Fun with Voltage Controller Heatsinks

[LostCause]

I would try the aluminum heatsink first. If that doesn't work out, I'd try building a simple cooling loop out of a heater core and an electric water pump. Using ethylene glycol and raising the pressure ~5psi, you should be good to 230F. If you build an efficient cooling system, the controller shouldn't reach those temps anyways.

I agree with others that the heatpipe is overly complex. If you do decide that route, I believe the working fluid is often alcohol...but I'm not sure.

- LostCause

[Randy]

I read once about someone making a butane heatpipe (with plastic pipe) for his motor controller. Sounded wacky, but apparently worked quite well, other than leaking and needing the occasional refill. The radiator was next to the windshield.

Heat pipes are actually pretty common, but there are a couple of crazy ideas here. The anti-freeze mixture would separate when evaporated, so it won't protect against freezing. Also, if you attach a vacuum to it, it will all boil off, leaving you with no working fluid. They initially evacuate the heat pipe, especially with water, but then they seal it up. If it's not static, it's a heat pump, not a heat pipe.

[Dradus]

Originally Posted by Randy

I read once about someone making a butane heatpipe (with plastic pipe) for his motor controller. Sounded wacky, but apparently worked quite well, other than leaking and needing the occasional refill. The radiator was next to the windshield.

Heat pipes are actually pretty common, but there are a couple of crazy ideas here. The anti-freeze mixture would separate when evaporated, so it won't protect against freezing. Also, if you attach a vacuum to it, it will all boil off, leaving you with no working fluid. They initially evacuate the heat pipe, especially with water, but then they seal it up. If it's not static, it's a heat pump, not a heat pipe.

The antifreeze isn't a must, its just the first thing that sprang to mind since I have a spare bucket full of it in my garage. If the butane worked without introducing pressure or vacuum then maybe thats what I'll eventually try, I'd just make sure to seal it properly.


It is a wacky idea, thats probably why I like it.

Most things are wacky if you think about them long enough.

[Ryland]

For the temperature you are talking about using 90% rubbing alcohol as the working fluid should work pretty well, for colder temperatures you can use things like propane, freon, butane, if you get really hot then you start to use things like water, like the evacuated tube solar hot water heat pipe collectors do, and with them it's an ounce or less of water, not much at all.

[Randy]

Originally Posted by Dradus

If the butane worked without introducing pressure or vacuum then maybe thats what I'll eventually try, I'd just make sure to seal it properly.

The problem was the clear tubing he was using was permeable to the butane. But it looked cooler than something that wouldn't leak, like copper pipe. Butane is the stuff in lighters (you can get bulk-refill canisters), and it's under pressure, but not a lot... about 30 psi at room temp. It's probably the lowest pressure you could get without having to support a vacuum, as air in the heat pipe will keep it from working well.