针对平行微通道散热器的沸腾流动不稳定性问题，以R134a制冷剂为工质，研究了内圆弧过渡形均流腔微通道散热器(MC-C)与传统方形均流腔微通道散热器(MC-S)的沸腾流动与传热特性。结果表明，与MC-S微通道相比，MC-C微通道入口均流腔减小了对工质的流动阻力，出口均流腔促进蒸气从散热器中排出，MC-C微通道的各微流道中的流型更加均匀。MC-C微通道沿程壁面温度先增大后减小再增大，MC-S微通道沿程壁面温度先减小后增大，相同工况下MC-C微通道可以实现更低的壁面温度。两种均流腔结构微通道的传热系数随质量流量增大而增大，随热流密度增大而增大；相同工况下MC-C可以实现更高的传热系数。当热流密度为242.6 kW/m2时，MC-C微通道较MC-S微通道的壁温最大降低了2.8℃；质量流量G=572 kg/(m2?s)时，随热流密度升高，MC-C微通道较MC-S微通道的沿程最大温差最多降低了2.2℃；当热流密度为242.6 kW/m2时，MC-C微通道较MC-S微通道平均传热系数最大提高了20.2%。

Aiming at the instability of boiling flow in parallel microchannels heat sink, the boiling flow and heat transfer characteristics of microchannel heat sink with flow sharing cavity with inner arc transition (MC-C) and microchannel heat sink with traditional square flow sharing cavity (MC-S) were studied. Using R134a as refrigerant, the two-phase flow pattern, wall temperature and heat transfer coefficient of microchannel were analyzed under the conditions of mass flow rate of 416~728 kg/(m2?s) and heat flux of 36.7~242.6 kW/m2. The working medium flowed into the inlet flow sharing cavity through the inlet pipe, then flowed through the microchannels, entered the outlet flow sharing cavity, and flowed out of the heat sink through the outlet pipe. The results showed that bubble flow, bubble-slug flow, slug flow, and annular flow changed in the channels when the heat flux increased from low to high. Compared with MC-S microchannels heat sink, the inlet flow sharing cavity of MC-C microchannels heat sink reduced the flow resistance of working fluid, and the outlet flow sharing cavity promoted the steam to be discharged from the microchannels heat sink, and the flow pattern in each microchannel of MC-C microchannels heat sink was more uniform. The wall temperature of MC-C microchannels heat sink increased first, then decreased and then increased, while that of MC-S microchannels heat sink decreased first and then increased. Under the same working conditions, MC-C microchannels heat sink can achieve lower wall temperature. The heat transfer coefficient in two kinds of microchannels heat sink increased with the increase of mass flow rate and heat flux. Under the same working condition, MC-C can achieve higher heat transfer coefficient. When the heat flux was 242.6 kW/m2, the wall temperature of MC-C microchannels was 2.8℃ lower than that of MC-S microchannels, and when the mass flux was 572 kg/(m2?s), the maximum temperature difference of MC-C microchannels was 2.2℃ lower than that of MC-S microchannels. When the heat flux was 242.6 kW/m2, the average heat transfer coefficient of MC-C microchannels was 20.2% higher than that of MC-S microchannels.