VARIATIONS OF MOLAR VOLUME AND HEAT-CAPACITY OF REACTIVE SOLIDS OF CACL2 USED FOR CHEMICAL HEAT-PUMPS

Variations of molar volume and heat capacity of reactive solids with g as absorption/desorption have been investigated experimentally for CaC l2 . nCH(3)NH(2), CaCl2 . nNH(3) and CaCl2 . nCH(3)OH, which are utili zable for driving gas-solid chemical heat pumps. Molar volume measurem ents were performed by the gas-displacement method, which we developed to measure the volume of reactive solids, and heat capacity measureme nts were performed by means of differential scanning calorimetry. Mola r volume and heat capacity of a reactive solid increase proportionally with the amount of reactive gas absorbed in it. Analysis of literatur e data has revealed that this linear relationship holds for various ki nds of hydrated and ammoniated salts, and that the increase in volume and heat capacity depends only on the amount of absorbed substance irr espective of the kind of salt.