Theoretical and experimental research on flow boiling heat transfer in microchannels for IGBT modules

Abstract

Two-phase microchannel heat sink has received extensive attention due to its small size, high heat transfer efficiency, good temperature uniformity, and low working fluid charge. Heat flux and mass flow rate are important parameters that affect the heat transfer performance of two-phase microchannel heat sink. For different heat fluxes, if the mass flow rate is not reasonable, dry-out may occur, which will significantly reduce the heat transfer performance. In order to further explore the influence of mass flow rate and heat flux on heat transfer characteristics, the flow boiling heat transfer performance and flow regimes under different mass flow rates and heat fluxes were studied for a two-phase microchannel heat sink using R245fa as the working fluid. The results showed that when the mass flow rate was 100 kg/(m2·s), the boiling heat transfer coefficient of R245fa showed a trend of increasing firstly and then decreasing with the increase of the heat flux. At a higher heat flux, the local dry-out in the microchannels began to appear, and the heat transfer performance decreased significantly. And the higher the heat flux was, the more serious the dry-out was. There was no obvious dry-out phenomenon when the mass flow rate was 150–300 kg/(m2·s) and the heat flux was below 500 kW/m2. The research provided a valuable reference for exploring the influence of the mass flow rate and the heat flux on the flow boiling heat transfer characteristics of the microchannel heat sink.