Investigation of performance and simulation modelling of a Stirling engine for residential cogeneration

Stirling engines are one market-ready technology suitable for residential cogeneration of heat and electricity to alleviate the increasing demand on central power grids. Characteristics of this external combustion engine include high cogeneration efficiency, fuel flexibility, low noise and vibration, and low emissions. A simulation model for combustion-based cogeneration devices has been recently developed, but available experimental data lacks adequate diversity to assess its suitability. The objective of this work is to collect and use a comprehensive experimental data set to assess and enhance performance characteristics in an existing simulation model of combustion-based cogeneration devices. An experimental apparatus is designed to integrate a natural gas-burning DC Stirling engine with components simulating thermal and electrical loads of a typical Canadian home. The apparatus is instrumented to enable evaluation of thermal and electrical efficiencies with acceptable uncertainty, and to facilitate control of steady-state and transient performance testing under a variety of operating conditions. The data set is used to critique performance characteristics in the existing model. A new form of the parametric model for steady-state efficiency is proposed and suggestions for refined transient state characteristics are made. Finally, cyclic operation of the tested Stirling engine under typical loading shows its power-to-heat ratio is insufficient for some Canadian homes and demonstrates the need for a simulation model to optimize the system.