Influence of the regenerator sub-division on the global performances of a Stirling engine: study of main parameters

Studying Stirling engines is important for advancing sustainable energy technologies, improving efficiency and reliability in power generation, reducing environmental impacts, and fostering innovation in engineering and energy systems. This paper extends prior research by conducting a comprehensive parametric analysis of key factors affecting Stirling engine performances. It investigates the influence of porous medium material, sub-regenerator divisions, and porosity distribution on regenerator efficiency and engine power output. Specifically, it introduces a Stirling regenerator model to characterize fluid flow and heat transfer. It uses the Brinkman-Lapwood-Forchheimer extended Darcy flow in the regenerator, which is a porous medium, to optimize flow and heat transfer. The main goal is to improve heat transfer intensification resulting in better overall performance. Numerical investigations were conducted using the Control Volumes based on the finite element method (CVFEM), provided from a proper CFD code we developed under Fortran Software. The study shows that power output and engine efficiency increase when porosity is reduced from 90% at the cooler interface to 70% at the heater interface. It also identified that Lanthanum Nickel alloy material was the best porous medium for the regenerator, resulting in the highest work and regenerator thermal efficiency. These findings could significantly improve the performance of Stirling engines in heat recovery applications, making them more sustainable and efficient.