Performance of Thermal Energy Storage Unit Using Solid Ammoniated Salt (CaCl₂-NH₃ System)

Abstract

The exothermic chemical reaction of CaCl 2 (calcium chloride) with NH 3 (ammonia) can be utilized as an energy storage system. Since this reaction is a typical gas-solid reaction, the reaction rate is controlled by the heat transfer rate. In order to improve the low heat transfer rate of the ammoniation and the deammoniation of CaCl 2 , the influence of a heat transfer media (Ti: titanium) on the heat transfer rate of the solid ammoniated salt (CaCl 2 &#46 mNH 3 ) was studied and tested experimentally. The performance tests were carried out under the conditions of various weight ratios of Ti. No decrease of the activation of chemical reaction and no corrosion of experimental apparatus were observed on the repeated runs (≥30 times each). The heat transfer rate of ammoniated salt was greatly improved by adding Ti under the constant pressure (0.5 MPa). The reaction time required for the ammoniation of CaCl 2 mixed with Ti was approximately 16% - 54% shorter than that of CaCl 2 alone, and the reaction time required for the deammoniation was also approximately 19% - 59% shorter than that of CaCl 2 alone.