Theoretical and experimental analysis of ceiling-jet flow in corridor fires

In tunnels or long corridors, the combustion products of the fire are confined to spread in one or two directions, forming a ceiling-jet flow. For safety assessment and emergency treatment, it is important to investigate and understand the behavior of the ceiling-jet flow. In this paper, a simple model has been presented, in terms of Richardson number and non-dimensional ceiling-jet thickness, to predict the temperature and the velocity of fire-induced ceiling-jet in a rectangular corridor. Besides, the location of hydraulic jump, occurring in ceiling-jet flow, has been estimated theoretically. In order to validate the theoretical predictions, a series of reduced-scale fire experiments were conducted in a 5 m long corridor. The predicted results, concerning non-dimensional excess temperature, agree favorably with experimental data in different fuels and heat release rates of the fire tests. Finally, the scaling issue has also been discussed and validated. (C) 2011 Elsevier Ltd. All rights reserved

Study on correlation between fire fighting time and fire loss in urban building based on statistical data

In this paper, the correlation between fire fighting time and fire loss (burned area of urban building) based on fire statistical data in Jiangxi Province (China) from 2000 to 2010 was studied. The results showed the probability distribution of fire fighting time met lognormal distribution. In the probability density function, the expectation of the distribution represents the average level of fire fighting time. We found the average fighting time of warehouse and workshop fires were higher than the average level of whole building fires. In addition, the probability distribution of the burned area in each fire fighting time interval also followed power function, which was valid in the case of the fire fighting time within 4 hours. Furthermore, the absolute value of the exponent of the function is positively correlated with the small-scale fires and negatively with the large-scale fires. The value decreased with the increase of the fire fighting time, indicating that the fire control ability became poor with longer fire fighting time. Also, the fire control ability in residential waned fastest as the fighting time increased, and the ability in warehouse waned slowest. en fire fighting time and fire loss in urban building based on statistical dat

Fire suppressing performance of superfine potassium bicarbonate powder

Fire suppression effectiveness of a new kind of dry powder based on potassium bicarbonate was studied in this paper. The powder consisted of superfine potassium bicarbonate and some organic and inorganic additives, which was denoted as 'K-powder'. The physical and chemical characteristics of the K-powder were characterized by a series of techniques of X-ray diffraction, scanning electron microscopy, Fourier transforms infrared (FTIR) and thermal gravity analysis, etc. Performance of the new potassium-based powder in fire suppression was studied by laboratory-scale experiments, which exhibited much superior fire suppression efficacy than that of the commercial bicarbonate powder. Such improvements could be reasonably ascribed to the special chemical composition, microstructure and radiation effect on the mechanisms. The preparation, fire suppression and possible fire-extinguishing mechanisms were studied in detail. Copyright (C) 2010 John Wiley & Sons, Ltd