Investigation On Single-Phase Liquid Flow And Heat Transfer In Microchannels

With the development of IC, it’s very hard for the traditional cooling technology to cool down the element with high heat flux density in narrow space. As a new cooling technology, heat transfer in microchannels gets more international attention.Ansys-CFX is used to simulate the single-phase liquid flow and heat transfer in microchannels with different aspect ratio in the condition of same Rein and heat flux. Because the thermal boundary layer is very thin in the thermal entrance region, the heat transfer coefficient is very high in this region. So the investigation of entrance region is significant. The length of flow and thermal entrance region is investigated in different conditions in this paper.According to the result of entrance region of200μm*700μm,200μm*500μm and200μm*200μm rectangular microchannels, a new structure microchannel which combines three rectangular microchannels is designed. Staggered microchannels destroy the thermal boundary layer and the heat transfer area increase along the flow direction. So the heat transfer is enhanced and the temperature on the heating surface is more uniform. Although the pressure drop is larger in flow entrance region which is longer in this combined microchannel, the total pressure drop is smaller than200μm*200μm rectangular microchannel.The effects of Rein and heat flux on pressure drop, frictional factor, heat transfer coefficient, Nu and the temperature on the heating surface are experimental investigated. The combined microchannel gets very high heat transfer coefficient which is similar to that of200μm*200μm rectangular microchannel with smaller pressure drop.