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

Abstract

In this article, the thermal and hydraulic capacity of a rectangular microchannel heat sink with different trapezoidal porous configuration’s inlet heights $H_{in}$ and outlet heights $H_{\mathit{out}}$ 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 $H_{in}$ and $H_{\mathit{out}},$ both the Nusselt number and pressure drop increase. However, at low $H_{\mathit{out}},$ microchannels with low $H_{in}$ possess higher FOMs, the parameter that evaluates the hydraulic and thermal performance at the same time. In contrast, at high${\mathrm{ }H}_{\mathit{out}},$ microchannels with higher $H_{in}$ 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.

Keywords:

• Heat transfer; microchannel heat sinks; porous medium; pressure drop; trapezoidal configuration

Disclosure statement

No potential competing interest was reported by the authors.