A note on heat transfer to turbulent liquid falling films at high prandtl number

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For heating of turbulent falling films at large Pr, the resistance to heat transfer exists almost entirely in the viscous sublayer near the wall, with the outer fully turbulent region being virtually isothermal. In this note, an approximate relation for the heat transfer coefficient is derived for heating or cooling of a fully turbulent falling film at high Prandtl number. The analysis used to determine the heat transfer correlation incorporates the high Prandtl number assumption in a manner similar to that of Sandall et al. (1984). However, the present analysis differs in that it accounts for the known variation of turbulent Prandtl number with distance from the wall. Sandall et al. (1984) assumed that the turbulent Prandtl number is constant across the film. The heat transfer coefficients predicted by the correlation obtained here are found to agree well with experimental data for heating of liquid films at moderate and high values of Prandtl number.