Analysis and modeling of a solar-assisted air conditioning and dehumidification system for applications in Puerto Rico.

摘要

This study tests the feasibility of different arrangements of solar-assisted air conditioning systems for applications in Puerto Rico and the Caribbean. The thermodynamic performance of a single-effect absorption system, alone and coupled to liquid and solid-desiccant based dehumidification systems, and powered by high performance flat-plate solar collectors, was investigated under variable cooling load conditions. A detailed heat transfer analysis was used to model a single-glazed, selective-surface, flat-plate solar collectors system. The modeling for the absorption system was based on performing heat and mass balances on each of its components, while the liquid-desiccant based dehumidification system was simulated using a cooling tower effectiveness model. A curve-fitting model on manufacturer's data was used to simulate the solid-desiccant based dehumidification system. System variables were optimized as function of geographic location and maximum cooling load. Optimization variables included the collectors' inclination angle, the thermal storage volume-to-collector surface area ratio, and the collector's surface area. Four Caribbean cities were used for this study: three in Puerto Rico, and one in Trinidad. Results for maximum cooling loads ranging from 18 to 176 kW indicated that average annual solar fractions exceeding 70% can be achieved at these cities for the absorption system alone, as well as for the absorption hybrid systems. The absorption hybrid systems required higher collector areas and increased their thermal performance under high latent cooling loads. Reasonable payback times were obtained from an economic analysis to the solar-assisted absorption system.