Experimental study of adiabatic capillary tubes: Critical flow of refrigerant/oil mixtures.

The critical flow of R-407C/oil mixtures through adiabatic capillary tubes is evaluated in this article. The available literature does not lead to def initive conclusions about the impact of oil on critical flow through capill ary tubes. This phenomenon was studied experimentally using oil concentrati ons ranging from 2.9% to 7.9% (by mass), degrees of subcooling ranging from 8.1 degreesC to 28.5 degreesC (14.6 degreesF to 51.3 degreesF), and a cond ensing pressure of 1763 kPa (241 psia). The results obtained clearly show t he trends of critical mass flow rate for several oil concentrations in the flowing fluid. The experimental data are analyzed and contribute to the kno wledge of the influence of oil on the performance of adiabatic capillary tu bes.