This slide will completely describes you about thermodynamics. The basics of thermo is explained in this slide. Intensive and Extensive Propeties are exolained in this properties.

1. Thermodynamics
Thermodynamics
Is a science which deals with the transformation of all kinds of energy one from
to other form.
The word thermodynamics derives from the Greek word therme, meaning
heat and dynamikos originally meaning power or powerful and now the
study of matter in motion.
Thus thermodynamics is the study of heat related to matter in motion. Much of the
study of engineering thermodynamics is concerned with work producing or
utilizing machines such as engines, turbines and compressors together with the
working substances used in such machines. Their development has given us the
ability to create our modern industrial society.

2. Difference between thermodynamics and heat
transfer
• To understand the difference between
thermodynamics and heat transfer let us
consider the cooling of a hot steel bar which is
placed in a water bath.
• Thermodynamics may be used to predict the
final equilibrium temperature of steel bar –
water combination.

3. Difference between thermodynamics
and heat transfer
• However , it will not help us to find out how
long it takes to reach this equilibrium
condition or what the temperature of the bar
will be after a certain length of time before the
equilibrium condition is attained.
• Heat transfer on the other hand may be used to
predict the temperature of both the bar and
water as a function of time.

4. Difference between thermodynamics and heat
transfer
• Thermodynamics
• It deals with the equilibrium states of matter.
• It helps to determine the quantity of work and
heat interaction.
• Heat transfer
• It is inherently a non equilibrium process.
• It helps to predict the distribution of
temperature.

5. System and Surroundings
• System
• A system is defined as a quantity of matter or
a region in space chosen for study.
• The mass or region o/s the system is called
surroundings.
• The real and imaginary surface that separates
the system is called boundary.

7. Types of system
• Open system
• A system in which mass and energy can enter
or leave the system is called open system.
• Most of the engineering devices such as air
compressor turbine and nozzle belong to the
open system.
• In case of air compressor air enter at low
pressure and leaves at high pressure. Here
both mass and energy crosses the system
boundary.

8. Closed system
• A system in which mass cannot enter but energy can
enter or leave the system is called closed system.
• Examples
• Hot liquid kept in a closed metallic flask.
• A certain quantity of gas confined in a cylinder
bounded by a frictionless piston.
Isolated system
• A system in which both mass and energy cannot enter
or leave the system is called isolated system.
• Example
• Thermo flask

9. State of a system
• State means condition in which the system exists.
• The condition of a system can be better
characterized by certain observable properties of
the system properties means temp, pressure
volume and composition.
• Steady state of system
• A system is said to be steady if it does not vary
with time.
• The term steady implies no change with time
• Example ??????

10. Thermodynamic Equilibrium
• Thermodynamic is very much concerned with the equilibrium
state of the system.
• Equilibrium term is used to imply a state of balance of a
system.
• Equilibrium is a word which denotes the static condition or
absence of change.
• In thermodynamics equilibrium means not only the absence of
any tendency towards change.
• But tendency towards change is caused by the driving force.
• Thus a system is said to be under equilibrium under such
condition that is no tendency for a change in its state.

11. Thermodynamic equilibrium
• Equilibrium may be of many kinds.
• A system in order to be in complete
thermodynamic equilibrium must satisfy the
conditions of the following three relevant types
of equilibrium.
• Thermal equilibrium
• Mechanical equilibrium
• Chemical equilibrium

12. Thermal equilibrium
• A system is said to be at thermal equilibrium
under such condition that there is no
temperature driving forces which tend to
bring the change.
• i.e ∆T = 0

13. Mechanical equilibrium
• A system is said to be in mechanical
equilibrium under such condition that there
are no mechanical forces such as pressure on
piston tend to cause energy transfer as work.
• Chemical equilibrium
• A system is said to be at equilibrium under
such conditions that there is no chemical
potential (composition of the system does not
change) which tend the substances to react
chemically.

