A Simulation Study on the Hydration of Magnesium-Based Thermochemical Heat Storage System for Residential Buildings

Thermochemical heat storage system has a great potential due to its advantages of high heat storage density and long storage time. In this paper, a thermochemical heat storage system is designed based on Mg(OH)₂/MgO and a two-dimensional mathematical model of exothermic process of the thermochemical energy storage reactor is established, which can be applied in residential buildings. The heat storage and exothermic processes of the heat storage units (HSU) are investigated by numerical simulation. The third boundary condition is adopted and the temperature change of the heat transfer fluid (HTF) in the channel is considered. After modeling the whole system, some parameters of the system are optimized, including the size of HSU, the inlet temperature of HTF, and the pressure of reaction bed, which is helpful to guide the design of thermochemical heat storage equipment in future. In addition, the results reveal that the reaction limit is in good agreement with previous literature and the energy storage density of magnesium-based thermochemical energy storage system is much higher than ordinary phase change materials such as paraffin. The heat storage system is expected to be a new type of heat storage system.