Page 105 - Mechanical Engineers' Handbook (Volume 4)

Mechanical Engineers’ Handbook: Energy and Power, Volume 4, Third Edition.

Edited by Myer Kutz

Copyright  2006 by John Wiley & Sons, Inc.

CHAPTER 3
THERMODYNAMICS FUNDAMENTALS
Adrian Bejan
Department of Mechanical Engineering and Materials Science
Duke University
Durham, North Carolina
1 INTRODUCTION 94 5 THE LAWS OF
THERMODYNAMICS FOR
2 THE FIRST LAW OF OPEN SYSTEMS 102
THERMODYNAMICS FOR
CLOSED SYSTEMS 97 6 RELATIONS AMONG
THERMODYNAMIC
3 THE SECOND LAW OF PROPERTIES 104
THERMODYNAMICS FOR
CLOSED SYSTEMS 99 7 ANALYSIS OF ENGINEERING
SYSTEM COMPONENTS 113
4 THE ENERGY MINIMUM
PRINCIPLE 102 REFERENCES 116

1 INTRODUCTION
Thermodynamics describes the relationship between mechanical work and other forms of
energy. There are two facets of contemporary thermodynamics that must be stressed in a
review such as this. The first is the equivalence of work and heat as two possible forms of
energy exchange. This facet is expressed by the first law of thermodynamics. The second
aspect is the one-way character, or irreversibility, of all flows that occur in nature. As ex-
pressed by the second law of thermodynamics, irreversibility or entropy generation is what
prevents us from extracting the most possible work from various sources; it is also what
prevents us from doing the most with the work that is already at our disposal. The objective
of this chapter is to review the first and second laws of thermodynamics and their implica-
tions in mechanical engineering, particularly with respect to such issues as energy conversion
and conservation. The analytical aspects (the formulas) of engineering thermodynamics are
reviewed primarily in terms of the behavior of a pure substance, as would be the case of the
working fluid in a heat engine or in a refrigeration machine. In the next chapter we review
in greater detail the newer field of entropy generation minimization (thermodynamic optim-
ization) and the generation of system configuration (constructal theory).

SYMBOLS AND UNITS
c specific heat of incompressible substance, J/(kg K)
specific heat at constant pressure, J/(kg K)
c P
3
constant temperature coefficient, m /kg
c T
specific heat at constant volume, J/(kg K)
c v
COP coefficient of performance
E energy, J
94