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ISSN Online: 2377-424X

ISBN Print: 0-89116-299-2

International Heat Transfer Conference 7
September, 6-10, 1982, Munich, Germany

HEAT TRANSFER IN THE THERMAL ENTRANCE REGION OF A TURBULENT FALLING LIQUID FILM UNDERGOING HEATING OR EVAPORATION

Get access (open in a dialog) DOI: 10.1615/IHTC7.1580
pages 125-130

摘要

A new analytical solution is presented for heating or evaporation in the thermal entrance and fully developed regions of a turbulent falling liquid film with the boundary condition of constant wall heat flux or constant wall temperature. A modified van Driest model, which incorporates a damping factor f and the effect of variable shear, is found to predict the average film thickness and local heat transfer coefficient accurately and in good agreement with previous experimental data and a finite difference numerical solution in the range of 1600≤Re≤17500 and 1.77≤Pr≤210. The calculations show that the thermal entrance length for evaporation is longer than that for heating and the length decreases with increasing Re or Pr, or both. The entrance effect is particularly important for a turbulent film with small Re and Pr when the heating or evaporation length is short.