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

The applicability of the Ca(OH)(2)/CaO thermochemical reaction for storing nighttime heat derived from electricity was studied. The heat releasing rate, heat output, and thermal efficiency were investigated experimentally by the use of a lab-scaled heat storage unit incorporated with a fin-type heat exchanger. It was found that when water vapor at ambient temperature of around 300 K was introduced to the reactor, the temperature of the CaO reactant bed during the heat releasing step was increased to around equiliburium temperature at 610 K. The hydration heat produced was then recovered by the heat exchanger medium (city water) the temperature of which was rapidly increased up 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 sensible heat of water in the same volume.