Effects of porous carbon materials on heat storage performance of CaCl2 hydrate for low-grade thermal energy

Na Gao; Lisheng Deng; Jun Li; Tao Zeng; Hongyu Huang; Noriyuki Kobayashi; Mitsuhiro Kubota; Xiaohu Yang

doi:10.1039/d3ra04859d

Effects of porous carbon materials on heat storage performance of CaCl₂ hydrate for low-grade thermal energy

RSC Adv. 2023 Nov 6;13(46):32567-32581. doi: 10.1039/d3ra04859d. eCollection 2023 Oct 31.

Authors

Na Gao^{1

2}, Lisheng Deng¹, Jun Li¹, Tao Zeng^{1

3}, Hongyu Huang¹, Noriyuki Kobayashi⁴, Mitsuhiro Kubota⁴, Xiaohu Yang³

Affiliations

¹ Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China dengls@ms.giec.ac.cn huanghy@ms.giec.ac.cn.
² University of Chinese Academy of Sciences Beijing 100049 China.
³ Science and Technology on Thermal Energy and Power Laboratory, Wuhan 2nd Ship Design and Research Institute Wuhan 430205 China.
⁴ Department of Chemical Engineering, Nagoya University Nagoya Aichi 464-8603 Japan.

Abstract

Thermochemical energy storage (TES) is a promising technology to overcome supply-demand mismatch in the recycling of low-grade industrial waste heat. A novel sorbent is developed for low-grade TES system by employing an ordered mesoporous carbon, CMK-3, as the matrix of CaCl₂ hydrates. Expanded graphite (EG) and activated carbon (AC) as matrixes are also discussed for a comparative study. All the composites show quick kinetic within 120 °C. Salt upload ability and heat storage capacity of the composites follow the order of CMK-3/CaCl₂ (2037.2 kJ kg^-1, 50.4 wt%) > EG/CaCl₂ (1637.6 kJ kg^-1, 48.1 wt%) > AC/CaCl₂ (1221.8 kJ kg^-1, 46.3 wt%). CMK-3/CaCl₂ show the best heat storage performance due to the ordered tubular mesostructure, which limits the deliquescence at a proper level and provided good accommodation for salt solution. The inner solution absorption presents positive thermal effect that add to total heat storage capacity, making actual heat sorption of CMK-3/CaCl₂ much higher than pure chemical reaction heat. A 25-cycle sorption-desorption experiment shows excellent cycling stability of CMK-3/CaCl₂. This study proves CMK-3/CaCl₂ to be a promising composite for low-grade TES system below 120 °C, and provides new insights for improving energy density of the heat storage materials.