ETD PPT UNIT-I R21.pptx

P.T.Lee Chengalvaraya Naicker College of Engineering and Technology
Vallal P.T.Lee Chengalvaraya Naicker Nagar, Oovery, Veliyur Post, Kanchipuram, 631 502.
Department of Mechanical Engineering
07-10-2022
ME3391 ENGINEERING THERMODYNAMICS, R.Ramesh Babu, M.E., AP/MECH.
1
ME3391 ENGINEERING THERMODYNAMICS
Branch: Mechanical Engineering Year: II Semester: 03
Academic Year : 2022-23
Anna University, Regulations: 2021
Prepared by
R.Ramesh Babu, M.E.,
Asst. Professor, Department of Mechanical Engineering.

07-10-2022
ME3391 ENGINEERING THERMODYNAMICS, R.Ramesh Babu, M.E., Department of Mechanical Engineering
2
Institute Vision:
“To create service based globally recognized technical institute providing academic excellence, research,
innovation and to blend with the futuristic technologies that develops human values and ethics with the emerging
society”.
Institute Mission:
M1. To promote quality student centric teaching Institute in teaching, learning and academic services to ensure
success in technical fields.
M2. To ensure widespread access to build career opportunities for students through Industry-Institute interaction.
M3. To promote research and development that exercises to create next generation Technology.
M4. To Inculcate Entrepreneurship expertise in students to become job creators.
M5. To strengthen Values and Ethics that will prepare the students to lead lives of personal integrity and civic
responsibility in a global society.

07-10-2022
3
DEPARTMENT OF MECHANICAL ENGINEERING
Department Vision:
To groom Motivated, Environmental friendly, Self-esteemed, Creative and Oriented Mechanical
Engineers.
Department Mission:
M1. To educate, prepare and mentor students to excel as professionals.
M2. To provide the facilities and environment conducive to high quality education to get diverse careers as well
as research in the field of Mechanical Engineering.
M3. To engage the students in academic as well as scholarly activities, which strengthen the department
reputation in global market.
M4. Creating awareness about the needs of mechanical industries through alumni and industry-institute
interactions
M5. "Prepare Engineering Students for Successful Careers"

07-10-2022
ME3391 ENGINEERING THERMODYNAMICS, R.Ramesh Babu, M.E., AP/MECH.
4
PROGRAM EDUCATIONAL OBJECTIVES (PEOs)
I. Effectuating success in careers by exploring with the design, digital and computational
analysis of engineering systems, experimentation and testing, smart manufacturing, technical
services, and research.
II. Amalgamating effectively with stakeholders to update and improve their core
competencies and abilities to ethically compete in the ever-changing multicultural global
enterprise.
III. To encourage multi-disciplinary research and development to foster advanced technology,
and to nurture innovation and entrepreneurship in order to compete successfully in the
global economy.
IV. To globally share and apply technical knowledge to create new opportunities that
proactively advances our society through team efforts and to solve various challenging
technical, environmental and societal problems.
V. To create world class mechanical engineers capable of practice engineering ethically with a
solid vision to become great leaders in academia, industries and society.

07-10-2022
ME3391 ENGINEERING THERMODYNAMICS, Mr. R.Ramesh Babu, M.E., AP/MECH.
5
Program Outcomes (POs)
Program Outcomes are statements that describe what students are expected to know and be able to do
upon graduating from the program. These relate to the skills, knowledge, attitude and behaviour that students
acquire through the program. NBA has defined the Program Outcomes for each discipline.
NBA has defined the following twelve POs for an engineering graduate. These are inline
with the Graduate Attributes as defined by the Washington Accord:
1. Engineering knowledge: Apply the knowledge of mathematics, science, engineering
fundamentals, and an engineering specialization to the solution of complex engineering
problems.
2. Problem analysis: Identify, formulate, review research literature, and analyse complex
engineering problems reaching substantiated conclusions using first principles of
mathematics, natural sciences, and engineering sciences.

