Significant parameters for energy consumption in frozen area of large supermarkets

The thermal behavior of large supermarkets is dominated by internal gains. Specifically, refrigerated and frozen food display units area is characterized by cool loads created by commercial cases, which are also moisture trap. A coupling approach of air conditioning with display cases operation is proposed in this paper, based on a model of the cold aisle phenomenon. In this area, the significant vertical stratification of air has to be considered to calculate electric consumption of display cases. Heat and moisture exchanges are calculated and typical values are given. Our study gives new elements to answer the questions : how the energy balance is affected by the ambiance setpoints, how interactions between display freezers and air conditioning systems can be characterized. Typical technical characteristics of roof-top air conditioners performance under various conditions are proposed to calculate energy consumption including auxiliary equipment (fans). Simulations made with the models for commercial display freezer loads and air temperature profile establish the impacts of different ambient temperature and humidity setpoints. To aggregate the comparison, all energy uses are taken into account: air conditioning, refrigeration and defrosting, it is an essential element for technico-economical analysis of innovative solutions.