The Influence of Cross-Sectional Features on Heat Transfer and Flow Characteristics of Microcapsule Phase Change Slurry in Wavy Microchannels

Abstract

Microchannel heat sinks have been proven to be an effective means of solving small-scale, high heat flux heat dissipation. This research comprehensively evaluates fluids' heat transfer and flow performance in wavy microchannels with different cross-sectional features by establishing heat and mass transfer models in finite element analysis software. And it is innovatively clarified the relationship between the included angle between the microchannel walls and the fluid heat transfer performance. Different characteristic cross-sections with the same hydraulic diameter included circular, hexagonal, rectangular, trapezoidal and triangular. The microcapsule phase change slurry(MPCS) was the heat transfer fluid with 10 wt%. And the performance evaluation indices included Nusselt number, Stanton number, Euler number, thermal resistance, dimensionless temperature, pressure drop, pump power, and maximum temperature. The research results show that the circular microchannel had the largest heat transfer coefficient and heat transfer efficiency. And the heat transfer coefficient of MPCS in circular microchannels was sensitive to changes in velocity at low Reynolds number. The triangular microchannel had the smallest relative momentum loss rate for flow characteristics. But after considering the cross-sectional area of the microchannel, the circular, hexagonal and trapezoidal microchannels all showed lower power consumption. Furthermore, when the cross-section had acute angles, the maximum temperature of the wall surface increased by 7.5-19.5℃. This is because there is an obvious weak flow velocity area near the acute angle, which significantly reduces the heat transfer coefficient near the wall surface. However, the existence of obtuse angles has little effect on the heat transfer performance of microchannels. So the results can provide theoretical support for the design of microchannel heat sinks.