Burning Characteristicsand Smoke Emission from MixedFuel Cribs

Experiments were conducted to study the burning characteristics and smoke emission from mixed fuel crib assemblies designed to represent the main components in structures. Cribs consisting of wood, drywall, and plastics were assembled into cubic structures, all with the same mass fraction for each material. Three packing densities and two crib sizes were studied. While a crib burned to completion, the smoke was collected in a fire calorimetry system for the heat release rate (HRR), combustion gases, and smoke measurements. The scale of cribs affected the burn duration and the total heat release, but the packing density had a greater effect on modified combustion efficiency, peak HRR, and the emission factors of CO₂, CO, formaldehyde, acrolein, SO₂, and total hydrocarbons. The variability in scale and packing density studied here can affect the structure fire emission estimates by 20% for CO₂ and smoke and up to 130% for SO₂ and formaldehyde. Therefore, packing density must be considered to properly evaluate structural fires.