[Stoves] Gas lamp efficiency

[AJH]

On Thu, 21 Sep 2006 08:28:54 GMT, steve wrote:

>That's one of my fields. I'd be happy to help.

Well it's about knowing the possibilities and their limitations
really. We've talked about Thermo Electric Generators for some time. A
number of firms have advertised products that are based on
semiconductor technology that offer electrical output an order of
magnitude greater than simple metal-metal junction TEGS. I have seen
one paper suggesting a "silicide" based one could offer 12% conversion
from a hot side of 550C and ambient cold side.

Given I am sold on forced draught burning then we seem to have most of
the elements needed, a fan for both forced draught and simultaneously
cooling the TEG plus it recycles waste heat to the fire. So small
efficient wood fire with a TEG powering 20W of bright white LEDs does
seem achievable, maybe with cooking on top. NB for our light we are
talking about less than a tenth of the power we normally need consider
for a cooking stove.

Having said all that I am aware from the photos  of wallwarts strewn
around the stoves at the stoves camp, that fan powered stoves do not
feature TEGs, not even the Phillips contribution though it was one of
its features we were told.

http://www.hi-z.com/websit03.htm

shows a device that appears to fit the bill 14W @ 1.65 Volts but its
impedance suggests you won't achieve very good power matching. 
Note they only claim at best 5% efficiency for the given heat flux.
With a stove only reckoned to deliver 30% of its heat to a pot I
wonder how much we could get through the TEG?? Also the cost at $124
is ten times likely more than our "clients" could stand. So that by
any reckoning my 6% and 12% conversion efficiencies are a hard target
to hit.

AJH