A Parametric Study of the Effect of Fire Source Elevation in a Compartment

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Virginia Tech

The objective of the present study was to acquire a better understanding of parameters controlling the species generation and transport from compartment fires. The experiments were performed in a half-scale ISO 9705 compartment and a 6.1 m long hallway connected in a head-on configuration. The buoyancy driven propane fire was provided by a burner and a continuous gaseous fuel supply system. All the measurements were obtained during the steady state of the fire. The ventilation conditions were fixed and three different fire source elevations were studied for heat release rates ranging from 20 kW to 150kW.

The species yields were obtained from performing detailed mapping measurements at the compartment and hallway exit planes. The measurements included local specie mole fractions of oxygen, carbon dioxide, carbon monoxide and unburned hydrocarbons. The local temperature and the local pressure (for local gas velocity calculations) were also measured. In addition, visual observations of the flow dynamic were performed through a window and the vents to give useful insights and lead to a better understanding of the combustion process.

The data obtained from the species generation study was analyzed using previously developed methods. The method based on equivalence ratio was presented and determined inappropriate for the present study where the global equivalence ratio was not equal to the plume equivalence ratio due to the complexity of the fire dynamic taking place. The method consisting of correlating the species yields based on the combustion within the compartment as a function of a non dimensional heat release rate allowed qualitative conclusions to be made. The non-dimensional heat release rate was based on the fuel load and the geometric parameters of the compartment. This methodology revealed similarities in the species production between the three fire source elevations investigated. A correlation of the data was obtained based on experimental data.

The transport of species to remote locations was studied for the three fire source elevations and fixed ventilation conditions. Species mole fractions and yields were obtained at the compartment exit plane (compartment/hallway interface) and at the hallway exit plane. The results were compared for various heat release rates and showed differences for some scenarios attributed to mixing along the hallway and oxidation reactions outside the compartment.

Carbon monoxide, species generation, building fires, burner elevation, species transport, near field air entrainment