Endoreversible thermodynamics are used for studying the performance of Carnot engines with heat leak. This is done by adding a heat leak term into a variation of the model suggested by DeVos [1]. Heat transfer across the engine is assumed to occur via a conduction/convection mechanism and Newton's law of cooling is employed to model the heat transfer processes. The efficiency at maximum power output is found to be deeply affected by the rate of heat leak. Moreover, the Curzon-Ahlborn relation [2] is shown to represent a special case of the new formulation. Since the suggested model allows more flexibility in predicting actual engines' performance, its use is recommended in thermodynamics courses.
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