DepartmentofTHEHONGKONGBuildingEnvironmentandEnergyEngineeringPOLYTECHNICUNIVERSITY建第璟境及能源工程學系香港理工大學Lecture 5: Ignition and FlammabilityXinyan Huang, Ph.D.AssistantProfessorDept.of Building Environment and Energy EngineeringResearchCentreforFireSafetyEngineering,PolyUxy.huang@polyu.edu.hkFireScience1DrXinyan Huang
Fire Science 1 Dr Xinyan Huang Xinyan Huang, Ph.D. Assistant Professor Dept. of Building Environment and Energy Engineering Research Centre for Fire Safety Engineering, PolyU xy.huang@polyu.edu.hk Lecture 5: Ignition and Flammability
What is ignition?0:07Ignitionisthestartoffire(scientifically).Ignition is the appearance of a flame (generally)https://www.youtube.com/watch?y=jTbUPOsGQT8FireScience2DrXinyan Huang
Fire Science 2 Dr Xinyan Huang What is ignition? • Ignition is the start of fire (scientifically) • Ignition is the appearance of a flame (generally) https://www.youtube.com/watch?v=jTbUP0sGQT8
Whatisexplosion?ExplosionisasuddenincreaseofvolumePhysicalprocess:bubble,balloonChemicalprocess:explosives,ignitionNuclearprocessIgnitionisathermalexplosion,sustainedbyheatreleasefromchemicalchainreactions.Heatrelease→thermalexpansionChainreactions→acceleratedprocessDeflagration(fire/flame)Detonation(super-sonicexplosion)FireScience3DrXinyan Huang
Fire Science 3 Dr Xinyan Huang What is explosion? Explosion is a sudden increase of volume: • Physical process: bubble, balloon • Chemical process: explosives, ignition • Nuclear process Ignition is a thermal explosion, sustained by heat release from chemical chain reactions. • Heat release → thermal expansion • Chain reactions → accelerated process o Deflagration (fire/flame) o Detonation (super-sonic explosion)
Explosion vs.IgnitionH202H2+02COLLFCFire ScienceDrXinyan Huang
Fire Science 4 Dr Xinyan Huang Explosion vs. Ignition
Explosion:fromIgnitionto Denotation1e36.01.357ns0.305.44.80.25]anaa884320.20ul.0.150.100.050.60.0Q0.40.60.88.00.21.0(cm)xSimulationbyElaineOranandHuahuaXiao(UniversityofMaryland)5FireScienceDrXinyan Huang
Fire Science 5 Dr Xinyan Huang Explosion: from Ignition to Denotation Simulation by Elaine Oran and Huahua Xiao (University of Maryland)