Numerical Investigation of Heat Transfer Enhancement due to Two-Phase Flow in Microchannel

Abstract

Microchannels play an important role in cooling applications of electronic devices, especially since the size of electronic devices is becoming smaller and the energy generated per unit volume is increasing. In order to understand the development of two-phase oil-air flow in a microchannel, a numerical investigation is performed that aims to uncover the effects of two-phase mixture on the heat transfer and pressure drop characteristics. The methodology consists of numerical simulation in a T-junction microchannel mesh that was built in Gambit software. Its dimensions are 1 mm thickness and 52 mm in length. Oil enters through one of the inlets and air enters through the other inlet. After the junction, the air-water two-phase flow forms Taylor bubbles. The two-phase flow is simulated by a computational fluid dynamics code developed in Python for use in general purpose and open source codes. The heat transfer is simulated with constant temperature wall boundary condition. Pressure drop is also studied as it can severely inhibit the efficiency of microchannel devices. The heat transfer characteristics show the effectiveness of the two-phase mixture for microchannel cooling purpose. Gas phase-liquid phase pressure drop are numerically simulated and compared with Martinelli and similar correlations, and the results indicate satisfactory and close correlation. Internal circulation is seen to enhance the heat transfer coefficient and the Nusselt number is 2-3 times higher compared to flow where there is only the single phase liquid.