The Thermodynamic Analysis of Manufacturing ProcessesTimothy G. GutowskiOverview1. Review of Basics2. Intro to Exergy (Available Energy)3. Analysis of Materials Transformation Processes4. Results for Manufacturing ProcessesReferences• Thermodynamics Revisited; de SwaanArons et al (handout)• Thermodynamics Analysis of Mfg Processes; Gutowski et al (on webpage)• Gyftopoulos and Beretta, Dover 20051stLaw• U = internal energy of molecules and atoms• E = U + K.E. + P.E. = U + ½mv² + mgz• “isolated” systems ∆E=0, or ∆U=0 (v=const, z=const)• “closed” system ∆U = Qin– Wout• “open system” can exchange energy and massThe 1st LawoutinoutinWQdUWQUδδ−=−=∆ ∫∫=− 0dWdQHeat EngineinoutininoutQQQQW−==ηTHTLQinQoutoutinoutQQW −=CarnotinoutinoutQQQW−==η 1HLTT−=η 1HLinoutTTQQ=),(LHTTfη=“Available Energy”• Work and Heat are no longer equivalent• Exergy, “B” is the available energy w.r.t. a reference environment, T0, and P0…• B(work) = W; B (heat) = Q(1-T0/T))1(maxHLinoutTTQW −=2ndlaw efficiency)1(HLinoutinputsoutputIITTQWBB−==ηProperties or State Variables• T = temperature• P = pressure• V = volume• U = internal energy• E = energy• B = exergy• H = enthalpy (H = U + PV)• S = entropyintensive variablesextensiveandintensivevariablesState Variables∫= 0dU0=∫TdQ∫=+ 0)( PVUd1212φφφ−=∫dEnthalpy H=U+PVHere the Work done is W = P(V2– V1)The First Law can be written as Q = (U+PV)2– (U + PV)1The quantity in parenthesis is Enthalpy H = U + PVThe First Law can be written asQin= ∆HConstant Pressure Equilibrium ProcessEnergy, E and Exergy, BB1-B2 = E1-E2reversible processB1-B2> E1-E2irreversible processE1, B1E2, B2Ref: Gyftopoulos and BerettaProperties for two different statesof the system shown by the boxes.This change may come about due to spontaneous changes or due to heator work interaction, or mass transfer.Entropy• They show CR= TR= T0• Entropy is a Property• Entropy is a measure of something lost( )[ ])(1121212BBEECSSR−−−+=Ref: Gyftopoulos and BerettaExample, Heat InteractionE2= E1+QB2= B1+ Q(1-T0/T)∆∆∆∆S = (1/T0)(Q – Q + Q(T0/T)) = Q/T∆∆∆∆S = Q/TQ, TT0Example, Work InteractionE2= E1 +WB2= B1+ W∆∆∆∆S = (W - W) = 0WOpen System with H, SConsider the Work to bring the system from the reference environment at standard conditions, To, poto the state at T, ppo, Top, TWQ, ToH, SH, S0 =+−−inoutoutinWQHH&&&&0=+−−generatedooutoutinSTQSS&&&&generatedooSTSTH&&&&+∆−∆=W From EQ 1 & 2, de Swaan AronsSteady State Work to bring system from Po, Toto P, TMinimum Work = Exergy)()( ,,,,minooooTpTpoTpTporevSSTHHSTHmWW−−−=∆−∆==&&oooSTHSTHB )()(−−−=outinrevBBmWW −==&&minExergySystem StateReference StateMaximum work obtainablebetween System and ReferenceStates; or minimum work neededto raise System from the referencestate to the System StateExergySystem StateReference StateMaximum work obtainablebetween System and ReferenceStates.Definition of Exergy “B”“Exergy is the amount of work obtainable when some matter is brought to a state of thermodynamic equilibrium with the common components of the natural surroundings by means of reversible processes, involving interaction only with the above mentioned