An experiment was carried out to study the effect of refrigerant mass flow rate, heat flux density, and saturation temperature on boiling heat transfer coefficient and frictional pressure drop in microchannel. Flow patterns are captured by a high-speed camera. HFO1234yf was used in rectangular microchannels with a hydraulic diameter of 0.5 mm. The results showed that there were eight flow patterns in the experiment, and the change of flow pattern is closely related to the change of heat flux and mass flow rate. The higher the heat flux and mass flow rate, the more the flow patterns appear. Different flow patterns have different heat transfer mechanisms. The heat transfer mechanism is mostly nuclear boiling at the region of bubble flow, slug flow, elongated slug flow, and agitated flow; the heat transfer mechanism is film convection boiling at the region of annular flow, and it is vapor convection at the region of dryout flow. When the dryness is about 0.4, the heat transfer mechanism changes from nuclear boiling to film boiling. The friction resistance decreases with the increase of dryness and saturation temperature.

通过实验研究了制冷剂质量流量，热通量密度和饱和温度对微通道沸腾传热系数和摩擦压降的影响。流动模式由高速摄像机捕获。HFO1234yf用于水力直径为0.5毫米的矩形微通道。结果表明，实验中存在八种流型，流型的变化与热通量和质量流量的变化密切相关。热通量和质量流率越高，出现的流型越多。不同的流型具有不同的传热机理。传热机理主要是在气泡流，团状流，伸长的团状流和搅动流的区域发生核沸腾。传热机理是在环流区域内薄膜对流沸腾，而在干燥流区域内则是蒸汽对流。当干燥度为约0.4时，传热机理从核沸腾变为膜沸腾。摩擦阻力随着干度和饱和温度的升高而降低。