DIFFUSION LAYER MODELING FOR CONDENSATION IN VERTICAL TUBES WITH NONCONDENSABLE GASES

Noncondensable gases significantly modify the mechanism of condensatio n for cocurrent downward flow in vertical tubes. Two-dimensional exper imental measurements presented here show similarity between gas concen tration distributions and the temperature distributions encountered in laminar and turbulent heat transfer. Thus the analogy between heat an d mass transfer, coupled with a reasonable condensate film model, can provide predictions of the local condensation rate. This work presents a simple 9-step iterative calculation procedure for calculating the l ocal heat flux. The empirical model, based on a modified Dittus-Boelte r formulation and utilizing an effective condensation thermal conducti vity, converges with 2 to 10 iterations at each axial location. Experi mental results from several investigators are compared with the predic tions of the model, with good agreement.