Heat storing/releasing characteristics of a chemical heat storage unit of electricity using a Ca(OH)2/CaO reaction

Abstract

The applicability of the Ca(OH)2/CaO thermochemical reaction for heat storage derived from night-time electricity was studied. The heat releasing rate, heat output, and thermal efficiency were investigated experimentally by using a laboratory/scale heat storage unit incorporated with a fin-type heat exchanger. It was found that, during the heat-releasing step, when water vapor at an ambient temperature of around 300K was introduced into the reactor, the temperature of the CaO reactant bed was increased to around its equilibrium temperature of 610 K. The hydration heat was then recovered by the heat exchanger medium (city water) the temperature of which was rapidly increased to above 343 K. The amount of the heat recovered from the CaO packed bed was about four times higher than that which might be recovered if the energy storage was carried out by the latent heat of water of the same volume. © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(6): 400–409, 1996