| Title |
Flow Condensation Heat Transfer of R22, R134a, R407C, and R410A in Plain and Microfin Tubes |
| Keywords |
Flow condensation ; 흐름응축 ; Heat transfer coefficients ; 열전달계수 ; Microfin tube ; 마이크로 핀관 ; Enhancement factor ; 열전달촉진계수 |
| Abstract |
Flow condensation heat transfer coefficients(HTCs) of R22, R134a, R407C, and R410A were measured on horizontal plain and microfin tubes. The experimental apparatus was composed of three main parts; a refrigerant loop, a water loop and a water/glycol loop. The test section in the refrigerant loop was made of both a plain and a microfin copper tube of 9.52mm outside diameter and 1.0m length. The refrigerant was cooled by passing cold water through an annulus surrounding the test section. Tests were performed at a fixed refrigerant saturation temperature of 40℃ with mass fluxes of 100, 200, and 300kg/m2s. Test results showed that at similar mass flux the flow condensation HTCs of R134a were similar to those of R22 for both plain and microfin tubes. On the other hand, HTCs of R407C were lower than those of R22 by 11～15% and 23～53% for plain and microfin tubes respectively. And HTCs of R410A were similar to those of R22 for a plain tube but lower than those of R22 by 10～21% for a microfin tube. In general, HTCs of a microfin tube were 2.0～3.0 times higher than those of a plain tube. |