Early Introduction of Entropy Concepts in the First Undergraduate Course in Thermodynamics

Abstract

Abstract A new introductory course in mechanical engineering thermodynamics is described. The course develops the basic concepts as natural extensions of the students previous experience. The first law and the second law are developed simultaneously and with equal emphasis. Entropy, entropy transfer and entropy generation are introduced in a manner analogous to the introduction of energy, energy transfer and generation of heat. Extensive use is made of isolated systems for analysis so that all relevant relations are systematically identified. The PVT, energy and entropy constitutive relations for subsystems are presented separately from the first law and second law relations for a given problem. With the early introduction of entropy, all of the constitutive relations, including entropy, are described at the same time. The concept of mechanical-to-thermal cross coupling within the constitutive relations is introduced and related to the Maxwell-relation partial derivatives. The energy conversion requirement for cross coupling is developed. Control volume and flow system relations are developed from closed system relations in a conventional manner. The course ends with a description of the models for several important energy conversion plants and a discussion of the reason that all practical plants are flow systems.