Enhancing the effectiveness of Stirling engine regenerators

Abstract

A discrete heat transfer model is developed to determine which parameters influence the effectiveness of Stirling engine regenerators and quantify how they influence it. It is revealed that the regenerator thermal mass ratio and number of sub-regenerators are the two parameters that influence regenerator effectiveness, and these findings were extended to derive expressions for the regenerator effectiveness and Stirling engine efficiency. It is determined that a minimum of 19 sub-regenerators are required to attain a regenerator effectiveness of 95%. Experiments validated the heat transfer model, and demonstrated that stacking sub-regenerators, such as wire meshes, provides sufficient thermal resistance to generate a temperature distribution throughout the regenerator. This is the first study to determine how Stirling engine designers can attain a desired value for the regenerator effectiveness, and/or a desired value for the Stirling engine efficiency by selecting appropriate values of regenerator thermal mass ratio and number of sub-regenerators.