[Stoves] TEGs

[ajheggie at gmail.com]

[Default] On Fri, 20 May 2016 23:45:55 +0000 (UTC),Nsamba Hussein
Kisiki <nsambahussein2000 at yahoo.com> wrote:

>Dear Prof Paul,
>Many thanks for your email. I am indeed passionate about retrofitting TEGs to already existing improved cooking stoves to increase their functions especially for the end user to be able to watch a television, able to treat water (UV treatment), able to listen to radios, provide LED lighting as well as charge mobile phones alongside biochar production.
>I assume this will make great contributions to the developing world, considering the fact that about 1.4 billion people have no access to power and since 2.8billion people are expected to be relying on traditional biomass for cooking by 2030.
>I assume the above could be achieved if upto 5Wh of power can be achieved from a conventional cooking stove retrofitted with TEG. 
>I am proposed to integrating the technology with the fan which could use could use less than a watt to supply more air to the stove and improve on the stove combustion efficiency, to further reduce on the dangers arising from indoor pollution.

Hussein


I too would be interested in your proposed use of TEGs.  How would you
propose to retrofit them? The problems I see is that they have
potential where there is waste heat, engine manufacturers have been
researching TEGs for exhaust heat recovery as an electricity source
for some time, but where in a cook stove can one be integrated?

The Philips stove seemed to parasitise the heat from the cooking which
presumably requires more fuel.

Modern semiconductor TEGs using bismuth compounds have to be protected
from excessive temperature (above 200C) but still only convert ~5% of
the total heat flux  through them. TEG air distribution fans sold here
for use on wood burning stoves have a bimetallic strip built into the
base which decouples the TEG from the heat source as the temperature
goes up.

As alternative is a bi metal TEG but their conversion efficiency is
below 1% I believe. They do have the advantage of enabling a high
temperature difference across them.

Honeywell had a metal thermopile flame sensor that did not need
amplification to control a solenoid and I always wondered how many
junctions and what metals they used.

Once you can allow a high temperature across the TEG there is scope
for recycling the waste heat into secondary combustion air so the
total heat cost is less.

AJH