General performance characteristics and parametric optimum bounds of irreversible chemical engines

Based on the weak-dissipation assumption, a general cycle model of irreversible chemical engines, including non-isothermal chemical engines, isothermal chemical engines, and other classes of heat engines is established, where finite-rate heat and mass transfers are considered. Expressions for the power output and efficiency of the cycle system are derived. The power output is optimized for a given efficiency of the cycle system by using the Lagrangian-multiplier method and the corresponding characteristic curves are represented. The region of the efficiency of the cycle system at the maximum power output is determined. The results obtained may be directly used to discuss the optimal performance of non-isothermal chemical engines, isothermal chemical engines, and heat engines. Furthermore, it is explained that when different values of two dissipation parameters in the model are chosen, these results obtained may be further used to derive the optimal performance of several novel thermodynamic cycles, such as quantum heat engines, Brownian heat engines, etc. It is thus clear that the results obtained here are not only universal but also important. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4765725]