On the optimum operation conditions of an endoreversible heat engine with different heat transfer laws in the thermal couplings

Within the context of Finite-Time Thermodynamics (FTT) we study the optimum operating conditions of an endoreversible engine model. In this model we consider different heat transfer modes from the hot reservoir to the working fluid, while the mode of heat transfer from the working fluid to the cold reservoir is governed by a Newtonian heat transfer law. In our analysis we use two modes of performance, the maximum power regimen and the so-called ecological function. We calculate the optimum temperatures of the working fluid and the optimum efficiency in terms of the relevant system parameters. We show how the efficiency under a maximum ecological function is greater than the maximum efficiency under maximum power conditions.