A universal model of an irreversible combined Carnot cycle system and its general performance characteristics

A universal model of ann-stage combined Carnot cycle system is established. Several major irreversibilities which often exist in real thermodynamic cycles, such as finite-rate heat transfer in the heat-exchange processes, heat leak losses of the heat source, and internal dissipation of the working fluid, are included in the model so that many models of irreversible and endoreversible Carnot cycles which appear in the literature can be regarded as special cases of the universal cycle model. The efficiency, power output and rate of heat input are optimized. Some characteristic curves of the cycle system are presented. Some important performance bounds are given. The optimal combined conditions between two adjacent cycles in the combined cycle system are determined. The optimal performance of an arbitrary-stage irreversible, endoreversible, and reversible combined Carnot cycle system can be directly derived for specific choices of some parameters. The results obtained here are of general significance for both physics and engineering.