Published 18 issues per year
ISSN Print: 1064-2285
ISSN Online: 2162-6561
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KINETIC CHARACTERIZATION OF EXPANDED GRAPHITE, CALCIUM CHLORIDE, AND MAGNESIUM HYDROXIDE COMPOSITE FOR THE CHEMICAL HEAT PUMP
ABSTRACT
A composite chemical heat storage material, EMC, comprising a mixture of expanded graphite (EG), magnesium hydroxide (Mg(OH)2), and calcium chloride (CaCl2) has been developed as a magnesium oxide/water chemical heat pump reactant. The reaction kinetic characterization of the optimized EMC (which was an optimized mixing weight ratio of the material) was conducted. From BET and thermal conductivity measurements, it was confirmed that an optimized EMC had a higher specific surface area and thermal conductivity values than pure Mg(OH)2 on adding EG. The durability of the optimized EMC was also investigated by thermobalance and XRD experiments. EMC maintained enough reacted conversion and unchanged crystal structure throughout the repetitive experiment. The film diffusion control model was suggested as a dominant reaction process for MgO hydration by kinetic analysis of experimental results. In conclusion, the optimized EMC showed shorter dehydration time corresponding to the heat storage process period and enhanced hydration conversion corresponding to the heat output capacity than pure Mg(OH)2 on adding EG, a moldable and porous carbon material, and a CaCl2 hydrophilic material.
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Guo Rui, Takasu Hiroki, Funayama Shigehiko, Shinoda Yasunari, Tajika Masahiko, Harada Takuya, Kato Yukitaka, Mechanical stability and heat transfer improvement of CaO-based composite pellets for thermochemical energy storage, Chemical Engineering Science, 255, 2022. Crossref
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Palacios Anabel, Navarro Maria Elena, Barreneche Camila, Ding Yulong, Water sorption-based thermochemical storage materials: A review from material candidates to manufacturing routes, Frontiers in Thermal Engineering, 2, 2022. Crossref