| Title |
Flow Condensation Heat Transfer Coefficients of Pure Refrigerants |
| Keywords |
Heat transfer coefficients ; 열전달계수 ; Flow condensation ; 흐름응축 ; Condensing correlation ; 응축상관식 ; Alternative refrigerants ; 대체냉매 |
| Abstract |
Flow Condensation heat transfer coefficients (HTCs) of R12, R22, R32, R123, R125, R134a, R142b were measured experimentally on a horizontal plain tube. The experimental apparatus was composed of three main parts; a refrigerant loop, a water loop and a water-glycol loop. The test section in a refrigerant loop was made of a copper tube of 8.8 mm inner diameter and 1000 mm length respectively. The refrigerant was cooled by passing cold water through an annulus surrounding the test section. All tests were performed at a fixed refrigerant saturation temperature of 40℃ with mass fluxes of 100, 200, 300 kg/m2s. The experimental result showed that flow condensation HTCs increase as the quality, mass flux, and latent heat of condensation increase. At the same mass flux, the HTCs of R32 and R142b were higher than those of R22 by 35∼45% and 7∼14% respectively while HTCs of R134a and R123 were similar to those of R22. On the other hand, HTCs of R125 and R12 were lower than those of R22 by 28∼30% and 15∼25% respectively. Finally, a new correlation for flow condensation HTCs was developed by modifying Dobson and Chato's correlation with the latent heat of condensation considered. The correlaton showed an average deviation of 13.1% for all pure fluids data indicating an excellent agreement. |