Performance characterization of salt-in-silica composite materials for seasonal energy storage design

This work presents the results of the performance characterization for novel salt-in-silica composites, destined for seasonal energy storage. The materials were synthesized using the Davisil® silica gel to support the hygroscopic inorganic salts of calcium chloride (CaCl2), magnesium chloride (MgCl2) or strontium bromide (SrBr2). The experiments were carried out on an open sorption laboratory setup under constant hydration conditions. The sample mass was 245 g, which is representative of a prototype control volume of 0.5 l, and the nominal air flow rate was 215 l min−1. Energy storage densities between 70 and 145 kWhm-3 of control volume were experimentally found at 30 °C (inlet air temperature) and for different inlet air relative humidity levels. Average specific thermal powers in the range between 93 and 311 Wkg-1 were measured. Based on the experimental results, the design and upscaling of the seasonal energy storage were demonstrated. The best feasible energy storage densities ranging from 50 to 90 kWh m-3 of up-scaled reactor were predicted to deliver 1000 W of rated thermal power.