Basics, Significance and laws

2. Introduction to
Thermodynamics
SIGNIFICANCE AND LAWS

3. Presented by Ali Ahssan
Roll No. 8630
Class BS Mech (3rd Semester)
Presented to Engr. Ghulam Murtaza
Government College University of Fasilabad Sub-Campus Sahiwal.

4. Course Content
1. What is thermodynamic.
2. Significance of Thermodynamics.
3. Some Basic Definitions.
4. Heat Work and System.
5. Sign Convections.
6. The State of the Working Fluid.
7. Process and its Types.
8. Criteria for Reversibility

5. Course Content
9. Reversible Work
10. 1st law of Thermodynamic.
11. Steady Flow Equation.
12. 2nd Law of Thermodynamic.
13. Boyle’s Law.
14. Charles Law

6. What is thermodynamic?
Thermodynamics can be defined as the science of energy.
The name thermodynamics stems form the Greek word thermo mean heat and dynamis means
power.
It is defined as the science of relationship between heat, work and properties of the system is
known as thermodynamics.

7. Significance of
thermodynamics
The heart is constantly pumping blood
to all parts of the human body, various
energy conversions occurs in trillion of
the body cells, and the body heat
generated is constantly rejected to the
environment.

8. Significance of
Thermodynamic
Many ordinary household utensil and
appliance are designed, in whole or in
part, by using the principles of
thermodynamics. Some examples
includes:
• Electric and gas ranges
• Heating and AC systems
• Refrigerator
• Computers and TV
• Pressure cooker

9. Significance of
Thermodynamic
On large scale, thermodynamics plays
a major part in the design and analysis
of:
• Automotive engines
• Rockets
• Jet engines
• Conventional or nuclear power
plants
• Solar collectors
• Design of vehicles from ordinary
cars to airplanes.

10. Significance of
Thermodynamic
All living things depends on the energy
for survival, and modern civilizations
will continue to thrive only if existing
sources of energy can be developed to
meet the growing demands.

11. Significance of
Thermodynamic
The chemical energy of combustion of
fossil fuels like oils, coals, gas etc and
waste like agricultural industrial
domestic etc are used to produce heat
which is used to produce heat to
provide mechanical energy in turbines
or reciprocating engine.

12. Significance of
Thermodynamic
Uranium atoms are bombarded
asunder and the nuclear energy
released is used as heat.

13. Significance of
Thermodynamic
The potential energy of large masses
of water is converted into electrical
energy as it passes through water
turbine on its way from the mountains
to sea.

14. Significance of
Thermodynamic
The kinetic energy of the wind is
harnessed by windmills to produce
electricity.

15. Significance of
Thermodynamic
The energy of the waves of the sea is
converted into electrical power in
floating turbines.

16. Significance of
Thermodynamic
The tides produces by the rotation of
the moon produce electrical energy by
flowing through turbines in large rivers
estuaries.

17. Significance of
Thermodynamic
The hot rocks and trapped liquids in
the depth of the earth are made to
released their energy to be converted
to electricity.

18. Significance of
Thermodynamic
The immense radiant energy of the
sun is trapped to heat water or by
suitable device is converted directly
into electricity.

19. Some Basic Definitions
Before starting the brief discussion of thermodynamics, we have to learn some basics definition
which are as following:
Temperature
Pressure
Specific Volume
Density
Energy
Power

20. Some Basic Definitions
Temperature:
The degree of hotness or coldness is known as temperature.
The SI unit of temperature is kelvin (K).
There are three different temperature scale.
Kelvin scale
Fahrenheit scale
Celsius

21. Some Basic Definition
Temperature Unit Conversions
F= Fahrenheit
C= Celsius
K= Kelvin
F=C(1.8)+32
C=(F-32)/1.8
K=C+273

22. Some Basic
Definitions
Pressure is defined as the force per
unit area.
P=F/A

23. Some Basic Definitions
Unit Conversions for Pressure:
1 bar = 100000 Pascal
1 mmHg = 13.3 Pascal
1 mm of water = 9.81 Pascal
The atmospheric pressure is 101325 Pascal

24. Some Basic
Definitions
Specific Volume
It is defined as the volume per unit
mass.
The formula is shown in the given fig.

25. Some Basic
Definitions
Density:
It is defined as the mass per unit
volume.

26. Some Basic
Definitions
Relationship between specific volume
and density:
Specific volume and density are
reciprocal to each other.

27. Some Basic
Definitions
Energy:
In physics, it is defined as the
capacity or ability to do work.
Its SI unit is joule.

28. Some Basic Definitions
Different Units of Energy:
Joule
Calories
BTU (British Temperature Unit)

29. Some Basic Definitions
Joule:
It is defined as the amount of energy required to raise the temperature of 1kg of water by 1
degree Celsius or 1 kelvin.
Calories:
It is defined as the amount of energy required to raise the temperature of 1 gram of water by 1
degree Celsius.
Cal=4.195 J
BTU:
Amount of energy to required to raise the temperature of 1 pound of water by 1 Fahrenheit.
1BTU=1055J

30. Some Basic Definitions
Power:
The rate of doing work is known as power.
The rate of transfer of heat is also known as power.
The SI unit of power is Watt.
Power=work/time
Where work is defined as the product of force and displacement when displacement is in the
direction of force.

