Long-Term Test Results from a Latent Heat Storage Developed for a Solar Heating and Cooling System
Abstract
In solar thermal installations, full annual utilisation is preferable. During the cold season, solar heat serves for space heating. During the warm season, solar heat can be converted into useful cold by means of sorption cooling. In the case that low temperature heating and cooling facilities like floor/wall heating systems or activated ceilings are applied for heating and cooling, a lowtemperature heat storage using the latent heat of phase change materials (PCM) can be used to significantly improve the performance of the system in the cooling mode and in the heating mode as well. A storage with about 2.4 tonnes of CaCl2Â6H2O as PCM and capillary tubes as heat exchanger was built in fall 2006. The storage consists of two modules with a total volume of 1.6 m³ and has a design storage capacity of 120 kWh in the temperature range between 25 °C and 33 °C. The storage is integrated into a system for solar heating and cooling of an institute building in Garching, Germany. This paper reports on standalone tests and long term results of the storage during system operation from 2007 until 2010.