HFC32 vaporisation inside a brazed plate heat exchanger (BPHE).

This paper presents HFC32 boiling heat transfer coefficients measured inside a small Brazed Plate Heat Exchanger (BPHE): the effects of heat flux, saturation temperature (pressure), and outlet conditions are investigated. The experimental tests were carried out at three different saturation temperatures (10, 15, and 20°C) and four different evaporator outlet conditions (vapour quality around 0.80 and 1.00, vapour superheating around 5 and 10°C). The heat transfer coefficients show great sensitivity to heat flux and outlet conditions and weak sensitivity to saturation temperature (pressure). The saturated boiling heat transfer coefficients were compared with a new model for refrigerant vaporisation inside BPHE: the mean absolute percentage deviation between calculated and experimental data is 4.7%. HFC32 exhibits heat transfer coefficients 20-30% lower than those of HFC410A under the same operating conditions.