A numerical study of the influence of design variable interactions on the performance of a Stirling engine System

Abstract This paper presents a study to determine the influence of design variable interactions on the performance of a Stirling engine, as well as a new methodology to identify and quantify such influence. An Alpha-type 2 kW Stirling engine was assessed using a second order model where the engine, heater, regenerator and cooler variables were simultaneously analyzed in pairs. The study includes 240 interactions corresponding to the 16 selected design variables. It was observed that the piston stroke and cylinder diameter variables have more significant interactions with the rest of the parameters due to their strong influence over mass flow. The piston crown length does not show significant interactions; however, it reduces individual thermal losses in the expansion zone. The cycle achieves its maximum net power at angles less than 90° due to pressure, heat losses, and the ratio between mass flow rates and swept volume. Finally, this work presents recommendations for the analyzed interactions. The global interactions scheme provides a qualitative and quantitative identification of the variables that affect the system, synthesized into a hierarchy of variables that indicates a critical path for their exploration for system design and optimization purposes.