High efficient heat pump system using storage tanks to increase COP by means of the ISEC concept. 2: thermal storage system.

The Isolated System Energy Charging (ISEC) concept allows for a high efficiency of a heat pump system for hot water production. The ISEC concept consists of two water storage tanks, one thermally charged and one thermally discharged. The charged tank is used for the industrial process, while the discharged tank is used for charging. The charging of the tank is done by recirculating water through the condenser and thereby gradually heating the water. The paper presents the description and the results from the dynamic modelling of the thermal storage system. Furthermore, an experimental test set up of the thermal storage system is reported, and the results are analyzed. The results show a significant improvement of the heat pump efficiency due to the thermal stratification in the storage tanks.