components of nature” [Szargut et al 1988].Manufacturing Systemsas open thermodynamicsystemsBalances for Mfg ProcessMFiioutiMFiiiniMFMNMNdtdm∑∑==−=1,1,)()(&&resMFprodMFmatMFMFECMFMFMFECMFiMFHHHWQQdtdE&&&&&&−−++−∑=←→←0MFirrresMFprodMFmatMFMFiMFECMFiMFSSSSTQTQdtdS,00&&&&&&+−−+−∑=→←MassEnergyEntropyWork Rate for Mfg Process in Steady StateMFirrMFECMFiimatMFresMFprodMFmatMFresMFprodMFMFECMFSTQTTSSSTHHHW,00001))(())((&&&&&&&&&+−−−+−−+=←>←∑Exergy and WorkoooSTHSTHB )()(−−−=MFirrMFECMFiimatMFresMFprodMFMFECMFSTQTTBBBW,0001))((&&&&&&+−−−+=←>←∑Branham et al IEEE ISEE 2008Examples: plastic work, melting, vaporizing etc.Mfg Process Use of Electricity1. Machining 2. Grinding3. Casting4. Injection Molding5. Abrasive Waterjet6. EDM7. Laser DMD8. CVD9. Sputtering10. Thermal OxidationEnergy Requirements at the Machine ToolJog (x/y/z) (6.6%)Machining (65.8%)Computer and Fans (5.9%)LoadConstant (run time) (20.2%)Variable (65.8%)Tool Change (3.3%)Spindle (9.9%)Constant (startup) (13.2%)Carousel (0.4%)Unloaded Motors (2.0%)Spindle Key (2.0%)Coolant Pump (2.0%)Servos (1.3%)Jog (x/y/z) (6.6%)Machining (65.8%)Computer and Fans (5.9%)LoadConstant (run time) (20.2%)Variable (65.8%)Tool Change (3.3%)Spindle (9.9%)Constant (startup) (13.2%)Carousel (0.4%)Unloaded Motors (2.0%)Spindle Key (2.0%)Coolant Pump (2.0%)Servos (1.3%)Production Machining Center Automated Milling MachineFrom Toyota 1999, and Kordonowy 2002.Electric Energy Intensity for Manufacturing ProcessesprocessedvoVkPP&+=Power (kW)Process Rate (cm3/sec)physicsauxiliary equipment & infrastructureProcess Rate (cm3/sec)Specific Energy (MJ/cm3)VEkVPVPvo=+=&&All-electric vs. hybrid0204060801001200 1 2 3 4 5 6 7 8 9 10 11 12 13 14Time (seconds)Power Required (kW)MM 550 Hybrid NT 440 All-ElectricPlasticizeInject highClamp open-closeInject lowton CoolTon BuildupThe hydraulic machine would be even higher than the hybrid curveSource: [Thiriez]All-electric vs. hybrid0204060801001200 1 2 3 4 5 6 7 8 9 10 11 12 13 14Time (seconds)Power Required (kW)MM 550 Hybrid NT 440 All-ElectricPlasticizeInject highClamp open-closeInject lowton CoolTon BuildupThe hydraulic plot would be even higher than the hybrid curveSource: [Thiriez]Injection Molding Machines0123456780 50 100 150 200Throughput (kg/hr)SEC (MJ/kg) HP 25HP 50HP 60HP 75HP 100Low Enthalpy - Raise Resin to Inj. Temp - PVCHigh Enthalpy - Raise Resin to Inj. Temp - HDPEVariable Pump Hydraulic Injection Molding Machines.Does not account for the electric grid. Source: [Thiriez ‘06]mEkmPmPmo=+=&&Thermal Oxidation, SiO2Ref: Murphy et ales&t 2003Power RequirementsRef: Murphy et ales&t 2003Injection Molding10.76 - 71.40 3.76 - 50.45of polymer processed 1.75E+03 - 3.41E+03 [Thiriez 2006]Machining2.80 - 194.80 0.35 - 20.00of material removed3.50E+03 - 1.87E+05[Dahmus 2004], [Morrow, Qi & Skerlos 2004] & [Time Estimation Booklet 1996] Finish Machiningof material removed[Morrow, Qi & Skerlos 2004] & [Time Estimation Booklet 1996] CVD14.78 - 25.00 6.54E-05 - 3.24E-03of material deposited on wafer area4.63E+06 - 2.44E+08[Murphy et al.
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