Using a Cross -grooved Inner Surface for Enhancement of Heat Transfer Characteristics Inside Horizontal Tubes for Zeotropic Refrigerant

First Report : Condensation Test

Abstract

The condensation characteristics of zeotropic refrigerant(R407C) inside horizontal tubes has been investigated experimentally using two types of new cross -grooved tube which are formed by varying the helix angle of second set of grooves at the same fin height. The performance of the two types of cross-grooved surface are compared to that of single -grooved surface. The improved cross-grooved tube(second helix angle β2=0°) has provided with higher condensation heat transfer coefficients than the single grooved tube at a low mass flow velocity. However, at a high mass flow velocity, the difference between condensation heat transfer coefficients for single and cross -grooved tube is not evident. The pressure drop of improved cross-grooved tube is slightly higher than that of the single grooved tube.