工业上使用的各种蒸汽压缩制冷系统采用冷凝设备，制冷剂蒸汽在管内流动时冷凝。例如，蒸发式冷凝器和一些管中管式水冷式冷凝器就是这种情况。本研究关注冷凝器中的传热和压降，尤其是回流弯管对其性能的影响。本次调查的目的是确定回流弯管引起的扰动是否仅是局部效应，还是延伸到冷凝器管的较长部分，从而改变传热和压降。引文:伊利诺伊州芝加哥ASHRAE Transactions第79卷第1部分

A wide variety of vapor-compression refrigeration systems utilized in industry employ condensing equipment in which the refrigerant vapor condenses while flowing inside tubes. This is the case, for example, in evaporative condensers and some water-cooled condensers of the tube-in-tube type. The present investigation is concerned with the heat transfer and pressure drop in condensers, and particularly the effect of return bends on their performance.The purpose of this investigation was to determine whether the disturbance caused by a return bend was only a localized effect or extended over a significant length of the condenser tube, modifying the heat transfer and pressure drop.