14. Properties of a system
• The characteristics which are experimentally
measurable and which enable us to define a
system are called its properties.
• Thus term property of a system stands for any
of its identifiable or observable characteristics.
• The properties may broadly be categorized
into the following two groups.
• Extensive property
• Intensive property

15. Extensive property
• The properties which depend on the quantity
of material or quantity of the mass of a system
are known as a extensive properties.
• E.g. volume length, surface area I.E etc.

16. Intensive property
• The properties which are independent of
quantity of materials are called (independent)
intensive properties e.g. temperature, pressure,
density sp. Volume specific heat etc. are I.
properties. Remember one thing that the ratio
of two extensive properties of a homogeneous
system is an intensive property.

17. State functions
• The measurable properties of a system which
describe the present state of the system are
known as functions.
• Thus the properties which depend only on
present condition and not depend on past
history or path followed by which substance
reached in the given state. Hence the state
functions are fixed for a particular state of a
system.

18. Path functions
• The path function is defined as one whose
magnitude depends on the path followed
during a process as well as one the end states.
• The state functions have exact differentials
and are represented by dH, dT, dP, etc.
• While path functions have inexact
differentials. Heat and work are inexact
differentials means their change cannot be
written as differences b/w their end states.

19. Reversible process
• A reversible process is defined as process that can be
reversed without leaving any trace on the surrounding.
i.e both system and surroundings are returned to their
initial states at the end of the reverse process.
• i.e heat and work exchange b/w system and
surrounding is zero.
• Reversible process don’t occur in nature.
• Reversible process are fictitious process and easy to
analyze.
• Reversible process require less amount of work e.g
compressors, fans, pumps consumes least work.
• Reversible process give maximum amount of work
• Example car engine, st/gas turbine

20. Reversible process
• Reversible process require infinite time.

21. Irreversible process
• A process is irreversible when its direction cannot be
reversed by change in the external conditions.
• Irreversible process occur very fastly
• Direction of such cannot be reversed
• Irreversible process require finite time
• There process goes from initial to final state in a single step.
• System is in equilibrium at initial and final state but not at
intermediate stages.
• Irreversible process are real process.
• Examples of irreversible process
• Expansion of gases
• Mixing of gases
• Combustion of fuel

22. ZEROTH Law of Thermodynamics
• Zeroth law of thermodynamics states that if
the bodies A and B are in thermal equilibrium
with a third body C separately then the two
bodies A and B shall also be in thermal
equilibrium with each other.
• Application of Zeroth law ?

24. Problems
• Problems related to topics.
• Chapter 01
• Book: Engg.Thermodynamics by Smith
• 1.5, 1.6, 1.7, 1.13, 1.14, 1.18, 1.19

25. Various Forms Of Energy
• Macroscopic
• Microscopic
• Microscopic forms of energy are related to
energy stored in the molecular and atomic
structure of the system.
• Vibrational+Translational+Rotational+Chemical+N
uclear Energy
• The portion of the internal energy associated
with atomic bonds in a molecule is called the
• Chemical Energy.

26. • Macroscopic forms of energy are those , which
a system possess as a whole with respect to
some outside reference frame such as K.E,P.E.

27. Internal Energy
• Internal energy is a state function of a system.
• The sum of all microscopic forms of energy is
called Internal Energy.
• I.E=Vibrational+Translational+Rotational+Che
mical+Nuclear Energy
• Thus total Energy of a system can be written
as
• E= Macroscopic Energy+ Microscopic Energy

28. • E= K.E+P.E+ U
• Internal Energy of a System is due to its
temperature.
• When temperature is raised then internal energy
increases similarly work also causes the change in
I.E
• The internal energy can be changed even when
no energy is transferred by heat, but just by
work
• Example: compressing gas with a piston
– Energy is transferred by work

29. First law of thermodynamics
• This law states that energy assumes many
forms , the total quantity of energy
remains constant and when energy
disappears, it appears in other form
simultaneously.
• The first law of thermodynamics is
applicable on to a process. Process can be
divided into system and surrounding.
Thus it applies on a system surrounding
not only on system alone.

