30 May 2005

CHARACTERISTICS OF TWO-PHASE EJECTOR IN CARBON DIOXIDE REFRIGERATION CYCLE


Recently, carbon dioxide has gained much attention as a natural refrigerant. Installation of two-phase
ejector is one of the most promising ways to improve the COP (Coefficient of Performance) of carbon
dioxide refrigeration cycle. However the flow inside two-phase ejector, in which working fluid undergoes
phase change, has not been clarified yet. The purpose of this research is to clarify the characteristics of the
supersonic two-phase flow of carbon dioxide in ejector, and improve the performance of ejector. In this
paper, it is shown that performance of ejector in compression refrigeration cycle is decided by the
characteristics of pressure recovery through ejector and pressure drop through suction flow passage. The
effect of mixing section diameter and the expansion valve was clarified experimentally, and 11% of COP
value was improved in this work.