Separation efficiency of oil separator directly affects the cooling effect in refrigeration system.The set of separation efficiency test stand of oil separator was proposed based on the weighting method.By means of the measurement of refrigerant and lubricant mass before and after the filtration process,separation efficiency of the test device can be calculated,providing a scientific and accurate test method for the key performance indicators of the oil separator.

A large quantity of cracking appeared in the welding parts of copper pipe and low carbon steel pipe.The cracking reasons were analyzed by means of macro examinaton on the cracking position,chemical compositions analysis,fracture observition by SEM and microstructure inspection.The results show that the comprehensive effect,which was induced the oxygen content in the material was over standard and grain boundary weakness by long time welding,made that the structural stress and thermal stress existed in the joint.The grain boundary cracked when the stress exceeded the limit of the material.The improved measures were also brought forward on the basis of analysis.