In-depth investigation of thermochemical performance in a heat battery: Cyclic analysis of K2CO3, MgCl2 and Na2S

Thermochemical materials K2CO3, MgCl2 and Na2S have been investigated in depth on energy density, power output and chemical stability in view of domestic heat storage application, presenting a critical assessment of potential chemical side reactions in an open and closed reactor concept. These materials were selected based on a recent review on all possible salt hydrates, within the frame of a thermochemical heat battery and considering recent advances in heat storage application. Judged by gravimetric and calorimetric experiments in operating conditions and worst-case-scenario conditions, K2CO3 is recommended for both an open and closed system heat battery. The compound is chemically robust with a material level energy density of 1.28 GJ/m(3) in an open system and 0.95 GJ/m(3) in a closed system, yielding a power output of 283-675 kW/m(3). Na2S and MgCl2 on the other hand are chemically not robust in heat storage application, although having a higher energy density, output power and temperature in one cycle.