Abstract: Liquid suction heat exchangers are commonly installed in refrigeration system with the intent of ensuring proper system operation and increasing system performance. Previous researchers have investigated performance of liquid suction heat exchangers, and some of them have concluded that the relative capacity change index (RCI) will increase with the increasing of heat recovery efficiency for certain refrigerants. In this study, two kinds of liquid suction exchangers set up with different baffles are numerical simulated by ANSYS FLUENT using the refrigerant R404A. They are used in an automotive air conditioning system and almost have the same geometrical parameters. The results indicated that for the same mass flow rate the overall heat transfer rate and average heat transfer coefficient of the shell-and-tube heat exchanger with continuous helical baffles (CH-STHX) are higher than that of the shell-and-tube heat exchanger (STHX) by 32.2% and 41.7%. The shell-side average heat transfer coefficient of the liquid refrigerant in the CH-STHX is about 3.5 times higher than that of the STHX. As the price of heat transfer enhancement, the shell-side pressure drop of the CH-STHX is extremely increasing to 11 times larger than that of the STHX. While the tube-side heat transfer coefficient and pressure drop of the CH-STHX almost keep the same with that of the STHX. And most importantly, the heat recovery efficiency increases from 0.21 to 0.29 for the CH-STHX, by 38.1%.

Key words: continuous helical baffles, liquid-suction heat exchanger, heat transfer enhancement, turbulent flow, numerical simulation, computational fluid dynamics

摘要： 带有气-液回热器的空调制冷系统已经被广泛使用，对相同几何尺寸的传统管壳式汽车空调回热器和新型连续螺旋折流板式回热器进行对比性的数值模拟研究。结果表明：以制冷剂R404A为工质，在相同质量流量下，回热器整体换热量提高32.2%，总传热系数提高41.7%；壳侧为制冷剂液体，壳侧平均传热系数提高3.5倍，同时壳侧压损也提高11倍；管侧为制冷剂气体，管侧平均传热系数和压损几乎不变。换热器整体回热效率从0.21提高到0.29，提高了38.1%。

关键词: 连续螺旋折流板, 回热器, 强化换热, 湍流, 数值模拟, 计算流体力学