在某些类型的制冷系统应用中，使用所谓的“液体再循环系统”具有特殊的优势制冷剂蒸发器被供给过量的液体制冷剂，即超过通过蒸发产生所需制冷效果所需的量。通常使用高达5:1的液体过量进料比。在此类系统的设计中，会出现输送两相气液混合物的管道尺寸的问题。在过去的25年里，人们对两相流体的流动动力学、传热和传质过程进行了广泛的研究。 1962年至1966年期间，古塞汇编了5000多份关于两相流过程的参考文献。他估计这些出版物的研究费用为22500万美元。在过去的七年中，发表的论文数量可能翻了一番。杜克勒和他的同事在美国天然气协会和美国石油学会的赞助下，收集并比较了大约100个来源的两相压降测量值。他们的研究包括8600多个数据点。1964年，Dukler、Wicks和Cleveland利用这些数据对提出的压降关联式进行了关键性比较。 本次调查的目的是首先检查现有的两阶段文献，重点是更新自1965年以来关于压降的信息。其次，旨在定量确定制冷剂再循环吸入管路管道尺寸计算中最有前途的压降计算方法。最后，建议编制管道设计表，以便在使用R12、R22、R502和R7l7（氨）的制冷剂再循环系统中遇到的各种条件下使用。引文:巴哈马拿骚ASHRAE Transactions第78卷第2部分

In certain types of application of refrigeration systems, partIcular advantages arise in the use of a so-called "liquid recirculation system." The refrigerant evaporator is fed an oversupply of liquid refrigerant, i.e., more than the amount necessary to produce the required refrigerating effect through evaporation. Liquid overfeed ratios of up to 5:1 are commonly used. In the design of such systems, there arises the problem of sizing the piping, which carries the two-phase gas-liquid mixture.Over the past 25 years there have been extensive investigations of the flow dynamics, heat, and mass transfer processes associated with two-phase fluids. During the period from 1962 to 1966 Gouse compiled a listing of over 5000 references on two-phase flow processes. He estimated an expenditure of $22,500,000 on the research leading to those publications. The rate of publications in the past seven years have now probably doubled that figure.Dukler and co-workers, under the sponsorship of the American Gas Association and American Petroleum Institute, collected and compared two-phase pressure drop measurements from some 100 sources. Over 8600 data points were included in their study. A critical comparison of proposed pressure drop correlations using this data was made by Dukler, Wicks, and Cleveland in 1964.It was the purpose of this investigation first, to examine the existing two-phase literature, with emphasis on updating the information on pressure drop since 1965. Secondly, it was intended to identify quantitatively the most promising methods of pressure drop calculation for use in pipe sizing of refrigerant recirculation suction lines.Finally, it was proposed to prepare pipe design tables for use over the range of conditions encountered in refrigerant recirculation systems using R12, R22, R502, and R7l7 (ammonia).