As environmental concern over the presence of chlorofluorocarbons (CFC's) in the atmosphere grows, the refrigeration industry has focused on the development of new, "ozonefriendly" refrigerants. Therefore, the development of new rating methods for adiabatic capillary tube performance is necessary. Previous capillary tube research had focused on CFC-12 and HCFC-22. However, CFC-12 is currently being phased out of production. As this process continues, new rating methods must be developed for the prediction of refrigerant flow rates through adiabatic capillary tubes for an unknown variety of refrigerants.

This study is an evaluation of four refrigerants and their subsequent flow rate behavior in adiabatic capillary tubes. Four refrigerants, (HFC-134a, HCFC-22, R-410A, and HFC- 152a), were examined for their performance in adiabatic capillary tubes. A wide range of data were taken for a variety of capillary tube geometries and inlet conditions.