Vaporisation of the low GWP refrigerant HFO1234yf inside a brazed plate heat exchanger

This paper presents the experimental heat transfer coefficients and pressure drop measured during vaporisation of the new low Global Warming Potential (GWP) refrigerant HFO1234yf inside a Brazed Plate Heat Exchanger (BPHE): the effects of heat flux, mass flux, saturation temperature (pressure) and outlet conditions are investigated. The heat transfer coefficients show great sensitivity to heat flux and outlet conditions and weak sensitivity to saturation temperature (pressure). The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on refrigerant mass flux. The saturated boiling experimental heat transfer coefficients are reproduced by two well-known equations for nucleate boiling, Cooper (1984) and Gorenflo (1993), with reasonable agreement. The heat transfer and pressure drop measurements are complemented with IR thermography analysis in order to quantify the portion of the heat transfer surface affected by vapour super-heating.