R22 대체냉매의 다채널 평판관내 흐름 응축에 관한 실험적 연구

초록

Flow condensation heat transfer coefficients(HTCs) of R22, R410A and R407C were measured on a horizontal 9 hole aluminum multi-channel tube. The main test section in the refrigerant loop was made of a flat multi-channel aluminum tube of 1.4 mm hydraulic diameter and 0.53 m length. Refrigerant was cooled by passing cold water through an annulus surrounding the test section. Data were obtained in the vapor qualities of 0.1-0.9 at mass flux of 200-400 kg/m2s and heat flux of 7.3-7.7 kW/m2 at the saturation temperature of 40℃. All popular correlations in single-phase subcooled liquid and flow condensation originally developed for large single tubes predicted the present data of the flat tube within 30% deviation when effective heat transfer area is used in determining experimental data. This suggests that there is little change in flow characteristics and patterns when the tube diameter is reduced down to 1.4 mm diameter range.