07-10-2022
6
3. Design/development of solutions: Design solutions for complex engineering problems
and design system components or processes that meet the specified needs with
appropriate consideration for the public health and safety, and the cultural, societal, and
environmental considerations.
4. Conduct investigations of complex problems: Use research-based knowledge and
research methods including design of experiments, analysis and interpretation of data, and
synthesis of the information to provide valid conclusions.
5. Modern tool usage: Create, select, and apply appropriate techniques, resources, and
modern engineering and IT tools including prediction and modelling to complex
engineering activities with an understanding of the limitations.
6. The engineer and society: Apply reasoning informed by the contextual knowledge to
assess societal, health, safety, legal and cultural issues and the consequent responsibilities
relevant to the professional engineering practice.

07-10-2022
7
7. Environment and sustainability: Understand the impact of the professional engineering solutions in
societal and environmental contexts, and demonstrate the knowledge of, and need for sustainable
development.
8. Ethics: Apply ethical principles and commit to professional ethics and responsibilities and norms of the
engineering practice.
9. Individual and team work: Function effectively as an individual, and as a member or leader in diverse
teams, and in multidisciplinary settings.
10. Communication: Communicate effectively on complex engineering activities with the engineering
community and with society at large, such as, being able to comprehend and write effective reports and
design documentation, make effective presentations, and give and receive clear instructions.
11.Project management and finance: Demonstrate knowledge and understanding of the engineering and
management principles and apply these to one’s own work, as a member and leader in a team, to manage
projects and in multidisciplinary environments.
12. Life-long learning: Recognize the need for, and have the preparation and ability to engage in independent
and life-long learning in the broadest context of technological change.

07-10-2022
8
PROGRAM SPECIFIC OUTCOMES (PSOs)
On successful completion of the Mechanical Engineering Degree programme, the
Graduates shall exhibit the following:
1. Apply the knowledge gained in Mechanical Engineering for design and
development and manufacture of engineering systems.
2. Apply the knowledge acquired to investigate research-oriented problems in
mechanical engineering with due consideration for environmental and social
impacts.
3. Use the engineering analysis and data management tools for effective
management of multidisciplinary projects.

07-10-2022
9
PEO
PO PSO
1 2 3 4 5 6 7 8 9 10 11 12 1 2 3
I. 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
II. 3 2 2 2 2 1 1 1 3 2 1 2 3 3
III. 3 1 2 1 2 2 1 1 2 3 3 2 2
IV. 2 2 2 2 2 2 1 2 2 3 3
V. 3 2 2 2 1 3 2 2 2 1 1 3 3 2 2
PEO’s – PO’s & PSO’s MAPPING:

07-10-2022
10
SEMESTER III
SEMESTER - III
SL.
NO.
COURSECODE
COURSE TITLE
CATE
GORY
PERIODS PER WEEK TOTAL CONTACT
PERIODS CREDITS
L T P
THEORY
1. MA3351 Transforms and PartialDifferential
Equations
BSC 3 1 0 4 4
2. ME3351 Engineering Mechanics ESC 3 0 0 3 3
3. ME3391 Engineering
Thermodynamics
PCC 3 0 0 3 3
4. CE3391 Fluid Mechanics andMachinery
ESC
3 1 0 4 4
5. ME3392 Engineering Materials andMetallurgy PCC 3 0 0 3 3
6. ME3393 Manufacturing Processes PCC 3 0 0 3 3
PRACTICALS
7. ME3381 Computer Aided MachineDrawing ESC 0 0 4 4 2
8. ME3382 Manufacturing Technology
Laboratory
PCC 0 0 4 4 2
9. GE3361 Professional Development$ EEC 0 0 2 2 1
TOTAL 18 2 10 30 25
SEMESTER III

07-10-2022
11
ME3391 ENGINEERING THERMODYNAMICS
COURSE OBJECTIVES:
1. Impart knowledge on the basics and application of zeroth and first law of
thermodynamics.
2. Impart knowledge on the second law of thermodynamics in analysing the
performance of thermal devices.
3. Impart knowledge on availability and applications of second law of
thermodynamics
4. Teach the various properties of steam through steam tables and Mollier
chart.
5. Impart knowledge on the macroscopic properties of ideal and real gases.

