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ISSN Online: 2379-1748
ISBN Flash Drive: 978-1-56700-483-0
ISBN Online: 978-1-56700-482-3
4th Thermal and Fluids Engineering Conference
CARNOT HEAT ENGINE EFFICIENCY, EXERGY, AND EXERGY GRADE LINE (XGL)
Abstract
A heat engine operating on the Carnot cycle between two temperature reservoirs, called Carnot heat engine, will have the most efficiency among all heat engines operating the same temperature reservoirs. The Carnot heat engine is an ideal engine and not existing. One of the significances developed by the Carnot heat engine is to establish a threshold of the highest efficiency that actual engines want to approach, but can not pass. The efficiency equation of the Carnot heat engine, however, doesn't reveal what energy loss a Carnot heat engine would have. This paper discusses the efficiency of the Carnot heat engine expressed by exergy and energy loss in the process. The author proposes the exergy grade line (XGL) graphically to describe the energy losses in the process of the Carnot heat engine. In the paper, the author first introduces the efficiency of the Carnot heat engine and sets up an expression between the Carnot heat engine efficiency and exergy. Then, the author presents the concept of XGL
which is similar to the energy grade line (EGL) in the fluid mechanics. By the analysis of XGL, the energy losses in the process of the Carnot heat engine is explicitly defined.