Thermal regenerator deployed as a mini-channel porous media using supercritical CO2 as a working fluid

Abstract

Supercritical carbon dioxide (sCO₂) flow has unique thermodynamic properties that enhance the solar dish Stirling engine’s thermal efficiency and overall system performance in optimising solar energy utilisation for sustainable power generation. A precise knowledge of the impact of sCO₂ flow in solar dish Stirling engines and corresponding fluid–structure (FSI) interaction is missing in the literature. Therefore, this study aims to develop a novel FSI model for solar dish Stirling engines and optimise the system’s thermal efficiency. An advanced FSI model was developed for mini-channel porous media. A comprehensive grid refinement was performed, and the computational model was validated with the preliminary experimental measurement. The study presents the computational findings of heat transfer and fluid flow through a three-dimensional (3-D) woven mesh aluminum_1100 alloy. This structure is deployed as a thermal regenerator for solar dish application in the Stirling engine. The numerical model reports that the non-similar regenerator thermal efficiency in all angular velocities is always higher than that of similar regenerators. Following the grid independence analysis and experimental validation, the numerical method used in this study is considered reliable. Increasing the angular velocity from 10 rad/s to 100 rad/s leads to reaching the maximum thermal efficiency value during a lower reduced length < 4. The highest deformation occurs in the first wire exposed to the hot stream in both similar (∼7.39 $\mu m$) and non-similar (∼7.42 $\mu m$) regenerators during the heating period. Using sCO₂ as a working fluid flow could significantly influence in contrast to space constraints. This research highlights the importance of sCO₂ flow in improving the efficiency of solar dish Stirling engines, crucial for optimising sustainable solar power generation.