3 ms·

I meant in air. I made a while ago an Unmanned underwater vehicles (UUV), the on-board SBC (nvidia jetson), despite having a waterproof case I still did have he

I meant in air. I made a while ago an Unmanned underwater vehicles (UUV), the on-board SBC (nvidia jetson), despite having a waterproof case I still did have heat shrink tube on it and the connectors as an extra measure, obviously it’s not as sophisticated as the OP coating tech, but the there were an around 45% thermal increase, would be interesting to see some benchmarks numbers on that!

bruce511 3y ago
I agree, numbers would be interesting. My guess is that the effect in air is minimal, because the coating is so thin. If the coating had impressive thermal properties (such a steep thermal gradient) , even at such tiny thickness, it would have other applications (where thermal insulation is desired.)
tonyarkles 3y ago
I’m curious about multiple things! - what kind of heat shrink was it? There’s the usual thin plastic type and the gooey double-layer type. I’m actually not sure which one would be worse for heat… the gooey type seems like it’d be a thermal insulator but maybe with that much close contact it might be a decent thermal conductor. The regular thin plastic type would probably have been trapping a bunch of air around the heatsink (dramatically reducing the surface area for convection) - how big was the waterproof enclosure? The stagnant air inside there seems like it would probably heat up pretty well. If the enclosure was plastic it would probably conduct that heat into the water quite poorly. If you end up in a similar situation down the road, you’re probably way better off making an aluminum plate with a raised pad that you can mount the CPU to directly and use a gasket to allow the outside of the aluminum to conduct the heat directly into the water. Assuming you’re not going to crazy depths I’d expect that to be viable and you’ll probably get “better than forced air” performance out of it
- tamimio 3y ago
  > what kind of heat shrink was it? The ones on the plugs/connectors were the usual ones, the one I put on the SBC was thick as I couldn’t find a thin big one, and I was afraid to damage the SBC while applying the heat, so maybe it was the double layer type? But I don’t know. >how big was the waterproof enclosure? It was big enough to house the SBC (jetson Nano) and some other components needed for the UUV, not exact size but probably ~20x15cm. > better off making an aluminum plate with a raised pad that you can mount the CPU to directly and use a gasket to allow the outside of the aluminum to conduct the heat directly into the water That’s actually a really smart idea, thanks!! I did have a heatsink (those small ones fit the cpu size) but it was under that heat shrink tube so probably made things worse. > Assuming you’re not going to crazy depths We didn’t exceed 50m depth, still I was concerned the pressure might leak some water into the enclosure and this I used the heat shrink.

bruce511 3y ago

I agree, numbers would be interesting. My guess is that the effect in air is minimal, because the coating is so thin. If the coating had impressive thermal properties (such a steep thermal gradient) , even at such tiny thickness, it would have other applications (where thermal insulation is desired.)

tonyarkles 3y ago

I’m curious about multiple things! - what kind of heat shrink was it? There’s the usual thin plastic type and the gooey double-layer type. I’m actually not sure which one would be worse for heat… the gooey type seems like it’d be a thermal insulator but maybe with that much close contact it might be a decent thermal conductor. The regular thin plastic type would probably have been trapping a bunch of air around the heatsink (dramatically reducing the surface area for convection) - how big was the waterproof enclosure? The stagnant air inside there seems like it would probably heat up pretty well. If the enclosure was plastic it would probably conduct that heat into the water quite poorly. If you end up in a similar situation down the road, you’re probably way better off making an aluminum plate with a raised pad that you can mount the CPU to directly and use a gasket to allow the outside of the aluminum to conduct the heat directly into the water. Assuming you’re not going to crazy depths I’d expect that to be viable and you’ll probably get “better than forced air” performance out of it

tamimio 3y ago
> what kind of heat shrink was it? The ones on the plugs/connectors were the usual ones, the one I put on the SBC was thick as I couldn’t find a thin big one, and I was afraid to damage the SBC while applying the heat, so maybe it was the double layer type? But I don’t know. >how big was the waterproof enclosure? It was big enough to house the SBC (jetson Nano) and some other components needed for the UUV, not exact size but probably ~20x15cm. > better off making an aluminum plate with a raised pad that you can mount the CPU to directly and use a gasket to allow the outside of the aluminum to conduct the heat directly into the water That’s actually a really smart idea, thanks!! I did have a heatsink (those small ones fit the cpu size) but it was under that heat shrink tube so probably made things worse. > Assuming you’re not going to crazy depths We didn’t exceed 50m depth, still I was concerned the pressure might leak some water into the enclosure and this I used the heat shrink.