Numerical simulation of magnetic field effect on thermal and thermo-hydraulic performance and entropy generation in silicon microchannel heat sink under uniform heat flux

In this numerical three dimensional study, the effects of uniform magnetic field on thermal and thermo-hydraulic performance and entropy generation of water flow through a trapezoidal silicon microchannel heat sink, with four different inlet/outlet configurations, have been investigated in three dimensions. An electronic chip embedded on the base plate of heat sink generates uniform heat flux of 50kW/m2. Simulations have been performed for mass flow rates of 0.02, 0.03, 0.04 and 0.05g/sec and Hartmann numbers of 0, 2, 4, 8 and 16. The results show that, in overall the best configuration is the A-type arrangement, in which the flow enters to the center of the distributing chamber and exits from the center of collecting chamber. For this arrangment and a constant mass flow rate, with increasing Hartmann number from 0 to 16, thermal resistance reduces between 4.39% and 9.15%, theta between 1.81% and 7.91% and performance evaluation criterion between 81.61% and 87.15%, but total entropy generation increases between 10.13% and 77.07%. Also for a constant Hartmann number, with increasing the mass flow rate, average Nusselt number, frictional entropy generation and magnetic entropy generation increase and thermal resistance, theta, performance evaluation criterion, solid and fluid thermal entropy generations and total entropy generation decrease. In the best arrangement, the best thermal performance occurs in the mass flow rate of 0.05g/sec and Hartmann number of 16 and the best thermo-hydraulic and entropy generation performances occur in the mass flow rate of 0.02g/sec and Hartmann number of zero.