Theoretical and Experimental Study on Fully-Developed Compartment Fires

To predict the effect of fire on the structures, one needs to understand physics of the fire growth in a compartment as to how the fuel interacts with the flame and its surroundings. This study explores these effects and applies them to the common fuel configurations such as pool and crib fires. The focus on the study is on the fully-developed fires where all available fuel becomes involved to the maximum extent and can potentially yield the severest damage to the structural elements. A single-zone compartment fire model is developed along with a fuel mass loss rate model that accounts for the thermal enhancement, oxygen-limiting feedback, and the fuel type and configuration. A criterion for a one-zone, fully-developed fire is established and validated with experiments. An empirical correlation for mixing of oxygen into the lower floor layer essential for the modeling is also developed. An experimental program for single-wall-vent compartment using wood crib and heptane pool as fuels is carried out to validate the mathematical model and explore a full range of phenomena associated with fully developed fires: extinction, oscillation, fire area shrinkage, and response of fuel to thermal and oxygen effects. The simulation from the model is able to capture these phenomena and shows good agreement with the experiments. Some generalities of the fuel mass loss rate and compartment gas temperature are presented using the experimental results and the model simulations. The developed model has a potential to give burning time and temperature in a fire for any fuel, scale and ventilation

Evaluating methods for preventing smoke spread through ventilation systems using fire dynamics simulator

Fires in enclosures equipped with mechanical ventilation remain one of the key issues for fire safety assessment in multifamily homes and industries. Therefore, a wide variation of methods for preventing smoke spread through the ventilation system exist and are applied, in performance-based designs. Through the use of the heating, ventilation and air conditioning (HVAC) model in the fire dynamics simulator, several different common and less common methods for preventing smoke spread in the ventilation system were tested. The effects on smoke spread with changing building leakage and fire growth rates were also investigated. The results were evaluated by determining the total soot spread from the fire room to other compartments connected to the ventilation system, as well as soot/thermal load on the fans and system in general. The maximum and average heat release rate was also of interest and hence compared between systems. It was found that, while many methods perform similar, a few proven methods, such as fire and smoke dampers, performed very well with very little smoke spread to the rest of the system. The study should be considered as an introduction to implementing a similar methodology in specific cases because different ventilations systems will present very different challenges and weaknesses