Experiments on the characteristics of evaporation of R410A in brazed plate heat exchangers with different geometric configurations

Experiments on the evaporative heat transfer and pressure drop in the brazed plate heat exchangers were performed with refrigerants R410A and R22. The plate heat exchangers with different 45degrees, 35degrees, and 20degrees chevron angles are used. Varying the mass flux of refrigerant (13-34 kg/m(2) s), the evaporating temperature (5, 10 and 15degreesC), the vapor quality (0.9-0.15) and heat flux (2.5, 5.5 and 8.5 kW/m(2)), the evaporation heat transfer coefficients and pressure drops were measured. The heat transfer coefficient increases with increasing vapor quality and decreasing evaporating temperature at a given mass flux in all plate heat exchangers. The pressure drop increases with increasing mass flux and quality and with decreasing evaporating temperature and chevron angle. It is found that the heat transfer coefficients of R410A are larger than those of R22 and the pressure drops of R410A are less than those of R22. The empirical correlations of Nusselt number and friction factor are suggested for the tested PHEs. The deviations between correlations and experimental data are within +/-25% for Nusselt number and +/-15% for friction factor. (C) 2003 Elsevier Science Ltd. All rights reserved.