四通换向阀是热泵空调中切换制冷、供热两种方式的关键部件 ,其容量值是选用的重要依据。目前对四通换向阀容量的测试均以空气为介质 ,将流量系数视为定值 ,不考虑工况变化带来的影响 ,得出的容量值比实际制冷剂循环中的容量值大得多。本文对产生这种差别的原因进行了分析 ,并给出了从空气测量数据到实际公称容量值的换算关系。研究还表明 ,四通换阀公称容量与工作方式 (制冷、供热 )有关。 Four-way valve is the heat pump air conditioning switching refrigeration, heating two key components, the capacity value is an important basis for selection. Currently on the four-way valve to test the volume of air as the medium, the flow coefficient as a fixed value, regardless of the impact of changes in conditions, the resulting capacity value is greater than the actual value of the capacity of the refrigerant cycle many. This paper analyzes the causes of this discrepancy and gives the conversion from the air measurement data to the actual nominal capacity values. The study also shows that the nominal capacity of the four-way valve is related to the working method (cooling and heating).