[Stoves] New type of electricity generator suiteable for stoves- early development stage.

[Ken Boak]

Crispin, List,

This topic seems to have degenerated into a discussion about the power 
dissipation of various CPUs - all completely irrelevant to the end goal of 
producing a small electrical power source or forced draught fan to be run 
from a woodstove.

The use of electrical resistive heating elements to prove the output of 
small heat engines is something that I have had some experience in.  Some 
years ago I ran performance tests on a small transferator engine ( a 
derivative of the Stirling engine) which was heated from a 150W domestic 
lightbulb, heavily thermally insulated, and drove a small generator salvaged 
from an old stepper motor. The resulting electrical output was measured as 
3W, with an upper temperature of 330 C.

Small hot air engines can be used to recover a low percentage of the heat 
from a hot body, such as a stove and make the energy available as either 
mechanical for working a bellows or a simple fan impeller or for conversion 
into electricity for battery charging etc.

The transferator engine lends itself to simple construction, utilising low 
cost stainless steel cooking containers. It was derived from an 1861 design 
by Laubereau, and widely researched by John Bourne and others in the UK in 
the 1970s as a small power source for model boat propulsion.  The Stirling 
Engine Society in the UK has recently taken an interest in this novel 
variant of the hot air engine.

Whilst exotic semiconductor thermoelectric generator modules might appear 
one solution to converting a small percentage of stove heat to electrical 
power, I suspect that the humble hot air engine, cheaply made in China, 
would be an equally valid approach to energy conversion in the sub 10W 
region.


regards,


Ken Boak