Exergy concept and exergetic analysis: review

Energy, entropy and exergy concepts come from thermodynamics and are applicable to all fields of science and engineering. Therefore, this article intends to provide background for better understanding of these concepts and their differences among various classes of life support systems with a diverse coverage and a study of these connections and a comprehensive and critical view on the most recent studies on this topic is presented. It also covers the basic principles, general definitions and practical applications and implications in various fields and its characteristic has been discussed and different forms of exergy have been derived. The exergy of an energy form or a substance is a measure of its usefulness or quality or potential to cause change. Exergy is naturally related to the concept of quality of energy. Therefore, exergy analysis has been widely applied in parallel with energy analysis in order to find the most rational use of energy. Also a brief comparison between energy and exergy analysis has been done. Finally, conclusions regarding the usability of the exergy method as a tool to promote a more efficient use of available energy sources are also derived.