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1. On the completion of this
period, you would be able
to understand
•State, Path and Process of a
thermodynamic system
•Quasi static process
•Thermodynamic cycle
•Thermo dynamic property
•Classification of properties
1
Objectives

2. Recap
In previous period we have studied
about
•Definition of thermodynamics
•Definition of thermodynamic system
•Classification of thermodynamic
system

3. Property of a
thermodynamic system
•A property of a system is an
observable characteristic of the
system
•The quantities which define the state
of the system are called properties
•Its value is independent of the
process
•The property is a point function

3

4. Classification of properties
Thermodynamic properties are
generally divided
into two classes
1.Intensive properties or
Intrinsic properties

2.Extensive properties or
Extrinsic properties

4

5. Classification of properties
(contd.,)
•1.Intensive properties or Intrinsic
properties:
These are independent of mass of the
substance
Ex: Pressure temperature

density specific gravity
specific volume surface tension
thermal conductivity etc

6. 2. Extensive properties or Extrinsic
properties:
These are dependent on mass of the
substance
Ex: mass weight
enthalpy entropy
internal energy etc.
6
Classification of
properties (contd..)

7. •The condition of a system as
specified by properties is called
state of a system
•Two independent properties are
sufficient to represent
the state of a system
•Properties are used as coordinates
to represent state of a system
7
State

8. • The series of states through
which the system passes during
change of state is called Path
8
Path
Fig 1 P - V diagram

9. Thermodynamic process
• A system is said to have undergone a
process when heat and work cross its
boundary
•A system is said to have undergone a
process if
change of state occurs

10. Examples of thermodynamic
processes
•Expansion or compression of a gas
•Expansion of steam through a
nozzle
• Conversion of water into steam
10
Thermodynamic process
(contd.,)

11. Quasistatic Process
•The process during which the system
remains almost in a state of
thermodynamic equilibrium from one end
of state to other end of state is called
quasi static process
•A system exists in a state of
thermodynamic equilibrium when no
change in any macroscopic property is
registered if the system isolated from
surroundings
11

12. Quasi static process.
Fig 2

13. Thermodynamic Cycle
•When a system from a given state
undergoes number of different
processes and finally returns to its
initial state, then the system is said to
have under gone a cycle
•Any process whose end states are
identical is called a cycle
• Example: water (steam) that
circulates through a steam power plant
under goes a cycle
13

14. Thermodynamic Cycle
Fig 3
1
2
A
B
P
V
•In the fig 3 the system has
under gone a process from
•state 1 to state 2 along path A
and again from state 2 to state
1 along path B
•system returns to its initial
state, thus completing a cycle

15. Summary
In this period, we have discussed about
1.Thermodynamic property
2.Classification of properties
3.State of thermodynamic system
4.Path and process of thermo dynamic system
5.Quasi static process
6.Thermodynamic cycle
15

16. Quiz
1. Identify the intensive property
a)Pressure
b)Temperature
c)Specific volume
d)All of the above

17. Quiz
3.Identify extensive property
a)Specific gravity
b)Enthalpy
c)Specific enthalpy
d)Specific volume