Investigation on a Vermiculite-Based Solar Thermochemical Heat Storage System for Building Applications

Abstract

Industrial processes and the building sector (e.g., for space and water heating) are responsible for the majority of the total energy consumed for heat. Although fossil fuels remain to dominate the heating sector, renewable heating technologies have been lately widely deployed. Thermochemical energy storage (TES) can be a promising advanced technology in addressing the mismatch between renewable energy supplies and the end-user's demand. In this paper, a novel Vermiculite-based Solar Thermochemical Heat Storage (VS-THS) system was proposed for domestic space heating applications, which could also overcome the intermittency challenges and realise long-term solar energy storage. A small-scale prototype was set up to evaluate the energy storage performance of the proposed system using a patented ChainStore panel to accommodate vermiculite-based composite. The unique design of the ChainStore arrangement offers great heat and mass transfer and good flexibility for system resizing in the case of varying the building energy demand. Due to the low regeneration temperature (63 °C) and high energy storage density (253.8 kWh/m 3 ) of the vermiculite-based adsorbent impregnated with MgSO 4 and CaCl 2 , it was chosen as the THS composite in the experiments. The experimental results showed that the proposed VS-THS is feasible for domestic space heating, with the highest space heating supply temperature of 37.6 °C, and the system COP in the reaction process is 7.9-10.4. In addition, the results also demonstrate that the composite of vermiculite impregnated with MgSO 4 and CaCl 2 , with a good water adsorption performance. This proposed concept of VS-THS could be sized for different building applications.

Cycling Stability of Calcium-Impregnated Vermiculite in Open Reactor Used as a Thermochemical Storage Material

“…Unlike sensible heat storage (thermal storage), which uses phase change materials to capture and store heat, such as the melting and solidifying of a wax, TCS captures and releases thermal energy through reversible exotherm/endotherm reactions [7][8][9], often involving the adsorption and desorption of reactant gas. TCS applications are used to capture solar thermal [10,11] energy or latent heat from an industrial process [10,12,13]. The benefit of using TCS is that it has a high energy density, utilizes inexpensive materials that have a low carbon footprint and is, therefore, potentially a more 'greener' and economical choice for domestic heating [9,14,15].…”