Experimental Investigation of the Flow of R-134a through Adiabatic and Diabatic Capillary Tubes

This paper presents the experimental investigation of the flow of refrigerant R-134a through adiabatic and diabatic capillary tube operating under similar conditions. The effect of various input parameters, such as capillary tube diameter capillary tube length, and capillary tube inlet subcooling on the mass flow rate of R-134a through a capillary tube tinder adiabatic and diabatic flow conditions, has been studied. The inlet pressure has been kept constant for both types of capillary tube. It has been observed that the suction-line superheat has an interfering effect on the mass flow rate through diabatic capillary tube. The acquired data from the present experimental setup have been analyzed, and separate empirical correlations to predict the mass flow rate through adiabatic and diabatic capillary tubes have been proposed. The mass flow rates predicted by the proposed correlations lie within the error band of +/-10%.