FPST 1213

1. FPST 1213 Chemistry & Physics of Fire Modified from a presentation developed by Thomas Woodford

2. The Basics • Heat Transfer • Conduction • Convection • Radiation

6. Combustion/Fire • Combustion indicates control • Internal Combustion Engine • Fire is rapid combustion, often uncontrolled • Wildfires • House Fire • Camp Fire

8. The Fire Tetrahedron • Oxidizer • Fuel (Reducing Agent) • Heat • Chemical Chain Reaction

19. Chemistry of Fire • Propane: C3H8 + 5O2 3CO2 + 4H2O plus heat + light Heat of Combustion more energy stored in C3H8 then CO2 and H2O

20. If we give the propane-air mixture a push (ignition source) • One molecule oxidizes giving off heat • This heat gives the push to other propane molecules • Away it goes

21. Two types of flames • Premixed • Bunsen Burner • Diffusion • Candle flame

22. Pre-Mixed Flames • Fuel and Oxidizer together • Flame has a characteristic velocity • If gas mixture flows at this velocity the flame appears to stay in place • Velocity too high – Blows out • Velocity too low – Flashes back

23. Diffusion Flame • Fuel on one side • Oxidizer on the other • Flame is the reaction zone