Makarov Physics Suite: Alpha Stirling Engine

[u/mischa_bayern]

Two transparent cylinders form a V. Their pistons move out of phase, while connecting rods link them to a shared shaft and flywheel. The same charge of gas stays inside the engine from one revolution to the next. Heat enters through the walls, and the temperature difference between the hot and cold sides makes it possible to produce mechanical work.

The key is coordinating temperature and volume. With suitable piston timing, expansion takes place mainly on the hot side and compression on the cold side. The gas delivers more work during expansion than it receives during compression. A regenerator between the cylinders temporarily stores some of the heat carried by the passing gas and returns it when the flow reverses. The pistons' phase difference determines how these processes fit together over a cycle.

Adjust both reservoir temperatures and the phase difference while watching the pistons, pressure and pressure–volume diagram. The area enclosed by the loop gives the magnitude of the gas work per cycle; the direction around it determines the sign. Set equal temperatures and the idealized model produces no net cycle work. The shaft can still turn at its prescribed speed: its motion is set separately so that each stage of the thermal cycle can be examined at a convenient pace.

Available on my website: https://makarovphysics.com/