Severe corrosion of steel and copper by strontium bromide in thermochemical heat storage reactors

Thermochemical heat storage exploits thermal solar energy to produce sustainable residential heating, obtained by exothermal reaction between bromides and water vapour. A protocol to test the corrosion of surrounding materials is discussed in the case of SrBr2 contacting copper or steel. Corrosion depth >1 mm y−1 is found for steel in conditions where the salt remains mostly solid, due to a reaction between SrBr2 and atmospheric CO2 that produces HBr. Temperature and the dissolution of the salt (deliquescence) also play a key role. Potentiodynamic tests, the limitations of which are discussed, corroborate the salt degradation in the case of steel.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Humidity dependence of transport properties of composite materials used for thermochemical heat storage and thermal transformer appliances

Water sorption thermochemical heat storage is a promising way to provide dwellings with renewable central heating. It requires the use of several cubic meters of materials per dwelling. Depending on the design of the heating system, specific heat and mass transfer issues occur. For instance, the heat transfer rate in reactive medium and the kinetics of sorption process determine the system thermal power. In addition, the moisture propagation during inter-seasonal storage must be understood. In this paper, the influence of the water mass uptake on the apparent thermal conductivity and apparent mass diffusivity of solid material were studied. The studied material was a composite of calcium chloride (CaCl2) encapsulated in mesoporous silica with a salt content of 40–43 wt.%. The thermal conductivity was measured by the transient hot bridge method and varied from 0.13 to 0.16 W m−1 K−1, having a threshold at 0.14 g/g of water mass uptake. The apparent water mass diffusivity was studied using a diffusion column. The water diffusivity – concentration dependency was established by using the modified Hall method. The apparent diffusion coefficient ranged from 3 × 10−10 to 2 × 10−8 m2 s−1 in experimental conditions.SCOPUS: ar.jinfo:eu-repo/semantics/publishe