Hot Water Stirling Engine

Turn a cup of hot water into a working heat engine The Hot Water Stirling Engine is a tabletop thermodynamic model that runs on nothing more than the temperature difference between a cup of hot water and the cooler air above it. Place the engine on a mug of hot water, give the flywheel a gentle push, and students watch a real heat engine convert thermal energy into continuous mechanical motion — no fuel, no batteries, no flames. Why Teachers Love It Runs on Classroom-Safe Hot Water – No open flames, no alcohol burner, no pressurized steam. Hot tap water or coffee is all it takes, making this safe and practical for demos at any grade level. Visible Piston Motion Teaches the Cycle – The transparent chamber lets students observe the displacer piston as it moves through compression and expansion, connecting the physical mechanism to the thermodynamic P–V diagram. Temperature Difference Is the Variable – As the water cools, the engine slows, giving students a live demonstration that engine output depends directly on the temperature gradient, which is a core concept of thermodynamics and the Carnot limit.