Local Exergy Cost Theory

Abstract:

The Exergy Cost Theory (ECT) is a technique extensively applied to optimizing, diagnosing and designing energy systems. But, despite of its wide applications it has its limitations. Such limitations have to do partly with the application to discrete systems solely and partly with the cost allocation problem. Thus in the present paper we go a step further in the scope of the ECT and propose to enlarge its applicability to continuous systems. Essentially, this is carried through by taking the concept of the exergy cost to a microscopic point of view. To put it another words, the exergy costs are connected to the law of continuum physics so that all phenomenological effects can be taken into account. This new formalism may be called as Local Exergy Cost Theory (LECT). The LECT method departs from the hypothesis that unit exergy costs for distinct exergy fluxes.e.g. heat, work, etc., are given the same cost in absence of external evaluations. From this new approach, it will be possible to model an space-time function of the unit exergy cost, k * ((r),t), besides it will be helpful in providing the rules of cost allocation with physical grounds otherwise to propose new ones. Theoretical aspects of this method are succinctly explained throughout the paper. Most importantly, in order to show the practical bias of the theory a series of proposed examples which are outlined are provided. By and large, results show that the unit exergy cost locally yielded contains a lot of useful information as, for instance, precise pinpointing of the points where exergy is destroyed and what is most importantly, the costs at those points. Lastly, by means of the LECT we can build up exergy cost maps for a particular system. Copyright © 2004 by ASME.

Año de publicación:

2004

Keywords:

Fuente:

scopus