2004年第2期

This paper presents experimental investigation on convective condensation heat transfer characteristics of alternative refrigerant R-134a in a helical pipe. The average condensation heat transfer coefficients were experimentally determined for R-134a at three different orientations (i.e., horizontal, vertical, and inclined orientation directions).The mass flux for R-134a ranges from 100 to 400 kg/(m2s) and the average temperatures of the cooling water are 12℃ and 22℃, respectively. The experimental results demonstrate that the different orientations of helical pipes have significant effect on the condensation heat transfer characteristics of R-134a . In addition, the mechanism of the effect of different orientations of helical pipes on convective condensation heat transfer is briefly analyzed by comparing with prevenient results. Fig.5Ref.18