Biomass Compartment Fire Dynamics & Egress Margin
How do compartment fire temperatures, ventilation rates, and ignition spread affect simulated flashover timing and occupant evacuation margins?
This interactive tool visualizes a simplified 2D cellular automaton model of a biomass storage facility. On a 72×40 grid, cells track local fuel density, thermal energy, and smoke concentration through nearest-neighbor diffusion and heuristic burning rates. In actual compartment fire safety engineering, flashover represents a critical transition where room surfaces ignite almost simultaneously under thermal radiation from fire gases in excess of 600°C. In this educational demo, flashover time and evacuation margins are estimated via empirical thresholds and a simplified worker-stepping heuristic rather than a full CFD solver.
The simulation uses discretized finite-difference diffusion across 2D cells rather than 3D Navier-Stokes or zone fire models (such as NIST CFAST or FDS). Flashover timing on this page is triggered when any cell in Bay B reaches 600°C, and the egress safety margin uses a heuristic linear evacuation penalty (simTime + unevacuated workers × 4.5s). While informative for qualitative layout analysis, it should not replace certified NFPA or building code egress calculations.
Try a worked example
Select the 'Firebreak Retrofit' preset scenario. The script reinforces Bay B's boundaries with 2-hour rated barrier cells (wall value 2), insulating the center egress corridor from convective thermal spread. When you click '▶ Start Simulation', Bay B reaches temperatures exceeding 600°C, but the surrounding barriers prevent thermal and smoke transfer into the primary egress spine, allowing the simulated workers in the adjacent spaces to exit with a positive egress safety margin.
Compartment Fire Dynamics and Flashover
Flashover is defined in fire dynamics as the rapid transition phase in a compartment fire where surfaces exposed to thermal radiation from hot fire gases in excess of 600°C reach their ignition temperatures almost simultaneously, causing rapid fire involvement across the entire space. Fire Dynamics | NIST
NIST experimental benchmarks indicate that radiant heat flux to the floor reaches approximately 20 kW/m² during flashover conditions, while upper gas temperatures in residential and industrial compartments rise sharply toward 1000°C once flashover occurs. Fire Dynamics | NIST
Simulation Mechanics & Egress Heuristics
In this page's JavaScript engine, combustion kinetics are evaluated per grid cell where fuel burns once local temperature exceeds 180°C. Thermal energy and smoke diffuse into the four cardinal adjacent neighbors with constant transfer coefficients (0.18 for temperature, 0.22 for smoke). Exhaust vents act as localized sink terms proportional to the HVAC purge setting.
Simulated occupants steer toward the nearest exit coordinates while their walking speeds degrade as local smoke concentration increases. The displayed 'Egress Safety Margin' represents the difference between Bay B's flashover timestamp and an estimated Required Safe Egress Time (RSET) formula based on remaining unevacuated workers.
Sources and further reading