Prediction of Condensation Heat Transfer Coefficient Outside a Horizontal Microscopic-grooved Tube with 3 Dimention Structure

Abstract

This study investigated condensation heat transfer characteristics outside a horizontal microscopic-grooved tube with 3 dimention structure and developed the predicted correlation. The test tube was an outer diameter of about 19 mm, R 134a, R 245fa, R 1234ze (E), and R 1234yf were used as the test refrigerants, were clarified the fundamental characteristics of condenstion heat transfer and were developed the predicted correlation by the experiment with a single tube and a simulating inundation using the liquid supply. In the single tube experiment, it was clarified that large effects of condensation heat transfer on the area magnification ratio, the ratio of surface tension and liquid density σ /ρliq and the liquid thermal conductivity. In the simulating inundation experiment, it was revealed that the condensation heat transfer of microscopic-grooved tube with 3 dimention structure was dominated by the convection heat transfer in the laminar region, and the effect of the film Reynolds number on the condensation heat transfer characteristics was small. The predicted correlation for condensation heat transfer coefficient outside a horizontal microscopic-groovedenhanced tube with 3 dimention structure can be correlated from -17 to + 23% was proposed based on the experimental results.