This document provides an overview of basic concepts in thermodynamics. It discusses the four laws of thermodynamics, the classification of thermodynamics into classical and statistical approaches, and definitions of key terms like system, surroundings, boundary, state, property, process, cycle, and path. The conversion of energy is governed by the first and second laws of thermodynamics, and thermodynamic equilibrium refers to thermal, mechanical, and chemical equilibrium within a system.

1. BY
K.ANAND BABU
MECHANICAL
ENGINEERING
Basic Concepts of
Thermodynamics

2. Basic Concepts
Thermodynamics:
This subject is about conversion of Energy, and the
laws governing it, In particular conversion of heat into
work and work into heat.
Work
Work Heat
Heat

3. Four laws that will be dealt in
Thermodynamics are,
• Zeroth Law of Thermodynamics
• First Law of Thermodynamics
• Second Law of Thermodynamics
• Third Law of Thermodynamics
The conversion of energy is governed by First and
Second Laws of Thermodynamics.

4. Classification of Thermodynamics
Two views of thermodynamics
Classical Thermodynamics
In this, study is carried out on large assemblage of atoms and it is also
termed as macroscopic approach
Statistical Thermodynamics
In this, study is carried out at the molecular level and it is also termed as
microscopic approach

5. System, Surrounding and Boundary
System :
• All engineering devices/Components are referred as Systems.
• A system is a finite quantity of matter or region upon which our attention is
focused.
Surrounding:
• Things that are external to the system are referred as Surrounding.
Boundary:
• It is an interface between system and surrounding.
• System and surrounding interact through boundary.
• Boundary can be real (or) imaginary.
Boundary can be fixed (or) moving.

6. Interaction Between System and Surrounding
Interaction
between
system and
surrounding
Mass Transfer
Energy Transfer
Heat
Work
Based on the type of interaction, the systems are
classified as
• CLOSED SYSTEM
• OPEN SYSTEM
• ISOLATED SYSTEM

7. Types of System
• CLOSED SYSTEM
No mass transfer occurs but only energy transfer occurs
Eg: A certain amount of gas enclosed in a cylinder piston arrangement.

8. • OPEN SYSTEM
Both mass transfer and energy transfer occurs
eg: A certain amount of gas entering and leaving a cylinder piston
arrangement.
Types of System

9. • ISOLATED SYSTEM
Neither mass transfer nor energy transfer occurs.
eg:If our entire universe is considered as a single system then it is an
isolated system.
Types of System

10. Various Systems-Comparison
Mass Transfer Energy Transfer Type of System
No Yes Closed System
Yes Yes Open System
No No Isolated System

11. Basic Concepts (contd.,)
Control Volume:
If the volume of the system under study remains
constant then it is called CONTROL VOLUME.
Control Surface:
The surface that bounds the control volume is
called CONTROL SURFACE.
Pure Substance:
A substance which has uniform chemical
composition throughout its mass.

12. Thermodynamic Equilibrium
A system is said to be in thermodynamic equilibrium
if it is in the following equilibriums
Thermal Equilibrium
Mechanical Equilibrium
Chemical Equilibrium

13. Thermodynamic Equilibrium
Thermal Equilibrium:
The temperature at all points of the system remains the same
and does not change with time.
Mechanical Equilibrium:
No unbalanced forces acts within the system or between system
and surrounding.
Chemical Equilibrium:
No chemical reaction takes place within the system.

14. Basic Concepts (contd.,)
State:
The condition or characteristics of a system is called
State.
Property:
• The characteristics of a system is defined by property
• There are two different types of properties
• Intensive Properties
• Extensive Properties

15. Intensive Properties:
These properties are independent of mass.
eg: Temperature, Pressure, Density etc.,
Extensive Properties:
These properties are dependent of mass.
eg: Volume, Enthalpy, Entropy etc.,

16. PATH
• It is the succession of intermediate states
passed during a change of state.
(OR)
• It is the loci of intermediate states passed
during a change of state.

17. PROCESS
If the path followed by the system
during change of state is specified or
defined completely, then it is called a
process.
eg: Constant pressure process
Constant temperature process
Constant volume process
Adiabatic process
Polytropic process

18. CYCLE
Series of processes executed by the system in
such a way that the initial and final states of the
system are same.

19. THANK YOU