STIRLING ENGINE

A coffee cup Stirling engine is a low-temperature difference Stirling engine with a round, horizontal displacer that is slightly larger than the coffee mug it will rest on. Stirling motors of this type, which can started up by temperature differences of less than 20°C and less, were realized for the first time by in the 1980s by Professor I. Kolin from the University of Zagreb and Professor J. Senft from the University of Wisconsin. These engines have a vertical flywheel that is supported on a stand above the displacer. It operates energy from the heat flow between the cover and base plate. To create this flow, the temperature difference between the plates must be sufficiently large. This can occur either by heating or cooling the base plate. To heat it up, warmth from a hot cup of coffee, a hand, a receiver, a computer monitor or other household appliances can be used. The motor can also be operated by cooling the base plate, which can be done by placing it on a bowl of ice cubes. In addition, it can also be used as a solar motor. The motor also operates if its dark top surface is heated by solar radiation and its base plate is therefore cooler than the cover plate. When operated with ice or solar power, the flywheel moves in the opposite direction, however, and the Stirling motor runs backwards. After the Stirling motor has been on source of heat or cold for one to two minutes, it can be started by gently cranking the flywheel in the correct direction.