Stirling Engine Attribute Survey and Construction

Electrical generation and building heating contributes ~25% of greenhouse gas emissions. Stirling engines are a quiet and efficient way to convert thermal energy into mechanical work, even utilizing the modest temperature differences found inside and outside buildings, in the range of 20 degrees C. We surveyed three major types, alpha, beta, and gamma, seeking preferences for specific applications. Building off prior research in house, there seems to be uniformity in the phase angle among all three. However, when we considered the energy conversion efficiency and multi-cylinder Stirling engines, the alpha configuration ranked far below the others while gamma edged out beta. Next an attempt was made to construct a Stirling engine from scratch using simple materials. Despite internet video examples, practical difficulties prevented immediate success. Excessive lash in mechanical linkages and friction in pistons had to be overcome. Initially, we started with a basic piston model using a syringe but soon attempted to use an existing engine’s piston to reduce friction, but both models failed. An appreciation for the fluid volumes and heat exchanger areas had to be gleaned from successful examples, the latter of which is ongoing with plans to increase heat exchange.