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Thermodynamics
An Engineering Approach
Fourth Edition
Yunus A. Çengel
Michael A. Boles
CHAPTER
1
Basic Concepts
of Thermodynamics
General overview
• Mechanical
Engineering
– Mechanics
– Energy
– Systems
– Design
The over arching goal is
design of products to
meet societal needs.
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
• Thermodynamics
– A part of the Energy
component of mechanical
engineering.
– Governs all energy
consuming and
transforming devices and
system.
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
The engineering framework
THEORY
DATA
JUDGMENT
(DESIGN)
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
FIGURE 1–5
Some application areas of
thermodynamics
.
Air vents
Diet
1-1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
FIGURE 1–7
The definition of the force units.
Check for dimensional homogeneity!
1 lbm will have a gravitational force on it of 1 lbf on earth.
1-2
Beginning ideas and
concepts...
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Macroscopic vs. microscopic
viewpoints...
A collection of atoms within a container, each with a unique velocity.
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Energy in a microscopic description
1
Energy of each atom = e  m V
2
2
Number of atoms = N
N
mV
Total Energy = eN 
2
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
2
N
  ke1
i 1
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
The macroscopic description
The energy in both cases
is the same, E. In the
macroscopic description,
atomistic concepts are
disregarded.
How we describe the
system chosen for study
requires careful selection of
properties that are based
on observable, measurable
quantities.
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
The macroscopic
viewpoint...
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
State of a
thermodynamic
system.
Enumeration of
all of its
properties.
In macroscopic thermodynamics,
the properties of system are
assigned to the system as a whole.
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Properties in macroscopic thermodynamics
 m 



 

  0
lim
Density, 
Limit of the macroscopic
model and assumptions.
Molecular and atomic
effects are important

Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
(m3)
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
How does the state of
system change?
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Energetic interactions
System Boundary
System
Surroundings
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Energy
Flow
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Basic definitions...
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
System
Closed
System
Mass Flow
dm
dt
0
Open
System
Mass Flow
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
System and surroundings
Universe = Systems +Surroundings
Surroundings
Closed System
System Boundary
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
System and surroundings
Surroundings
Mass flow
Control Surface
Open System
( Fixed space or
volume)
Open systems have mass flow across
their boundaries.
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Interactions between
system and surroundings...
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Closed system
Surroundings
Heat
System
Work
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Open system
Surroundings
Mass Flow
Heat
System
Power
Mass
Flow
Usually look at rates.
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Example: Piston and cylinder - a closed system
m
Piston
Gas at pressure, p
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Example: The gas turbine engine - an open system
Fuel Flow In
Combustor
Air Flow In
Shaft Work Output
Compressor Work Out
Exhaust Gases Out
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
FIGURE 1–17
A control volume may involve fixed,
moving, real, and imaginary
boundaries.
A control volume is an open system
1-5
Key concepts and terms
Closed System
Open System
System Boundary
Surroundings
Universe
Thermodynamic Properties
Thermodynamic State
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Equilibrium states and
properties
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Properties
Properties:
•Temperature
•Pressure
•Volume
•Internal energy
•Entropy
System
The system can be either open or
closed. The concept of a property
still applies.
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Classes of properties
• Extensive
– MASS
– VOLUME
– ENERGY
• Intensive
– TEMPERATURE
– PRESSURE
– DENSITY
Specific Properties
ADDITIVE OVER
THE SYSTEM.
NOT ADDITIVE OVER
THE SYSTEM.
Continuum approach is valid if system is large
compared to distance between molecules
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
State
• At a given state, all the properties of the
system have fixed values.
• If the value of one property changes, the
state changes.
• If no properties are changing, then it is at
equilibrium
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Equilibrium
• Thermodynamics deals with equilibrium
states.
• No driving forces
• Mechanical equilibrium
– No change in pressure with time
• Thermal equilibrium
– Temperature is same throughout system
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
Equilibrium
• Phase equilibrium
– No change in the amounts of different phases
• Chemical equilibrium
– Chemical composition does not change with
time.
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics
State Postulate
• The state of a simple compressible system
is completely specified by two
independent, intensive properties
• Simple compressible system:
– Absence of electrical, magnetic, gravitational,
motion and surface tension effects.
– Independent if one property can be held
constant while another is varied
Instructor’s Visual Aids
Heat Work and Energy. A First Course in Thermodynamics
© 2002, F. A. Kulacki
Chapter 1 Module 1 Slide ‹#›
Energy, Heat and Work
Introduction to Macroscopic Thermodynamics