Solar thermochemical fuel production is a promising approach for efficient solar energy storage, where redox materials are used to drive water and carbon dioxide splitting reactions. This process enables the production of renewable hydrogen and synthetic fuels with high theoretical solar-to-fuel efficiencies, enabled by the absence of intermediate energy conversion steps. However, the development of these systems is hindered by low experimental efficiencies achieved so far, mainly due to high operating temperatures, radiation losses, and the limited reduction extent of state-of-the-art redox materials such as ceria. To enhance the process performance, alternative materials like perovskites as well as improved reactor designs, including indirectly irradiated configurations with heat recovery, are being explored. This study investigates the reduction step of an indirectly irradiated ceria-based solar reactor using a comprehensive 3D multiphysics model developed with the commercial software COMSOL Multiphysics®. The model simulates the complete coupling among fluid flow, heat transfer, and redox chemistry. The reactor performance and its optimal operating conditions in a base-case geometrical configuration are analysed under the thermodynamic equilibrium assumption between the gas phase and the solid reactive phase, simulated as state-of-the-art dual-scale porosity reticulated porous ceramics made of ceria. The simplification of thermodynamic equilibrium was verified at different pressure levels by integrating the kinetics of the redox reaction in the existing model. A general method to implement the thermodynamics of a generic redox material under different temperature and oxygen partial pressure conditions was developed and integrated in the model. With this addition, two novel perovskites (namely, SrTi₀.₅Mn₀.₅O₃ and CaTi₀.₅Mn₀.₅O₃) were considered as alternative redox materials, that was not reported so far in the literature. Since the thermophysical properties of these materials are not yet well documented, a sensitivity analysis was conducted to assess their influence on reactor performance, considering reasonable values as a first approximation.