variable thermal resistance
variable thermal resistance
(OP)
Is there a component or technique which will allow me to vary the the thermal resistance between two parts?
I want to control the temperature of the first part by changing the amount of heat transferred to the second part. The second part is maintained at a colder temperature than the first.
It can be a mechanical, pneumatic or electrical control.
The only thing I have found in google was a couple of heat pipes used in satellites. They were very expensive.
TIA
I want to control the temperature of the first part by changing the amount of heat transferred to the second part. The second part is maintained at a colder temperature than the first.
It can be a mechanical, pneumatic or electrical control.
The only thing I have found in google was a couple of heat pipes used in satellites. They were very expensive.
TIA





RE: variable thermal resistance
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: variable thermal resistance
Variable Conductance Insulation
With insulation good enough to keep the converter temperature greater than 300°C for 24 hours after the engine is turned off, what keeps the converter from overheating while the engine is running at high speed? NREL has answered this challenge with a third innovation—variableconductance insulation. Certain compounds of hydrogen and metals release their hydrogen above a particular temperature and then reabsorb hydrogen below that temperature. Because hydrogen gas is a good heat conductor, releasing it into a vacuum "turns off" the insulation provided by the vacuum. The VCI catalytic converter has a small amount of metal hydride within the vacuum envelope. As the converter approaches its maximum safe temperature (about 900°C), the hydride releases its hydrogen, allowing excess heat to escape. As the converter cools back down, it reabsorbs the hydrogen, thus reestablishing the vacuum.
RE: variable thermal resistance
The 1st part will be between 80k and 200k.
The 2nd cold part will be at 77k.
The Peltier (TE cooler) I know do not get that cold.
Ivymike
Very interesting but I didn't give enough information to get the right answer.
RE: variable thermal resistance
And, IRstuff's idea is a good one too - I believe BiTe (Bismuth Telluride) thermoelectrics become more efficient at very low temperatures, although the specific alloy(s) used may change; check wikipedia. I know there are thermoelectric arrays used for cooling the optics? or PM tubes for infrared telescopes, a job that was once done with liquid nitrogen...
RE: variable thermal resistance
So the question revolves around unsupplied data, i.e., how much heat is to be transferred, and does the hot side stay at its temperature.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: variable thermal resistance