07-10-2022
12
UNIT I BASICS, ZEROTH AND FIRST LAW 9
Review of Basics – Thermodynamic systems, Properties and processes Thermodynamic Equilibrium - Displacement work - P-V
diagram. Thermal equilibrium - Zeroth law – Concept of temperature and Temperature Scales. First law – application to closed and
open systems – steady and unsteady flow processes.
UNIT II SECOND LAW AND ENTROPY 9
Heat Engine – Refrigerator - Heat pump. Statements of second law and their equivalence & corollaries. Carnot cycle - Reversed
Carnot cycle - Performance - Clausius inequality. Concept of entropy - T-s diagram - Tds Equations - Entropy change for a pure
substance.
UNIT III AVAILABILITY AND APPLICATIONS OF II LAW 9
Ideal gases undergoing different processes - principle of increase in entropy. Applications of II Law. High- and low-grade energy.
Availability and Irreversibility for open and closed system processes - I and II law Efficiency
UNIT IV PROPERTIES OF PURE SUBSTANCES 9
Steam - formation and its thermodynamic properties - p-v, p-T, T-v, T-s, h-s diagrams. PVT surface. Determination of dryness
fraction. Calculation of work done and heat transfer in non-flow and flow processes using Steam Table and Mollier Chart.
UNIT V GAS MIXTURES AND THERMODYNAMIC RELATIONS ` 9
Properties of Ideal gas, real gas - comparison. Equations of state for ideal and real gases. vander Waal's relation - Reduced
properties - Compressibility factor - Principle of Corresponding states - Generalized Compressibility Chart. Maxwell relations - TdS
Equations - heat capacities relations - Energy equation, Joule- Thomson experiment - Clausius-Clapeyron equation.
TOTAL: 45 PERIODS

07-10-2022
13
TEXTBOOKS:
1. Nag.P.K., “Engineering Thermodynamics”, 6th Edition, Tata McGraw Hill (2017), New Delhi.
2. Natarajan, E., “Engineering Thermodynamics: Fundamentals and Applications”, 2nd Edition (2014),
Anuragam Publications, Chennai.
REFERENCES:
1. Cengel, Y and M. Boles, Thermodynamics - An Engineering Approach, Tata McGraw Hill,9th Edition, 2019.
2. Chattopadhyay, P, “Engineering Thermodynamics”, 2nd Edition Oxford University Press, 2016.
3. Rathakrishnan, E., “Fundamentals of Engineering Thermodynamics”, 2nd Edition, Prentice Hall of India
Pvt. Ltd, 2006.
4. Claus Borgnakke and Richard E. Sonntag, “Fundamentals of Thermodynamics”, 10th Edition, Wiley
Eastern, 2019.
5. Venkatesh. A, “Basic Engineering Thermodynamics”, Universities Press (India) Limited, 2007

07-10-2022
14

07-10-2022
15
Beyond the Syllabus:

07-10-2022
16

07-10-2022
17
Applications:
Automobile engines
Turbines, Compressors & Pumps
Propulsion system for aircraft and rockets
Combustion systems
HVAC systems: Vapor compression & absorption refrigeration, Heat pumps
Cooling of electronic equipments
Power stations: Nuclear, Thermal, etc.
Alternative energy systems
Biomedical applications: Life-support systems, Artificial organs

07-10-2022
18
Application Areas of Thermodynamics

07-10-2022
19
Application Areas of Thermodynamics

07-10-2022
20
Course Outcomes (COs):
Upon the completion of this course the students will be able to
1. Apply the zeroth and first law of thermodynamics by formulating temperature scales
and calculating the property changes in closed and open engineering systems.
2. Apply the second law of thermodynamics in analysing the performance of thermal
devices through energy and entropy calculations.
3. Apply the second law of thermodynamics in evaluating the various properties of steam
through steam tables and Mollier chart
4. Apply the properties of pure substance in computing the macroscopic properties of
ideal and real gases using gas laws and appropriate thermodynamic relations.
5. Apply the properties of gas mixtures in calculating the properties of gas mixtures and
applying various thermodynamic relations to calculate property changes.

