International Journal of Thermodynamics 

About: International Journal of Thermodynamics is an academic journal published by International Centre for Applied Thermodynamics. The journal publishes majorly in the area(s): Exergy & Exergy efficiency. It has an ISSN identifier of 2146-1511. Over the lifetime, 522 publications have been published receiving 5981 citations. The journal is also known as: IJoT.

A brief Commented History of Exergy From the Beginnings to 2004

Abstract: This paper presents a brief critical and analytical account of the development of the concept of exergy and of its applications. It is based on a careful and extended (in time) consultation of a very large body of published references taken from archival journals, textbooks and other monographic works, conference proceedings, technical reports and lecture series. We have tried to identify the common thread that runs through all of the references, to put different issues into perspective, to clarify dubious points, to suggest logical and scientific connections and priorities. It was impossible to eliminate our respective biases that still affect the “style” of the present paper: luckily, some of our individual biases “cancelled out” at the time of writing, and some were corrected by our Reviewers (to whom we owe sincere thanks for the numerous and very relevant corrections and suggestions). The article is organized chronologically and epistemologically: it turns out that the two criteria allow for a quite clear systematization of the subject matter, because the development of the exergy concept was rather “linear”. This work is addressed to our Colleagues who are involved in theoretical research, industrial development, and societal applications of exergy concepts: if they extract from this article the idea of an extraordinary epistemological uniformity in the development of the concept of exergy, our goal will be achieved. The other addressees of this paper are Graduate Students taking their first steps in this field: in their case, we hope that consultation of our paper will prompt them to adopt and maintain throughout their career a scholarly valid method of research, which implies studying and respecting our scientific roots (the sources) but venturing freely and creatively into unknown territory. In the Conclusions we try to forecast future developments: this is the only part of the paper that is an intentional expression of our own views: the previous historical-scientific exposition is instead based on verifiable facts and accepted opinions.

Supercritical Fluid Parameters in Organic Rankine Cycle Applications

Abstract: Nowadays, the use of Organic Rankine Cycle (ORC) in decentralised applications is linked with the fact that this process allows to use low temperature heat sources and offers an advantageous efficiency in small-scale applications. Many state of the art applications like geothermal and biomass fired power plants as well as new applications like solar desalination with reverse osmosis, waste heat recovery from biogas digestion plants or micro-Combined Heat and Power (micro-CHP) systems can successfully use the ORC process. The investigation of supercritical parameters in ORC applications seems to bring promising results in decentralised energy production. This paper presents the results from the simulation of the ORC process in normal and supercritical fluid parameters and discusses the efficiency variation in various applications.

A Brief Review of Methods for the Design and Synthesis Optimization of Energy Systems

Abstract: The optimization of energy systems is of crucial importance for a rational use of natural and economic resources and for minimizing their adverse effects on the environment. Optimizing such systems may be considered at three levels: synthesis (configuration), design (component characteristics), and operation. The first two of these levels are ex-amined in this article. After a discussion on the uniqueness of the solution and the pos-sibility of finding this solution, the principal approaches and methods for solving the optimization problem are described in brief.

Advanced Exergy Analysis for Chemically Reacting Systems – Application to a Simple Open Gas-Turbine System

Abstract: A conventional exergy analysis has some limitations, which are significantly reduced by an advanced exergy analysis. The latter evaluates: (a) the interactions among components of the overall system (splitting the exergy destruction into endogenous and exogenous parts); and, (b) the real potential for improving a system component (splitting the exergy destruction into unavoidable and avoidable parts). The main role of an advanced exergy analysis is to provide engineers with additional information useful for improving the design and operation of energy conversion systems. This information cannot be supplied by any other approach. In previous publications, approaches were presented that were appropriate for application to closed thermodynamic cycles, without chemical reactions (e.g., refrigeration cycles). Here a general approach is discussed that could be applied to systems with chemical reactions. Application of this approach to a simple gas-turbine system reveals the potential for improvement and the interactions among the system components. This paper is an updated version of a paper published in the ECOS'08 proceedings.

Analytical and Neural Network Models for Gas Turbine Design and Off-Design Simulation #

Abstract: This paper presents a gas turbine design and off-design model in which the difficulties due to lack of knowledge about stage-by-stage performance are overcome by constructing artificial machine maps through appropriate scaling techniques applied to generalized maps taken from the literature and validating them with test measurement data from real plants. In particular, off-design performance is obtained through compressor map modifications according to variable inlet guide vane closure. The set of equations of the developed analytical model is solved by a commercial package, which provides great flexibility in the choice of independent variables of the overall system. The results obtained from this simulator are used for neural network training: problems associated with the construction and use of neural networks are discussed and their capability as a tool for predicting machine performance is analyzed. This paper was presented at the ECOS'01 Conference in Turkey, July 4-6, 2001 and revised