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# PPT - Second Law Of Thermodynamics Civil Engineering (CE) Notes | EduRev

## Civil Engineering (CE) : PPT - Second Law Of Thermodynamics Civil Engineering (CE) Notes | EduRev

``` Page 1

The Second Law of
Thermodynamics – Introduction
The absence of the process illustrated above indicates
that conservation of energy is not the whole story. If it
were, movies run backwards would look perfectly normal
to us!
Page 2

The Second Law of
Thermodynamics – Introduction
The absence of the process illustrated above indicates
that conservation of energy is not the whole story. If it
were, movies run backwards would look perfectly normal
to us!
The Second Law of
Thermodynamics – Introduction
The second law of thermodynamics is a statement about
which processes occur and which do not. There are many
ways to state the second law; here is one:
Heat can flow spontaneously from a hot object to a cold
object; it will not flow spontaneously from a cold object
to a hot object.
Page 3

The Second Law of
Thermodynamics – Introduction
The absence of the process illustrated above indicates
that conservation of energy is not the whole story. If it
were, movies run backwards would look perfectly normal
to us!
The Second Law of
Thermodynamics – Introduction
The second law of thermodynamics is a statement about
which processes occur and which do not. There are many
ways to state the second law; here is one:
Heat can flow spontaneously from a hot object to a cold
object; it will not flow spontaneously from a cold object
to a hot object.
15-5 Heat Engines
It is easy to produce thermal energy using work, but how
does one produce work using thermal energy?
This is a heat engine;
mechanical energy can
be obtained from thermal
energy only when heat
can flow from a higher
temperature to a lower
temperature.
Page 4

The Second Law of
Thermodynamics – Introduction
The absence of the process illustrated above indicates
that conservation of energy is not the whole story. If it
were, movies run backwards would look perfectly normal
to us!
The Second Law of
Thermodynamics – Introduction
The second law of thermodynamics is a statement about
which processes occur and which do not. There are many
ways to state the second law; here is one:
Heat can flow spontaneously from a hot object to a cold
object; it will not flow spontaneously from a cold object
to a hot object.
15-5 Heat Engines
It is easy to produce thermal energy using work, but how
does one produce work using thermal energy?
This is a heat engine;
mechanical energy can
be obtained from thermal
energy only when heat
can flow from a higher
temperature to a lower
temperature.
Heat Engines
We will discuss only engines that run in a repeating
cycle; the change in internal energy over a cycle is zero,
as the system returns to its initial state.
The high temperature reservoir transfers an amount of
heatQ
H
to the engine, where part of it is transformed
into workW and the rest,Q
L
, is exhausted to the lower
temperature reservoir. Note that all three of these
quantities are positive.
Page 5

The Second Law of
Thermodynamics – Introduction
The absence of the process illustrated above indicates
that conservation of energy is not the whole story. If it
were, movies run backwards would look perfectly normal
to us!
The Second Law of
Thermodynamics – Introduction
The second law of thermodynamics is a statement about
which processes occur and which do not. There are many
ways to state the second law; here is one:
Heat can flow spontaneously from a hot object to a cold
object; it will not flow spontaneously from a cold object
to a hot object.
15-5 Heat Engines
It is easy to produce thermal energy using work, but how
does one produce work using thermal energy?
This is a heat engine;
mechanical energy can
be obtained from thermal
energy only when heat
can flow from a higher
temperature to a lower
temperature.
Heat Engines
We will discuss only engines that run in a repeating
cycle; the change in internal energy over a cycle is zero,
as the system returns to its initial state.
The high temperature reservoir transfers an amount of
heatQ
H
to the engine, where part of it is transformed
into workW and the rest,Q
L
, is exhausted to the lower
temperature reservoir. Note that all three of these
quantities are positive.
Heat Engines
A steam engine is one
type of heat engine.
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## Thermodynamics

56 videos|92 docs|33 tests

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