| Title |
Study on Evaporation Heat Transfer of R-134a, R-407C, and R-410A in the Oblong Shell and Plate Heat Exchanger |
| Keywords |
Oblong shell and plate heat exchanger ; 오블롱 셀 플레이트 열교환기 ; Evaporation ; 증발 ; Heat transfer coefficient ; 열전달계수 ; Vapor quality ; 건도 |
| Abstract |
The evaporation heat transfer coefficient for R-134a, R-407C(a mixture of 23 wt% R-32, 25wt% R-125, and 52wt% R-134a) and R-410A(a mixture of 50wt% R-32 and 50wt% R-125) flowing in the oblong shell and plate heat exchanger were investigated experimentally in this study. Four vertical counterflow channels were formed in the exchanger by four plates of commercial geometry with a corrugated sinusoid shape of a chevron angle of 45 degree. The effects of the mean vapor quality, mass flux, heat flux, and saturation temperature of different refrigerants on the evaporation heat transfer were explored in detail. Similar to the case of a plate heat exchanger, even at a very low Reynolds number, the flow in the oblong shell and plate heat exchanger remains turbulent. It is found that the evaporation heat transfer coefficient in the plates is much higher than that in circular pipes. The present data show that the evaporation heat transfer coefficients of all refrigerants increase with the vapor quality. At a higher mass flux is higher than for the entire range of the vapor quality. Raising the imposed wall heat flux was found to slightly improve, while is found to be lower at a higher refrigerant saturation temperature. A comparison of the performance of the various refrigerants reveals that R-410A has the highest heat transfer performance followed by R-134a, and R-407C had the lowest performance of the refrigerants tested. Based on the present data, empirical correlations of the evaporation heat transfer coefficient were proposed. |