I saw this video and it hit me we could do the same with the wood gasiifier, or the exhaust of a generator, pipe it thru sand and charge it up for heat, then heat exchange to pull it into your home or heat water with it.
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This is interesting. I like the idea of trying to make every BTU of combustion exhaust purposeful. I am wondering if a engine exhaust could be piped through a series of tubes inside the sand battery like a fire tube boiler. On my Rocket Mass Heater in the greenhouse the ducting goes through an 18 foot bed that is two foot high and 30 inches wide. It starts out at 5 to 600 degree F on the surface of the barrel and by the time it exits the bed to be exhausted outside it’s down to 70 degrees F. and the bed with is filled with cob we heat to 70 F and hold overnight to about 50 F. with outside temps at 32. The ducting is only 6 iches in Diameter. With the length of the duct run it would have be much better had I used 8 in ducts but it’s not something you can fix later.
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It would almost have to, or else the engine couldn’t pump any air. it would be like a banana stuck in a tailpipe.
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Yeah, may need a venturi fan to help it thru the sand battery… Another thought is the sand could be in a chamber like an oven where the heat could move up, yet the exhaust go out… I am impressed the Chinese gen worked… I guess one could try different lengths of pipe till one found a working solution.
I had to rewatch, he is actually using a pipe inside the tanks, (I must have skipped through that part the first time) and he has downward flow of the gases, so the CO actually sinks out the bottom. The bigger problem is if it gets plugged by a hornet, mouse, snow, freezes, etc.
For wood gas, it would work. but you have the likeyhood of trace amount of tar and ash. And it would work with multiple pipes and such.
He was really careful about safety for a youtube video. but it really isn’t a battery as much as a heat exchanger. sand is probably unnecessary it delays the heat radiation, but since he has the coils of tube on the inside more towards the outside of the tank, it is radiating out the tank anyway. It is storing -some- energy but if you want to actually store energy you would move the pipes more as tom suggested to the middle, and probably leave the insulation on. And maybe another series of pipes with a fan to release the heat, or even use the same pipes and have separate inlet and outlets that are controlled by valves.
Yeah other problems as I look at it would be c02 released if there was a problem in the pipes…
They are calling it a battery in several locations, but the standard terms people use is “Thermal mass”…
I am doing testing now with using solar panels with dry sand to store heat, and I am impressed with how long it can store heat ( I am using 8 quart pan ) and with the high temps I got with a stove burner hooked to 5 solar panels each putting out 222 watts of power. Temps got over 800 degrees per my meter. I put a stick in that sand and it immediate burst into flames…
So I am looking to keep adding more dry sand to this and see how much heat it stores from the previous day from solar. I have read that dry sand makes a good insulator, I am finding that is true with my tests… Once I find the limits of how much heat it can store for say a week of 1000 watts of solar, I will then add some pex for a heat exchange. If I can get into the range of 180 deg I should get some good hot showers out of that. I have plenty of sand, I just need to dry it and add it…
My plan is to have the thermal mass outside, and then pipe it in as needed, but I will do more experimenting to find the limitations.
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Are these PV panels and some sort of heating elements Mart? I had no idea you could get it that hot.
Makes me wish I would have used sand instead of cob in the bed of my Rocket Mass Heater. The cob bled water for a year as it was drying out. My main heat sink in my greenhouse will be water, when I can get the damned tank sealed. I’d like to know more about your experimental set up.
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Yeah I am using a 240 v stove top element at present.
I took an 8 quart stock pot and put the element in the middle of the dried sand. got up to over 700 degrees but temp varies as the outside of the pot acts as a heat sync and I loose much heat there…
All of my soil is sand, so I plan on using the solar to dry the sand and keep adding it to this 100 gal propane tank. Next I will bury that coil in the middle of that propane tank, and fill with dried sand and see what temps are on the outside of the propane tank when that is done. Then I may take a 55 gal tank on the outside of that and fill that with dry sand, or I may make an air gap…
I am thinking about putting 3 feet of dry sand around the entire thing and then noting what the temps are of the sand after a week or two. learning what the limitations are, my thought is I can take my pex pipe and put it in there and get hot showers, if I put the pex at the right distance away from the burner… I may put in some rebar deep into the sand to help the heat transfer the metal is doing a great job of heat transfer, I may need to use an air gap to help stop the heat from escaping.
5 solar panels in series each about 222 Watts, I need to check the amps this is drawing and find the ohms on the coil so I can match the voltage better.
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You will need insulation to keep the heat in. DIY starlite might work.
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Dry sand itself has a good insulation value. I was looking at aircrete mixed with styrofoam.
I wonder how the added exhaust back pressure will affect the diesel heater’s “tuning” and operation. My son recently got one and it failed in only a few weeks. Lots of black goo inside, and he isn’t even doing anything to the exhaust. I watched a couple of videos about repairing them and from what I have seen, you probably don’t want to mess around by compromising the design by messing with the exhaust.
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This video answers alot of questions I had… £0.03p per KW heater modification - Top facts & lies on diesel heaters - waste veg oil burn success - YouTube
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