30. First law of thermodynamics
• The basic form of 1st law of thermodynamics
can be written as.
• (Energy of the system) –( energy of surrounding) =0
• As system is closed, then no mass
can’t enter but energy crosses the
boundary between system and
surrounding which appears as heat
and work.

31. First law of thermodynamics
• For closed system the total energy of the
surroundings is expressed in terms of heat and
work interactions.
• Energy of surrounding= Q+W
• ∆E =Q-W
• In differential form dE =dQ-dW -------- (A)
• dE = d(K.E) + d (P.E)+du ------------------ (B)
• Comparing both eqs

32. First law of thermodynamics
• dQ-dW = d(K.E)+d(p.E)+du
• In most of the cases K.E,P.E are very small,
therefore equation reduces to
• du = dQ-dW
• du+dW=dQ

33. Sign conventions:
• Wby is –ive
• Won is +ive
• Qin is taken +ive
• Qout is taken –ve

34. Steady flow Energy Equation
• Consider the special case of steady state
process in which flow rates must be constant at
all pts and there is no accumulation of energy
material at any pt.
• Following fig represents such a process in
which a unit mass of fluid is entering at
position 1 and exiting at position 2 as shown in
fig.

36. • Consider the overall changes which occur in
this unit mass of fluid as it flows through
apparatus from position 1 to position 2.
• Change in kinetic energy as unit mass of fluid
passes through 1→2
• ∆Ek = ½ U2
2-1/2U2
1
• = ½ (∆u2)
• =∆u2/2
• ∆Ek =∆u2/2

37. • Similarly
• ∆Ep = gZ1-gZ2
• = g (Z1-Z2)
• ∆Ep = g∆Z
• The first law of thermodynamics is given as
• ∆U+∆Ek+∆Ep =Q+W
• ∆u+∆U2/2+g∆Z=Q+W

38. Steady flow Energy Equation
• But
• W=total work=work done at entering + work
done at exit + shaft work
• Shaft work = Ws
• Work done when fluid enters on the
system=W1=P1v1
• Work done by the system when fluid exits the
system=-W2=-P2v2

39. • Eq. B becomes as
• ∆U+∆U2/2+g∆Z =Q+P1v1-P2v2+Ws
• =Q+Ws+ (P1v1-P2v2)
• ∆U+∆u2/2+g∆z+∆pv=Q+Ws
• If velocity and height changes are too small then
above example becomes as
• ∆U+∆ (pv) =Q+Ws
• ∆H=∆u+∆pv=Q+Ws
• So
• H=Q+Ws
• Or
• ∆H+∆u2/2gc+g/gc∆z=Q+Ws mathematical form

40. Problems:
• In a steady flow open system a fluid substance flows
at the rate of 4 Kg/s. It enters the system at a pressure
of 600 KN/m2, a velocity of 220 m/s, internal energy
2200 KJ/Kg and specific Volume 0.42 m3/Kg. It
leaves the system at a pressure of 150 KN/in2, a
velocity of 145m/s, internal energy 1650 KJ/kg and
specific volume 1.5 m3/kg.During its passage through
the system , the substance has a loss by heat transfer
of 40 KJ/kg to the surroundings. Determine the
Power of the system stating whether it is from or to
the system.
• Rayner jones page no.44

41. Problem
• In the turbine of a gas turbine unit the gases
flow the turbine at 17Kg/s and the power
developed by the turbine is 14000KW. The
specific Enthalpies of the gases at inlet and
outlet are 1200KJ/Kg and 360 KJ/Kg
respectively, and velocities of the gases at inlet
and outlet are 60 m/s and 150 m/s. Calculate
the rate at which heat is rejected from the
turbine.
• McConkey page no.21

42. Solution
• On Board