Development of a Cost Efficient Buried Hot Water Storage – Conception and First Results
Abstract
Ground buried hot water storage tanks overcome the spatial limitations of an indoor installation. Larger storage volumes can be chosen in order to increase the solar fractions of the heating demand. The paper presents the tasks and aims of a research project1 in which a buried storage is developed, consisting of a concrete cistern, a XPS insulation and an inliner foil combining EPDM and aluminium. The storage operates under atmospheric pressure. During the prototypes construction and implementation, first experiences regarding methods of manufacturing and installation efforts have been gained. A large number of sensors has been installed for surveying long-term properties and the thermal performance of the storage. For the 5.5 m³ prototype a heat loss rate of about 5 W/K has been measured, corresponding to a temperature decrease of approximately 1 K/d when cooling down from 85 to 65°C. An important task beside the tank and heat exchanger design is the development of a new insulation material based on enhanced polystyrene foam, which shall have a long term reliability at temperatures up to 95°C.