HEAT TRANSFER IN A SUBCOOLED WATER FILM FALLING ACROSS A HORIZONTAL HEATED TUBE

A numerical simulation and an experimental study were carried out for sensible heat transfer for a subcooled water film falling across a horizontal heated tube. A laminar model and a turbulent model were adopted to calculate the heat transfer coefficient. The whole wetting zone on the tube surface was divided into two zones: the top stagnation zone and the lateral free film flow zone. The initial boundary conditions for the free film flow zone were determined by calculating the fluid and the temperature fields in the stagnation zone. A modified wall function method was used for the turbulent model. The comparisons between the experimental data and the numerical solutions show that the experimental data agree reasonably well with the laminar model solutions. Finally, two simple correlations were proposed for predicting the convective heat transfer of a falling film for engineering applications.