The generation of electrical power from photovoltaics and wind energies is often mismatched with the demand of energy scheduled by industrial processes. Chemical heat storage technology allows the conversion of heat from electricity surplus, solar heat or industrial waste heat into chemical energy, which can be reutilized on-demand, either for industrial processes requiring heat or for re-conversion into electricity. This energy buffer technology would contribute in stabilizing the mismatch between demand and offer and improve the resilience of energy supply into the decarbonized Society. A main bottleneck for practical utilization of chemical heat storage is related to the poor heat transfer ability in the packed bed reactor. In this work it is tried to clarify numerically the effects of thermal conductivity and thermal contact conductance on the exergy efficiency of heat transfer during the dehydration reaction (heat storage mode). A fixed packed bed reactor with flat geometry based on Ca(OH)2 dehydration has been considered: chemical heat storage performance indicators like average heat storage rate and exergy efficiency were obtained via numerical simulations by changing the values of thermal conductivity of packed bed's material, thermal contact conductance between packed bed and reactor's wall and size of the packed bed. It was found that thermal conductivity enhancement is necessary but not sufficient for achieving the highest average heat storage rate, thermal contact conductance results important for maximizing the benefits of thermal conductivity enhancement, while a decrease of size of the packed bed results beneficial for achieving higher exergy efficiencies.
CITATION STYLE
Zamengo, M., Funayama, S., Takasu, H., Kato, Y., & Morikawa, J. (2022). Numerical Analysis on the Effect of Thermal Conductivity and Thermal Contact Conductance on Heat Transfer during Dehydration Reaction in a Fixed Packed Bed Reactor for Thermochemical Heat Storage. ISIJ International, 62(12), 2559–2566. https://doi.org/10.2355/isijinternational.ISIJINT-2022-165
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