Numerical Study on the Effect of Tunnel Aspect Ratio on Evacuation with Unsteady Heat Release Rate Due to Fire in the Case of Two Vehicles

Park, Younggi; Lee, Youngman; Na, Junyoung; Ryou, Hong Sun

doi:10.3390/en12010133

Cited by 8 publications

(8 citation statements)

References 13 publications

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“…Applying the actual heat release rates obtained from this study to the numerical analysis study, Park et al published a study on the effect of a vehicle accident on the evacuation in various tunnel aspect ratio [27]. The maximum heat release values obtained by other studies are shown in Table 4 and compared with the results obtained through this experiment.…”

Section: Heat Release Ratementioning

confidence: 90%

Experimental Study on the Fire-Spreading Characteristics and Heat Release Rates of Burning Vehicles Using a Large-Scale Calorimeter

2019

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In this article, large-scale experimental studies were conducted to figure out the fire characteristics, such as fire-spreading, toxic gases, and heat release rates, using large-scale calorimeter for one- and two-vehicle fires. The initial ignition position was the passenger seat, and thermocouples were attached to each compartment in the vehicles to determine the temperature distribution as a function of time. For the analysis, the time was divided into sections for the various fire-spreading periods and major changes, e.g., the fire spreading from the first vehicle to the second vehicle. The maximum temperature of 1400 °C occurred in the seats because they contained combustible materials. The maximum heat release rates were 3.5 MW and 6 MW for one and two vehicles, respectively. Since the time to reach 1 MW was about 240 s (4 min) before and after, the beginning of the car fire appears to be a medium-fast growth type. It shows the effect on the human body depending on the concentration of toxic substances such as carbon monoxide or carbon dioxide.

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Section: Heat Release Ratementioning

confidence: 90%

Experimental Study on the Fire-Spreading Characteristics and Heat Release Rates of Burning Vehicles Using a Large-Scale Calorimeter

2019

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“…When the merging ratio is equal to 0.4, the stairs evacuation capacity is optimal. In general, 0.5 is regarded as the optimal merging ratio [2], but the pedestrian output rate of the oor platform is calculated by the pedestrian number of oor platforms. Appropriately increasing the width of the stairs or decreases the width of the oor channel can improve the pedestrian output rate of the oor platform.…”

Section: Discussionmentioning

confidence: 99%

“…(1) Every pedestrian possesses independent movement characteristics; (2) e stairs pedestrian merging obeys a Poisson distribution; (3) e density of pedestrians can in uence the merging process; (4) e stairs evacuation adopts the FCFS (First Come First Served) involved in the scheduling theory.…”

Section: Calculation Of Pedestrian Output Rate Of Floor Platformmentioning

confidence: 99%

“…In the context of a building evacuation, stairs can be regarded as an emergency area, and the evacuation performance of the stairs is related to the safety of pedestrians [1,2]. Due to the high density of pedestrians and the particular characteristics of staircases as slopes, congestion is more likely to occur in the staircase of a building, and casualties and property damage may occur during an emergency [3].…”

Section: Introductionmentioning

confidence: 99%

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A Stairs Evacuation Model Considering the Pedestrian Merging Flows

Zheng

Tian

Zhang

et al. 2019

Discrete Dynamics in Nature and Society

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Pedestrian merging flows are common in a stairs evacuation process, which involves complex interactions among pedestrians that substantially restrict the efficiency of the stairs evacuation process. Analyzing the pedestrian merging flows process and improving the efficiency of stairs evacuation are urgent and essential tasks. A novel simplified stairs evacuation model for simulating and analyzing the stairs evacuation process, which considers the impact of merging flows, is proposed in this process. The dynamic pedestrian output rate of a floor platform is calculated by the number of pedestrians on the floor platform. The merging ratio determined by the design size of stairs is adopted to determine the ratio between the stairs pedestrian flow and the floor pedestrian flow in the pedestrian output rate of the floor platform. To evaluate the stairs evacuation process is divided into three stages based on the pedestrian merging flows process, and the evacuation time at each stage is computed by the dynamic pedestrian output rate of the floor platform. The stairs evacuation capacity is calculated by the evacuation time and the number of pedestrians. A case study of a six-floor building evacuation is investigated, and the reliability and feasibility of the proposed model is verified. By establishing different merging ratios, the optimal merging ratio is obtained by comparing the evacuation capacities of different merging ratios, which provides a reference of stairs design for designers.

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“…A review of recent multiscale modeling approaches for tunnel fire modeling is presented in the study by Ralph and Carvel [27]. Recently, research regarding the tunnel aspect ratio has been studied by experiments [28] and by modeling [29].…”

Section: Introductionmentioning

confidence: 99%

Tunnel Fire Dynamics as a Function of Longitudinal Ventilation Air Oxygen Content

2019

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Longitudinal ambient air ventilation is the most common methodology for maintaining an amicable environment in tunnels during normal operations while providing an evacuation path during tunnel fire emergencies. The present work investigates the influence of forced ventilation air oxygen concentrations on tunnel fire dynamics. Mixing inert gasses such as nitrogen, argon, or carbon dioxide with ambient air changes the ventilation air oxygen concentration. In order to quantify the influence of the oxygen content on the critical tunnel safety parameters, multiple computational fluid dynamics (CFD) simulations were done on a reduced-size tunnel while preserving the system Froude number. Analytical expressions were developed to describe the importance of oxygen content on the tunnel fire dynamics. By employing Froude scaling, the resulting relations were extrapolated to real scale tunnels. For the ambient air ventilation, the extrapolated expressions displayed good agreement with experimental literature data. By adjusting the oxygen concentration, parameters such as maximum tunnel ceiling temperature, fire growth rate, maximum heat flux to the tunnel floor, maximum flux on the tunnel ceiling, and maximum heat release rate can be controlled. This is the case also for oxygen levels where people can survive. This may increase the possibility for evacuation and improve the conditions for firefighting, significantly improving tunnel fire safety.

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Numerical Study on the Effect of Tunnel Aspect Ratio on Evacuation with Unsteady Heat Release Rate Due to Fire in the Case of Two Vehicles

Cited by 8 publications

References 13 publications

Experimental Study on the Fire-Spreading Characteristics and Heat Release Rates of Burning Vehicles Using a Large-Scale Calorimeter

Experimental Study on the Fire-Spreading Characteristics and Heat Release Rates of Burning Vehicles Using a Large-Scale Calorimeter

A Stairs Evacuation Model Considering the Pedestrian Merging Flows

Tunnel Fire Dynamics as a Function of Longitudinal Ventilation Air Oxygen Content

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