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From: larry@kitty.UUCP
Newsgroups: sci.electronics
Subject: Re: Russian Thermoelectric Generator
Message-ID: <1630@kitty.UUCP>
Date: Tue, 3-Mar-87 22:27:54 EST
Article-I.D.: kitty.1630
Posted: Tue Mar  3 22:27:54 1987
Date-Received: Fri, 6-Mar-87 01:41:19 EST
References: <24300001@silver>
Organization: Recognition Research Corp., Clarence, NY
Lines: 66
Summary: Thermal batteries...

In article <24300001@silver>, commgrp@silver.bacs.indiana.edu writes:
> During World War II, the Soviet Union manufactured a thermoelectric
> generator which was used to charge lead-acid batteries for radios.  It
> replaced the chimney of a kerosene lamp, and looked like a radial array
> of fins.
> 
> Does anyone know details of this device?  One might surmise that it was
> an array of high-current thermocouples, probably made of inexpensive
> materials, e.g., iron and copper, but it must have produced at least 2.2
> volts.

	I don't know anything about the above Russian device, but I can
comment about a "thermal battery" which was developed during World War II
for use as a power source for electronic proximity fuses used in artillery
shells and rockets.
	This thermal battery was developed by the Wurlitzer Company (of
piano, organ and jukebox fame).  Wurlitzer turned their resources from
manufacturing consumer goods to military materiel during the war, as did many
other companies.
	This thermal battery consisted of two thermopiles (i.e., an array of
thermocouple junctions in series-parallel): one for low-voltage, high-current
for filament power, and the other for high-voltage, low-current for plate B+
power.  The thermopiles were powered by the hot exhaust gases and burning
propellant of mortar shells, anti-submarine rockets, etc. 
	The thermal battery is an interesting device since it must be capable
of several years shelf-life, but yet be ready for instant use with a high
degree of reliability.  The actual operational life of the battery is usually
measured in seconds.
	Thermal batteries are still used in the above and other military
applications, but they are no longer made by Wurlitzer - who got out of
that military business during the 50's.  Thermal batteries generally use a
a semiconductor as one or both of the thermocouple elements (after all,
we want power, not temperature -> voltage linearity here :-) ).  I don't
recall what Wurlitzer used during World War II, but contemporary thermal
batteries use such materials as lead telluride, germanium-silicon alloy,
and a silver-antimony-tellurium alloy.  Thermal batteries are not known for
efficiency; it is generally less than 5%.
	Another type of battery used in artillery applications (where the
shell is propelled from a gun with an external explosive) is a primary
cell whose electrolyte is sealed in a frangible container which ruptures
upon acceleration.
	I have always been somewhat bemused by the design philosphies behind
the above batteries: here's a battery which must be reliable, have a shelf
life of many years, have an operational life measured in seconds, and yet
the battery can never be "tested" prior to use! 

> A device called the "Compact Silent Generator" now being marketed in the
> US generates 5 watts at 12 v., probably contains Peltier semiconductor
> refrigeration units operating in reverse.  It's a nice gadget but $119
> is too much!

	I have seen thermoelectric generators manufactured by Westinghouse
that put out 50 watts and use propane, butane or natural gas fuel with an
input energy around 15,000 BTU/hr.  A flame heats a junction array to a
temperature around 250 deg C.  The 50-watt size is not very large: about
1 foot in diameter and 3 feet high, including "chimney".  These generators
are handy for telemetering and control purposes on gas pipelines where
commercial electric power is not available.  The operational philosophy
is to have the thermal battery trickle charge ni-cads, which contain the
reserve energy needed to operate motor-driven valves, and for use during a
thermal generator "flameout".

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
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