Chap. 1 SummaryEnergyTransferEnergyRelationshipstoTransformationsmatterpropertiesThermodynamicsApplicationareasZerothLawThe FirstLawCarnot PrinciplesTheSecondLawAScienceofEnergyTheIncreaseofetcEntropyPrincipleSystemClosed systemOpensystemThermodynamic SystemBoundary/SurroundingAdiabaticsystemIsolatedsystemAsetofpropertiesthatcompletelydescribestheconditionofthesystemStateEquilibrium:: Temperature(T), mechanical (P),phase, chemical State postulate: The state of a simple compressible system is completelyspecified bytwoindependentintensiveproperties.E.g.T(temperature)&v(specificvolume).orP&T (onephase)Isothermal,Isobaric,Path, CycleState 1 to State 2Isometric.IsoentropicQuasi-equilibrium:aprocessinwhichsystemremainsinfinitesimallyclosetoan equilibriumProcessstateaf alltimecReversible processSteadyflowprocessIreversibleprocessExtensivepropertiesV,E,H,SIntensive properties T.P,pPropertiesK273.15Triplepoint=0.01C=273.16K1Pascal=1N/m^2Pgage=Pabs - PatmPvac=Patm - Pabs
Chap. 1 Summary 1 Thermodynamics Energy Application areas A Science of Energy Thermodynamic System Zeroth Law The First Law The Second Law The Increase of Entropy Principle Carnot Principles etc Energy Transformations Relationships to matter properties Closed system Open system Isolated system Adiabatic system Intensive properties T, P, ρ Extensive properties V, E, H,S State State postulate: The state of a simple compressible system is completely specified by two independent, intensive properties. E.g. T(temperature)& ν (specific volume), or P&T (one phase) Equilibrium:: Temperature(T), mechanical (P), phase, chemical Path, Cycle Process State 1 to State 2 Steady flow process T K ℃ 273.15 Triple point=0.01℃=273.16K 1Pascal=1N/m^2 Pgage=Pabs - Patm Pvac=Patm - Pabs Transfer A set of properties that completely describes the condition of the system Properties Quasi-equilibrium: a process in which system remains infinitesimally close to an equilibrium state at all times. Isothermal, Isobaric, Isometric, Isoentropic Reversible process Irreversible process P System Boundary/Surrounding
Chap.2 SummaryTotal Energy, EIntermal Energy,UPotentialEnergy,PEKinetic Energy. KEEnergyForms of EnergyE=U+KE+PE=U+mV2/2+mgzMechanical energy,Nuclearenergy,Chemical Energy,SensibleenergyLatentenergy.Thermalenergy.Heat,Work,FlowworkConvectionTemperature diffBy Heat, QRadiationConductionEnergy Transfer, EForce*distanceBy Work, WForms ofwork:mechanical.shaft,spring,electrical,etcBy Mass, m=o,foraclosedsystemclosed systemQ=△U+ WEin-Eout=AEsystem1stLawofThermodynamicsEnergybalance:Ein-Eout=(Qin-Qout)+(Win-Wout)+(Emass,in-Emass,out)=EsystemEnergyChangeEffciency=desiredoutput/requiredinputEnergy Conversion EfficiencyCombustion efficiency.Overall efficiency,efficiency of generator, motor, pump, turbine, etc.福Energyand Environment
E=U+KE+PE=U+mV2 /2+mgz Chap.2 Summary 2 Forms of Energy Energy Transfer, E Total Energy, E Kinetic Energy, KE Potential Energy, PE Conduction Convection Radiation Effciency =desired output/ required input Ein-Eout= ∆Esystem Internal Energy,U 1st Law of Thermodynamics Energy balance: Ein-Eout=(Qin-Qout)+(Win-Wout)+(Emass,in-Emass,out)= ∆Esystem Energy Conversion Efficiency Energy and Environment Mechanical energy, Nuclear energy, Chemical Energy, Sensible energy, Latent energy, Thermal energy, Heat, Work, Flow work Energy By Heat , Q Temperature diff Forms of work: mechanical, shaft, spring,electrical, etc By Work, W Force*distance By Mass, m =0, for a closed system closed system Q=∆U+ W Energy Change: Combustion efficiency, Overall efficiency, efficiency of generator, motor, pump, turbine, etc
Chapter2.Energy,EnergyTransferandGeneral EnergyAnalysis
Chapter 2. Energy, Energy Transfer and General Energy Analysis 3
2-1. IntroductionQuestion:ArefrigeratorinaroomRoom:closedandwell-insulated,no heat exchangewith outsideRoomRefrigerator:dooropen,electricityconnected.Tairintheroom:Increase?Decrease?Constant?A,:decrease:refrigeratorwill cooltheairdown国Az:increase:motor of refrigeratordissipateswasteheattowarm air upRight: increasetakethe ROOM+Refrigrator asa system, walls as boundaryMASS?NO!Aclosed system.Heat?NO!AnadiabaticsystemHave energy interactionby electricityNothing is storing the energySo: Electrical energy will transform to thermal energy. Tair will increaseaccordingtotheconversationofenergyprinciple
2-1. Introduction • Question: A refrigerator in a room. – Room: closed and well-insulated, no heat exchange with outside. – Refrigerator: door open, electricity connected. – Tair in the room: Increase? Decrease? Constant? • A1 : decrease: refrigerator will cool the air down • A2 : increase: motor of refrigerator dissipates waste heat to warm air up • Right: increase • take the ROOM+Refrigrator as a system, walls as boundary – MASS? NO! A closed system. – Heat? NO! An adiabatic system 4 – Have energy interaction by electricity. – Nothing is storing the energy – So: Electrical energy will transform to thermal energy. Tair will increase according to the conversation of energy principle
2-2, Forms of energyTotal energy/总能 (E, KJ):the sum of numerous forms of energy,e.g.:thermalmechanical,kinetic,potential,electric,magnetic,chemical,nuclear.e=E/m (kJ/kg)total energyperunitmassE Energy flow rate, kJ/s E= meThermodynamicsprovidesnoinformationabouttheabsolute valueofthetotalenergy. It deals only with the change of the total energy.Microscopicform: related tothe molecularstructureofa system,isdegreeofthe molecular activity,and independentof outsiderefInternal energy/热力学能 (U):the sumofallthemicroscopicformsofenergy- Sensible energy: internal energy associated with the kinetic energies of themoleculesLatent energy: internal energy associated with the phase of a systemMacroscopicform:systempossessesasawholewithoutsideref.kineticenergy/动能(KE):KE=(m*V2)/2V,asresultsofitsmotionrelativetosomereferenceframe.potential energy/势能 (PE):PE=(mgz)z,asa result of its elevation ina gravitationalfield.4
2-2, Forms of energy • Total energy/总能 (E, KJ): the sum of numerous forms of energy, e.g.: thermal, mechanical, kinetic, potential, electric, magnetic, chemical, nuclear. – e=E/m (kJ/kg) total energy per unit mass – Thermodynamics provides no information about the absolute value of the total energy. It deals only with the change of the total energy. – Microscopic form: related to the molecular structure of a system, is degree of the molecular activity, and independent of outside ref. • Internal energy/热力学能 (U): the sum of all the microscopic forms of energy. – Sensible energy: internal energy associated with the kinetic energies of the molecules – Latent energy: internal energy associated with the phase of a system – Macroscopic form: system possesses as a whole with outside ref. • kinetic energy/动能(KE): KE=(m*V2 )/2 V, as results of its motion relative to some reference frame. • potential energy/势能 (PE): PE=(mgz) z, as a result of its elevation in a gravitational field. 5 Energy flow rate, kJ/s