Smoke Filling in a Confined Compartment with Single Ceiling Vent
A simple analytical model which is suitable to determine the smoke filling time in a confined compartment with single ceiling vent is presented in this paper. In addition to the theoretical analysis, an experimental study is conducted to evaluate the feas
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Qiang Li, Jinmei Li, Shijing Ren, and Jiaqing Zhang
Abstract
A simple analytical model which is suitable to determine the smoke filling time in a confined compartment with single ceiling vent is presented in this paper. In addition to the theoretical analysis, an experimental study is conducted to evaluate the feasibility of the application of the model. The experimental results show that smoke filling time varies with different dimensions of the ceiling vent when the dimension of fire source is relatively small (the diameter of fire source is 0.1 m). However, in the case of a high heat release rate of fire source (the diameter of fire source is no smaller than 0.14 m), the effect of the dimension of the ceiling vent on smoke filling time could be approximately ignored. Zukoski’s ceiling exit model can be used to predict the smoke filling process in confined compartment with single ceiling vent. Keywords
Compartment fire Ceiling vent Smoke filling
Nomenclature A D g H m Q S
Area (m2) Diameter of pan (m) Acceleration due to gravity (m/s2) Height of compartment (m) Mass (kg) Energy (kJ) Area of compartment floor (m2)
T V z
Temperature (K) Volume (K) Height of smoke layer interface above floor (m)
Greek Symbols ρ
Density (kg/m3)
Q. Li (*) State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui, 230026, China Department of Fire Protection Engineering, Chinese People’s Armed Police Academy, Hebei, Langfang 065000, China e-mail: [email protected] J. Li Department of Fire Protection Engineering, Chinese People’s Armed Police Academy, Hebei, Langfang 065000, China University of Science and Technology Beijing, 30 xueyuan road, haidian district, Beijing 100083, China
S. Ren Department of Fire Protection Engineering, Chinese People’s Armed Police Academy, Hebei, Langfang 065000, China J. Zhang Anhui Province Key Laboratory of Electric Fire and Safety Protection, State Grid Anhui Electric Power Research Institute, Hefei, Anhui 230022, China
# Springer Science+Business Media Singapore 2017 K. Harada et al. (eds.), Fire Science and Technology 2015, DOI 10.1007/978-981-10-0376-9_80
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Subscripts
80.2
a g p roof
With the exchange flow through the horizontal ceiling vent, Fig. 80.1 shows a schematic of the case we will consider. A compartment with a horizontal vent at ceiling level has a height H and a lower layer height z. The fire is treated as a point source of heat, and no account is taken of the fuel mass flow rate. The mass flow rate flowing out through the horizontal vent is due to the expansion of hot gases and the density difference between inside cabin and external environment. The mass flow rate from the lower layer to the upper layer is given by m_ p , the plume mass flow rate. The mass flow rates flowing out and in through the vent are taken, respectively, as m_ out and m_ in . Since the smoke filling process in the compartment occurs in the initial stage of fire development, the exchange mass flow rate through the horizontal vent
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