Flow characteristics of HFC407C/HC600a/HC290 refrigerant mixture in adiabatic capillary tubes

HCFC22, the commonly used refrigerant in window air-conditioner is to be phased out completely due to Montreal Protocol regulations. Hence the search for drop in substitutes to retrofit window air-conditioner is of current interest. Capillary tube is commonly used in domestic refrigeration and air conditioning systems as expansion devices. This paper presents an experimental study on the flow characteristics of HFC407C/HC600a/HC290 a new refrigerant mixture in adiabatic capillary tubes. The experimental work investigates the effect of capillary length, capillary diameter, condensing pressure, and refrigerant subcooling on the mass flow rate through the capillaries. Based on the experimental data for HCFC22 and HFC407C/HC600a/HC290 refrigerant mixture, a new correlation has been developed to predict the mass flow rate through the adiabatic capillary tubes for different operating conditions, capillary tube geometry and refrigerant properties. The non-dimensional correlation predicts closely the mass flow rates which are in good agreement with the experimental data for HCFC22 and HFC407C/HC600a/HC290 with average deviations of 0.618% and −0.11% and mean deviations of 5.536% and 4.448%, respectively. The mass flow rates predicted using the developed correlation are found to be in good agreement with the results in published literature also.