Prediction of heat transfer in evaporation of saturated falling films on bundles of horizontal tubes

Abstract

Falling film evaporators consisting of bundles of horizonal tubes are widely used in many applications including refrigeration, chemical processing, desalination, etc. While many experimental studies have been done, as yet there is no well-verified method for the prediction of heat transfer. The research reported here was done to fulfill this need. A correlation is presented for heat transfer before occurrence of CHF which has been verified with a wide range of data from 12 sources. The data include plain and enhanced tubes of many types and materials, diameters 15.9 to 25.4 mm, P/D 1.1 to 2.0, liquid film Reynolds number from 43 to 6449, and heat flux from 1 to 94 kWm −2 . Included are eight diverse fluids (water, halocarbon refrigerants) with reduced pressures from 0.000046 to 0.172. The correlation predicts 2708 data points with mean absolute deviation of 17.4%. The correlation and its verification are presented and recommendations are made for its use.