy.com
Haida Gwaii, BC Canada