Abstract

Mass transfer limitations due to decreasing permeabilities of the absorbing matrix has been observed to decrease the performance of thermochemical energy storage systems. In this study, the permeability of a reactive complex consisting ammoniated magnesium chloride salt and graphite was measured. It was shown that the permeability of the compound depends on the bulk density of the compound, as well as the amount of NH3absorbed in the magnesium chloride matrix. Additionally, the permeability of magnesium chloride (MgCl₂) ammoniate reactive compound is compared with the permeability of the manganese chloride (MnCl₂) reactive compound reported by other researchers. The two salts have similar reactions with ammonia gas with similar reaction kinetics. Although the graphite contents of the reactive compounds were different, it is shown that the permeabilities of both compounds are within the same order of magnitude. However, it is shown that upon absorbing ammonia, the permeability decrease in magnesium chloride compound was larger than the decrease of permeability in the manganese chloride compound.

Keywords: Thermal energy storage; Thermochemical; Porosity; Permeability; Ammonia; Magnesium chloride