Laboratory-Scale Stirling-Vuilleumier Hybrid System Part I: Application of Similarity-Based Design

Abstract

By inserting a second regenerator in the connecting duct of a -Stirling engine, a so-called hybrid cycle is created, featuring both mechanical power generation and a heat pump effect. This cycle can be converted into a Vuilleumier heat pump cycle by adding a fourth cylinder volume on the reverse side of the compression piston. So, it is possible to devise a convertible machine that can be operated in these three modes depending on current demands, and that therefore offers remarkable opportunities as a decentralized residential energy supply system due to its variable heat-to-power ratio, particularly if a larger number of such machines are operated under central control to cut peak power demands and to generally optimize energy supply grids according to macroeconomic criteria. To experimentally demonstrate the feasibility at a reduced manufacturing and operating effort, a similarity-based scaling procedure is applied to an original full-scale design, which was previously optimized for typical operating conditions derived from statistical data and for minimum series production costs. This first part of a two-part contribution primarily addresses the theory and the limitations of this scaling procedure, as well as possible means to correct any associated errors, and present the experimental design.