| Title |
A Study on Heat Transfer Characteristics in Flow Boiling of Pure Refrigerants and Their Mixtures in Horizontal Tube |
| Keywords |
Pure refrigerant ; 순냉매 ; Zeotropic mixture ; 변온증발 혼합냉매 ; Flow pattern ; 유동양식 ; Mole fraction ; 몰비 |
| Abstract |
An experimental study was carried out in a uniformly heated horizontal tube to examine heat transfer characteristics of pure refrigerants, R134a and R123, and their mixtures during flow boiling. The flow pattern was also observed through tubular sight glasses with an internal diameter of 10mm located at the inlet and outlet of the test section. Tests were run at a pressure of 0.6MPa and in the heat flux ranges of 5～100kW/m2, vapor quality 0～100 percent and mass velocity of 150～600kg/m2s. The observed flow patterns were compared to the flow pattern map of Kattan et al., which predicted well the present data over the entire range of mass velocity employed in this study. Heat transfer coefficients of the mixture were less than the interpolated values between pure fluids both in the low quality region where the nucleate boiling is dominant and in the high quality region where the convective evaporation is dominant. |