香港理工大学：《火灾科学与城市安全》课程教学课件（讲稿）Introduction to Combustion（Combustion Fundamentals）

THEHONGKONGPOLYTECHNICUNIVERSITY香港理工大BSE533:FireDynamicsLecture 4:Introduction to CombustionXinyan Huang,PhD, CEngAssistantProfessorDept.ofBuildingEnvironmentandEnergyEngineeringResearchCentreforFireSafetyEngineering,PolyUxy.huang@polyu.edu.hkPolyUBEEE1DrXinyanHuang

PolyU BEEE 1 Dr Xinyan Huang BSE533: Fire Dynamics Lecture 4: Introduction to Combustion Xinyan Huang, PhD, CEng Assistant Professor Dept. of Building Environment and Energy Engineering Research Centre for Fire Safety Engineering, PolyU xy.huang@polyu.edu.hk

THEHONGKONGPOLYTECHNICUNIVERSITY香港理工大1.IdealGasLaw2.DiffusionFlame3.PremixedFlame4.FlameChemistry2PolyUBEEEDrXinyanHuang

PolyU BEEE 2 Dr Xinyan Huang 1. Ideal Gas Law 2. Diffusion Flame 3. Premixed Flame 4. Flame Chemistry

IdealGasLawWhy we need to learn thepropertiesofGASbeforelearningcombustion?All combustion reactions occursCH4+20zCO2+2H2Oingaseousphase,liketheflamesupportedbynatural gasThis law also works for solid(wood)andliquid(gasoline)fuels3PolyUBEEEDrXinyan Huang3

PolyU BEEE 3 Dr Xinyan Huang Ideal Gas Law 3 • All combustion reactions occurs in gaseous phase, like the flame supported by natural gas. • This law also works for solid (wood) and liquid (gasoline ) fuels. Why we need to learn the properties of GAS before learning combustion?

Ideal GasLawGas exists everywhere,on earth,in the universe.andeveninsideyourbody.PolyUBEEEDrXinyan Huang4

PolyU BEEE 4 Dr Xinyan Huang Ideal Gas Law 4 Gas exists everywhere, on earth, in the universe, and even inside your body

Ideal GasLawBasedontheobservationinnormallife,wemayknow somebasiccharacteristics of gas:Asthe gas temperaturechange,thegas volume will change.Asthegasvolumechanges,thegaspressure will also changeThere are relationships.000betweenthe gaspressurevolume andtemperaturePolyU BEEE5DrXinyanHuang5

PolyU BEEE 5 Dr Xinyan Huang Ideal Gas Law 5 Based on the observation in normal life, we may know some basic characteristics of gas: • As the gas temperature change, the gas volume will change. • As the gas volume changes, the gas pressure will also change. There are relationships between the gas pressure, volume and temperature

Ideal GasLawI:PistonAirH:MercuryU-tube (mercurymanometer)Whenpushingthepiston,theairinsideredboxwill becompressedH,=compressedairvolume(V),andHm=compressedairpressure(P).Inthisway,Boylefoundthat:Robert Boyle,anIrish born in1627,isthefirstonetoexploreP × V=Constantthe natureof gas byexperiments.6PolyUBEEEDrXinyanHuang6

PolyU BEEE 6 Dr Xinyan Huang Ideal Gas Law 6 Robert Boyle, an Irish born in 1627, is the first one to explore the nature of gas by experiments. Piston U-tube (mercury manometer) Mercury Air Ha Hm • When pushing the piston, the air inside red box will be compressed. • Ha = compressed air volume (V), and Hm = compressed air pressure (P). • In this way, Boyle found that: P × V = Constant

Ideal GasLawhttps://en.wikipedia.org/wiki/Boyle%27slawRobert Boyle,anIrish born inNCSSM1627,isthefirstonetoexploreOnlinethenatureofgasbyexperiments.7PolyUBEEEDrXinyan Huang

PolyU BEEE 7 Dr Xinyan Huang Ideal Gas Law 7 Robert Boyle, an Irish born in 1627, is the first one to explore the nature of gas by experiments. https://en.wikipedia.org/wiki/Boyle%27s_law

IdealGasLawWhatCharlesfoundisthat at afixedpressure,the divisionofgasvolume(V)bytemperature (T)isalsoconstant.MassABRRFrozen:Mass&PressCVol651.50250HARIRSPress.Temp.JacquesCharles,aFrenchbornin1746vwhoisfamousforhisrecognitioninthe=Constantrelationshipbetweengasvolume (V)andTtemperature (T).8PolyUBEEEDrXinyanHuang8

PolyU BEEE 8 Dr Xinyan Huang Ideal Gas Law 8 Jacques Charles, a French born in 1746, who is famous for his recognition in the relationship between gas volume (V) and temperature (T). • What Charles found is that at a fixed pressure, the division of gas volume (V) by temperature (T) is also constant. V = Constant T

Ideal GasLawBoyle'law:P:ConstantTP X V=ConstantCharles'law:v= ConstantTLussac'law:Gay Lussac,a Frenchbornin1778,famousforhisfindingPthat wateris made oftwoparts=ConstantPrestipeTof hydrogen and one part ofoxygen.9PolyUBEEEDrXinyan Husng

PolyU BEEE 9 Dr Xinyan Huang Ideal Gas Law 9 Gay Lussac, a French born in 1778, famous for his finding that water is made of two parts of hydrogen and one part of oxygen. P × V T × NA = Constant P × V = Constant Boyle’ law: V = Constant T Charles’ law: P × V T × NA = Constant Lussac’ law:

IdealGasLawAfixedvolumeofgasthatV= Constantcontains Naparticlesis calledNA1 mol of gas.AmedeoAvogadro,anItalianbornin1776famousforhis findingofAvogadroconstant Na=6.02× 1023.10PolyUBEEEDrXinyanHuaog

PolyU BEEE 10 Dr Xinyan Huang Ideal Gas Law 10 Amedeo Avogadro, an Italian born in 1776, famous for his finding of Avogadro constant NA = 6.02 × 1023 . V = Constant NA • A fixed volume of gas that contains NA particles is called • 1 mol of gas