Basics of Thermodynamics

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INTRODUCTION TO MECHANICAL
ENGINEERING

2. • Thermodynamics
• Heat Transfer and its modes
• Refrigeration and Air Conditioning
• IC Engines
• Renewable and Non-Renewable energy
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3. Thermodynamics
• Thermodynamics is a branch of science and
engineering that deals with interaction of energy
mainly in the forms of heat and work.
• It is concerned with thermal behaviour of matter
and its interaction with other physical and chemical
behaviour of matter.

4. • Pressure is defined as force per unit area.
Pressure (symbol: p or P) is the force applied
perpendicular to the surface of an object per
unit area over which that force is distributed.
(1 Pa=1N/m^2)
• Volume is the quantity of three-dimensional
space enclosed by a closed surface, for example,
the space that a substance (solid, liquid, gas,
or plasma) or shape occupies or contains

5. • System : system defined as definite area or space
where thermodynamics process taking place. The
surface separating the system and the
surroundings is known as the control system or
system boundary.
The control surface may be movable or fixed.
Everything beyond the system is surroundings.
• Closed system
• Open system
• Isolated system

6. • Closed system(Mass fixed , heat and work can cross
the boundary)
• For example, the contents of a pressure cooker on a stove with its lid
tightly closed and the whistle in position, is a closed system as no
mass can enter or leave the pressure cooker, but heat can be
transferred to it.
• Open system(Mass and heat can flow)
• Boiling soup in an open saucepan on a stove, the energy and matter
are being transferred to the surroundings through steam
• Isolated system(Neither heat nor mass can flow)
• A perfectly insulated, rigid and closed vessel is an example of an
isolated system as neither mass nor energy can enter or leave the
system. A thermoflask is the best example of an isolated system
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8. • State At any instant of time the condition of a
system is called state.
State is defined by the properties of the system such as
pressure, volume, temperature etc.
Value of such properties depend upon state not on the
history of the system.
In thermodynamics, a thermodynamic state of a system is its
condition at a specific time; that is, fully identified by values
of a suitable set of parameters known as state variables,
state parameters or thermodynamic variables.

9. • Extensive properties- Depends upon size or extent
of the system. property of system whose value for
the entire system is equal to the value of individual
part.(Volume, energy)depends upon mass of
system
• Intensive properties- Independent of size or extent
of the system.(Pressure , temperature). Does not
depend upon mass of system.

10. • Process When system changes its state from one
equilibrium state to another equilibrium state then
path of successive state through which the system
has passed is known as thermodynamic process.
When a system undergo sequence of processes and
return to its initial state ,it is said to have undergone
a cycle