Condensation Heat Transfer of R134a Outside Horizontal Enhanced Tubes - Effect of Fin Parameters

摘要

Experimental studies of film condensation of R134a on single horizontal smooth tube and nine enhanced tubes have been conducted.The objective is to enrich the basic data for film condensation of R134a on enhanced tubes and to obtain optimum fin density for the condensation of R134a on finned tubes.The fin number per meter varies from 736 to 2156.The results indicate that the predicted condensation heat transfer coefficients of R134a on smooth tube from Nusselt theory agree with the experimental data within 12 percent.It is found that the optimum fin density is about 1720fpm for R134a condensing outside integralfin tubes.Compared with the smooth tube,at a saturated temperature of 40°C and for the identical temperature difference,the average enhancement factors of the five enhanced tubes(No.1 to No.5) are 6.00,6.13,5.27,4.29,3.62,respectively.The experimental results show that the tube will have good performance in condensation heat transfer,which made by larger cut angle,while the cut deepness runs the same effect,too.