R-134a를 이용한 전열촉진관내 증발 열전달 특성

Experimental evaporation heat transfer coefficients were measured for in a horizontal micro-fin tube with HFC-134a. The test section was a straight, horizontal copper micro-fin tube which had a 9.2㎜ an outside diameter and 4.9 m long: The micro-fin tube had 60 fins with a height of 0.12 ㎜ and a 25° spiral angle. The electric heating method was used and the local evaporation heat transfer coefficients for each small section were obtained. Experiments were conducted for HFC-134a with test conditions as follows : the evaporation temperature, 5℃~15℃ ; mass flux, 70 ㎏/㎡s ~ 160 ㎏/㎡s ; heat flux, 5 ㎾/㎡ ~ 15 ㎾/㎡. The measured evaporation heat transfer coefficients of micro-fin tube were compared to those of smooth tube.