在空调或制冷系统中，一小部分润滑油从曲轴箱流出，进入工作液。与这种现象相关的两个主要问题是（i）这种油对系统中的压降有什么影响，以及（ii）在什么条件下，油被输送回压缩机？这两个问题都与部件的尺寸和装置的效率有直接关系。关于第二个问题，曲轴箱中的机油不足最终会导致系统因缺乏润滑而停机。在之前的两篇论文中，对油对压降的影响以及吸入和排出管线中油输送的必要条件（1,2）进行了描述和关联。这是本次讨论的目的。以更直接适用于行业的形式报告这些相关性的重铸。 计算也首次包括R-502和R-500。虽然最初的实验研究仅针对R-12和R-22进行，但相关性的性质表明，可以将其推广到其他制冷剂。将简要介绍适当的关系，并对列表结果进行解释。有关实验的更多细节和这些相关性的基础，请参阅参考文献1至3。引文:密歇根州底特律ASHRAE交易，第85卷，第2部分

In an air-conditioning or refrigeration system, a small percentage of the lubrication oil migrates out of the crankcase and into the working fluid. Two main concerns associated with this phenomenon are (i) what is the effect of this oil on the pressure drop in the system and (ii) under what conditions is the oil transported back to the compressor? Both questions have a direct relationship to the sizing of components and the efficiency of the unit. In relation to the second question, a deficiency of oil in the crankcase will eventually cause the system to shut down because of lack of lubrication.In two previous papers, experiments were described and correlations developed for the effect of oil on pressure drop and the necessary conditions for oil transpor in suction and discharge lines (1,2). It is the purpose of this discussion to. report the recasting of these correlations in a form which is more directly applicable to the industry. Computations are also included for the first time for R-502 and R-500. Although the original experimental studies were conducted only with R-12 and R-22, the nature of the correlation suggest that extension can be made to other refrigerants.A brief synopsis will be given of the appropriate relationships along with an explanation of the tabulated results. For further details of the experimentsand the bases for these correlations, refer to Ref. 1 through 3.