Ventilation Effects On Compartment Fire Characterization

Abstract

Compartment fire experiments were performed using either natural or overhead forced ventilation to assess the effect of ventilation on the compartment fire environment. The ventilation rate was varied by changing the vent size in natural ventilation tests and mechanically in forced ventilation tests. Three fuels were used: diesel fuel, wood cribs, and polyurethane slabs. For naturally ventilated fires, it was noted that the vent size and geometry had a significant impact on the vertical temperature and oxygen concentration profiles. Both the temperature and oxygen concentration measurements were representative of two-layer environments. However, in terms of oxygen concentration, forced ventilation fires resulted in a well-mixed compartment regardless of the ventilation rate. In contrast, temperature measurements showed either a two-layer or linear variation with respect to compartment height, depending on the scenario. These results defy the conventional assumption that compartment temperatures and gas concentrations have the same vertical distribution. Furthermore, these results identify the need to go beyond the classic twolayer paradigm. In addition, reduced oxygen concentrations at the flame base resulted in reduced mass loss rates. The relationship between these burning rates and the oxygen concentration at the flame base was examined, and a correlation was developed. The results show that temperature and flashover potential assessments based on furniture calorimeter data may be significantly overestimated.

Air Starved Wood Crib Compartment Fire Heat Release and Toxic Gas Yields

“…The principle of supplying the air ventilation at a fixed rate to the fire compartment was developed by the authors [6][7][8] and has also been used in studies of pool fires by Utiskul et al [17]. Although most compartment fires have an open door compartment [18][19][20][21][22] they are usually of full room height which controls the pressure difference that entrains air into the fire. In smaller compartments such as the present with a 1.5 m height natural ventilation would result in lower ventilation rates than real compartment fires and the forced ventilation technique overcomes this problem.…”

“…In smaller compartments such as the present with a 1.5 m height natural ventilation would result in lower ventilation rates than real compartment fires and the forced ventilation technique overcomes this problem. In the fully developed fire stage of compartment fires the ventilation rate is normally relatively constant and fixed by the room height and the area of the open door [18][19][20][21][22] and hence the present procedures are not far away from real compartment fires.…”

“…The cribs were three times the size of those that the authors have previously investigated [6,8] and this was to bring the fire loads closer to reality. A feature of the work with smaller cribs was that the fires had mainly lean equivalence ratios and the rich mixtures that often occur with ventilation restricted fires [18][19][20][21][22] were not encountered. The calorific value of pine is 17 MJ/kg and this gives 78 MJ of energy in the 4.8 kg pine cribs.…”

Assessment of the Burning Rate of Liquid Fuels in Confined and Mechanically-Ventilated Compartments using a Well-Stirred Reactor Approach

“…(9) expresses the oxygen effect on the fuel mass loss rate (i.e. linear decrease) in vitiated conditions as proposed in [5].…”

“…A large body of the literature has been devoted to a comprehensive characterization of naturally-ventilated enclosure fires (e.g. [1][2][3][4][5][6][7][8][9][10][11]), whereas fewer studies have focused on mechanically-ventilated room fires (e.g. [12][13][14][15][16][17]).…”