Exergy-based methods for computer-aided design of energy conversion systems

Abstract

Exergy-based methods (conventional and advanced exergetic, exergoeconomic and exergoenvironmental analyses) are powerful tools for developing, evaluating and improving an energy conversion system. This paper briefly presents these methods that facilitate the computer-aided design of energy conversion systems. Exergoeconomics is a unique combination of exergy analysis and cost analysis conducted at the component level to identify the location, the magnitude and the causes of monetary costs. An exergoenvironmental analysis is conducted in analogy to an exergoeconomic one, to identify the causes of environmental impact. Conventional exergetic, exergoeconomic, and exergoenvironmental analyses have few limitations, some of which are removed by advanced exergy-based analyses. The latter evaluate (a) the interactions among components of the overall system, and (b) the real potential for improving a system component. The main role of advanced exergy-based analyses is to provide designers and operators of energy conversion systems with information useful for improving such systems from the viewpoints of thermodynamics, costs and environmental impact. This information cannot be provided by any other means. By splitting the exergy destruction (thermodynamic inefficiencies), the capital investment cost and the environmental impact associated with each single component of an energy conversion system into endogenous/exogenous and avoidable/unavoidable parts and by using a further splitting of the exogenous exergy destruction, we improve (a) our understanding of the processes that take place, and (b) the quality of the conclusions obtained from the analyses. Software for computer-aided design using these methods is under development.