Demand side management through latent thermal storage in HVAC systems coupled with commercial refrigeration units

The electrical energy demand of an HVAC plant can be better managed by using latent thermal energy storage when time-of-use tariffs or peak tariffs are in force, in a view of Demand Side Management of the electrical grid. Nonetheless, air conditioning systems show a marked use of electrical power during the day, and the peak in the cooling load mostly corresponds to the lowest performance of the chiller due to outdoor conditions, thus giving rise to a marked peak in electricity use. An HVAC plant of a supermarket is supplied with an ice thermal energy storage, with the main aim of shaving the peak in electrical power use. The latent thermal storage is charged at night-time by employing the CO2 commercial refrigeration system of the supermarket, which is considerably part-loaded during the shop closing time. During daytime, the thermal storage can be operated in replacement of or in parallel to a reversible heat pump, operating as a water chiller for air conditioning. The same heat pump operates at wintertime for heating purposes, in parallel with heat recovery from the CO2 commercial refrigeration plant. A model of the whole system is presented, and possible solutions are shown for demand side management purposes.