A general correlation for heat transfer during evaporation of falling films on single horizontal plain tubes

Abstract

Falling film evaporators are widely used in many industries including desalination, petrochemical, and refrigeration. Hence ability to correctly predict heat transfer in these evaporators is important. While many prediction methods have been proposed, none has been validated with data from many sources covering a wide range of parameters. Hence there is a need for a well-verified general correlation. This research was done to fulfill this need. A correlation has been developed for heat transfer coefficient of single horizontal tubes with falling film evaporation. It is shown to be in good agreement with data from 22 sources that cover a very wide range of parameters. Included in the data are 11 fluids (water, ammonia, halocarbon refrigerants, hydrocarbons), tube diameters from 12.7 mm to 50.8 mm, heat flux from 1 to 208 kWm−2, and liquid film Reynolds number 19 to 10,734. A total of 1237 data points are predicted with a mean absolute deviation of 17.4%. The new correlation is presented together with details of its verification.