This document provides an overview of thermodynamics and related concepts. It defines thermodynamics as the study of energy and its transformation, heat flow, and work potential. Key topics covered include the microscopic and macroscopic approaches to studying thermodynamics, thermodynamic systems and properties, processes like reversible and irreversible processes, and thermodynamic cycles. Dimensional analysis and various thermodynamic units of measurement are also discussed.

1. THERMODYNAMICS 1
By:
Orley G. Fadriquel

2. WIND TURBINE
Blade or Propeller
Turbine
Storage
Battery
Transformer
High Wind Velocity
Lower Wind Velocity
Generator
Generator

3. Transformer
Air Fuel
Piston Cylinder
Crank Shaft
Brake power
Indicated
Power
INTERNAL
COMBUSTION
ENGINE
Generator

4. Thermodynamics is
the study of energy and
its transformation, the
direction of flow of heat,
and the availability of
energy to do work.

5. The word
thermodynamics
derives from the two
Greek words “therme”
which means “heat:
and “dynamikos”
which means “power”.

6. Approaches in the Study of
Thermodynamics
1.Microscopic or statistical
approach
2.Macroscopic approach

7. Microscopic or Statistical Approach
• Structure of matter is considered and a
large number of variables are needed to
describe the state of matter.
• The matter is composed of several
molecules and behaviour of each
individual molecule is studied.

8. • Each molecule is having
certain position, velocity and
energy at a given instant.
• The velocity and energy
change very frequently due to
collision of molecules.

9. Macroscopic approach
• In macroscopic approach the
structure of matter is not
considered, in fact it is simple,
and only few variables are used
to describe the state of matter.

10. • In this approach, a certain
quantity of matter composed of
large number of molecules is
considered without the events
occurring at the molecular level
being taken into account.

11. • In this case, the properties of a particular
mass of substance, such as its
temperature, pressure, and volume are
analyzed. Generally, in engineering, this
analysis is used for study of heat engines
and other devices. This method gives the
fundamental knowledge for the analysis
of a wide variety of engineering
problems

12. Applications of Thermodynamics
• Application of thermodynamic
principles in practical design tasks,
may be of a simple pressure cooker
or of a complex chemical plant.
The applications of thermodynamic
laws and principles are found in all
fields of energy technology.

13. • steam and nuclear power plants
• gas turbines
• internal combustion engines
• air conditioning
• Refrigeration
• gas dynamics
• jet propulsion
• compressors
• others

14. DIMENSIONS AND UNITS

15. • Dimensions implies physical quantities.
Examples are length, time, mass, force,
volume and velocity. In engineering
analysis, it is most important to check the
dimensional homogeneity of an equation
relating physical quantities. This means
that the dimensions of terms on one side
of the equation must equal those on the
other side.

16. Primary dimensions implies
units of physical quantities
conceived of and used to
measure other physical
quantities related by definition
and laws

17. Secondary dimensions
implies other physical
quantities measured using
primary dimensions

18. • Unit is a definite standard or
measure of a dimension.
• For example, foot, meters and
angstroms are all different units with
the common dimension of length.
• A unit is any specified amount of a
quantity by comparison with which
any other quantity of the same kind
is measure.

19. In any dimensional
system, the units of
length, time, mass and
forces are related
through Newton’s
second law of motion.

20. The total force acting on a
body is proportional to the
product of the mass and the
acceleration in the direction of
the force, thus,
F  ma ; F = 1/k ma
where k is the proportionality
constant.

21. UNITS OF DIFFERENT DIMENSIONAL SYSTEMS
Name of
system
Unit
of
Mass
Unit of
Lengt
h
Unit of
time
Unit
of
force
K in
F = 1/k ma
Definition of terms
SI
(mks)
kgm m Sec N 1.0
9.806
1.0 N is the force needed to accelerate a
mass of 1.0 kg at 1.0 m/s2
1.0 kgf is the force needed to accelerate a
mass of 1.0 kgm at 9.8066 m/s2
English
Eng’g
lbm Ft Sec lbf 32.17 1.0 lbf is the force needed to accelerate a
mass of 1.0 lbm at 32.174 ft/sec2
Absolute
Eng’g
Slug Ft Sec lbf 1.0 1.0 lbf is the force needed to accelerate a
mass of 1.0 slug mass at 1.0 ft/sec2
Absolute
metric
(cgs)
gm Cm Sec dyne 1.0
980.66
1.0 dyne is the force needed to accelerate a
mass of 1.0 g at 1.0 cm/sec2
1.0 gf is the force needed to accelerate a
mass 1.0 gm at 980.66 cm/s2
2
f
m
skg
mkg