07-10-2022
21
UNIT I BASICS, ZEROTH AND FIRST LAW 9
Review of Basics – Thermodynamic systems,
Properties and processes Thermodynamic
Equilibrium - Displacement work - P-V diagram.
Thermal equilibrium - Zeroth law – Concept of
temperature and Temperature Scales. First law –
application to closed and open systems – steady
and unsteady flow processes.

07-10-2022
22
KEY POINTS
 Basic concepts- microscopic and macroscopic approach.
 Path and point functions.
 System and their types.
 Displacement work and other modes of work .P-V diagram.
 Zeroth law of thermodynamics.
 First law of thermodynamics –application to closed and open systems.
 steady and unsteady flow processes.

07-10-2022
23
Basic concepts
What is Thermodynamics?
“Thermodynamics is the science that deals with heat and work and those
properties of substances that bear a relation to heat and work.”
Thermodynamics: The science of energy. Energy: The ability to cause changes.
thermodynamics stems from therme (heat) and dynamics (power).
Some keywords:
• Properties : density, temperature, pressure, Etc.
• State : a collection of properties
• Process : a path between states
• Energy : heat, work, internal energy, enthalpy
• Entropy : degree of disorder

07-10-2022
24
What will we learn ?
 Identification of thermodynamic properties and states
Basic law of thermodynamics.
Zeroth law deals with thermal equilibrium, relates to the concept of equality of
temperature.
First law pertains to the conservation of energy and introduces the concept of
internal energy.
Second law relates the direction of flow of heat, dictates limits on the conversion
of heat into work and introduces the principle of increase of entropy.
Third law defines the absolute zero of entropy.
- These laws are based on experimental observations and have No Mathematical
Proof.

07-10-2022
25
Concept of continuum
In microscopic approach the substance is assumed to be continuously
distributed, ignoring the space between the molecules. This is known as
continuum hypothesis.
• Classical thermodynamics: A macroscopic approach to the study of
thermodynamics that does not require a knowledge of the behavior of individual
particles (continuum). - EASY
• Statistical thermodynamics: A microscopic approach, based on the average
behavior of large groups of individual particles. – NOT EASY!

07-10-2022
26
MACROSCOPIC AND MICROSCOPIC POINTS OF VIEW
Thermodynamic studies are undertaken by the following two different approaches.
1. Macroscopic approach—(Macro mean big or total)
2. Microscopic approach—(Micro means small)
macroscopic approach, certain quantity of matter is considered,without a
concern on the events occurring at the molecular level. These effects can be perceived
by human senses or measured by instruments. eg: pressure, temperature
microscopic approach, the effect of molecular motion is Considered.
eg: At microscopic level the pressure of a gas is not constant, the temperature of a gas
is a function of the velocity of molecules.

07-10-2022
27
Sr.
No.
Macroscopic Approach Microscopic Approach
1 In this approach a certain quantity of matter is
considered without taking into account the events
occurring at molecular level.
The matter is considered to be comprised of a large number
of tiny particles known as molecules, which moves randomly in
chaotic fashion. The effect of molecular motion is considered.
2 Analysis is concerned with overall behavior of the
system.
The Knowledge of the structure of matter is essential in analyzing
the behavior of the system.
3
This approach is used in the study of
classical thermodynamics. This approach is used in the study of statistical thermodynamics.
4
A few properties are required to describe the
system.
Large numbers of variables are required to describe the
system.
5
The properties like pressure, temperature, etc.
needed to describe the system, can be easily measured.
The properties like velocity, momentum, kinetic energy,
etc. needed to describe the system, cannot be measured easily.
6
The properties of the system are their average values. The properties are defined for each molecule individually.
7
This approach requires simple
mathematical formulas for analyzing the system.
No. of molecules are very large so it requires advanced statistical
and mathematical method to explain any change in the system.
comparison of microscopic and macroscopic approach

07-10-2022
28
PATH AND POINT FUNCTIONS
CYCLE
Any process or series of processes whose end states are identical is termed a cycle.
POINT FUNCTION
When two properties locate a point on the graph (co-ordinate axes) then
those properties are called as point function.
Examples. Pressure, temperature, volume etc.
PATH FUNCTION
There are certain quantities which cannot be located on a graph by a point but
are given by the area or so, on that graph. In that case, the area on the
graph, pertaining to the particular process, is a function of the path of the
process. Such quantities are called path functions.
Examples. Heat, work etc.

