A Novel Alginate/Expanded Graphite based Composite for use in Solar and Waste Heat Storage
Abstract
Thermochemical heat storage composites based on hydrated salts offer a promising route for storing energy collected from transpired conventional solar collectors (<70°C) or low-grade waste heat sources (<150°). A CaCl2 salt enclosed within an expanded graphite/alginate polymer matrix has been synthesized which offers several advantages. The method outlined offers flexibility in the size and shape of the composite material to best suit the application, with the option of easily being scaled up. The incorporated CaCl2 can release and store heat through the reversible hydration and dehydration reaction. The charge reaction is studied using static heat, while the discharge reaction is studied by passing a flow of variable humid air through the materials. Both reactions are compared to previously studied Vermiculite/CaCl2. Further to this salt loading, surface area, bulk density, surface porosity, moisture sorption and thermal conductivity are all considered.