MATHEMATICAL MODELLING AND SIMULATION OF DROPWISE CONDENSATION AND INCLINED SURFACES EXPOSED TO VAPOR FLUX

Computer simulation of dropwise condensation on a substrate, having randomly spaced nucleation sites, is described. A numerical model is presented for simulation of dropwise condensation on flat and inclined surfaces exposed to a vapor flux. The model incorporates the effect of contact angle, inclination, contact angle hysteresis and saturation temperature at which the condensation is carried out. Simulation accounts for direct condensation growth, coalescence, fall-off and renucleation of droplets. Numerical computations are conducted for various contact angles and substrate inclination angle as a parameter. Drop size distributions and spatial patterns of condensation are presented. The simulation results are satisfactorily compared with experimental data. NOMENCLATURE A Area of cross section (m2) Void fraction (-) Tw Temperature of the solid wall (K) Tsat Saturation temperature of the condensate (K) hlv Latent heat of vaporization of the liquid (kJ/kg) hl Interfacial heat transfer coefficient (W/m 2-K) Kc Condensate thermal conductivity (W/m-K) rmin Minimum Radius of droplet (m) rmax Radius of the departing droplet (m) rb Base radius of the droplet (m) rcrit Critical radius of droplet on an inclined substrate (m) r Radius of droplet (m) Alv Area of liquid vapor interface (