Thermal and hydraulic performance of rectangular microchannel heat sinks with trapezoidal porous configuration

In this article, the thermal and hydraulic capacity of a rectangular microchannel heat sink with different trapezoidal porous configuration's inlet heights Hin and outlet heights Hout are examined. A three-dimensional model is used for microchannels with miscellaneous trapezoidal porous configuration's inlet and outlet heights, and the laminar fluid flow and conjugate heat transfer equations are numerically solved. Darcy-Brinkmen-Forchheimer equation is utilized for transport through the porous region. For microchannels with miscellaneous porous distribution's inlet and outlet heights, the Nusselt number, pressure drop and figure of merit (FOM), a criterion for the assessment of heat transfer and hydraulic performance simultaneously, are calculated and compared to one another and a microchannel without porous medium. It is identified that with the increase of Hin and Hout, both the Nusselt number and pressure drop increase. However, at low Hout, microchannels with low Hin possess higher FOMs, the parameter that evaluates the hydraulic and thermal performance at the same time. In contrast, at high Hout, microchannels with higher Hin have higher FOMs. Furthermore, the effect of the inlet velocity and porosity are studied on the thermal and hydraulic behaviors. Reducing both the inlet velocity and porosity result in a better hydraulic and thermal performance combined, higher FOMs.