12.7mm 마이크로 핀관 내 자연냉매의 증발 열전달 특성에 관한 실험적 연구

Abstract

In this study, evaporation heat transfer experiments were performed in 12.7mm micro-fin tube using natural refrigerants. The test rig had a straight, horizontal test section and refrigerant was heated by water through an annulus surrounding test section. Evaporation heat transfer coefficient was increased with increasing quality, refrigerant mass flux. The local and average evaporation heat transfer coefficients in micro-fin tube were compared to those a bare tube. The local evaporation coefficients of R-22 and natural refrigerants for the micro-fin tube were 131% and 96~124% higher than bare tube. EF(enhancement factor) is defined as the ratio of the micro-fin tube heat transfer coefficient to that of a comparable bare tube at a similar mass flux, heat flux, pressure level, and inlet outlet quality. EF of R-22 and natural refrigerants are presented average 2.68 and 2.41 at the all refrigerant mass flux in the experiment range.