07-10-2022
ME3391 ENGINEERING ME8391 ENGINEERING THERMODYNAMICS, Mr. R.Ramesh Babu, M.E., AP/MECH.
29

07-10-2022
30
PROPERTIES OF SYSTEMS
A property of a system is a characteristic of the system which depends upon its
state, but not upon how the state is reached. There are two sorts of property :
1. Intensive properties: These properties do not depend on
the mass of the system. Examples : temperature, pressure,
and density, etc
2. Extensive properties: These properties depend on the
mass of thesystem. Example : mass and volume.

07-10-2022
31
Thermodynamic System and Control Volume
Thermodynamic System
“It is defined as a quantity of matter or a region in the space upon which attention is
concentrated for the investigation or analysis of the thermodynamic problems i.e. heat
transfer, work transfer, etc.”
Surroundings or Environment
“It is the matter or region outside the system”
Boundary
“The system and surroundings are separated by
an envelope called boundary of the system”
· Fixed or moving boundary Fig. 1.2 System, Surroundings and Boundary
· Real or imaginary boundary
Types of boundary
System + Surrounding = Universe

07-10-2022
32
Definition Work Heat Mass
Isolated system No No No
Closed system Also called Control Mass Yes Yes No
Open system Also called Control Volume Yes Yes Yes
Types of Thermodynamic System
Open System
In an open system mass and energy (in form of heat and work)
both can transfer across the boundary.
Most of the engineering devices are open system.
Examples: Boiler, Turbine, Compressor, Pump, I.C. Engine, etc

07-10-2022
33
B. Closed System
 A closed system can exchange energy in the form of heat and
work with its surroundings but there is no mass transfer across the
system boundary.
The mass within the system remains constant though its volume can
change against a flexible boundary.
Further, the physical nature and chemical composition of the mass may
change.
- Examples: Cylinder bounded by a piston with certain quantity of
fluid, Pressure cooker and Bomb calorimeter, etc.

07-10-2022
34
C. Isolated System
 There is no interaction between system and surroundings.
 It is of fixed mass and energy, and hence there is no mass and energy transfer across
the system boundary.
Examples: The Universe and Perfectly insulated closed vessel (Thermo flask).

07-10-2022
35

07-10-2022
36

07-10-2022
37
D. Adiabatic System
 Boundaries do not allow heat transfer to take place across them.
 An adiabatic system is thermally insulated from its environment.
 It can exchange energy in the form of work only. If it does not, it becomes
isolated.
Example: A perfectly insulated piston-cylinder arrangement.
Piston

07-10-2022
38
Fig. A Open System with one inlet and
one exit

07-10-2022
39
STATE AND EQUILIBRIUM
State: Condition of a system
Thermodynamics deals with equilibrium states.
Equilibrium: A state of balance with no unbalanced potentials
(or driving forces) within the system.
1. Thermal equilibrium: temperature is the same throughout the
entire system.
2. Mechanical equilibrium: no change in pressure at any point of
the system with time.
3. Phase equilibrium: If a system involves multiple phases and
when the mass of each phase reaches an equilibrium level and
stays there.
4. Chemical equilibrium: chemical composition of a system does
not change with time, that is, no chemical reactions occur.

07-10-2022
40
THERMODYNAMIC EQUILIBRIUM
A system is in thermodynamic equilibrium if the temperature and pressure at all points are same ; there
should be no velocity gradient ; the chemical equilibrium is also necessary. Systems under temperature and
pressure equilibrium but not under chemical equilibrium are sometimes said to be in metastable equilibrium
conditions. It is only under thermodynamic equilibrium conditions that the properties of a system can be
fixed.
1. Thermal equilibrium. The temperature of the system does not change with time and has same
value at all points of the system.
2. Mechanical equilibrium. There are no unbalanced forces within the system or between the
surroundings. The pressure in the system is same at all points and does not change with respect to time.
3. Chemical equilibrium. No chemical reaction takes place in the system and the chemical
composition which is same throughout the system does not vary with time.

07-10-2022
41
Thermodynamic state of a system/substance: Exact condition of a system/substance
is called state.

