Parameter control in synthesis of Vermiculite-CaCl2 composite materials for thermochemical adsorption heat storage

Zhang, Yong; Chen, Ziwei; Zhang, Yanan; Su, Yuehong; Riffat, Saffa

Abstract

This study utilised vermiculite as a matrix to explore various impregnation methods for synthesising vermiculite-CaCl2 composite materials (VCMs), focusing on the impact of these methods on the performance of VCMs as thermochemical materials. Results indicate that alternative impregnation methods (e.g., multi-step, vacuum, high pressure, and high temperature) reduce VCM porosity compared to single impregnation, resulting in higher salt content as confirmed by CaCl2 content tests. Multi-step impregnation yields VCMs with an exceptional salt content of 81.37 wt%, surpassing the highest literature value (68 wt%) and the control group VCM-s (51 wt%). Vacuum impregnation notably increases salt penetration, leading to VCM-vac having the lowest porosity. However, this reduced porosity results in lower hydration and dehydration rates. Notably, VCM-vac exhibits the highest energy storage density of 2.05 GJ/m³, which is approximately three times the reported literature values and 1.5 times greater than the study's control group VCM-s. It also exceeds the CaCl2-rich VCM-m by 0.2 GJ/m³. It also demonstrates superior cyclic stability, with most CaCl2 remaining internalised, minimising agglomeration and CaCl2 loss. The energy consumption for vacuum impregnation is estimated at 3.51 kWh/kg(salt), indicating relatively low energy usage. The findings indicate vacuum impregnation emerges as a preferred method for synthesising thermochemical composite materials.

Citation

Zhang, Y., Chen, Z., Zhang, Y., Su, Y., & Riffat, S. (2024). Parameter control in synthesis of Vermiculite-CaCl2 composite materials for thermochemical adsorption heat storage. Energy, 291, Article 130478. https://doi.org/10.1016/j.energy.2024.130478

• Journal Article Type: Article
• Acceptance Date: Jan 24, 2024
• Online Publication Date: Jan 29, 2024
• Publication Date: Mar 15, 2024
• Deposit Date: Feb 1, 2024
• Publicly Available Date: Feb 1, 2024
• Journal: Energy
• Print ISSN: 0360-5442
• Electronic ISSN: 1873-6785
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 291
• Article Number: 130478
• DOI: https://doi.org/10.1016/j.energy.2024.130478
• Keywords: Thermochemical energy storage; Thermochemical material; Vermiculite; Composite material; Material characterisation; Impregnation method
• Public URL: https://nottingham-repository.worktribe.com/output/30661012
• Additional Information: This article is maintained by: Elsevier; Article Title: Parameter control in synthesis of Vermiculite-CaCl2 composite materials for thermochemical adsorption heat storage; Journal Title: Energy; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.energy.2024.130478; Content Type: article; Copyright: © 2024 The Authors. Published by Elsevier Ltd.