4 - Hamiltonian optimization of imperfect cascades

Abstract

We investigate a multistage system in which each stage contains the fluid at flow, an imperfect work generator or consumer, and the environment. The problem investigated searches for a limiting yield or consumption of power by the fluid that interacts sequentially with the environment in a finite time. A discrete, finite-rate model subsumes irreducible losses of the work potential caused by thermal resistances. Dynamical bounds on the power yield are obtained that limit the one-stage or multistage energy converters with production or consumption of power. These limits are expressed in terms of classical exergy and a residual minimum of entropy generation. The link between the system efficiency and the entropy production at a stage is discussed. A discrete generalization of the classical exergy is found for finite holdup times, derived from the analysis of the discrete system with finite number of imperfect stages.