07-10-2022
42
Thermodynamic process: When one or more of the thermodynamic properties of
a system change, we say that there is a change of state of the system. This change
of state of a system is referred to as thermodynamic process.
Fig. A Process between state 1 and state 2 and process path

07-10-2022
43
Quasi-static process: A quasi-static process is one in which the deviation from
equilibrium is infinitesimally small. All the states through which a system passes
during a process can be considered as a succession of equilibrium states.

07-10-2022
44
Thus quasi-equilibrium process takes place very slowly. If one property remains
constant during a process, the prefix “iso” is used to describe such a process.
E.g. Isothermal process – Constant temperature process
Isobaric process – Constant pressure process
Isochoric process – Constant volume process.
Reversible and irreversible process:
A process is called a reversible process if it can be completely reversed and the
system and the surroundings come back to its original states.
A process which cannot be exactly reversed and the system cannot be brought
back to the initial state without leaving a net change in the surroundings is called
irreversible process.

07-10-2022
45
Thermodynamic cycle: When a number of processes in sequence bring the
system back to its initial state, then the system is said to have undergone a
thermodynamic cycle.
In Fig 1-2-3-4-1 is cycle consisting of four processes. The change in value of any
property is zero for a cyclic process.

07-10-2022
46
Energy: Energy may be defined as the capacity a body possesses for doing work.
All forms of energy are mainly classified as i) Stored energy ii) Transient energy or
energy in transition or transient energy.
Stored energy is the energy possessed by a system within its boundaries.
E.g., K.E, P.E, and I.E.
Transit energy is the energy possessed by a system which is capable of crossing its
boundaries. E.g. Heat and Work.
Heat: Heat is defined as the energy transferred without transfer of mass across the
boundary of a system due temperature difference between the system and the
surroundings. The energy in transition is called heat. Heat energy cannot be stored
in a system.
Unit for heat and any other form of energy is joule (J).
Heat flow into a system is positive and heat flow out of a system is negative.

07-10-2022
47

07-10-2022
48

07-10-2022
49
Work: Work is defined as the energy transferred without transfer of mass across the
boundary of a system because of intensive property difference other than temperature
that exists between the system and the surroundings. Work also cannot be stored in a
system. Unit of work done is N-m or joule.
Work done by the system is positive and work done upon the system is negative.
Internal energy: It is the energy possessed by a body or system due to its molecular
arrangement and motion of the molecules.
It is the sum of internal K.E and internal P.E of the molecules. It is a function of
temperature and can be increased or decreased by adding or subtracting heat to or from
the substance.
Absolute value of the I.E cannot be measured but change in I.E can be measured when a
substance undergoes a change of state from 1 to 2. It can be expressed in general way as;
du = u2 - u1

07-10-2022
50
Enthalpy:
Enthalpy is nothing but total heat and heat content. Enthalpy or total heat = Internal
energy + Product of absolute pressure and volume.
h = u + pv
Absolute value of enthalpy cannot be measured, only change in enthalpy can
be measured.
dh = h2 – h1 = (u2 - u1) + (pv2 – pv1)
Entropy
It is represented by the symbol ‘s’. Small increase of entropy ‘ds’ of a substance is
defined as the ratio of small addition of heat dQ to the absolute temperature T of the
working substance at which the heat is supplied.
ds = dQ/T or dQ = T.ds
Unit of entropy is J/kg/K.

07-10-2022
51
Definition of work in Mechanics: The work is done by a force as it acts upon a
body moving in the direction of the force.
The action of a force through a distance is called mechanical work. The
product of the force and the distance moved parallel to the force is the magnitude
of the mechanical work.
Thermodynamic work:
In thermodynamics, work transfer is considered as occurring between
system and surroundings. Work is said to be done by a system if the sole effect on
things external to the system can be reduced to the raising of a weight.
“Work shall be done by the system if the total effect outside the system is
equivalent to the raising of weight and this work shall be positive work ”.
The weight may not actually be raised, but the net effect external to the
system would be reduced to the raising of a weight.

