A heat engine is a physical or theoretical device that converts
thermal energy to mechanical output. The mechanical output is called
work, and the thermal energy input is called
heat. Heat engines typically run on a specific
thermodynamic cycle. Heat engines are often named after the thermodynamic cycle they are modeled by. They often pick up alternate names, such as gasoline/petrol, turbine, or steam engines. Heat engines can generate heat inside the engine itself or it can absorb heat from an external source. Heat engines can be open to the atmospheric air or sealed and closed off to the outside (Open or closed cycle).
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