[Stoves] Gas lamp efficiency

[AJH]

On Sat, 23 Sep 2006 10:26:58 GMT, steve wrote:

> 
>> I'm still open to suggestions, it strikes me a metal to
>> metal one is feasible for a 3kW(t) stove requiring a 3W(e)
>> fan but for an efficient device to provide some light and
>> space heat then the semiconductor TEG looks more
>> appropriate.
>
>TEGs are very delicate mechanically - they are made with
>ceramic plates ! So their mounting surfaces have to be
>exquisitely flat, and the clamping forces applied have to be
>very evenly applied. Either that, or you solder onto them
>directly, which is at least equally fraught, if not  more
>so. That would worry me in a practical device.  I am trying
>to think of a suitable topology and materials of
>construction that we could use to use metal T/C.
>
>Looking at "Global Thermoelectric" http://www.globalte.com
>lists several thermo-generators, the smallest, at 15W 12V
>output has an efficiency of only 2.7% from Propane to
>electricity.  Their largest unit 110W @6.7 V manages 4%, and
>thats with semiconductor elements.
>
>Steve

OK so it's looking quite a bit worse than my initial 6% scenario but
we do have Crispin's suggestion that in bulk the price of these things
falls quite a bit.

I take Kevin's point, and indeed always have, that getting a stove
that's "good enough" in terms of pollution is the aim and perfection
is a waste of resource but when combined with a need for space heat
and light there may be a substantial demand for such a device.

For the simple fan stove we need an electrical generator that converts
about 0.1% of the total thermal power to electricity as long as all
the heat is recycled. 

AJH