Thermal Management : How to go fanless in a small space?

[daslolo]

I tested the idea of using PGS as heatpipe and here is what I found:
1- SSM is impressive at dissipating heat, better than a heatsink with Kryonaut, 20C drop
2- it could be that there was too much distance between the heatsink and the source and Kryonaut isn't magic
3- making a heatpipe by binding two strands of PGS with Kryonaut then interfacing to the SSM with cryonaut doesn't increase dissipation
4- binding a large sheet of PGS to the heatpipe (with Kryonaut) drops 4C
5- if the contact between the SSM and the heatpipe isn't wide, there is no dissipation at all

[ebastler]

I tested the idea of using PGS as heatpipe and here is what I found:
1- SSM is impressive at dissipating heat, better than a heatsink with Kryonaut, 20C drop
2- it could be that there was too much distance between the heatsink and the source and Kryonaut isn't magic
3- making a heatpipe by binding two strands of PGS with Kryonaut then interfacing to the SSM with cryonaut doesn't increase dissipation
4- binding a large sheet of PGS to the heatpipe (with Kryonaut) drops 4C
5- if the contact between the SSM and the heatpipe isn't wide, there is no dissipation at all

I must still be missing something (or maybe you are). With all this work going into heatpipes -- where do the heatpipes deliver the thermal energy? I.e. how does the energy get removed from your device and dissipated into the environment eventually?

When you talk about SSM "dissipating" heat, do you use the SSM as a heatsink, in contact with the environmental air? I thought SSM is designed as a heat-conductive seal, to bridge gaps between heat sources and heatpipes, or heatpipes and heatsinks. So, how does the heat get out into the environmental air eventually? Have you found a fanless solution for that?  -- Thanks!

[daslolo]

I must still be missing something (or maybe you are). With all this work going into heatpipes -- where do the heatpipes deliver the thermal energy? I.e. how does the energy get removed from your device and dissipated into the environment eventually?

When you talk about SSM "dissipating" heat, do you use the SSM as a heatsink, in contact with the environmental air? I thought SSM is designed as a heat-conductive seal, to bridge gaps between heat sources and heatpipes, or heatpipes and heatsinks. So, how does the heat get out into the environmental air eventually? Have you found a fanless solution for that?  -- Thanks!

The SSM test in [1] was conducted like this: a vtx was set to 600mW power, left running for 10 minutes, temperature measured in the back of the PCB then the RF shield that also serves as heatsink was removed and SSM was applied instead, another 10 minutes then same measurement. Nothing else so I assume that we're seeing heat balancing through the SSM and heat dissipation through the air.