ReversibilityReversible ProcessPlotting ReversibilityReversible CycleCarnot EngineExpansionCompressionCarnot EfficiencyUnderwaterReversibilityReversibilityReversible ProcessReversible ProcessQuasi-static processes Quasi-static processes meant that each step was meant that each step was slo enough to maintain slo enough to maintain equilibrium.equilibrium.If the process is reversed the If the process is reversed the work and heat also just work and heat also just reverse sign.reverse sign.Heat lost to friction is not Heat lost to friction is not reversible.reversible.Reversible process is infinitely slow; system stays at equilibrium. Irreversible process has heat loss to friction; system has net loss of useful energy.Plotting ReversibilityPlotting ReversibilityThe PV diagram can plot a quasi-static, reversible The PV diagram can plot a quasi-static, reversible process.process.Irreversible processes cannot be plotted.Irreversible processes cannot be plotted.PV111,, TVP222,, TVPPV111,, TVP222,, TVPReversible CycleReversible CycleA series of reversible A series of reversible processes can be plotted on processes can be plotted on a PV diagram.a PV diagram.A reversible cycle is a set of A reversible cycle is a set of reversible processes that reversible processes that return to the initial state.return to the initial state.PV111,, TVP333,, TVP222,, TVPCarnot EngineCarnot EngineAn ideal Carnot engine An ideal Carnot engine consists of four processes.consists of four processes.1) expand gas isothermally.1) expand gas isothermally.2) expand gas adiabatically.2) expand gas adiabatically.3) compress gas isothermally.3) compress gas isothermally.4) compress gas adiabatically.4) compress gas adiabatically.ExpansionExpansionDuring the isothermal During the isothermal expansion there is work expansion there is work done with heat in.done with heat in.There is no heat flow during There is no heat flow during the adiabatic expansion, but the adiabatic expansion, but work is done.work is done.PV111,, TVP222,, TVP1212lnVVnRTQWHH333,, TVPVPVPCCCCVPVP/33/22CompressionCompressionDuring the isothermal During the isothermal compression work is compression work is returned with heat out.returned with heat out.There is no heat flow during There is no heat flow during the adiabatic compression, the adiabatic compression, but work is returned.but work is returned.PV111,, TVP444,, TVP4334lnVVnRTQWLL333,, TVPVPVPCCCCVPVP/11/44Carnot EfficiencyCarnot EfficiencyThe heat and temperatures are related in a Carnot The heat and temperatures are related in a Carnot engine.engine.•||QQLL| / || / |QQHH| = | = TTLL / / TTHHThis is the ideal engine efficiency.This is the ideal engine efficiency.HLidealTTe 1UnderwaterUnderwaterA nuclear plant produces A nuclear plant produces 540 MW of power while the 540 MW of power while the fuel releases 1590 MW. fuel releases 1590 MW. Steam enters the turbine at Steam enters the turbine at 556 K and is discharged at 556 K and is discharged at 313 K.313 K.What is the ideal and actual What is the ideal and actual efficiency?efficiency?The ideal efficiency assumes The ideal efficiency assumes a Carnot engine.a Carnot engine.The actual efficiency is found The actual efficiency is found from the power usage. from the power usage. next%7.431 HLidealTTe%34s-MW 1590s-MW
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