This document provides an introduction to thermodynamics, including:
- A definition of thermodynamics as the study of energy and energy transformations between a system and its surroundings.
- A brief history of thermodynamics beginning with Otto von Guericke's vacuum pump in 1650 and the formulation of Boyle's Law by Robert Boyle and Robert Hooke.
- Explanations of key thermodynamics concepts and terminology like system, boundary, properties, and the zeroth, first, and second laws of thermodynamics.
- Summaries of processes involving perfect gases like isobaric, isochoric, and adiabatic processes, as well as thermodynamic cycles like the Carnot,
2. CONTENTS
1) Title
2) Contents
3) Introduction
4) History
5) Etymology
6) Definations
7) Terminology
8) Laws of
Thermodynamics
9) Laws of perfect gas
10) Processes of
Perfect gas
11) General law
12) Some cycles
13) References
3. INTRODUCTION
• Thermodynamics is a branch of physics that
deals with the laws governing the energy
and work of a system, which may be described
as the exchange of heat energy to and from
other forms of energy within a given system.
• Careful study of these concept is essential for
good understanding of topics in
thermodynamics.
• specifically, it defines macroscopic variables,
such as internal energy, entropy, and pressure.
4. HISTORY
•The history of thermodynamics as a scientific
discipline generally begins with Otto von
Guericke who, in 1650, built and designed the
world's first vacuum
pump and demonstrated
a vacuum using his
Magdeburg
hemispheres.
Magdeburg hemispheres
5. CONTINUE……
• Shortly after, the physicist
and chemist Robert
Boyle had learned of
Guericke's designs and,
in coordination with the
scientist Robert Hooke,
built an air pump in 1656.
• Using this pump, Boyle
and Hooke noticed a
correlation
between pressure, tempe
rature, and volume. In
time, they
formulated Boyle's Law.
6. CONTINUE……
• Based on these concepts, an associate of
Boyle's named Denis Papin built a steam
digester, which was a closed vessel with a
tightly fitting lid that confined steam until a high
pressure was generated.
• The first thermodynamic textbook was written in
1859 by William Rankine.
• The first and second laws of thermodynamics
emerged simultaneously in the 1850s, primarily
out of the works of William Rankine, Rudolf
Clausius, and William Thomson (Lord Kelvin).
7. Etymology
• The components of the word thermo-
dynamic are derived from
the Greek words therme meaning "heat,"
and dynamics meaning “power”.
• The term thermo-dynamic was first used in
January 1849 by William Thomson, later Lord
Kelvin, in the phrase a perfect thermo-dynamic
engine to describe Sadi Carnot's heat engine. In
April 1849, Thomson added an appendix to his
paper and used the term thermodynamic in the
phrase the object of a thermodynamic engine.
8. DEFINATIONS
• It can be define as the study of energy, energy
transformations and its relation to matter. The
analysis of thermal systems is achieved through
the application of the governing conservation
equations, namely Conservation of Mass,
Conservation of Energy.
• In other words,it’s science which deals with the
energies possesed by gases and vapours, that
includes the conservation of these energies in
terms of heat and mechanical work and their
relation with properties of system.
9. Thermodynamic system –
It’s defined as a definite area
or a space where some
thermodynamic process takes
place.
Surroundings – Boundries and anything outside
the boundries is called surroundings.
Boundary- The real or imaginary surface that
separates the system from its surroundings. The
boundaries of a system can be fixed or movable.
Mathematically, the boundary has zero
thickness, no mass, and no volume.
TERMINOLOGY
10. •
Closed system- Fixed amount
of mass. only heat or work, can
cross the boundary.
Open system- Both mass
and energy can cross the
boundary of a control volume.
Isolated system- fixed
mass and no heat or
work cross its boundry.
Rigid system: A closed
system that
communicates with the
surroundings by heat
only.
11. CONTINUE……
• Properties of system- all the quantities such as
volume, pressure, temperature, density and internal
energy etc identify state of a system are called
properties.
1)Extensive- The properties whose value for the entire
system is equal to the sum of their values for
individual part of the system.
i. e. Total volume, total mass, total energy
2)Intensive- The properties whose value for the entire
system is NOT equal to the sum of their values for
individual part of the system.
i.e. temperature, pressure, density etc
12. CONTINUE……
• Thermal equilibrium- when the temperature is
the same throughout the entire system.
• Mechanical equilibrium- when there is no
change in pressure at any point of the system.
