Mass, momentum and heat transfer from a falling film to a countercurrent air stream

Simultaneous mass, momentum and heat transfer rates from a vertical falling liquid film to an upward flow of air are reported. Air formed a laminar external boundary layer along the liquid film. The dimensionless transport coefficients were determined from property gradients measured at the inner edge of the vapor boundary layer. The velocity, temperature and vapor mole fraction profiles were measured using hot wire anemometric, thermocouple probe and isokinetic sampling with gas chromatographic analysis techniques. The transport phenomena were studied on two different types of countercurrent liquid films: (1) slow moving nonrippling film and (2) fast moving rippling film. The particular numerical and integral solutions of boundary layer equations are in good agreement with data. Differences between the predicted and measured transport coefficients are shown to be attributed to ripples.