Heat removal 1

[Dougt115]

I need some ideas for heat removal.

The heat source is inside an insulated container with a limited access area, .5cm^2. The units total volume is 200 cm^3. The temperature range is 70 to 160°F, I would like to keep it down to 110°F.

I don't need to remove all of the heat but 30 to 50% would be great. The duty cycle of the heat source is periodic and equals about 20% of the time during a 30 period. On for .3 seconds off for 1.2 seconds.

There is no room for fans or volume for heat sinks and weight is an issue. Also it has to pass a hinge so it needs a flex point at the insulation barrier.

The motion is reciprocating so I am trying to use springs but the limited area is putting a real constraint on me.

Any suggestions that I could pursue would be appreciated.

 

[IRstuff]

The heat source is inside an insulated container with a limited access area, .5cm^2. The units total volume is 200 cm^3. The temperature range is 70 to 160°F, I would like to keep it down to 110°F.

I don't need to remove all of the heat but 30 to 50% would be great. The duty cycle of the heat source is periodic and equals about 20% of the time during a 30 period. On for .3 seconds off for 1.2 seconds.

>> the above is logically inconsistent. In order to keep the temperature at 110F, ALL of the heat must be removed. What sets the temperature is the thermal resistance through which ALL the heat travels.

There is no room for fans or volume for heat sinks and weight is an issue. Also it has to pass a hinge so it needs a flex point at the insulation barrier.

>> Given the constraints, only heat pipes and thermal straps are plausibly applicable. Even the heat pipe would need to be coiled to provide the degree of freedom necessary to support a hinge motion.

TTFN
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[chicopee]

what is the heat source and what is the temperature at the heat source?

 

[Dougt115]

The heat source is an adjustable hydraulic damper. The control valve locks up at 160°F.

Run the damper for a period of time, about 20 minutes, and it will heat to 160°F and lock up the control valve. (But the time needed is closer to 40 minutes.) Then stop and it will begin to cool, when it goes below 160° it unlocks and begins to work. Fine. I am trying to make it so that I can run it longer, all 40 minutes, before it reaches the 160° mark.

What I am trying to get rid of is the excess heat to keep it below 160°. Or about 50% of the generated heat.

I will look at the heat straps as I don't think the heat pipes will flex enough. Estimated life is 2 million cycles at 15°.

 

[LittleInch]

If your access hole is 0.5 cm2 I make this an 8mm hole correct?

Your only chance is possibly to inject something like butane or other liquid which vaporises at normal pressure and hence cools down and then flows out through the rest of your hole, but has low weight. You could only insert a small flexible tube so not sure how much cooling you would get, but without some idea of the heat output and overall sketch of this contraption it is very difficult to see any other means.

When you say the control valve "looks up" at 160F, what exactly do you mean?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[MintJulep]

If you have heat producing equipment that you need to keep cool don't put it inside an insulated container.

 

[IRstuff]

I think you need to provide some pictures. Unclear how much volume is available to do anything

Phase change material is one approach to delaying the onset of a threshold temperature.

TTFN
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[billhen]

I think MintJulep is on the right track. I suspect the insulation is for personnel protection and could be removed and replaced with a wire screen permitting the heat to leave the system faster and gain time to max. heat up. Just how much would require all of the shape, material, fluid details, and analysis.

If this heat build up is influence by a recycle stream, you might look for a very small inline chiller in the lab and microlab equipment world.