However, the pressure may vary within the
system due to gravitational effects.
• Phase equilibrium- in a two phase system,
when the mass of each phase reaches an
equilibrium level.
• Chemical equilibrium- when the chemical
composition of a system does not change with
time, i.e., no chemical reactions occur.
13. CONTINUE……
• Perfect Gas- Its define as a state of substance
whose evaporation from its liquid state is complete, If
evaporation is partial the substance is called Vapour.
• Absolute zero Temperature- At which the volume of
a gas becomes zero.
Its -273°c OR 0 k.
• Specific Heat- The amount of heat required to raise
the temperature of its unit mass through 1°.
• Joules Law- “The change of internal energy of a
perfect gas is directly proportional to the change of
the temperature.” Mathematically,
dE = m.c dT
14. Laws of Thermodynamics
1) Zeroth law of thermodynamics- When two bodies
are in thermal equilibrium with a third body, they are
also in thermal equilibrium with each other.
2) First law of thermodynamics- Heat and mechanical
work are mutually convertible. or Energy can
neither be created nor destroyed,it can transfer from
one form to another.
3) Second law of thermodynamics- There is a definite
limit to the amount of mechanical energy, which can
be obtained from a given quantity of heat energy.
15. CONTINUE……
• Claussius states that “it’s impossible
for a self acting m/c working in a
cyclic process, to transfer heat from a
body at a low temperature to higher
without the aid of external source”.
• Kelvin-Plank that “it’s impossible to
construct an engine working on a
cyclic process, whose sole purpose is
to convert heat energy in to work”.
16. Laws Of Perfect Gas
1) Boyle’s law- “The absolute pressure of a given mass
of perfect gas varies inversely as its volume, when
the temperature remain constant”. Mathematically
pv = constant (T= const.)
2) Charles law- “The volume of a given mass of a
perfect gas varies directly as its absolute
temperature, when the pressure remains constant”.
Mathematically, V/T = constant (p= const.)
3) Gay-lussac law- “The absolute pressure of a given
mass of a perfect gas varies directly as its absolute
temperature when volume is constant.”
Mathematically, P/T = constant (v= const.)
17. Thermodynamics processes
of Perfect Gas
1) Const. Volume/ isochoric process:
-Temperature and Pressure will increase
-No change in volume and No work done by gas
-Governed by Gay-Lussac law
2) Const. Pressure/ isobaric process:
- Temperature and volume will increase
- Increase in internal energy
- Governed by Charles law
18. CONTINUE……
3) Hyperbolic process:
- pressure and volume remains constant
- Governed by Boyles law (p.v = constant)
4) Constant temperature/ isothermal process:
- No change in internal energy
- No change in Temperature
5) Adiabatic/ isentropic process:
- No heat leaves or enters the gas
- Temperature of the gas changes
- Change in internal energy is equal to the work
done
19. CONTINUE……
6) Polytropic process:
- It is general law of expansion and compression of the
gases.
p.v^n = Constant
7) Free expansion:
- When a fluid Is allowed to expand suddenly into a
vacuum chamber through on orifice of large
dimensions.
Q = 0, W = 0, and dU = 0.
8) Throttling process: When a gas expands through
an aperture of minitue dimensions, such as a narroe
throat or slightly opened valve.
21. • Thermodynamic cycle: Area
under each curve gives the
work done to the scale.
• Classification:-
1) Reversible cycle: The initial
conditions are restored at the end
of the cycle.
- There should not be any loss of heat due to friction,
radiation or conduction.
- Heat pump operets reverced cycle and regarded as
refrigerator, because it pumps heat from the cold body to
the hot body.
- constant volume, constant pressure, constant
temperature, adiabatic and polytropic are all reversible
processes.
22. 2) Irreversible cycle: In it initial conditions are not
restored at the end of the cycle.
- There is loss of heat due to friction, radiation or
conduction.
- Causes are:-
(a) mechanical and fluid friction
(b) unrestricted expansion
(c) heat transfer with temperature difference
-Throttling is irreversible process.
29. • Mechanical Eng (Conventional and objective
type) by R S KHURMI and J K GUPTA
• https://www.google.co.in/webhp?
sourceid=chrome-
instant&ion=1&espv=2&ie=UTF-8
• http://www.sfu.ca/~mbahrami/ENSC
%20388/Notes/Intro%20and%20Basic
%20Concepts.pdf
• http://www.schoolphysics.co.uk/age11-
14/Matter/text