2
m
sN
mkg


2
f
m
slb
ftlb


2
f slb
ftslug


2
m
sdyne
cmg


2
f
m
sg
cmg



22. International System Institutes(SI)
Base Unit
Specified once a set of primary dimensions
is adopted
quantity unit symbol
mass kilogram kg
length meter m
time second s
(Systeme Internationale d’Unites)

23. Derived Unit
Also termed secondary unit, these are
units derived from the base units: given new
names, normally after a famous scientist.
Selected SI-derived units
Newton, N 1 N = 1 kg-m/s2
Pascal, Pa 1 Pa = 1 N/m2
Joule, J 1 J = 1 N-m
Watt, W 1 W = 1 J/s

24. SI unit prefixes
Factor prefix symbol Factor prefix symbol
1012 Tera T 10-2 centi c
109 Giga G 10-3 milli m
106 Mega M 10-6 micro 
103 Kilo k 10-9 nano n
102 hecto h 10-12 pico p
101 deca da 10-15 femto f
10-1 deci d 10-18 atto a

25. English Engineering Units
Base unit
quantity unit symbol
mass pound-mass lbm
length foot ft
time second s

26. Derived unit
Quantity unit symbol
force pound-force lbf
pressure pound-force psi
per square inch

27. THERMODYNAMIC SYSTEM
System is defined as any collection of
matter or any region in space
bounded by a closed surface or wall.
• Surrounding
• Boundary

28. Piston
Cylinder
Boundary
Surrounding
System
boundary
Heat
Thermodynamic
System
gas
Weight

29. CLASSIFICATION OF THERMODYNAMIC
SYSTEM
• Closed system- a system of fixed
mass. In this system, energy may
cross the boundary, and the total
mass within the boundary is fixed.
The system and it’s boundary may
contract or expand in volume

30. PISTON MOVEMENT
gas 1 2
Q

31. Surrounding
Boundary
Energy in
Energy out
Thermodynamic
System
W
Gas
Q
Heat

32. Open System- one in which matter
crosses the boundary of the
system. There may be energy
transfer also, i.e, both energy and
mass crosses the boundary of the
system. Most engineering devices
belong to this type.

33. PISTON MOVEMENT
gas 1 2
Q

34. Air out
Work in
Heat
boundary
Air in
Thermodynamic
System Surrounding
Energy out
Energy out
Mass in
Mass out

35. Note: If the inflow of mass is
equal to the outflow of mass,
then the mass in the system is
constant and the system is
known as steady flow.

36. Isolated System - one in which neither
mass nor energy crosses the system
boundary. It is of fixed mass and
energy. The system is not affected by
the surrounding, i.e. there is no
interaction between the system and
surroundings.

37. Thermodynamic System
Surrounding
Flow through pipe
1 2 43 5

38. HOMOGENEOUS AND
HETEROGENEOUS SYSTEM
If the substance within the system
exists in a single phase like air, steam,
liquids then the system is called
HOMOGENEOUS SYSTEM. In these
systems, the substance exists in only
one phase.

39. If the substance within
the system exists in more
than one phase, then the
system is HETEROGENEOUS.

40. THERMODYNAMIC PROPERTIES
A property is either a directly
observable or an indirectly
observable characteristic of a
system. Any combination of such
characteristics is also a property.

41. THERMODYNAMIC PROPERTIES
The distinguishing characteristics of a
system by which its physical condition
may be described are called the
properties of the system. They are
quantities that we must specify to give a
macroscopic description of the system.

42. Two other properties -
temperature and entropy- are
unique to thermodynamics.
Together with energy, they play a
most important role in the
structure of thermodynamics.

43. Two types of classical
thermodynamic properties
• Intensive Property
These properties are independent
of mass such as pressure,
temperature, voltage and density.

44. .
• Extensive Property
These properties are dependent
of mass and are total values such as
total volume, total energy and
entropy.

