2nd law of Thermodynamics Carnot Cycle Lecture 30 2nd Law of Thermodynamics Thermodynamic Cycles System returns to initial state Work in cycles area enclosed in the cycle Clockwise more positive ID: 546520
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Slide1
Thermodynamic cycles2nd law of ThermodynamicsCarnot Cycle
Lecture 30: 2nd Law of ThermodynamicsSlide2
Thermodynamic Cycles
System returns to initial state
Slide3
Work in cycles
= area enclosed in the cycle
Clockwise: more positive
than negative
Counter-clockwise: more negative
than positive
Slide4
Heat engineSlide5
EfficiencySlide6
2
nd
Law of Thermodynamics
Clausius:Heat flows naturally from a hot object to a cold object; heat will not flow spontaneously from a cold object to a hot object.Kelvin-Planck:No device is possible whose sole effect is to transform a given amount of heat completely into work.impossible to construct perpetual motion machineof 2nd kindSlide7Slide8
Carnot Cycle
1-2 isothermal expansion
2-3 adiabatic expansion
3-4 isothermal compression4-1 adiabatic compressionSlide9
Carnot Cycle
1-2 isothermal expansion
2-3 adiabatic expansion
3-4 isothermal
compression
4-1
adiabatic compressionSlide10
Efficiency of Carnot Cycle
1-2 isothermal expansion
3-4 isothermal
compression4-1 adiabatic compression2-3 adiabatic expansionSlide11
Carnot Cycle has maximum efficiency
Heat transfer during isothermal process reversible
No heat transfer during process that involves temperature change
Carnot cycle is reversibleIf more efficient engine existed:Couple hypothetical engine with reverse Carnot engineTransforms amount of heat completely into workViolates 2nd Law More efficient engine can not exist
Maximum efficiency of any cycle
operating between
and