HFC32 and HFC410A flow boiling inside a 4 mm horizontal smooth tube

This paper presents the comparative analysis of HFC32 and HFC410A during vaporisation inside a 4 mm smooth tube. The experimental tests were carried out at three different saturation temperatures (5, 10, and 20 degrees C) at increasing vapour quality up to incipient dryout to evaluate the specific contribution of heat flux, refrigerant mass flux, mean vapour quality; and saturation temperature (pressure). HFC32 and HFC410A heat transfer coefficients exhibit great sensitivity to heat flux and weak sensitivity to refrigerant mass flux and mean vapour quality and this tendency is particularly evident for increasing saturation temperature (pressure) and is more relevant for HFC410A refrigerant. HFC32 and HFC410A frictional pressure drops show great sensitivity to saturation temperature (pressure), refrigerant mass flux and mean vapour quality and weak or null sensitivity to heat flux. HFC32 exhibits heat transfer coefficients and frictional pressure drops higher than those of HFC410A under the same operating conditions. (C) 2015 Elsevier Ltd and International Institute of Refrigeration. All rights reserved.