American Stirling Co. - Stirling engines, Waste heat consulting, Sterling engines.
Gas expands when heated, and contracts when cooled.
Stirling engines move the gas from the hot side of the engine, where it expands, to the cold side, where it contracts. When there is a temperature difference between upper displacer space and lower displacer space, the engine pressure is changed by the movement of the displacer. The pressure decreases when the displacer is moved to the lower part of the cylinder. The displacer only moves the air back and forth from the hot side to the cold side. It does not operate the crankshaft and the engine.