This lecture is very important to increase to knowledge

2. Thermodynamics can be defined as the science of
energy.
Thermodynamics = Therme + Dynamics
(Heat) (Power)
the branch of physical science that deals with the
relations between heat and other forms of energy
(such as mechanical, electrical, or chemical energy),
and, by extension, of the relationships between all
forms of energy
Thermodynamics

3. Energy Conversion Diagram.

4. Introduction
 Applied thermodynamics
Applied thermodynamics is the science of
relationship between heat, work and properties
of systems.
 Heat Engine
A heat engine is the name given to a system
which by operating in a cyclic manner
produces net work from a supply of heat.

5. Conservation of energy principle

6. Application of thermodynamics
Human Body
Refrigeration and Air conditioners
IC Engines
Gas Turbines
Water Heater
Solar Collectors
Pressure cooker ….

7. Introduction …Contd.
 Heat
Heat is a form of energy which is transferred
from one body to another body at a lower
temperature , by the virtue of temperature
difference between the bodies.
 Work
The product of a force and the distance moved
in the direction of the force.

8. System, Surroundings & Boundary
 System
 A system is defined as a quantity of matter or a region in space chosen for study.
 Surroundings
 The mass or region outside the system is called the surroundings.
 Boundary
 The real or imaginary surface that separates the system from its surroundings is
called the boundary.

9. System, Surroundings & Boundary

10. Closed System/Control Mass
 A closed system consists of a fixed amount of mass, and no
mass can cross its boundary. No mass can enter or leave a
closed system. But energy, in the form of heat or work, can
cross the boundary and the volume of a closed system does
not have to be fixed.
 In some special case, even energy is not allowed to cross
the boundary, that system is called an isolated system.

11. Close system with fixed and moving boundary

12. Isolated System
ISOLATED
System
m = const.
E = const.
Mass NO
Energy NO

13. Open System/Control Volume
 An open system is one that freely allows both energy and matter to be transferred
in an out of a system. For example, boiling water without a lid. Heat escaping into
the air. Steam (which is matter) escaping into the air.
 e.g. Water Heater, Car Radiator, Turbine, Compressor

14. An open system (a control volume) with one inlet and one exit.

15. Properties of a system
 Intensive Properties
• Intensive properties are those that are independent of the mass of a system, such
as temperature, pressure, and density.
 Extensive Properties
• Extensive properties are those whose values depend on the size or extent of the
system. Total mass, total volume, and total momentum are some examples of
extensive properties
 Specific Properties
• Extensive properties per unit mass are called specific properties. Some examples of
specific properties are specific volume (v =V/m) and specific total energy (e =E/m).

16. Criterion to differentiate intensive and
extensive properties.

17. Density & Specific Gravity
 Density is defined as mass per unit volume.
 The reciprocal of density is the specific volume v, which is
defined as volume per unit mass.
 The ratio of the density of a substance to the density of
some standard substance at a specified temperature .

18. State & Equilibrium
 Set of properties to completely describe the condition of the system
is known as its STATE
m = 2 kg
T1 = 25 ºC
V1 = 1 m3
STATE 1
m = 2 kg
T1 = 25 ºC
V1 = 3 m3
STATE 2

19. State & Equilibrium
Thermal Equilibrium :
- NO Temperature Gradient throughout the system.
Mechanical Equilibrium :
- NO Pressure Gradient throughout the system.
Phase Equilibrium :
- System having more than 1 phase.
- Mass of each phase is in equilibrium.
Chemical Equilibrium :
- Chemical composition is constant
- NO reaction occurs.
EQUILIBRIUM : State of Balance

20. Path & Process
State 1 State 2
Pressure
Quasi-Static
Process Path
Volume
NOTE : Process Path is a
CONTINUOUS line only if it is
having Quasi-Static Process.
Non-Quasi-Static Process is
denoted by a DASHED line.
State 1 State 2
Pressure
Volume
Non-Quasi-Static
Process Path

21. Cycle
CYCLE :
A system is said to have undergone a
cycle if it returns to its ORIGINAL
state at the end of the process.
Hence, for a CYCLE, the INITIAL and
the FINAL states are identical.
Property A
State 1
State 2
Property
B

22. The End