Compartment fires

As a fuel-controlled fire grows in size and involves more fuel surface area and more fuel packages, it can reach a condition where the entire fuel load in the compartment burns at once. When this condition takes place as a transition suddenly, it is termed as flashover. The transition from fuel-controlled to ventilation-controlled conditions usually takes place at flashover event. 

Fundamentals of Fire Phenomena James G. Quintiere 2006 John Wiley Sons, Ltd ISBN 0 470 09113 4 

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Chung, G., N. Siu, and G, Apostolakis, 1985, Improvements in Compartment Fire Modeling and Simulation of Experiments, Nuclear Technology, 69, p. 14. 

Ito, V., N. SiLi, G. Apostolakis, 1985, COMPBRN III-A Computer Code for Modelling Compartment Fires, UCLA Report - ENG-8524, November. 

Siu, N. 1983, COMPBRN - A Computer Code for Modeling Compartment Fires, NUREG/ CR3239, UCLA - ENG-8257... 

Siu, N., 1980, Probabilistic Models for the Behavior of Compartment Fires, UCLA-ENG-8090,... 

Braun, E. Levin, B.C. Paabo, M. Gurraan, J.L. Clark, H.M. Yoklavich, M.F. Large-Scale Compartment Fire Toxicity Study Comparison with Small-Scale Toxicity Test Results, NBSIR 88-3764. National Institute of Standards and Technology, Gaithersburg, MD, 1988. 

The basic principle used to calculate the temperature in a compartment fire is the conservation of mass and energy. Since the energy release rate and the compartment temperature change with time, the application of the conservation laws will lead to a series of differential equations. 

Andersson, B., "Model Scale Compartment Fire Tests With Wall Lining Materials", Report LUTVDG/(TVBB-3041), Department of Fire Safety Engineering, Lund University,... 

Here T is the uniform temperature in the CV. Equations (3.45) and (3.48) are all equivalent under the three approximations, and either could be useful in problems. The development of governing equations for the zone model in compartment fires is based on these approximations. The properties of the smoke layer in a compartment have been described by selecting a control volume around the smoke. The control volume surface at the bottom of the smoke layer moves with the velocity of the fluid there. This is illustrated in Figure 3.10. 

Table 7.1 lists heat flux levels commonly encountered in fire and contrasts them with perceptible levels. It is typically found for common materials that the lowest heat fluxes to cause piloted ignition are about 10 kW/m2 for thin materials and 20 kW/m2 for thick materials. The time for ignition at these critical fluxes is theoretically infinite, but practically can be (9(1 min) (order of magnitude of a minute). Hashover, or more precisely the onset to a fully involved compartment fire, is sometimes associated with a heat flux of 20 kW/m2 to the floor. This flow heat flux can be associated with typical... 

The scope of this chapter will focus on typical building compartment fires representative of living or working spaces in which the room height is nominally about 3 m. This scenario, along with others, is depicted in Figure 11.1, and is labeled (a). The other configurations shown there can also be important, but will not necessarily be addressed here. They include ... 

The study of fire in a compartment primarily involves three elements (a) fluid dynamics, (b) heat transfer and (c) combustion. All can theoretically be resolved in finite difference solutions of the fundamental conservation equations, but issues of turbulence, reaction chemistry and sufficient grid elements preclude perfect solutions. However, flow features of compartment fires allow for approximate portrayals of these three elements through global approaches for prediction. The ability to visualize the dynamics of compartment fires in global terms of discrete, but coupled, phenomena follow from the flow features. 

The above discussion lays out the physics and chemical aspect of the processes in a compartment fire. They are coupled phenomena and do not necessarily lend themselves to exact solutions. They must be linked through an application of the conservation equations as developed in Chapter 3. The ultimate system of equations is commonly referred to as zone modeling for fire applications. There are many computer codes available that represent this type of modeling. They can be effective for predictions if the... 

The transient term can be neglected in most cases, but any sudden change in the energy will result in a pressure change. This can be responsible for puffing effects seen in compartment fires, especially when the burning is oscillatory. 

The dimensionless x-loss factors are parameters that effect temperature, and occur in modified forms in many correlations in the literature for compartment fire temperature. 

One aspect of fully developed fires that will not be addressed here is their production of combustion products. When compartment fires become ventilation-limited, they bum incompletely, and can spread incomplete products such as CO, soot and other hydrocarbons throughout the building. It is well established that the yield of these incomplete products goes up as the equivalence ratio approaches and exceeds 1. More information on this issue can be found in the literature [1],... 

Bullen, M. L. and Thomas, P. H., Compartment fires with non-cellulosic fuels, in 17th International Symposium on Combustion, The Combustion Institute, Pittsburgh, Pennsylvania, 1979, pp. 1139 18. 

Kim, K. I., Ohtani, H. and Uehara, Y., Experimental study on oscillating behavior in a small-scale compartment fire, Fire Safety J., 1993, 20, 377-84. 

Naruse, T., Rangwala, A. S., Ringwelski, B. A., Utiskul, Y., Wakatsuki, K. and Quintiere, J. G., Compartment fire behavior under limited ventilation, in Fire and Explosion Hazards, Proceedings of the 4th International Seminar, Fire SERT, University of Ulster, Northern Ireland, 2004, pp. 109-120. 

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