On the thermal efficiency of power cycles in finite time thermodynamics

摘要

The Carnot, Diesel, Otto, and Brayton power cycles are reconsidered endor-eversibly in finite time thermodynamics (FTT). In particular, the thermal efficiency of these standard power cycles is compared to the well-known results in classical thermodynamics. The present analysis based on FTT modelling shows that a reduction in both the maximum and minimum temperatures of the cycle causes the thermal efficiency to increase. This is antithetical to the existing trend in the classical references. Under the assumption of endoreversibility, the relation between the efficiencies is also changed to eta(Carnot) >eta(Brayton) >eta(Diesel) >eta(Otto), which is again very different from the corresponding classical results. The present results benefit a better understanding of the important role of irreversibility on heat engines in classical thermodynamics.