Document Type

Conference Paper


Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence



Publication Details

McGovern, James A. and O'Toole, Francis, 'A virtual-system concept for exergy analysis of flow network plant; Part I: Principles,' in ECOS'92, Proceedings of the international symposium on efficiency, costs, optimization and simulation of energy systems, Zaragoza, Spain, ed. Valero, A. and Tsatsaronis, G., American Society of Mechanical Engineers, June 15-18, 1992, pp. 155-160.


A new type of virtual system, named a flow constraint system (FCS), is proposed to facilitate, clarify, and simplify exergy analyses of plant that involve material flow networks. The need for the virtual system is outlined and the concept is demonstrated by applying it to a CHP steam cycle. The FCS concept allows the physical constraints on the exergy interactions associated with flow streams to be taken into account fully. It also simplifies the treatment of bifurcations in material flows and considerably reduces the need for absolute exergy evaluations. The new concept follows from the work already published by the authors on conceptual devices for exergy analysis and builds on this and the work of other authors relating to exergy and exergoeconomic analysis, especially using matrix methods. A bond graph type of diagram is described as an alternative to the usual Grassmann diagram. A numerical illustration is given in a separate paper — Part II.