Condensation heat transfer enhancement using steam-ethanol mixtures on horizontal finned tube

Abstract

Abstract Condensation of steam-ethanol mixtures was investigated experimentally on instrumented, finned copper tube. The tube had length 70\u202fmm, fin root diameter 12.7\u202fmm. Height, thickness and inter-fin space was of rectangular fins was 1.6\u202fmm, 0.5\u202fmm and 0.6\u202fmm. Concentration of ethanol by mass in the boiler when cold prior to the start-up were 0.025, 0.05, 0.1, 0.5 and 1.0%. Experiments were conducted over a range of vapor-to-surface temperature difference at three pressures of 14\u202fkPa, 55\u202fkPa and atmospheric. Maximum upstream vapor velocity on condensing finned test tube at atmospheric pressure and 14\u202fkPa was 7.5 and 15.0\u202fm/s respectively. Heat transfer enhancement as compared to pure steam of around 3 times was obtained over a range of vapor to surface temperature difference. Results have been compared with the available data for pure steam condensation on finned tube and steam-ethanol condensation on the smooth tube under same conditions of pressure, vapor velocity and vapor to surface temperature difference. Photographs showing increase of retention angle due to ethanol are included in the paper.