微通道内R245fa沸腾换热和压降特性  

Boiling Heat Transfer and Pressure Drop Characteristics of R245fa in Microchannel

作　　者：李冲 方贤德[1] LI Chong;FANG Xiande(Key Laboratory of Aircraft Environment Control and Life Support,Ministry of Industry and Information Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]南京航空航天大学飞行器环境控制与生命保障工业和信息化部重点实验室,南京210016

出　　处：《工程热物理学报》2024年第12期3750-3755,共6页Journal of Engineering Thermophysics

基　　金：国家自然科学基金(No.52076107,No.51576099)。

摘　　要：对微通道内径1.83 mm和加热长度170 mm水平铜管内R245fa的沸腾换热和压降特性进行实验研究,分析热流密度、质量流率及过冷度对T_(5)(沿实验段加热长度的轴向位置为z=130 mm)处沸腾换热和总压降的影响。实验热流密度40和50 k W·m^(-2),质量流率530、830和1130 kg·m^(-2)·s^(-1),过冷度10和15 K,饱和压力177.79 kPa。结果表明:R245fa在管内沸腾换热的过程中,随着热流密度的逐级增加,管内T_(5)处相继出现单相流、过冷沸腾和饱和沸腾,其中过冷沸腾和饱和沸腾阶段的换热形式是核态沸腾。换热系数随着热流密度的增大而增大,质量流率决定饱和沸腾起始的热流密度。热流密度、质量流率和过冷度对单相流换热和两相流换热的影响不同,且对压降的影响主要由管内摩擦压降和加速压降的大小决定。Experimental study on the boiling heat transfer and pressure drop characteristics of R245fa in a horizontal copper tube with a microchannel inner diameter of 1.83 mm and a heat-ing length of 170 mm.The effects of heat flux,mass fux,and inlet subcooling on boiling heat transfer at Ts(axial position z=130 mm along the heating length of the test section)and total pres-sure drop were analyzed.Experimental parameters included heat fuxes of 40 and 50 kW·m^(-2),mass fuxes of 530,830 and 1130 kg·m^(-2)·s^(-1),inlet subcoolings of 10 and 15 K,and saturation pressure of 177.79 kPa.The results show that the single-phase flow,subcooled boiling,and saturated boiling appear successively in the tube as heat flux increased step by step in process of boiling flow.Specif-ically,the heat transfer mechanism of subcooled boiling and saturated boiling stages is nucleate boiling.The heat transfer coefficient increases with the increase of heat flux,and the mass fux determines the heat fux at which saturated boiling begins.The effects of heat flux,mass flux,and inlet subcooling on single-phase fow heat transfer and two-phase fow heat transfer are different,and the impact on pressure drop is mainly determined by the magnitude of frictional pressure drop and accelerational pressure drop inside the tube.

关 键 词：微通道 R245FA 沸腾换热 压降 

分 类 号：TK124[动力工程及工程热物理—工程热物理]