A variational optimization of a finite-time thermal cycle with a nonlinearheat transfer law

In this paper we use a variational approach to study an endoreversible Curz on-Ahlborn-Novikov (CAN) heat engine under both maximum power and maximum e cological function conditions. By means of this procedure we analyze the pe rformance of a CANheat engine with a nonlinear heat transfer law (the Dulon g-Petit law) to describe the heat exchanges between the working substance a nd its thermal reservoirs. Our results are consistent with previous ones ob tained by means of other procedures. In addition, we obtain expressions for the temperatures of the isothermal branches of the working fluid under max imum power conditions. Finally, we present an expression for a kind of none ndoreversible Carnot efficiency. (C) 1999 Elsevier Science Ltd, All rights reserved.