31. Heat Work and
System
Heat:
Heat is a form of energy which
transfer from one body to another
body at a lower temperature by virtue
of the temperature difference
between bodies.

32. Heat Work and
System
Types of heat transfer:
Conduction:
The transfer of heat by the direct
contact is called conduction.

33. Heat Work and
System
Types of heat transfer:
Convection:
The heat transfer by the actual
moment of the matter is called
convection.

34. Heat Work and
System
Types of heat transfer:
Radiation:
The heat transfer due to the
electromagnetic waves is called
radiations.

35. Heat Work and
System
Work:
The product of force and
displacement moved in the direction
of force. The transfer of heat is also
known as work.

36. Heat Work and
System
System:
A collection of things which are
under observation is known as system
.
Surrounding:
Everything which is external to the
system is known as surrounding.
Boundary:
The line which separates the
system form the surrounding is called
boundary.

37. Heat Work and System
Types of System:
Closed System:
The system in which work and heat can cross the boundary of the system but mass cannot
cross the boundary of the system is known as closed system. It is also known as constant mass
system.
Example:
Piston Cylinder.

38. Heat Work and System
Types of system:
Open system:
The system in which both mass and energy can cross the boundary of the system is called
open system. It is also known as constant volume system.
Example
Turbine, nozzle, pump.

39. Heat Work and System
Types of System:
Isolated system:
The system in which heat and work cannot cross the boundary of he system and mass can
also cannot cross the boundary of the system is called isolated system.
Example
Duct system

40. Sign Convention
Heat supplied to the system is, Q, is positive.
Work input to a system W, is positive
Heat supplied by the system is, Q, is negative.
Work input by the system W, is negative.
Power produce devices such as an internal combustion engine or turbine, the work input by the
system is positive.
A condenser the heat supplied to the system is always negative.

41. Sign Convention

42. The State of the
Working Fluid
Working Fluid:
Matter Contained within the
boundaries of the system can be
liquid, vapour or gas is known as
working fluid.
State:
At any instant the state of the
working fluid may be defined by the
certain characteristics called its
properties.

43. Process and its
Types
Process:
A thermodynamic process is a
passage of a thermodynamic from an
initial to a final state of
thermodynamic equilibrium.

44. Process and its
Types
Type of Process:
1. Isothermal Process:
A isothermal process is a change of
the system, in which the temperature
remain constant

45. Process and its
Types
Types of Process:
2. Isochoric Process:
An isochoric process, which is also
called constant-volume process, in
thermodynamic process during which
the volume of the closed undergoing
such a process remain constant.

46. Process and its
Types
Types of Process:
3.Isobaric Process:
Isobaric is a thermodynamic
process in which the pressure stays
constant. The heat transfer to the
system does work, but also changes
the internal energy of the system.

47. Process and its
Types
Types of Process:
4. Adiabatic Process:
An adiabatic process occur
without transfer of heat mass of
substance between a thermodynamic
system and its surroundings. In an
adiabatic process, the energy is
transferred to the surrounding only as
work.

48. Process and its
Types
Types of Process:
5. Reversible Process:
In thermodynamic, a reversible
process is process whose direction can
be reversed by inducing infinitesimal
change to some properties of the
system via its surrounding.

49. Criteria of the Reversibility
The criteria of the reversibility are as follow:
1. The process must be frictionless.
2. The difference in pressure between the fluid and its surrounding during the process must be
infinitely small.
3. The difference in the temperature between the fluid and its surroundings during the process
must be infinitely small.

50. Reversible Work

51. Laws of
Thermodynamics

52. 1st Law of
Thermodynamic
It is stated as:
The energy cannot be created
cannot be destroyed but it can change
form one form to another form.
It is also known as the Law of
Conversation of Energy.

53. 1st Law of Thermodynamic
Heat and work are mutually interchangeable.
Mathematically:
W+Q=0
Where
W=work
Q=heat

54. 1st Law of
Thermodynamic
For any closed cycle, during the
various processes that make up the
cycle work is done on or by the fluid
and heat is rejected or supplied; the
net work input can be defined as ∑W
and the net heat supplied as ∑Q is
equal to zero

55. 1st Law of Thermodynamic

56. Steady Flow Equation

57. 2nd Law of Thermodynamic
The second law of thermodynamic gives us more information about thermodynamic process.
Second law may be defined as:
“Heat cannot flow itself from colder body to a hotter body.”
The second law is also used to determine the theoretical limits for the performance of mostly
used in engineering system like heat engine and pumps.

58. 2nd Law of
Thermodynamic
The second law of the thermodynamic
in case of the entropy.

59. 2nd Law of
Thermodynamic
When heat transfer form cold body to
hot body.

60. 2nd Law of Thermodynamic
Aspect of the Second Law of Thermodynamics:
Predicting the direction of process.
Establishing the conditions for equilibrium.
Determine the best theoretical performance of the cycle, engines and other devices.
Evaluating quantitatively the factors that preclude attainment of the best theoretical
performance level

61. Boyle’s Law

62. Boyle’s Law
PV diagram of the Boyle’s Law is
shown as

63. Boyle’s Law
Mathematical form of the Boyle’s law:

64. Charles Law
Concept of the Charles Law:

65. Charles Law

66. Charles Law
TV Diagram at constant pressure is
shown in the fig.