The Thermodynamic Drinking Bird

Thermodynamic Heat Engine. Wow! Thermodynamics & pressure differentials! Enjoy this classic physics demonstration in a handy duck shape. This thirsty bird perpetually bobs long as it has a glass of water to dunk in. Instructions on box.   This is not a toy. Age 14+. Fragile Glass   The drinking bird is a heat engine that exploits a temperature difference to convert heat energy to a pressure difference within the device, and performs mechanical work. Like all heat engines, the drinking bird works through a thermodynamic cycle. The initial state of the system is a bird with a wet head oriented vertically. The process operates as follows:[9] The water evaporates from the felt on the head. Evaporation lowers the temperature of the glass head (heat of vaporization). The temperature decrease causes some of the dichloromethane vapor in the head to condense. The lower temperature and condensation together cause the pressure to drop in the head (governed by Equations of state). The higher