A NUMERICAL STUDY OF THE THERMAL PERFORMANCE OF MICROCHANNEL HEAT SINKS WITH MULTIPLE LENGTH BIFURCATION IN LAMINAR LIQUID FLOW

A rectangular, straight microchannel heat sink with multiple length bifurcation has been designed, and the corresponding laminar flow and thermal performance have been investigated, numerically. Five different cases with multiple length bifurcation and various arrangements are investigated, as well as one case without bifurcations. All laminar fluid flow and surface heat transfer results are obtained using computation fluid dynamics, and a constant heat flux thermal boundary condition is applied to the heated surfaces. The inlet velocity ranges from 0.6m/s to 1.4m/s, with the corresponding Reynolds number from 220 to 520. The local pressure, velocity, temperature distributions, and averaged heat transfer coefficient are presented. The overall thermal resistances subjected to inlet Reynolds number are evaluated and compared for six different microchannel heat sinks. Numerical results show that the thermal performance of the microchannel heat sink with bifurcation flow is better than that of the corresponding straight microchannel heat sink, especially the heat sink with longer length bifurcation. The usage of multiple length bifurcated plates in microchannel heat sink can reduce the overall thermal resistance by a factor of up to 2, and make the temperature of a heated surface more uniform, especially for the heat sink having a short bifurcation in the center and two bifurcations near the sides (case 4). It is suggested that proper design of the multiple length bifurcation could be employed to improve the overall thermal performance of microchannel heat sinks.