Coupled thermo-chemo-mechanical modeling of reactive solids: Applications to thermochemical energy storage materials

Abstract

A continuum-scale thermo-chemo-mechanical modeling framework is developed to investigate the multiphysics behavior of thermochemical energy storage (TES) materials undergoing hydration and dehydration during thermal cycling. The formulation integrates species diffusion, chemical reaction kinetics, heat generation/transport, and mechanical deformation within a unified theoretical framework to resolve spatial and temporal evolution of species concentration, reaction progress, temperature, and stress across material domains. A series of non-dimensional parametric studies quantifies the influence of key material parameters, including thermal conductivity, diffusivity, and reaction kinetics, on transformation dynamics, revealing critical interdependencies among physical processes that govern TES performance. To illustrate the capabilities of the framework, simulations of representative potassium carbonate pellets are presented with constitutive models and material properties adopted from the literature. In order to isolate chemo-thermal effects and facilitate comparison with fully coupled simulations, initial case studies focus on pellet hydration/dehydration without mechanical coupling, demonstrating the predictive capability of the model in capturing chemo-thermal gradients and transient performance. Subsequently, a fully coupled simulation is presented to explicitly illustrate the influence of mechanical stresses on the progression of the reaction. Mechanical stress can alter local chemical equilibrium conditions, thereby enhancing or suppressing hydration and dehydration reactions. By systematically accounting for interactions between stress, reaction pathways, and transport phenomena, this framework enables a mechanistic understanding of the dynamic interplay of physical processes that govern energy storage efficiency and material reliability, ultimately supporting the design of more robust and high-performance TES systems.