EXPERIMENTAL STUDY ON R-407C EVAPORATION HEAT TRANSFER CHARACTERISTICS IN PLATE AND SHELL HEAT EXCHANGER

Evaporation heat transfer experiments were conducted with a plate and shell heat exchanger (P&SHE) without oil in a refrigerant loop using R-407C (a mixture of 32 wt% R-32, 25 wt% R-125, and 52 wt% R-134A). An experimental refrigerant loop has been developed to measure the evaporation heat transfer coefficient of R-407C in a vertical P&SHE. The effects of the refrigerant mass flux, average heat flux, refrigerant saturation temperature and vapor quality of R-407C on the measured data were explored in detail. The quality change of R-407C between the inlet and outlet of the refrigerant channel ranged from 0.04 to 0.15. Similar to the case of a plate heat exchanger, even at a very low Reynolds number, the flow in the P&SHE remains turbulent. The present data show that the evaporation heat transfer increases with the vapor quality. A rise in the refrigerant mass flux causes an increase in h_r. Also, a rise in the average heat flux causes an increase in h_r. On the other hand, h_r is found to be lower at a higher refrigerant saturation temperature. Based on the present data, empirical correlation of the evaporation heat transfer coefficient was proposed.