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CFD study of fire-induced pressure variation in a mechanically-ventilated air-tight compartment

Junyi Li (UGent) , Tarek Beji (UGent) and Bart Merci (UGent)
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Abstract
The present work describes Computational Fluid Dynamics (CFD) simulations of fire-induced pressure rise and ventilation duct flow rate in a mechanically-ventilated air-tight compartment, which represents a passive house. Overlapping wooden slats were used as fire source in the experiments and were represented in the simulations by a 0.4 m × 0.4 m × 0.4 m cube with a prescribed HRR based on the experimental results. The maximum ventilation volume flow rate was set to 80 m3/h in the experiments, in line with Belgian requirements for residential ventilation. Two methods were used to set up the ventilation volume flow rate in the simulations to meet the requirement of maximum ventilation flow rate by modifying the fan curve, and adding dampers. As expected the combination of the real fan curve and dampers, which resembles reality better, is morein line with the experimental results. The maximum over-pressure in the fire room was about 420 Pa, resulting in a reverse flow in the supply duct and an enhanced flow in the exhaust duct. The reversed inlet volume flow rate and increased outlet volume flow rate reached 137 m3/h and 175 m3/h respectively. The fire-induced pressure is high enough to hinder evacuation and fire rescue operations due to the impossibility of opening inward-open doors over a certain period of time. Moreover, the pressure rise in the adjacent room also reaches a dangerous level. Reducing the gap area between rooms can significantly decrease the pressure rise in the adjacent room, but leads to an increase of pressure in the fire room. As expected, when applying mechanical ventilation, the influence of leakage pressure exponent on pressure rise is smaller compared to cases without ventilation.
Keywords
CFD modeling, duct reverse flow, fire-induced pressure, passive house fire

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MLA
Li, Junyi, Tarek Beji, and Bart Merci. “CFD Study of Fire-induced Pressure Variation in a Mechanically-ventilated Air-tight Compartment.” Proceedings of the 9th International Seminar on Fire and Explosion Hazards. Ed. Alexander Snegirev et al. Vol. 1. Saint-Petersburg: Saint-Petersburg Polytechnic University Press, 2019. 574–583. Print.
APA
Li, Junyi, Beji, T., & Merci, B. (2019). CFD study of fire-induced pressure variation in a mechanically-ventilated air-tight compartment. In A. Snegirev, F. Tamanini, D. Bradley, N. Liu, V. Molkov, & N. Chaumeix (Eds.), Proceedings of the 9th International Seminar on Fire and Explosion Hazards (Vol. 1, pp. 574–583). Presented at the 9th International Seminar on Fire and Explosion Hazards, Saint-Petersburg: Saint-Petersburg Polytechnic University Press.
Chicago author-date
Li, Junyi, Tarek Beji, and Bart Merci. 2019. “CFD Study of Fire-induced Pressure Variation in a Mechanically-ventilated Air-tight Compartment.” In Proceedings of the 9th International Seminar on Fire and Explosion Hazards, ed. Alexander Snegirev, Franco Tamanini, Derek Bradley, Naian Liu, Vladimir Molkov, and Nabiha Chaumeix, 1:574–583. Saint-Petersburg: Saint-Petersburg Polytechnic University Press.
Chicago author-date (all authors)
Li, Junyi, Tarek Beji, and Bart Merci. 2019. “CFD Study of Fire-induced Pressure Variation in a Mechanically-ventilated Air-tight Compartment.” In Proceedings of the 9th International Seminar on Fire and Explosion Hazards, ed. Alexander Snegirev, Franco Tamanini, Derek Bradley, Naian Liu, Vladimir Molkov, and Nabiha Chaumeix, 1:574–583. Saint-Petersburg: Saint-Petersburg Polytechnic University Press.
Vancouver
1.
Li J, Beji T, Merci B. CFD study of fire-induced pressure variation in a mechanically-ventilated air-tight compartment. In: Snegirev A, Tamanini F, Bradley D, Liu N, Molkov V, Chaumeix N, editors. Proceedings of the 9th International Seminar on Fire and Explosion Hazards. Saint-Petersburg: Saint-Petersburg Polytechnic University Press; 2019. p. 574–83.
IEEE
[1]
J. Li, T. Beji, and B. Merci, “CFD study of fire-induced pressure variation in a mechanically-ventilated air-tight compartment,” in Proceedings of the 9th International Seminar on Fire and Explosion Hazards, Saint-Petersburg, 2019, vol. 1, pp. 574–583.
@inproceedings{8613727,
  abstract     = {The present work describes Computational Fluid Dynamics (CFD) simulations of fire-induced pressure rise and ventilation duct flow rate in a mechanically-ventilated air-tight compartment, which represents a passive house. Overlapping wooden slats were used as fire source in the experiments and were represented in the simulations by a 0.4 m × 0.4 m × 0.4 m cube with a prescribed HRR based on the experimental results. The maximum ventilation volume flow rate was set to 80 m3/h in the experiments, in line with Belgian requirements for residential ventilation. Two methods were used to set up the ventilation volume flow rate in the simulations to meet the requirement of maximum ventilation flow rate by modifying the fan curve, and adding dampers. As expected the combination of the real fan curve and dampers, which resembles reality better, is morein line with the experimental results. The maximum over-pressure in the fire room was about 420 Pa, resulting in a reverse flow in the supply duct and an enhanced flow in the exhaust duct. The reversed inlet volume flow rate and increased outlet volume flow rate reached 137 m3/h and 175 m3/h respectively. The fire-induced pressure is high enough to hinder evacuation and fire rescue operations due to the impossibility of opening inward-open doors over a certain period of time. Moreover, the pressure rise in the adjacent room also reaches a dangerous level. Reducing the gap area between rooms can significantly decrease the pressure rise in the adjacent room, but leads to an increase of pressure in the fire room. As expected, when applying mechanical ventilation, the influence of leakage pressure exponent on pressure rise is smaller compared to cases without ventilation.},
  author       = {Li, Junyi and Beji, Tarek and Merci, Bart},
  booktitle    = {Proceedings of the 9th International Seminar on Fire and Explosion Hazards},
  editor       = {Snegirev, Alexander and Tamanini, Franco and Bradley, Derek and Liu, Naian and Molkov, Vladimir and Chaumeix, Nabiha },
  isbn         = {9785742264965},
  keywords     = {CFD modeling,duct reverse flow,fire-induced pressure,passive house fire},
  language     = {eng},
  location     = {Saint-Petersburg},
  pages        = {574--583},
  publisher    = {Saint-Petersburg Polytechnic University Press},
  title        = {CFD study of fire-induced pressure variation in a mechanically-ventilated air-tight compartment},
  url          = {http://dx.doi.org/10.18720/spbpu/2/k19-25},
  volume       = {1},
  year         = {2019},
}

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