Water-loop self-contained systems in supermarkets providing also evaporative cooling: an energy and economic analysis.

Supermarkets are the largest energy users in the commercial sector in many countries. They are also responsible of a large amount of both direct and indirect CO2 emissions. Nowadays advanced supermarket systems can reduce both annual energy consumption and total equivalent warming impact. One of these advanced solutions is the water-loop self-contained refrigeration system with modulating compressors (WLSC). The most critical aspect (from the energy efficiency perspective) of a WLSC plant is that two refrigeration cycles (in the cabinet and in the water-loop chiller) might be required during the hottest period of the year. In this paper a WLSC plant is experimentally studied, evaluating above all energy performance and cost in different outside conditions: the main conclusion is that the chiller should be activated only when the external temperature is extremely high. In all the other periods, the dry-cooler utilization should be preferred. Evaporative cooling is also considered with the purpose of further reducing the water-loop temperature.