Microchannel Versus Porous Heat Sink!! 1

[thermcool]

Have anyone had experience with the Forced convection liquid cooling using Microchannel and sintered Porous heat sinks. Any suggestions, Which one is superior?

 

[ko99]

I've only had experience with air-cooled versions of these. Results are very application specific, but for what it's worth, microchannels worked better in my case.

The primary drawback of the porous material was despite it's high thermal conductivity it did not conduct well due to the imperfect contact between fibers.

ko (

http://www.ecooling.biz)

 

[thermcool]

Ko99,
Thanks for the reply,
you are right, According to my experiment with the forced liquid cooling through the microchannels and Porous Structure, I have experience that Microchannels are more efficient.
Actually, the bulk of the data at this time with me was not large enough to draw a valid conclusion so i try to get valuable views from the engtip forum professionals.

Further experimentation in this respect has help me to clarify the integrity of my data. The problem with the sintered structure lies more with the effective thermal conductivity of the saturated wick. Unlike the microchannel in which the heat flow is through the high conductive solid material, in the case of porous sintered structure the effective thermal conductivity decrease immensely. For copper with thermal conductivity of 380 W/mK, when saturated with water, thermal conductivity goes as low as 32 W/mK. So, in the porous structure major heat transfer just takes place from the borrom layers of the sink direcly in contact with the heat sink and less from the top due to the low conductivity along the thickness while for the microchannel (not exactly uniform) but better heat transfer takes place through the fins. Also, probability of formation of vapour along the heated wall (inside the wick bulk) also adds to performance degradation.

Contact between the porous struture and metal wall also dictates the heat transfer in porous structures.

Porous structures as heat sink in micro heat exchanger is not fully development technology as yet.