Enclosure Fire Dynamics Chapter 1: Introduction Chapter 2: Qualitative description of enclosure fires Chapter 3: Energy release rates Chapter 4: Plumes and flames Chapter 5: Pressure and vent flows Chapter 6: Gas temperatures (Chapter 7: Heat transfer) Chapter 8: Smoke filling (Chapter 9: Products of combustion) Chapter 10: Computer modeling Each course unit represents breaking down the problem into individual pieces

Goals and expectations Account for: How size, geometry, openings and buildning material affects an enclosure fire Typical fire development Different ways to characterise an enclosure fire

Ignition

Spread to additional fuel

Free burn Lv is the smoke visibility distance in meters (or cm) Phi is the equivalence ratio, with a value > 1.0 indicating unburned fuel

Fire growth CO concentrations are now hazardous Only 3 times more air available for combustions

Flashover Unburned fuel in upper layer is able to burn once it mixes with oxygen outside the doorway. Insufficient air now available for combustion

Temperature history during the course of a compartment fire Not all fires follow this ideal history It is very difficult to predict early growth during an immediately after ignition Usually assume burning starts with HRR=50kW.

Definition of flashover 20 kW/m2 Heat flux to floor Sufficient to ignite common combustibles Smoke layer temperature of 500-600 oC Flames out through opening t.ex. Few regulations for carpeting because it does not usually become involved until closer to flashover

Influence of oxygen depletion

Similar fires in compartments of a different size Larger room in able to dissipate more of the heat, resulting in a lower flux for flame spread

Ignition - little influence from the compartment

Spread to second fuel package

Real differences evident

Insufficient oxygen in smaller compartment

Lack of oxygen

Lack of oxygen

Lack of oxygen

Questions? Next unit: fire growth/design fires Release of pentane from a large spherical storage vessel Is this a premixed flame?