Experimental Studies on Seasonal Heat Storage Based on Stable Supercooling of a Sodium Acetate Water Mixture
Abstract
Theoretical studies have shown that a 36 m² solar heating system can fully cover the yearly heat demand of a low energy house in Denmark if the solar heating system is based on a 6000 l seasonal heat storage with a sodium acetate water mixture supercooling in a stable way. The heat storage is divided into a number of separate modules. The heat storage concept is based on the advantage of stable supercooling to achieve a partly heat loss free heat storage. If a sodium acetate water mixture, which has a melting point of 58°C, has been fully melted, it can cool down in its liquid phase to the surrounding temperature and still preserve the latent heat related to the heat of fusion. The heat storage can be left in this state with no heat loss until a heat demand occurs, in which case solidification is activated, the heat of fusion is released, and the heat storage temperature increases almost immediately to the melting point. The investigations of a seasonal heat storage module described in this paper are carried out within the IEA Task 42 project “Compact Thermal Energy Storage: Material Development and System Integration”.