Numerical Simulation of Heat Transfer Enhancement in Periodic Converging-Diverging Microchannel

Heat transfer performance and fluid flow in three-dimensional converging-diverging microchannel of circular cross-section are studied numerically. Three different types of microchannel, diameter 100 mu m and length 6.125 mm each are used for simulation for the Reynolds number range of 50 to 1000. The effect of Reynolds Number, converging-diverging angle and converging-diverging cross-section length on pressure drop and heat transfer in proposed microchannels are investigated and discussed. The result indicated that the flow in the converging-diverging cross-section induces stronger recirculation and flow separation, which decreases with decreasing the converging and diverging angle and increases with increasing aspect ratio. However, the local and global heat transfer performances in the channels are improved by the converging-diverging cross-section at the expense of higher pressure drop compared to the straight channel with the same cross-section. Conversely, special attentions are given to analyze the thermal performance of microchannels through variation of thermal resistance with pumping power. (C) 2015 The Authors. Published by Elsevier Ltd.