制冷和空调系统必须设计为可变制冷量。可变容量要求可能是由于可变负载，或者仅仅是因为系统设计用于预期峰值负载，而工作负载远远低于峰值负载。这需要某种形式的容量控制，如热气旁通、吸入管线节流、吸入阀卸载、变速驱动、间歇运行等。所有这些容量控制方法都有其缺点。主要缺点是热力和容积效率降低，排放温度f通常灾难性升高- 或CQM压缩机以减少的质量流量连续运行的方法:在压缩机间歇运行的情况下，也会出现控制和启动和停止问题。本论文仅考虑通过持续降低压缩机的质量流量来实现容量控制的系统（因此不包括热气旁通）。讨论仅限于通过金属零件从排气到吸入气体的传热效果。（在密封压缩机的情况下，未考虑电机产生的热量的影响）。 引文:宾夕法尼亚州费城ASHRAE Transactions第77卷第1部分

Refrigeration and air conditioning systems have to be designed for variable cooling capacity. The variable capacity requirement may be due to a variable load or simply to the fact that the system was designed for the expected peak load, while the working load is considerably lower than the peak load. This will require some form of capacity control such as hot-gas bypass, suction-line throttling, suction-valve unloading, variable-speed drive, intermittent running, etc. All of these methods for capacity control have their drawbacks.The major drawback is the lowering of the thermodynaniic and volumetric efficiencies and the often catastrophic increase of the discharge temperature, f-or methods where the cqmpressors are running continuouslY at reduced mass flow: for control, and start and stop problems in the cases where the compressors are runnmg intermittently, also occur.The present paper considers only systems that achieve capacity control by continuous reduction of the mass flow rate through the compressor (hot-gas bypass is therefore excluded). The discussion is limited to the effect of heat transfer through the metal parts fro:q1 the discharge gas to the suction gas. (The effects of the heat generated by the motor in the case of hermetic compressors has not been considered).