Thermoelectric power

Thread Starter

jpanhalt

Joined Jan 18, 2008
7,699
I have just acquired a vacation home that has hot water heating and can use either or both propane or an outside wood burner for a heat source. There is plenty of waste wood to burn (it is in the middle of a large area of woods). However, either source requires electricity to run a circulating pump. The required pump is not terribly big. A 1/12 HP might work. The standard is 1/6 to 1/4 HP.

Has anyone looked at using a thermo electric generator to charge a battery/inverter system, so the entire system could be independent, if needed, except for the wood? Typical water temperatures in the heating system ranges from 60°C to 82°C. It is a low pressure system so steam is probably out of the question.

I was pleased to find this device: http://customthermoelectric.com/tecs/pdf/12711-5L31-09CQ_spec_sht.pdf

It would not take many of them to run a 1/4 HP motor.

John
 

retched

Joined Dec 5, 2009
5,197
How about a thermal loop rather than a pump? That should be even more efficient.

A lot of homes that use solar water heaters use a loop rather than a circulating pump.

Easiest way, insulate everything except the last 15ft of line. That 15ft of cooling will allow the water to cool enough to start and continue a current. As long as the incoming cool water is at the bottom of the storage tank.
 
Last edited:

3ldon

Joined Jan 9, 2010
82
I have just acquired a vacation home that has hot water heating and can use either or both propane or an outside wood burner for a heat source. There is plenty of waste wood to burn (it is in the middle of a large area of woods). However, either source requires electricity to run a circulating pump. The required pump is not terribly big. A 1/12 HP might work. The standard is 1/6 to 1/4 HP.

Has anyone looked at using a thermo electric generator to charge a battery/inverter system, so the entire system could be independent, if needed, except for the wood? Typical water temperatures in the heating system ranges from 60°C to 82°C. It is a low pressure system so steam is probably out of the question.

I was pleased to find this device: http://customthermoelectric.com/tecs/pdf/12711-5L31-09CQ_spec_sht.pdf

It would not take many of them to run a 1/4 HP motor.

John
You might get 2 watts out of those things when you run them backwards.
If you have a lathe I'd build a sterling engine.
 

Thread Starter

jpanhalt

Joined Jan 18, 2008
7,699
Good point, I grabbed the wrong link. It seemed too good to be true and was. I have more than a little problem reading. Here is the correct link:http://customthermoelectric.com/powergen/pdf/1261G-7L31-10CX1_spec_sht.pdf

As for a Stirling engine, from further reading, a low temperature differential version would have to be quite large for even that low a power output.

I guess I am stuck with a small diesel generator.

John

Edit: Right now, it is just a second home. Once I am there most of the time, I may experiment with using pentane or ethanol as the working fluid in a closed system. Their vaporization and condensation temps seem about right for a system that is limited to 180°C for the hot side. The whole concept of being completely independent from outside energy sources, except wood, is just too appealing to resist. jpa
 
Last edited:

3ldon

Joined Jan 9, 2010
82
Good point, I grabbed the wrong link. It seemed too good to be true and was. I have more than a little problem reading. Here is the correct link:http://customthermoelectric.com/powergen/pdf/1261G-7L31-10CX1_spec_sht.pdf
its not too good to be true because you posted to the wrong link, its too good to be true because those things are so in efficiant.
As for a Stirling engine, from further reading, a low temperature differential version would have to be quite large for even that low a power output.
why is the hot side limited to 180C?


Edit: Right now, it is just a second home. Once I am there most of the time, I may experiment with using pentane or ethanol as the working fluid in a closed system. Their vaporization and condensation temps seem about right for a system that is limited to 180°C for the hot side. The whole concept of being completely independent from outside energy sources, except wood, is just too appealing to resist.
That it what I would do, except I would use isobutane/propane, not pentane
If you can manage to get the rotor to float on an "air" bearing, then you can completly enclose the radial inflow turbine and use a direct drive air core alternator.
 

Thread Starter

jpanhalt

Joined Jan 18, 2008
7,699
why is the hot side limited to 180C?
In my first post, I converted to Celsius, but screwed up here. Actually, the hot side is limited to 180°F, another error. I have had some severe lower back spasms being treated with pain killers (day 6). I am not quite sober. Sorry for all of my recent slips.

In any event, it is a hot water system, not steam. The control valves are set with an 82°C limit.

Your idea for a wetted alternator is appealing (wetted with the working fluid). One of the circulating pumps for the water is constructed that way. I joined the "hot air" forum, but it seems mostly related to solar and is not very active.

Do you have any leads at all to a design of an alternator like we are discussing?

John
 

3ldon

Joined Jan 9, 2010
82
Due to the low temperature I would look into purchasing a geothermal heat engine off the shelf.

I do know of a few commertial products that basically run an off the shelf scroll compressor backwards, (lost the links a year or so back), this is also a home brew solution if you have 15KW of heat available to run a 3 kw compressor, i don't know if you can get anything smaller.(basically remove the check valve and that's all there is to it)
 
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