An Experimental Study of Dropwise Condensation on Horizontal Condenser Tubes.

摘要

Three types of drop promoting coatings were applied to the outside of 15.9 mm (5/8 in) outside-diameter condenser tubes to determine their effect on heat transfer performance. The coatings included a new fluorolepoxy, a commercial series of fluorocarbon coatings, and sputtered TFE. Coating thickness varied from 0.02 to 12.7 microns. Steam at about 21 KPa (3 psia) was condensed on the outside surface of each coated tube. Each test tube was cooled on the inside by water at velocities of 0.80 to 7.60 m/sec (3 to 25 ft/sec). The overall heat transfer coefficient was determined directly from experimental data. The inside and outside heat transfer coefficients were determined by using the Wilson Plot technique. Of the commerical fluorocarbon coatings, the 'Nedox' coating on a copper-nickel tube enhanced the outside heat transfer coefficient by 53% and improved the corrected overall heat transfer coefficient by 27%. Of the sputtered TFE coated tubes, the 0.08-micron thick coating on a copper-nickel tube enhanced the outside heat transfer coefficient by 45% and improved the corrected overall heat transfer coefficient by 21%.