CH-85-09-4 -- Evaluation of Gas-Fired Desiccant-Based Space Conditioning for Supermarkets PDF

Using gas-fired desiccant dehumidification for supermarket air conditioning affords many benefits. Supermarkets have a disproportionately high latent-to-sensible load ratio. Air conditioners must overcool the air to achieve adequate dehumidification and then reheat the air to control dry-bulb temperature. This results in inefficient operation. Depressed humidity levels, which are easily achieved only by desiccant systems, provide additional savings by reducing the latent load on refrigerated cases. A computer model was formulated to allow the extension of field test results to many climates, system types, store types, and shopping patterns. Results indicate a favorable scenario in climates of moderate and high humidity, with utility rate structures that favor the switch from electricity to gas. The trend toward energy-efficient architecture and increased food-refrigeration capacity, both of which increase latent-to-sensible load ratio, and electrical rate penalties for peak power demand suggest that the concept will be even more cost-effective in the future. As a result, an integrated system, which incorporates the most desired features and best balance of desiccant-based and vapor-compression cooling, is currently under development.