Solar-powered open absorption cycle modeling with two desiccant solutions

This paper presents the modeling and simulation of solar-powered desiccant regenerator used for open absorption cooling system. The input heat, which is used to re-concentrate the desiccant solution, is estimated via a real-time solar radiation model in terms of the location, day of the year and time of the day. Lithium chloride (Lid) and calcium chloride (CaCl2) solutions are applied as the working desiccants in this investigation. To compute the thermo-physical properties, a state equation is used for the calcium chloride desiccant while tabulated data along with an artificial neural network (ANN) model is used for the lithium chloride desiccant. A finite difference method is used to simulate the combined heat and mass transfer processes that occur in the liquid desiccant regenerator using the Matlab-Simulink platform. Using the proposed model, the effect of the important parameters, namely the regenerator length, desiccant solution flow rate and concentration, and air flow rate, on the performance of the system is investigated. It has been found that the vapor pressure difference has a maximum value for a given regenerator length with higher values obtained with the calcium chloride desiccant than those obtained with the lithium chloride desiccant. The proposed model can be successfully used for investigating the effect of different operating parameters under different ambient conditions and for predicting the overall performance of the system. (C) 2011 Elsevier Ltd. All rights reserved.