Forever Flasher (& flashlight)

[Mjolinor]

[snip]

750 millivolt thermopiles, (and 30 millivolt thermocouples)
out of old gas furnaces. A thermopile contains multiple
thermocouples. Could feed a Germanium transistor stepup forward
converter. For example see:
http://www.icca.invensys.com/uniline/c/c84.pdf

From what I've read, the thermocouples require a difference in heat to
work. You have to have one end cooled by a heatsink. So part of the
problem is to connect a couple of them in series to get a higher
voltage, but still insulate them so they don't short.

And then there's the problem of getting a hot enough source of heat to
give the needed voltage. I was checking for efficiency and found
this. I assume that this efficiency is more than a standard
thermocouple found in commercial appliances.

I remember Lucas in the UK developing a thermopile system for car battery
charging where the thermopile fitted round the car exhaust, they never
produced it because a significant market was alternators / dynamoes and the
business case didn't add up. Probably wouldn't work now becasue of the need
for a hot exhaust with catalytic converters.

 

[Stepan Novotill]

I was checking for efficiency and found
this. I assume that this efficiency is more than a standard
thermocouple found in commercial appliances.

RTG Module
Fuel mass 250WT
Voltage 28V
Power 20.5W
Mass 2.2kg
Specific power 9.4W/kg
Thermocouple type Silicon-Germanium
Thermocouple efficiency 7.6%
Number of thermocouples 8
Fuel pile PuO2/Iridium/Graphite

Silicon-Germanium? Thats a Peltier device more than a thermocouple:

http://jchemed.chem.wisc.edu/Journal/Issues/1996/Oct/abs940.html

Quote from above URL:
------------------------
Narrow band-gap semiconductors are generally used for cooling and for
power-generation applications.(9) Most Peltier coolers are made with
alloys of bismuth telluride (Bi2Te3), antimony telluride (Sb2Te3),
and/or bismuth selenide (Bi2Se3), the best materials to date for
near-room-temperature operation. At higher temperatures, lead
telluride (PbTe) is used. For power generation systems, which
typically operate at still higher temperatures, silicon-germanium
(Si-Ge) alloys are often used.

 

[Fred Abse]

Fuel pile PuO2/Iridium/Graphite

Real tree-hugger bait that, not to mention a bit difficult to get

Try asking for PuO2 and the force *will* be with you!

 

[Clint Sharp]

I remember Lucas in the UK developing a thermopile system for car battery
charging where the thermopile fitted round the car exhaust, they never
produced it because a significant market was alternators / dynamoes and the
business case didn't add up. Probably wouldn't work now becasue of the need
for a hot exhaust with catalytic converters.

I would have thought it would work post cat.