A feasibility study of a solar desiccant air-conditioning system. Part II : Transient simulation and economics

In this paper, a solid desiccant cooling system with a backup vapour compression system is simulated using TRNSYS and the performance of the system is evaluated in four cities in the United States with different climates. Economic analysis is performed in order to assess the feasibility of these systems and to determine the relevant economic parameters such as life cycle costs, life cycle savings and payback periods. Results show that the system has higher COP values for the locations with more latent loads. The air conditioner was able to meet the cooling demand in all four regions, but it needed more auxiliary energy in the Eastern and Mountain regions than in the Central region, because of the higher solar fraction in the Central region. The simulation also showed that the desiccant cooling system by itself was capable of meeting the cooling demand and hence the requirement of a backup system may be eliminated. Thermal and economic parameters were analysed for varying solar subsystem sizes which proved helpful in optimizing the design of the solar system. Recommendations to minimize the auxiliary energy costs using different methods for supplying the thermal energy for desiccant regeneration are described. Copyright © 1999 John Wiley & Sons, Ltd.