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CHAPTER 2
FIRST LAW OF THERMODYNAMICS
THERMODYNAMICS - I
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Law of Thermodynamics-An Overview
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First Law of Thermodynamics
James Prescott Joules
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First Law for a Closed System Undergoing a
Cycle / Joule’s Experiment
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First Law for a Closed System Undergoing a
Cycle / Joule’s Experiment
It states that, “Whenever a closed system executes
a cyclic process or cyclic change, the algebraic sum
of work transfer is proportional to the algebraic sum
of heat transfer” i.e. algebraic sum of all energy
transfer across system boundaries is zero.
Mathematically,
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THERMODYNAMICS - I
First Law of Thermodynamics for a closed
system undergoing a change of state
It states that, “Whenever a closed system executes
a cyclic process or cyclic change, the algebraic sum
of work transfer is proportional to the algebraic sum
of heat transfer” i.e. algebraic sum of all energy
transfer across system boundaries is zero.
Mathematically,
1
Q2
= (E2
– E1
) + 1
W2
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THERMODYNAMICS - I
Energy is a Property of the system
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First Law of Thermodynamics for a closed
system undergoing a change of state
Any system which violates the first law of
thermodynamics is called the Perpetual Motion
machine of first kind. i.e.,
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THERMODYNAMICS - I
Application of First law of Thermodynamics for
flow processes
Steady flow process:
•The state of the fluid at each point in the control volume
does not vary with time ie process must be steady flow.
•Heat and work interactions across the boundary of
control volume are at constant rate.
•Fluid is uniform in composition and there is no chemical
reaction within the control volume.
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THERMODYNAMICS - I
Application of First law of Thermodynamics for
flow processes
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Application of First law of Thermodynamics for
flow processes
Steady flow process:
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Application of SFEE
1. Nozzle and Diffuser
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Application of SFEE
1. Throttling Device
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Application of SFEE
3.Turbine and Compressor
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Application of SFEE
4. Heat Exchanger
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Application of SFEE
5. Evaporator
