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Thermoelectric in conjuction with Rocket Mass Heaters?  RSS feed

 
Jason LaVoy
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Is it possible to utilize the heat from a RMH both for thermoelectric and space heating? I saw a "small" camping stove that used thermoelectric to charge a mobile phone. A large RMH puts out a lot more heat.
 
Jason LaVoy
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Possibly integrating water heating to help keep the temperature difference at a maximum?
 
allen lumley
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Jason L. : This is a good question !

The best answers I can give cover a lot of territory, 1st the amount of,or % of Electrical energy that can be produced from using the thermo-electric effect
has shown some improvement in the last 70 years. However the totals of volts, amps and watts produced all measure in small fractions in all these Units.

If and when a break thru comes in our ability to capture a higher percentage of lost energy, it will still be exactly that a % of Waste Heat Energy that becomes
converted to electrical energy. The so called Heat Engine or Sterling Engine(s) can be useful in recovering waste energy where there is no easy way to use
this heat energy, like at the end of a chemical process producing waste heat ! Simply Googling heat or sterling engine will help you find lots of information
on this subject !

Generally the higher the temperature of that waste energy the fractionally more efficient it can be converted. Water without dangerous pressurization is
basically at too low a temp with too little heat energy to work directly, however as some types of Sterling engines work off of a difference in temperatures,
water could be used to cool the cold side of a Sterling engine, maintaining the needed Temperature spread between the units two ends !

Some trade-off of Heat energy to Electrical energy is useful in remote locations where micro amounts of electricity is needed to capture and store data for
signaling/transmission to a master control, especially in locations where it is difficult to keep and service a battery pack !

A major breakthrough in power transmogrification would be instantly used by the entire Transportation Industry. Most of the devices that currently show much
progress are at the present time too bulky -rather than too heavy for present Efficient use. A Tractor-Trailer that was half full of Thermo-electric generator
would not be very useful to the trucking industry !

Short term expectations for the camp stove you saw would likely be to be able too charge 1.5 cell phones. Carrying a similar weight in organic solar cells -
(greatly more efficient )would allow you to capture and store more Electrical Energy!

I hope this helps and is timely ! Big AL

 
allen lumley
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Jason L. : Paul Wheaton who is our host here at Permies.com is further hosting a group of 5-6 rocket mass heater innovators and has tasked them to successfully
include Thermoelectric devices, thermopiles and pelters into a few of the planned build being made this month at the secret labs in Montana.

I have shared that I think the greatest future for all thermo-electrics is making electricity from waste heat, obviously there are parts of the Americas with long
heating seasons, and even in the middle of summer people still like hot food to eat often as often as 3 times a day !

There will always be waste heat and seeking it out and using pelters etc to transform one type of energy to another will have an interesting future. Are you signed
unto get the Blogs posted by Paul W. ? For the Good of the Crafts! Big AL
 
Steven Harris
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Yes, it is possible, in fact that question is right now on the wheaton laboratories forum, and I tried to answer it, but I can't post there, they are trying to fix it right now.

The short answer is that its possible to create double digit watts and the closer you get to 100 watts the more expensive and harder it will be. Paul just want to make a small amount of electricity that will power a duct fan that will improve the draft through the RMH, plus having some extra left over for doing basic charging, like AA batteries, small lights and your electronic devices.

I feel that the avocation of a stirling engine to you for getting heat off of an RMH is foolish, because there is not one stirling engine made on the planet, that is not some damn toy, is available to you as a civilian with a credit card. I might as well tell you go and use magic beans to convert heat energy to electricity.

Through another forum, I have discovered someone that is reported to be taking orders on their website for a sterling engine, although its not wired for electricity and if you do add something to it for electricity its output is around 40 watts. This might be the 1st stirling available for purchase in 100 years. I'm still investigating it, but like I said, its 40 watts.

Steve
 
Jason LaVoy
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Awesome! Yes, I get Paul's daily emails and I'll be keeping watch to see how this works out.

If I may contribute a suggestion. If they're also planning to include thermosiphon water heating, The place where the "cold" line feeds back in would be the place with the greatest temperature difference. I hope that makes sense.
 
Steven Harris
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Jason, any thermoelectric system based on peltier junctions, and that's about all there is at the moment unless you get into rare metals, you want a dedicated heat sink for the 'cold' side of things. I would NEVER have the system based on the variable of the cold side of a thermosiphon system. I would want a dedicated heat sink for the cold side, that can be boiling water, yes, boiling water is the COLD side of a thermal electric heater, it'll never get above 212F, or I'd want a dedicated force air cooling system with fans and a heat sink.

If you run out of cooling on the 'cold' side then the whole peltier junction will heat up and melt the solder that holds the peltier junctions together. A massive boiling water heat sink would be the way I would go, as in, 5 gallons of water, that might never boil due to heat exchange with the environment, but at worst case, boiling. It takes 1 BTU to raise 1lb of water 1 degree F, it takes 950 BTU's to change 1 lb of water at 212F liquid to 1 lb of water of vapor at 212F. So it makes the most awesome heat sink.

Steve
 
r john
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Steven Harris wrote:Yes, it is possible, in fact that question is right now on the wheaton laboratories forum, and I tried to answer it, but I can't post there, they are trying to fix it right now.

The short answer is that its possible to create double digit watts and the closer you get to 100 watts the more expensive and harder it will be. Paul just want to make a small amount of electricity that will power a duct fan that will improve the draft through the RMH, plus having some extra left over for doing basic charging, like AA batteries, small lights and your electronic devices.

I feel that the avocation of a stirling engine to you for getting heat off of an RMH is foolish, because there is not one stirling engine made on the planet, that is not some damn toy, is available to you as a civilian with a credit card. I might as well tell you go and use magic beans to convert heat energy to electricity.

Through another forum, I have discovered someone that is reported to be taking orders on their website for a sterling engine, although its not wired for electricity and if you do add something to it for electricity its output is around 40 watts. This might be the 1st stirling available for purchase in 100 years. I'm still investigating it, but like I said, its 40 watts.

Steve


Whispergen have been making off the shelf commercial stirling engines for years. KHB have incorporated the whispergen engine into a wood pellet CHP plant which you can buy off the shelf and Precer have incorporated a whispergen stirling engine into there wood pellet off road buggy.
 
Jason LaVoy
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Steven Harris wrote:Jason, ... you want a dedicated heat sink for the 'cold' side of things. I would NEVER have the system based on the variable of the cold side of a thermosiphon system. I would want a dedicated heat sink for the cold side, that can be boiling water, yes, boiling water is the COLD side of a thermal electric heater, it'll never get above 212F, or I'd want a dedicated force air cooling system with fans and a heat sink.



Steve


That's what I was trying to describe. A hot water heating set-up that's a heatsink for the system.
 
r john
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Should be easy to modify a RMH to operate one of these or even use gas direct from a wood gasifier

http://cleanergy.com/solutions/#chp-systems
 
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