| In Part I the hydrodynamic and thermal characteristics of thin, laminar wavy-film flow are considered. A theoretical model is developed to predict the hydrodynamic features of asymptotic wavy-flow states. The mathematical closure question arising in asymptotic-state analyses is satisfactorily resolved here for the first time. The model accurately predicts published experimental data for mean film thickness, trough-to-crest dimension, wave celerity, and wavelength.; The Nusselt theory for laminar film condensation is shown to significantly underpredict existing experimental data due to the presence of waves on the condensate film surface. Consequently, a heat transfer model is developed incorporating the wavy-film hydrodynamic model results. The subsequent predictions agree well with experimental data and, in addition, indicate the appropriate data trend with flow length.; In Part II other thin-film phenomena are described, including continuous-film breakdown, rivulet flow, and sputtering. All of these phenomena are present in the operation of a heat transfer device known as the two-phase closed thermosyphon. Accordingly, this device is experimentally investigated. Parameters of investigation include the tube material, working fluid, fill quantity, heat flux, condenser/adiabatic/evaporator section lengths, condenser temperature, and tube inclination. |
