Performance of a Solar Desiccant Cooling System

A solar desiccant cooling system was operated at the Solar Energy Applications Laboratory, Colorado State University, throughout the 1986 summer. The system comprises an American Solar King fresh air heating/desiccant evaporative cooling unit, a Sunmaster evacuated tube solar collector, hot water solar storage tank, auxiliary electric boiler, controls, and accessories. The cooling unit is operated in the ventilation mode, fresh air being dried in a rotating desiccant matrix, and cooled by heat exchange and evaporative cooling. Return air is used as a cooling medium in a rotating heat exchange matrix, heated by solar energy in a heat exchange coil, and discarded through the rotating desiccant bed. The solar-driven system provided over 90 percent of the seasonal cooling requirements in an experimental, residence type building at average COP levels of 1.0 and solar collection efficiencies of 50 percent when supplied with solar heated water at temperatures of 50 to 65° C. Detailed operating results, including total and average solar cooling provided, coefficients of performance, and overall solar cooling performance ratios are presented.