Feasibility of lowering the condenserʹs inlet water temperature of a chiller using thermal water storage

A novel approach is proposed for applying cool thermal storage to reduce the on-peak demand of a water-cooled chiller. By charging the store at night via a cooling tower, and using this water to supply the condenser of a chiller during on-peak hours, cooler than normal water is supplied to the chiller. A feasibility study of this system was conducted using TRNSYS — a transient simulation modeling program examining varying capacities of cooling tower and thermal store volumes. These systems were tested using geographic weather data that demonstrated conducive diurnal changes in wet-bulb temperature (Twet). Results suggest that the use of cool water thermal storage in this way can reduce both on-peak energy demand and on-peak power use by as much as 35%. System optimization is dependent on the thermal storage efficiency, the capacity of the cooling tower, and the diurnal change in Twet.