M.S.E. – Baripada

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Dept. of Automobile Engineering

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3^rd Semester, Winter - 2021

LAWS OF THERMODYNAMICS

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Prepared by :

Er. Sourin Mohanty

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Contents

1. The Zeroth Law
2. First Law of Thermodynamics
3. Second Law of Thermodynamics
4. Kelvin – Planck Statement
5. Clausius Statement
6. Practical Uses of 2^nd Law
7. Refrigerator Vs Heat Engine
8. Equivalence of Kelvin – Plack & Clausius Statements

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The Zeroth Law

• If objects A and B are each in thermal equilibrium with object C, then A and B are in thermal equilibrium with each other.

• This law is concerned with thermal equilibrium.
• It states

equilibrium

if two with a

bodies third

are separately in thermal body then they must be in

thermal equilibrium with each other.

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Slide courtesy of NASA

1^st law of thermodynamics

• The first law of thermodynamics is an extension of the

law of conservation of energy.

• The change in internal energy of a system is equal to the heat added to the system minus the work done by the system.

ΔU = Q - W

If heat added to a system, there are two things that can be done

• Change the internal energy of the system, or Cause the system to do work.
• Combination of the two.

Slide courtesy of NASA

1^st Law of thermodynamics

1^st Law of thermodynamics

2^nd Law of thermodynamics

• Concept of temperature gradient as a natural phenomenon.
• The 2^nd Law can also be stated that heat flows spontaneously from a hot object to a cold object (spontaneously means without the assistance of external work)

Slide courtesy of NASA

KELVIN – PLANCK STATEMENT

PMM – II

KELVIN – PLANCK STATEMENT

CLAUSIUS STATEMENT

CLAUSIUS STATEMENT

PMM – II

Practical Uses of 2^nd Law

• Automobile engines, refrigerators, and air conditioners all work on the principles laid out by the 2^nd Law of Thermodynamics

REFRIGERATOR Vs HEAT ENGINE

Equivalence of Kelvin – Planck & Clausius Statement

CASE - 1

CASE - 2

THANK YOU