Performance Characteristics of Open-Flow Liquid Desiccant Solar Collector/Regenerator for Solar Cooling Applications. Part 1: Two Dimensional Analysis of Heat and Mass Transfer for Open Flow over Rough Inclined Surfaces

摘要

This work presents an analytical approach to simulate the combined heat and mass transfer on the interface between wetted collector surface and ambient air. Emphasis was placed on the development of a mathematical model of turbulent natural convection on an inclined rough plate. The effect of surface velocity is also considered. The systems of partial differential equations governing fluid motion, heat and mass transfer along an inclined flat plate were formulated in terms of vorticity transport and stream function equations. One-equation model of turbulence was used to compute the turbulent viscosity. The length scale used in this model was expressed algebraically in terms of the mixing length. A length scale modified function was derived to take into account the bouyancy effects on turbulence. The effect of surface roughness was taken into a account by introducing a characteristic roughness length. A computational technique was developed to solve the resulting elliptic partial differential equations. This technique involved an 'inflow-outflow' scheme to determine the free boundary conditions at the leading and trailing edges of the inclined plate. The validity of this computational technique was tested and confirmed by some testing problems. Among these are (1) laminar natural convection on an inclined isothermal plate (2) turbulent natural convection on a vertical isothermal plate and (3) turbulent natural convection on an inclined constant heat flux flat plate. (ERA citation 10:044065)