Study on medium-temperature chemical heat storage using mixed hydroxides

Abstract

It was demonstrated that chemical heat storage materials mixed with metal hydroxides were capable of storing heat at medium temperatures of approximately 200–300 °C. The performances of the developed materials were demonstrated in a thermo-balance and packed bed reactor. The mixed hydroxides can increase the operation heat storage temperature by changing the composition of mixed metal oxides in the material. Mg α Ni 1− α (OH) 2, which is a mixed hydroxide of magnesium hydroxide, Mg(OH) 2, and nickel hydroxide, Ni(OH) 2, is a candidate heat storage material. The mixed hydroxide was dehydrated, that is, it was capable of storing heats at 200–300 °C, at which pure Mg(OH) 2 could not be dehydrated and could not store heat. The heat output performance of the material was examined in a packed bed reactor. It was shown that the mixed hydroxide material was potentially useful for chemically storing medium-temperature heat such as waste heats emitted from internal combustion engines, solar energy system and high-temperature processes.