| Title |
Effects of Hydrophilic Surface Treatment on Condensation Heat Transfer at the Outside Wall of Horizontal Tube |
| Keywords |
Hydrophilic surface treatment ; 친수성 표면처리 ; Absorption refrigerator ; 흡수식 냉동기 ; Condensation heat transfer ; 응축열전달 ; Heat transfer coefficient ; 열전달계수 ; Condenser ; 응축기 |
| Abstract |
Condensation heat transfer characteristics have been investigated experimentally when a water vapor is condensed on the outside of a horizontal copper tube in a condenser. This problem is of particular interest in the design of a LiBr-water absorption system. Hydrophilic surface modification was performed to increase the wettability on the copper tube. The optimum hydrophilic treatment condition using acethylene and nitrogen as reaction gas is also studied in detail. The results obtained indicate that the optimum reaction gas ratio of acethylene to nitrogen for hydrophilic surface modification was found to be 7 : 3 for the best condensation heat transfer. In the wide ranges of coolant inlet temperatures, and coolant mass flow rates, both the condensation heat transfer rate and the condensation heat transfer coefficient of a hydrophilic copper tube are increased substantially, compared with those of a conventional copper tube used in a condenser. It is also found that the condensation heat transfer enhancement by the hydrophilic surface modification still remains even after a hundred cycles of wet/dry processes. |