Simple analysis of a forced flow solar regeneration system

Abstract

This paper reports on the derivation of a simple expression to determine the rate of desorption of water if it is assumed that the temperature, concentration, and vapor pressure of the weak absorbent solution are constant at the arithmetic average of these values at the beginning and end of the regenerator. Thermal performance depends on the rate of evaporation of water from the weak solution, which will vary along the flow length of the regenerator. Factors to be considered include climatic variables such as insolation, wind velocity, ambient temperature, and the flow rates and initial parameters of the absorbent solution and air. Calcium chloride is analyzed as the absorbent, while the forced convective heat transfer coefficient between the solution film and airstream is evaluated for laminar and turbulent conditions. Figures are presented showing effect of water vapor pressure in air on rate of desorption and effect of preheating the solution and air. It is concluded that solution regeneration is more effective while preheating the air than while preheating the solution.