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I have a small device emitting up to ~90 Watts thermal power over a surface of 2x2 square centimeters. What is the best way (both commercially and DiY) for keeping the temperature of the device constant, maybe +- 1 degree at room temperature?

I have a thermoelectric element I could use, which has a surface area of 18x10 square centimeters for the cold plate. It is capable of removing up to ~75 Watts thermal power at 0 degrees temperature difference. How efficient will it be when I put the electric device on top of it? How much will the size difference effect the efficiency of the TEC? I know that it is rated for lower thermal powers, but it can be used as intermediary solution while keeping the device at lower powers.

The device itself is a solid state laser diode, which means that even small changes in the temperature (i.e. degrees) will shift the wavelength, something I do not want (I prefer having it at ~20 degrees). The diode can emit up to 90 Watts, depending on how much output power I request, but the upper limit is 90 Watts.

arc_lupus
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  • do you care about size/weight/cost/external power/ of the cooling system? Those are important constraints on the problem. – agentp Oct 19 '17 at 12:07

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A CPU cooler is the first thing that springs to mind DIY - Heatsinks coupled with forced convection are a tried-and-tested method of heat removal.

Provided the heat output from the diode is constant, and the room doesn't change, then this should remain at a constant temperature, albeit above the ambient temperature of the room.

In the application you describe, it seems that some form of thermostatic control would be required to keep the diode temperature constant as you vary the output power. DIY, This means hooking up a thermocouple to an arduino or similar, to control the power delivered to the thermoelectric element that you described previously. Adding a Heat-Sink/Fan to the hot side of the element will improve efficiency, and give you more control. Varying the fan speed will have an effect on the cold-side temperature, and this can be used in addition to simply varying the voltage into the element.

Jonathan R Swift
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