45. • Examples of thermodynamic properties,
besides pressure, volume and
Temperature, are: internal energy,
enthalpy, and entropy. Other properties
include: velocity, acceleration, moment
of inertia, electric charge, conductivity
(thermal and electrical), electromotive
force, stress, viscosity, reflectivity,
number of protons, and so on

46. Definition of properties
Mass – amount or absolute
quantity of matter in a certain
body.
Volume – the space occupied by
a certain body

47. .Density
1. Mass density – the mass of substance
divided by the volume the mass occupies
of simply, the mass per unit volume.
Water at standard conditions at 4oC (39.2oF)
ρwater = 1 gm/cm3 = 1000 kgm/m3 = 62.4 lbm/ft3

48. .2. Weight density – also known as
the specific weight, it is defined as
the weight per unit volume.
Where :
g = 9.80665 m/s2 = 32.174 ft/s2
Water at standard conditions,
water = 9.81 kN/m = 62.4 lb/ft3

49. Specific volume - defined as the
volume per unit of mass of the
reciprocal of density
Weight, W – force exerted by
gravity on a given mass, depends on
both the mass of the substance and
the gravitational field strength,
W = mg

50. • Specific gravity – the
dimensionless parameter, it is
defined as the ratio of the
density (or specific weight) of
a substance to some standard
density(specific weight)

51. For liquid substances
For gaseous substances
at STP = 1.2 kg/m3 at 1 atm, 21.1 oC
air
gas
air
gas
.G.S






OH
LIQUID
OH
LIQUID
22
.G.S







52. .
Pressure – defined as the normal
force exerted by a system on a
unit area of its boundary.
Manometer – the instrument used
in measuring pressure.

53. Standard reference atmospheric
pressure
1 atm = 14.7 psia
= 760 mm Hg
= 29.92 in Hg at 32oF
= 760 torrs
= 101.325 kpa
= 34 ft H20
= 1.033 kg/cm2

54. Types of pressure
a. Gage pressure, Pg – pressure of a fluid
and the atmospheric pressure,
measured using manometer or bourdon
gage
Note:
-Vacuum pressure is negative pressure;
-measured using fluid pressure <
atmospheric pressure

55. b. Atmospheric pressure, Patm
- measured using a barometer, refer to
standard atmospheric cited above
c. Absolute pressure, Pabs – sum of the
gage pressure and atmospheric
pressure.

56. Relationships among the types of
pressure
For Pabs > Patm
Pabs = Patm + Pg
For Pabs < Patm
Pabs = Patm – Pv
Also, Pg = h = ρgh

57. Temperature – it is an
intensive property,
originates with our sense
perceptions, rooted in the
notion of hotness or
coldness of a body

58. Types of Temperature
a. Arbitrary, t – man made calibrated
a.1 Celsius scale, oC (used to be
Centigrade scale). Named after Anders
Celsius, a Swedish
– - steam point - equilibrium temperature of pure
liquid water in contact with its vapor at one
atmosphere; 100oC
– - ice point – equilibrium temperature of ice and air-
saturated liquid pressure at a pressure of one
atmosphere. 0oC

59. a.2 Fahrenheit scale ,oF
Named after Gabriel Fahrenheit, a
German who devised the first mercury-
in-glass thermometer; earlier
thermometer fluids used were alcohol
and linseed oil
- steam point : 212oF
- ice point : 32oF

60. b. Absolute, T – measured from absolute zero,
all molecular motion cease. 0 Kelvin or 0
Rankine
b.1 Kelvin Scale, K
Named after William Thomson, aka Lord
Kelvin who related absolute scale to the
Celsius scale. The ice point is assigned with a
value of 273.15 K and the steam point is
assigned with the value 373.15 K. The triple
point of water is 273.16 K.

61. b.2 Rankine Scale, R
Named after William Macquorn
Rankine, a Scotish. The ice
point is assigned with a value
of 491.67 R and the steam
point is assigned with the
value 671.67 R The triple point
of water is 491.69 R.

62. THERMODYNAMIC STATE OF A SYSTEM
Thermodynamic
property B
Thermodynamic
property A
1
2

63. ZEROTH LAW
This law states that when two
bodies, isolated from other
environment are in thermal
equilibrium with a third body,
the two are in thermal
equilibrium with each other.

