MEC309 BASIC THERMODYNAMICS
1
Ideal Gases vs. Real Gases
Week 5
MEC309 BASIC THERMODYNAMICS
2
Recalling ideal gas equation of state:
p v RT
or
where
Alternative forms:
(on mass basis)
pv RT
v Mv
(on molar basis)
M
m
n
(m3/kmol or ft3/lbmol)
p RT
p m R T

MEC309 BASIC THERMODYNAMICS
1
System Integration
Combination of components or devices to become a complete system to achieve an overall objective or
purpose is called system integration.
For example: A simple steam power cycle for the purpose of producing

MEC309 BASIC THERMODYNAMICS
1
Gas Power Systems (Chapter 9)
As the name stated, a gas power system uses gas as working fluid throughout the entire system, without
any vaporization or condensation.
Internal Combustion (IC) Engines
Two principal types of re

MEC309 BASIC THERMODYNAMICS
1
Maximum Performance of Power Cycles
Q
Q
T
reversible = 1 C
Since C
= C:
Q reversible T
Q
PC
H
H
H
cycle
T
= 1 C
reversible
TH
cycle
According to the first Carnot corollary, irreversible PC < reversible PC .
TC
TH
power

MEC309 BASIC THERMODYNAMICS
1
Isentropic Processes
Considering a closed system undergoing an internally reversible process 1-2, its entropy change between
0 (int. rev.)
state 1 and 2 is
Qj
Qj
Qj
CM
S ]closed = S 2 S1 =
+ S ]closed = S 2 S1 =
Tj
mass, m

MEC309 BASIC THERMODYNAMICS
1
T dS equations
Applying 1st law to an internally reversible closed system (control mass), neglecting the changes in KE
and PE, gives
(Q)int rev
dU = (Q )int rev (W )int rev
mass, m
(W)int rev
CM
For a simple compressible syst

MEC309 BASIC THERMODYNAMICS
1
Chapter 3: Evaluating Properties
Applications of energy balance (i.e. E = Q W ) may require the knowledge of the properties of the
system (e.g. V, z, U) and how the properties are related (e.g. p = p() through p d work)
The p

MEC309 BASIC THERMODYNAMICS
1
Chapter 2: Energy and the 1st Law of Thermodynamics
1st Law for a control mass (CM) or closed system
First lets define a control mass or closed system:
If we are referring to a certain fixed quantity of matter as our system o

MEC309 BASIC THERMODYNAMICS
1
Control Volume Energy Analysis (Chapter 4)
Control volume: fixed region of space (CV)
Up to now we have been dealing with CMs.
In CVs, matter will often enter and leave the system over a time period considered.
And its energy

Chapter 1 Introductory Concepts and Definitions
Objective
The word thermodynamics stems from the Greek words therme (heat) and dynamis
(force). Although various aspects of what is now known as thermodynamics have been of
interest since antiquity, the form

Chapter 2 Energy and the First Law of Thermodyanmics
Objective
Energy is a fundamental concept of thermodynamics and one of the most significant
aspects of engineering analysis. In this chapter we discuss energy and develop equations
for applying the prin

MEC309 BASIC THERMODYNAMICS
1
Thermodynamics (TD)
What is TD?
ENERGY
Properties
of Matter
Work W
Heat Q
Thermodynamics is the science of the interactions between work, heat, and properties of matter.
Chapter 1
Total Energy of System, E
E = sum of energies

MEC309 BASIC THERMODYNAMICS
1
Energy Transfer by Work (continued)
Work Modes (WM) (read section 2.2)
1. Expansion/compression of a gas or liquid
2. Power transmitted by a shaft
3. Electrical work
4. Extension of a solid (both tension and compression)
5. S

MEC309 BASIC THERMODYNAMICS
1
1st Law Statement or Energy Balance for a Closed System or
Control Mass (CM) (Chapter 2)
Initial (time = t1)
Middle (t1 < t < t2)
Final (time = t2)
Q1-2
E1
State 1
Q1-2 =
E2
W1-2
Process 1-2
State 2
Qi = net heat transfer to