Last week there was an interesting debate about raising the altitude of a satellite by using magnertic fields.
Carrying on the wacky ideas theme, I've been looking at producing power by using thermocouples and not solar cells.
Question: Does anyone know the 'current' or the impedance of the voltage source represented by a thermocouple?
A thermocouple generates an emf (voltage) proportional to the difference in temperature between its two junctions.
Given that we know a white object in space gets very cold, while Aluminium gets very hot it's interesting looking at the possibility of thermocouple power....Even if it's just to understand its limitations
A thermocouple can be made very small so it should be possible to manufacture an array of them in a reasonable space.
Example: A junction of two wires, one made from constantan and one from Chromel will generate a voltage of 58 microvolts for every degree difference between the junctions.
That means for a 100 degree C difference you generate 5.8mV. For 350 junctions in a chain you generate 2.03 V and for 6 chains (if you wanted to risk all those junctions in series) you could have 12.18V
But.........how much power can you draw from it ??
73
David
Carrying on the wacky ideas theme, I've been looking at producing power by using thermocouples and not solar cells.
To demonstrate Radioisotropic Thermoelectric generators for spacecraft for our students, we use the modern day higher efficiency Peltier junctions, that come something like 144 to the square inch module and have about 8 modules all in series, and we get about 3 volts at enough current to run a small solar-cell motor, maybe 20 mA. That's with the heat of 6 candles (about 300 watts of heat). At 20 mA and 3 volts, then that's about 0.06 watts for an efficiency of about .00002 efficiency.
We decided it is of no practical value unless you have free nuclear heat out at Pluto where you also have plenty of cold and no sunlight.... We also considered making a black/white solar thermo panel and conlcuded that we would be far-far better off with cheap solar cells than thermoelectic generation...
Bob, WB4aPR
Like one of these... http://www.hi-z.com/websit04.htm
More Thermoelectric Generator Manufacturers referenced here: http://www.peltier-info.com/generators.html
73, Steven WI2W
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of G0MRF@aol.com Sent: Monday, February 26, 2007 6:47 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Thermocouple power
Last week there was an interesting debate about raising the altitude of a satellite by using magnertic fields.
Carrying on the wacky ideas theme, I've been looking at producing power by using thermocouples and not solar cells.
Question: Does anyone know the 'current' or the impedance of the voltage
source represented by a thermocouple?
A thermocouple generates an emf (voltage) proportional to the difference in temperature between its two junctions.
Given that we know a white object in space gets very cold, while Aluminium gets very hot it's interesting looking at the possibility of thermocouple power....Even if it's just to understand its limitations
A thermocouple can be made very small so it should be possible to manufacture an array of them in a reasonable space.
Example: A junction of two wires, one made from constantan and one from Chromel will generate a voltage of 58 microvolts for every degree difference between the junctions.
That means for a 100 degree C difference you generate 5.8mV. For 350 junctions in a chain you generate 2.03 V and for 6 chains (if you wanted to risk all those junctions in series) you could have 12.18V
But.........how much power can you draw from it ??
73
David
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Subject: [amsat-bb] Re: Thermocouple power
Like one of these... http://www.hi-z.com/websit04.htm
More Thermoelectric Generator Manufacturers referenced here: http://www.peltier-info.com/generators.html
Apparently these produce a lot more power than we were getting from our modules, probably because we were operating at much lower temperature differences in the student lab. At the 15 Watt output of the above module example, it might be fun to attach some of these to the exhaust flue on my boiler! WB4APR
At 03:46 PM 2/26/2007, G0MRF@aol.com wrote:
Carrying on the wacky ideas theme, I've been looking at producing power by using thermocouples and not solar cells.
I think it probably could be done. Would require some really intense thermal engineering. An introduction to some of the issues can be found at http://www.tellurex.com/cthermo.html Of course this talks about performance of the thermoelectric devices and does not discuss how one would integrate them into a spacecraft.
participants (4)
-
Franklin Antonio -
G0MRF＠aol.com -
Robert Bruninga -
Steve Holly