- Jan 29, 2012
Not missing it, but unfortunately the heat sink with its interface is poorly connected (thermally) to the host. Its great that copper can transfer the heat really quickly away from the sink, but getting rid of that heat is a problem when it hits the 3 Wm-1K-1 grease barrier blocking its heat transfer out of the sink. In both cases with Al and Cu this will be the limiting factor.You seem to be missing that the "heatsink" doesn't do any dissipation. Its only a storage and movement conduit for the heat. All dissipation is done by the host. We use the term heatsink but in standard terms they don't actually do any by definition heatsinking. They should be called heat transferrers.
If you assume the interface is perfect then you still have the efficacy of the aluminium host as your limiting factor to cooling the sink. If you heat both sinks to the same temp they still are limited by the aluminium host and its intrinsic thermal conductivity and effectiveness at dissipating that heat. :beer:
Edit: If you want to have a play around with some numbers this might be of interest:http://www.roymech.co.uk/Related/Thermos/Thermos_HeatTransfer.html
I havent had the time to read though it all but it looks like it could be useful.