64. ZEROTH LAW
If two closed system with
different temperatures are brought
together in thermal contact with a
third system, the heat will flow from
the system with high temperature
to the system with low temperature
until the bodies reach thermal
equilibrium with each other.

65. Coffee in a cup
Tcoffee = Tcup=Tsurroundings

66. THERMODYNAMIC PROCESS
If any one or more
properties of a system change,
the system is said to have
undergone a process; there
has been a change of state.

67. Thermodynamic processes that
are commonly experienced in
engineering practice:
1.Constant pressure/ Isobaric process
2.Constant volume/ Isochoric process
3.Constant temperature/ Isothermal
process
4.Reversible adiabatic/ Isentropic process
5.Polytropic process
6.Throttling process/ Iso-enthalpic process

68. REVERSIBLE AND
IRREVERSIBLE
PROCESS

69. Reversible Process
• A reversible process for a system is
an ideal process which once having
taken place can be reversed in such a
way that the initial state and all
energies transformed during the
process can be completely regained
in both systems and surroundings.

70. This process does not leave
any net change in the system
or in the surroundings. A
reversible process is always,
quasi-static.

71. Irreversible Process
• If the initial state and energies
transformed cannot be
restored without net change in
the system after the process
has taken place, it is called
irreversible.

72. Quasi-Static Process
•Quasi means “almost”.
Infinite slowness is the
characteristic feature of
this process. It is also a
reversible process.

73. THERMODYNAMIC CYCLE
•When a certain mass of
fluid in a particular state
passes through a series of
processes and returns to its
state, it undergoes a cycle.

74. p
v
v1
p2
p1
v2
A
B
1
2
C
Cycles. By our convention of signs, cycles that
trace a clockwise path, as A-1-B-C-A or A-1-B-2-
A are delivering work; cycles tracing a
counterclockwise path, as A-C-B-1-A or A-2-B-
1-A, are receiving work.

75. LAW OF CONSERVATION
OF MASS
•The law of conservation
of mass states that mass
is indestructible.

76. The verbal form of the law is


















systemtheinstored
massofchange
leaving
mass
entering
mass

77. m m
velocity
area
density

78. Assume that each point of any
cross section where the fluid flows,
the properties are the same and use
average velocity normal to the
section and assumed to be the same
at each point. Thus, if the density is
the same in all points of the cross
section of area A, then mass rate of
flow is
m = ρelA

79. A steady flow system is an open
system in which there is no
change of stored mass; having an
equation called the continuity
equation of steady flow;
m1 = m2 = m
m = ρ11A1 = ρ22A2

80. GENERAL METHODOLOGY
FOR PROBLEM SOLVING IN
ENGINEERING
THERMODYNAMICS
As suggested by HUANG

81. 1.Read the problem carefully
2.Since a sketch almost always aids
in visualization, draw a simple
diagram of all the components of
the system involved. This could
be a pump, a heat exchanger, gas
inside a tank, or an entire power
plant.

82. 3. Select the system whose behavior we
want to study by properly and clearly
locating the boundary of the system.
Do we have an isolated system, a
closed system, or an open system.
4. Make use of the appropriate
thermodynamic diagrams to locate
the state points, and possibly the
path of the process. These diagrams
are extremely helpful as visual aids in
our analysis.

83. 5. Show all interactions (work, heat,
and mass) across the boundary of
the selected system.
6. Extract from the statement of the
problem the unique features of the
process and list them. Is the
process isothermal, constant
pressure, constant volume,
adiabatic, isentropic, or constant
enthalpy?

84. 7. List all the assumptions that
one might need to solve the
problem. Are we neglecting a
change of kinetic energy and
change of potential energy?
8. Apply first law equation
appropriate to the system we
have selected.

85. 9.Apply the principle of mass
conservation appropriate to
the system that we have
selected.
10.Apply the second law
equation appropriate to the
system we have selected

86. 11.Apply the appropriate
property relations. That is,
bring in data from tables,
charts, or appropriate property
equations.
12.Try to work with general
equations as long as possible
before substituting in numbers

87. 13.Watch out for units. For
example, when we use h = u
+pv, h, u, and pv must all have
the same units.
14.Make sure that absolute
temperature, in degrees
Rankine or Kelvin, is used in
calculation.