07-10-2022
52
Piston and cylinder arrangement

07-10-2022
53

07-10-2022
54
(displacement work or p-dV work):
Consider a gas in thermodynamic equilibrium in a frictionless piston and cylinder
arrangement as shown in Fig.

07-10-2022
55
Zeroth law of thermodynamics:
Statement: When two systems have thermal equilibrium with a third
system, they in turn have thermal equilibrium with each other.

07-10-2022
56
Thermometer and thermometric property: The Zeroth law provides the basis
for the measurement of temperature. The third body 3 in Zeroth law is called
the thermometer.
THERMOMETER THERMOMETRIC PROPERTY
1. Alcohol or mercury in glass Length
2. Electrical resistance Resistance
3. Thermocouple Electromotive force
4. Constant volume gas Pressure
5. Constant pressure gas Volume
6. Radiation (Pyrometer) Intensity of radiation

07-10-2022
57

07-10-2022
58

07-10-2022
59

07-10-2022
60

07-10-2022
61

07-10-2022
62
First Law of Thermodynamics
When a system undergoes a thermodynamic cycle then the net heat supplied to the system
from the surroundings is equal to net work done by the system on its surroundings.
dQ = dW
APPLICATION OF FIRST LAW TO A PROCESS
1. Reversible Constant Volume (or Isochoric) Process (v = constant)
2. Reversible Constant Pressure (or Isobaric) Process (p = constant
3. Reversible Temperature (or Isothermal) Process (pv = constant, T = constant)
4. Reversible Adiabatic Process( pvƳ = constant)
5. Polytropic Reversible Process (pvn = constant)
6. Free Expansion

07-10-2022
63
•Isobaric
•P = constant
•Isovolumetric
•V = constant
•W = 0
•Isothermal
•T = constant
•U = 0 (ideal gas)
•Adiabatic
•Q = 0
V
V
V
V
P
P
P
P

07-10-2022
64

07-10-2022
65
Constant
Volume
Process

07-10-2022
66

07-10-2022
67
Constant
Pressure
Process

07-10-2022
68

07-10-2022
69

07-10-2022
70

07-10-2022
71

07-10-2022
72

07-10-2022
73

07-10-2022
74

07-10-2022
75

07-10-2022
76

07-10-2022
77

07-10-2022
78

07-10-2022
79

07-10-2022
ME3391 ENGINEERING THERMODYNAMICS, R.Ramesh Babu, M.E., Department of Mechanical Engineering80

07-10-2022
81

07-10-2022
82

07-10-2022
83
Process
Index n
Heat added 1
2
pdv
p, v, T
relations
Specific heat, c
Constant
pressure n = 0 cp(T2 – T1) p(v2 – v1)
T2 = v2
T1 v1 cp
Constant volume
n = cv(T2 – T1) 0
T1 = p1
T2 p2 cv
Constant
temperature n =1
v2
1
v2
1
p1v1 = p2v2
Reversible
adiabatic
n =  0 p v p v
 1
p v  = p v 
1 1 2 2
T v  1
T1 v2
 1
p2 
= P
1
0
Polytropic n = n cn (T2 T1)
=  n
×(T2 T1)
=  n × work
 1
done (non flow)
p1v1 p2v2
n 1
p v n = p v n
1 1 2 2
T2 v1
n 1
T =
1 2
n 1
p2 n
= p 1
c = c  n
n v 1 n

07-10-2022
84
1.In an internal combustion engine, during the compression stroke the
heat rejected to the cooling water is 50 kJ/kg and the work input is 100
kJ/kg.Calculate the change in internal energy of the working fluid stating
whether it is a gain or loss.
Solution. Heat rejected to the cooling water, Q = – 50 kJ/kg
(–ve sign since heat is rejected)
Work input, W = – 100 kJ/kg (–ve sign since work is
supplied to the system) Using the relation, Q = (u2 – u1) + W
– 50 = (u2 – u1) – 100
or u2 – u1 = – 50 + 100 = 50 kJ/kg
Hence, gain in internal energy = 50 kJ/kg. (Ans.)

