Influence of cooling load profile on the prediction of energy use in commercial refrigeration plants

The cooling load of a commercial refrigeration system is affected by the operating conditions of the refrigerated display cabinets and cold rooms, mainly through their mutual interactions with the indoor environment in terms of temperature and humidity. In this paper, the effects of cooling load profiles in the prediction of the annual energy use are investigated, comparing constant and simplified load functions to a more realistic simulation-based approach. The latter is made using a calibrated hourly model of the whole commercial refrigeration system, which includes a transcritical CO2 booster system with its control rules and the simulation of the display cabinets and cold rooms. These user-defined components are implemented in the TRNSYS environment and linked to the dynamic building simulation. The analysis is performed for different system configurations and weather conditions. The results show that the load profile affects the comparison in terms of energy effectiveness among different system configurations, and should be considered for a fair assessment