引射器出口背压对满液式蒸发器回油的影响

压缩机失油是满液式冷水机组常见的问题。通过制作引射器模型并测试引射器出口在不同的背压下引射管的流量值，探讨压缩机失油的成因。测试结果表明：在产品设计或生产中不注意引射器出口背压，是压缩机失油的主要原因之一；在出口处安装弯头、截止阀，会使背压增大，流量减小，甚至出现倒流。因此提出建议：在满液式蒸发器的回油管路中，引射器出口尽量不要使用截止阀、弯头等类似管件；引射管出口管路应水平或向下布置。

Effect of ejector outlet back pressure on oil return of flooded evaporator

Compressor oil shortage is common in flooded chiller. In order to study the reasons of compressor oil shortage,an ejector model is built and the ejecting flow on different ejector outlet back pressure is measured. The test results show that one of the main reasons of compressor oil shortage is incorrect ejector outlet back pressure which is caused in process of design or manufacture,installation of stop valves or elbows after the ejector outlet will make the back pressure increase and ejecting flow decrease, even occur back flow. So some suggestions are proposed： in the oil return pipe line of flooded chiller, it＇s not to use any pipe fitting such as stop valves,elbows etc. after the ejector outlet as possible,the ejector outlet direction should be horizontal or downward.