Abstract
From the viewpoint of global warming, there is an urgent need for refrigerants with lower Global Warming Potential (GWP) values. However, since they have different physical properties from conventional refrigerants, the performances of their heat transfer tubes are insufficient. The purpose of this study is to prepare predicted correlations of the outside condensation heat transfer coefficient corresponding to refrigerants with different physical properties. In this experiment, a smooth tube and four types of enhanced tubes, each with an outer diameter of approximately 19 mm, were used as test heat transfer tubes. The experiments were conducted using R245fa and R134a as the test refrigerants, at a condensation saturated temperature of 40 °C, and with a film Reynolds number range of 40 to 1500. The enhanced tubes displayed different tendencies from that of the smooth tube in the high film Reynolds number range. The experimental results of the smooth tube showed good correlation with the proposed predicted correlation.
Published Version
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