CH-95-05-2 -- Analysis of a Field-Installed Hybrid Solar Desiccant Cooling System PDF

Monitors and assesses the performance of a commercial hybrid solar solid desiccant air-conditioning system in a high-humidity restaurant application. air is heated in the regeneration section by a heat recirculator coil, a condenser waste heat recovery coil, and a solar cell, accounting for roughly 27%, 24%, and 49% of the regeneration heat, respectively, when solar energy is available. The specific humidity change across the desiccant wheel varies from 4 to 90gr/lb (0.57 to 12.86g/kg) over the 108degF to 197degF (42.2degC to 91.7degC) regeneration temperature range. The coefficient of performance (COP), defined as the usable cooling capacity divided by the heat input, increased from 0.2 to 1.0 at the rate of 0.01 for every 10degF rise in the regeneration temperature. The results from this project provide much valued field data as well as a design basis for future work. The desiccant unit supplies conditioned ventilation air to two conventional packaged vapour-compression air-conditioning units, thereby forming a hybrid system. The effect of this arrangement on the performance of the vapour-compression units was investigated. The desiccant unit accounts for about one-fourth of the dehumidification capacity available to the restaurant. The cooling capacity of the desiccant cooling system varies over the day, mostly with solar insolation and to a lesser degree with ambient relative humidity. The desiccant unit provides an average capacity of 21.560Btu/h (6.32kW). Since the retrofit of the hybrid system, the kitchen air temperature has decreased by about 15degF and specific humidity has decreased by about 30gr/lb (4.29g/kg).

KEYWORDS: year 1995, desiccants, cooling, solar energy, heat recovery, restaurants, humidity, relative humidity, kitchens, air temperature, insolation, solar cooling, performance, monitoring, electricity consumption, energy consumption, coefficient of performance, unit air conditioners, natural gas, comparing, latent heat.