Author : Rajneesh Kaushal 1
Date of Publication :24th January 2018
Abstract: Heat transfer through falling film evaporation has wide industrial applications like in cooling towers of thermal power plants and refrigeration and air conditioning industries. There are various factors which can improvise the falling film evaporation performance or effectiveness like enhanced tube surface geometry and working conditions. The relative humidity of air has a great influence on falling film evaporation. Also, dry out of the surface of tubes because of excessive thermal loading or less flow rate of cooling water film has a significant role in the effectiveness of falling film evaporation. Thus, a comprehensive review has been conducted to study the effects of surface geometry (horizontal smooth and plain tubes, porous structures, finned and enhances surfaces, liquid feeder configuration etc.), falling film pattern, dry out crisis phenomenon and relative humidity of the air. Finned and enhanced surfaces were supposed to increase the heat transfer rate than the others. Dry out a phenomenon which occurs due to instability problem can be checked by stability factor or minimum wetting rate. The humidity of air leads to increment in mass transfer coefficient and heat flux.
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