Effect of wall contact angle on the conjugate heat transfer for flow boiling processes in rectangular microchannels

Abstract

Microchannel boiling heat transfer offers a promising solution to address extreme high heat flux in miniaturized and high-density integrated electronic devices. In this work, we performed numerical studies to elucidate the complex flow boiling process in a square microchannel using the open-source platform OpenFOAM. The governing equations of the two-phase flow was solved based on the finite volume framework, and the surface tension together with phase change models were incorporated to study the wettability and conjugate heat transfer in the microchannel. First, the stability of the liquid film shows that smaller contact angles lead to thicker and stable liquid films near the solid wall, while larger contact angles result in thinner and fragile films. Second, the heat transfer, represented by the dimensionless parameter Nu, shows that smaller contact angles result in higher and more uniform distribution of Nu. The velocity gradient causes the Nu to be higher for the sidewalls than for the bottom wall. The contact angle also affects the peak value of Nu. Small contact angles result in large solid wall temperature gradients and more efficient heat transfer. Finally, the simulation results show that smaller thermal conductivity of the solid results in larger temperature gradient in the flow direction, implying that the conjugate heat transfer is less efficient. Overall, the present numerical findings provide useful guidance for efficient thermal management in electronic devices.