SECOND LAW CONSTRUCTAL DESIGNS OF HYBRID SINGLE-FINNED AND STAGGER-FINNED MICROCHANNEL HEAT SINKS

The 3-D models of the hybrid rectangular single-finned and stagger-finned microchannel heat sink are established, the constructal designs are performed with the fixed microchannel heat sink volume and the volume ratio of the internal fin to the heat sink, respectively. The minimization of dimensionless entropy generation rate is taken as the objective, the cross-section aspect ratio of fin(s) and staggered spacing of fins are taken as the design variables. The results show that, thin and tall fin in the hybrid rectangular single-fined microchannel heat sink can reduce the maximum temperature difference and temperature gradient inside the hybrid microchannel heat sink, increase the temperature uniformity of the hybrid microchannel heat sink, hence significantly reduce the entropy generation rate. Staggering the rectangular single-fin in microchannel can further reduce the entropy generation rate. The spacing with appropriate size of the staggered fins can avoid the local flow stagnation and the local flow disturbance, hence significantly reduce the entropy generation rate. Releasing the two constraints of the staggered spacing of fins and the number of staggered fins simultaneously can further reduce the entropy generation rate than just releasing only one of the constraints can do, the twice minimized entropy generation rate is reduced by 56.86% compared with entropy generation rate of finless MCHS. And the larger number of staggered fins is beneficial to reduce the entropy generation rate.