7/29/2019 Chpt05 Mod03 Second Law-3(24)
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
THE SECOND LAW OF
TMERMODYNAMICS-3The Equivalence of the Clausius
and Kelvin-Planck Statements ofthe Second Law
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Clausius statement...
7/29/2019 Chpt05 Mod03 Second Law-3(24)
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Clausius statement
It is impossible for anysystem to operate in such a
way that the sole result
would be an energy transfer
by heat from a cooler to a
hotter body.
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Clausius Statement - foundations
Heat will generally flow froma hot region to a cold region,
i.e., in the direction ofdecreasing temperature.
Recall the development of theZeroth Law.
7/29/2019 Chpt05 Mod03 Second Law-3(24)
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Clausius Statement - foundations
If we put a cyclic heatpump between two thermal
reservoirs, then we can getheat to flow toward the
higher temperature.
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Wcycle
High Temperature reservoir
Low Temperature Reservoir
Q1
Q2
Schematic of heat pump/refrigeration cycle
to raise heat to the high temperature reservoir.
cyclecyclecycle
Cycle Cycle
WQQ
QW
,2,1
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Kelvin-Planck statement...
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Kelvin-Planck Statement
It is impossible for any system to
operate in a thermodynamic cycle
and deliver a net amount of workto its surroundings while
receiving energy by heat transferfrom a single thermal reservoir.
7/29/2019 Chpt05 Mod03 Second Law-3(24)
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Kelvin-Planck statement - foundations
Mass
Pulley
Thermal ReservoirQ1Q2
System
cycleW
cycle cycle
WQ But.these types of systemsare never practically possible.
7/29/2019 Chpt05 Mod03 Second Law-3(24)
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Equivalence...The internal self consistency of the
two statements of the Second Law
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
The two statements of the
Second Law are internallyconsistent, or equivalent.
Assume a violation of one
form and prove the
violation of the other.
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Heat flow from a low toa higher temperature: A
violation of the Clausius
Statement
Cyclic heat engine, E, is
added to produce work.
TH
TC
Q
TH
TC
Q E
cycleW
Q
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Cyclic heat engine, E, violates the Kelvin-Planck form
of the Second Law.
The net effect is
the extraction
of heat from the
reservoir at
THand theperformance of an
equal amount of
work, Wcycle.
cycleW
E
TH
TC
cycleWQ
Q
Q
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Assume that a cyclic engine exists that withdraws heat
from a single reservoir and does and equivalent amountof work and thus violates the Kelvin-Planck form of the
Second Law.
Q
QWcycle
TH
E
CycleCycleCycle
Cycle Cycle
WQQ
WQ
,2,1
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
cycleWQ cycleHC WQ
TC
cycleW
TH
E
HCQ
Cyclic heat engine, E, plus the refrigerator violates the
Clausius form of the Second Law. The net effective is
the transfer of heat QC-Hfrom a low to high
temperature without net work being done.
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Chapter 5 Module3 Slide #
The Second Law of Thermodynamics -The Equivalence of theClausius and Kelvin-Planck Statements of the Second Law
Instructors Visual Aids
Heat, Work and Energy. A First Course in Thermodynamics 2001, F. A. Kulacki
Key concepts and terms
The Second Law - Clausius Statement
The Second Law - Kelvin-Planck
Statement
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