9M305.1.ppt hgvjmbhfvhvmnbvvghkhgvbkhnhj

concept of refrigeration

1. Objective
On completion of this period, you would be
able to understand

• Definition of Thermodynamics
• Thermodynamic System
• Surroundings
• Boundary
• Classification of Thermodynamic
System

2. 2
Thermodynamics
•Thermodynamics is the
science which deals with
the relations between
heat, work and those
properties of substances
which are connected with
heat and work.

3. 3
•The field of engineering which deals
with the
applications of thermodynamics and
its laws is called
thermal engineering
•It forms basis for study of
–Power plants,
–Refrigeration and Air conditioning
systems.
Thermal Engineering

4. 4
Applications of Thermodynamics
Fig.1 Thermal power plant
In thermal power plants energy from coal or oil is converted
into electrical energy

5. 5
•In automobile engines heat
energy is converted into work
energy which drives the vehicles
Fig.2 Automobiles
Applications of Thermodynamics

6. 6
Fig.3 Jet and Rocket engines
Rocket and Jet engines .
Applications of Thermodynamics

7. 7
Refrigeration and Air conditioning is used to maintain
required temperature.
Fig.4 Air conditioner and Refrigerator
Applications of Thermodynamics

8. 8
Thermodynamic System
Thermodynamic system or
simply system is a region
in space containing certain
quantity of matter upon which
attention is focused for study
Fig 5 Thermodynamic System
Boundary
System
Surroundings

9. 9
• System may be quantity of steam,
mixture of vapour and gas or an I.C
engine cylinder with its contents
• System is enclosed by a
boundary
• Boundary separates the system
from the surroundings
• The boundary may be real or
imaginary, fixed or movable
• Any thing outside the boundary
is called it surroundings
Thermodynamic
System (contd.,)

10. 10
1) Closed system
2) Open system
3) Isolated system
Classification of
Thermodynamic System

11. 11
Closed System

The system is called closed system
if only the heat and
work energies are transferred
across the system boundary
• For closed system the mass
content of the
system remains same

12. 12
composition of the mass in
closed system can
• However the physical nature
and chemical
change
Ex: Gas in the cylinder
Closed System
(contd.,)

13. 9M 305.1 13


System (gas)
boundary
surroundings
(Heat)
Mechanical work
Fig 6
Closed System (contd.,)

14. 14
Open System
• The system is called open
system if both mass and energy
transfer across the system
boundary
• In open system matter
crosses the boundary of the
system

• Heat and work may also
cross the boundary

Ex: Motor driven compressor

15. 15
Open System (contd.,)
System (Air
Compressor)
Motor
Heat loss
boundary
Work in
Air out
Air in
Fig.7

16. 16
Isolated System
•If the boundary of the system
does not allow the matter of the
energy to flow into or out of the
system, then it is
known as isolated system
•It is completely unaffected by
the surrounding
•It is of fixed mass and fixed
energy system
•Ex: Thermodynamic universe

17. 17
Summary
We have discussed about
• Definition of
Thermodynamics.
• Thermodynamic System.
• Surroundings.
• Boundary.
• Classification of
Thermodynamic System

18. 9M 305.1 18
Quiz
1. Thermodynamic system may be defined as matter upon
which attention is focused for study if
a)It is bounded by real surfaces
b)It is bounded by imaginary surface
c)It is bounded by either real surface or imaginary surface
irrespective of shape or volume
d) None

19. 9M 305.1 19
Quiz
2. When neither mass nor energy is allowed to cross the
boundary of a system, it is called
a)Closed system.
b)Open system
c)Isolated system.
d)None of the above.

20. 9M 305.1 20
Quiz
3. A centrifugal fan is an example for
a)Closed system
b)Open system
c)Isolated system
d)None of the above