07-10-2022
85
2.In an air motor cylinder the compressed air has an internal energy of
450 kJ/kg at the beginning of the expansion and an internal energy of 220 kJ/kg after
expansion. If the work done by the air during the expansion is 120 kJ/kg, calculate the heat
flow to and from the cylinder.
Solution. Internal energy at beginning of the expansion,
u1 = 450 kJ/kg
Internal energy after expansion,
u2 = 220 kJ/kg
Work done by the air during expansion,
W = 120 kJ/kg
Heat flow, Q :
Using the relation, Q = (u2 – u1) + W
Q = (220 – 450) + 120
= – 230 + 120 = – 110 kJ/kg
Hence, heat rejected by air = 110 kJ/kg. (Ans.)

07-10-2022
86
APPLICATION OF FIRST LAW TO STEADY FLOW PROCESS Steady Flow
Energy Equation (S.F.E.E.)
In many practical problems, the rate at which the fluid flows through a machine or
piece of apparatus is constant. This type of flow is called steady flow.
Assumptions :
The following assumptions are made in the system analysis : (i) The mass flow
through the system remains constant.
(ii) Fluid is uniform in composition.
(iii) The only interaction between the system and surroundings are work and heat.
(iv) The state of fluid at any point remains constant with time.
(v) In the analysis only potential, kinetic and flow energies are considered.

07-10-2022
87

07-10-2022
88

07-10-2022
89
1. 50kg/min of air enters the control volume in a steady flow system at 2 bar and 100°c
and at an envelope elevation of 100m above the datum. The same mass leaves the
control volume at 150m elevation with a pressure of 10 bar and temperature of 300°c. The
entrance velocity as 2400m/min and the exit velocity is 1200m/min. During the process
50000kj/hr of heat is transferred to the control volume and the rice in enthalpy is 8kj/kg.
Calculate the power developed.
Given data:
M=50kj/kg=50/60=0.83kj/sec
P1=2bar=200kN/m2
T1=100°c=373k, Z1=100m, Z2=150m
P2=10bar=1000KN/m2, T2=300°c=573k
C1=2400m/min=2400/60=40m/sec
C2=1200m/min=1200/60=20m/sec
Q=50000KJ/hr=50000/3600=13.89KJ/sec
H2-h1=8KJ/kg
To find:
Power developed P=?

07-10-2022
90
Solution:
SFEE is
Gz1+c1
2/2+u1+p1v1+Q=gz2+c2
2/2+u2+p2v52+W
W=g(z1-z2)+c1
2-c2
2/2+(h1-h2)+Q
W=9.81(100-150)+402-
202/2+8×103+13.89×103
W=5999.5J/kg
W=6Kj/kg
Power developed
P=W×mass
=6.0×0.83
P=4.98KJ/sec
P=4.98KN

07-10-2022
91
2. A room for four persons a has two for each consuming 0.18KW power and three
lamps. Ventilation air at the rate of 80kg/hr enters with an enthalpy of 84kj/kg In each
person put out heat of the rate of 630Kj/hr. Determine the rate at which heat is to be
removed by a room cooler so that a steady state is maintained in the room.
Given data :
Np=4(person); nf=2
Wf=0.18kw
Wl=100w
Mass of air m=80 kg/hr=80/3600=0.022kg/s
h1=84kj/kg
h2=59kj/kg
Qp=630kj/hr
To find:
Rate of heat is to be removed =?

07-10-2022
92
Solution:
E=m(h1-c1
2/2+gz1+Q)-m(h2+C2
2/2+Z2g+w)
Assuming that ,
C1
2-C2
2/2=0.(z1-z2)g=0.
Q=E-m(h1-h2)-w
E=-npQp
=-4×630/3600
W=-0.7Kw
m(h1-h2)=80/3600(84-59)
=0.55kw
W=electrical energy in put
W=nfwf+newe
=2×0.8+3×100/1000
W=0.66kw
Q= E- m(h1-h2)-w
=-0.7-0.5-0.66 Q=-1.916kw.

07-10-2022
93

07-10-2022
94

ETD PPT UNIT-I R21.pptx

Recommended

Recommended

More Related Content

Similar to ETD PPT UNIT-I R21.pptx

Similar to ETD PPT UNIT-I R21.pptx (20)

Recently uploaded

Recently uploaded (20)

ETD PPT UNIT-I R21.pptx