Methodology for thermal design of solar tubular reactors using CFD techniques

This work presents the main steps for the development of a Computational Fluid Dynamics (CFD) model to evaluate the performance of a solar tubular reactor design from the thermal point of view. In this paper a detailed description of the methodology is presented step by step. A simplified reactor design, which consists of a cubical cavity with a single tube, has been selected as base case to illustrate the different models and parameters which take part in the CFD simulations. This base case represents a solar tubular reactor for hydrogen production by means of ferrite thermochemical cycle. The accurate modeling of heat transfer to the packed bed in the interior of the tube is presented, including the effect of the radial distribution of porosity within the porous media. According to the type of reactor and the operating conditions, models and model parameters are analyzed and selected in order to solve the simulation balancing accuracy and required computational time, and the main results are presented. To conclude, the methodology is presented as a powerful tool to identify weaknesses in the design of solar tubular reactor. In addition, the reactor performance at different operating conditions can be evaluated.