Numerical investigating the gas slip flow in the microchannel heat sink using different materials

In this work, slip flow of helium gas has been studied in a three dimensional rectangular microchannel heat sink with 11 microchannel and 10 rectangular fins. Helium gas flow is considered ideal and incompressible. The finite volume method with using coupled algorithm is employed to carry out the computation. To validate the present work, comparison with numerical and experimental studies is done and it is seen that the computed results have good agreement. To investigate the effect of fins and walls material on heat sink performance, all simulations are carried out and compared with each other for three materials consisting of aluminum, silicon and copper. The results show that along the microchannel, local Knudsen number decreases. Also thermal resistance increases continuously with increasing Knudsen number from 0.006 to 0.048. The results indicate that for various inlet Knudsen numbers, copper heat sink has the lowest thermal resistance. Furthermore, copper heat sink has the highest average Nusselt number for Knudsen number higher than 0.024 but for Knudsen number lower than 0.024, silicon heat sink has higher average Nusselt number than copper heat sink.