Nonlinear analysis of Stirling engine thermodynamics

Numerical solutions to a simplified mathematical formulation for Stirling engine thermodynamics, including some major loss mechanisms and their interactions, are presented. Numerically accurate solutions to the nonlinear equations for verification of a simplified linear analysis recently developed at Oak Ridge National Laboratory are presented. The formulation requires that the piston motions be specified; that is, it does not include the dynamics of free pistons. The equations of the formulation were numerically solved using a standard IBM software package, called the Continuous System Modeling Program, that basically involves numerical integration. The results were used to show the effects of four major loss mechanisms on the performance parameters of the RE-1000 free-piston Stirling engine. These losses are: adiabatic cylinder effects, transient heat transfer, pressure drop, and seal leakage. The performance parameters calculated were power output and efficiency. Some discussion of the results and a further analysis of this engine model are also presented.