A Study on Ceiling Temperature Distribution and Critical Exhaust Volumetric Flow Rate in a Long-Distance Subway Tunnel Fire with a Two-Point Extraction Ventilation System

Smoke control is a crucial issue in a long-distance subway tunnel fire, and a two-point extraction ventilation system is an effective way to solve this problem, due to the characteristics of controlling the smoke in a limited area and removing high-temperature and toxic smoke in time. In this study, the ceiling temperature distribution and the critical exhaust volumetric flow rate to control the smoke in the zone between two extraction vents were investigated in a long-distance subway tunnel fire with a two-point extraction ventilation system. Experiments were carried out in a 1/20 reduced-scale tunnel model based on Froude modeling. Factors, including the heat release rate (HRR), the extraction vent length, the internal distance between two extraction vents and exhaust volumetric flow rate, were studied. Smoke temperature below the ceiling, exhaust volumetric flow rate and smoke spreading configurations were measured. The ceiling temperature distribution was analyzed. Meanwhile, an empirical equation was developed to predict the critical exhaust volumetric flow rate based on the one-dimensional theory, experimental phenomenon and the analysis of forces acting at the smoke underneath the extraction vent. The coefficients in the empirical equation were determined by experimental data. Compared with the experimental results, the developed empirical equation can predict the critical exhaust volumetric flow rate well. Research outcomes in this study will be beneficial to the design and application of two-point extraction ventilation system for a long-distance subway tunnel fire.

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Effect of Extraction Vent Length on Critical Exhaust Volumetric Flow Rate in Long-distance Subway Tunnel Fires with Two-point Extraction Ventilation

2019 9th International Conference on Fire Science and Fire Protection Engineering (ICFSFPE) ◽

10.1109/icfsfpe48751.2019.9055802 ◽

2019 ◽

Author(s):

Peng Zhao ◽

Zhongyuan Yuan ◽

Nanyang Yu

Keyword(s):

Flow Rate ◽

Volumetric Flow Rate ◽

Subway Tunnel ◽

Long Distance ◽

Tunnel Fires

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A physical model-free ant colony optimization network algorithm and full scale experimental investigation on ceiling temperature distribution in the utility tunnel fire

International Journal of Thermal Sciences ◽

10.1016/j.ijthermalsci.2021.107436 ◽

2022 ◽

Vol 174 ◽

pp. 107436

Author(s):

Bin Sun ◽

Zhenbiao Hu ◽

Xiaojiang Liu ◽

Zhao-Dong Xu ◽

Dajun Xu

Keyword(s):

Experimental Investigation ◽

Temperature Distribution ◽

Ant Colony Optimization ◽

Physical Model ◽

Full Scale ◽

Ant Colony ◽

Model Free ◽

Tunnel Fire ◽

Ceiling Temperature ◽

Utility Tunnel

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Flow-Field Characteristics of High-Temperature Annular Buoyant Jets and Their Development Laws Influenced by Ventilation System

The Scientific World JOURNAL ◽

10.1155/2013/826514 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11

Author(s):

Yi Wang ◽

Yanqiu Huang ◽

Jiaping Liu ◽

Hai Wang ◽

Qiuhan Liu

Keyword(s):

High Temperature ◽

Flow Field ◽

Cross Section ◽

Flow Rate ◽

Ventilation System ◽

Volumetric Flow Rate ◽

Outer Diameter ◽

Exhaust Hood ◽

Buoyant Jets ◽

Flow Field Characteristics

The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to −5 Pa.

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Experimental and numerical investigation of thermal and flow conditions inside a large pharmaceutical storage after the ventilation system failure

Thermal Science ◽

10.2298/tsci210522346t ◽

2021 ◽

pp. 346-346

Author(s):

Ilija Tabasevic ◽

Rastko Jovanovic ◽

Dragan Milanovic

Keyword(s):

Temperature Distribution ◽

Flow Field ◽

Flow Rate ◽

Ventilation System ◽

Pharmaceutical Products ◽

System Failure ◽

Flow Conditions ◽

Cfd Simulations ◽

Depth Analysis ◽

Good Agreement

Safe storage of pharmaceutical products is of great importance due to potential hazards for human health. The aim of this study was to assess the ability of pharmaceutical storage to recover design temperature during ventilation system recovery. The performed CFD simulations showed good agreement with experimental temperature measurements. Numerical results allowed in-depth analysis of flow field and temperature distribution inside the storage. It was discovered that the flow field is highly non-uniform, which consequently leads to an uneven temperature distribution of pallets with products. However, a high inlet mass flow rate ensured that all pallets reach the designed temperature.

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Numerical Studies on the Performance of Saccardo Ventilation System in Emergency Fire Scenarios

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.527.146 ◽

2014 ◽

Vol 527 ◽

pp. 146-151

Author(s):

Rouhollah Ganjiazad ◽

Ali Kazemipour ◽

Hossein Afshin ◽

Bijan Farhanieh

Keyword(s):

Flow Rate ◽

Inclination Angle ◽

Ventilation System ◽

Volumetric Flow Rate ◽

Smoke Plume ◽

Numerical Studies ◽

Air Jet ◽

Before And After ◽

Fire Scenarios ◽

Inclination Angles

In this study, the influence of volumetric flow rate and inclination angle of air jet is evaluated on the performance of a Saccardo ventilation system in a straight rectangular tunnel in case of fire. Simultaneous effects of volumetric flow rate and inclination angle of jet exiting the Saccardo nozzle on the behavior of smoke plume is considered by studying the structure of velocity profile before the fire source. It is found that this factor has a remarkable influence on the behavior of smoke plume and therefore, on the temperatures experienced near the fire. Besides, the influence of tunnel slope on the performance of the Saccardo system to sweep the plume is investigated. It is shown that the slope effect on the behavior of smoke plume and temperature profiles is completely different for locations before and after the fire, in both negative and positive slopes. Finally a range of volumetric flow rates and inclination angles is proposed as the optimized range of performance in an emergency fire scenario.

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Active Disturbance Rejection Control of a Longitudinal Tunnel Ventilation System

Energies ◽

10.3390/en13081871 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1871

Author(s):

Liyun Si ◽

Wenping Cao ◽

Xiangping Chen

Keyword(s):

Flow Rate ◽

Disturbance Rejection ◽

Air Flow ◽

Ventilation System ◽

Active Disturbance Rejection Control ◽

Air Flow Rate ◽

Long Distance ◽

Tunnel Ventilation ◽

Active Disturbance Rejection ◽

Disturbance Rejection Control

This paper proposes an innovative approach for controlling pollutant release in a long-distance tunnel via longitudinal ventilation. Enhanced by an active disturbance rejection control (ADRC) method, a ventilation controller is developed to regulate the forced air ventilation in a road tunnel. As a result, the pollutants (particulate matter and carbon monoxide) are reduced by actively regulating the air flow rate through the tunnel. The key contribution of this study lies in the development of an extended state observer that can track the system disturbance and provide the system with compensation via a nonlinear state feedback controller equipped by the ADRC. The proposed method enhances the disturbance attenuation capability in the ventilation system and keeps the pollutant concentration within the legitimate limit in the tunnel. In addition to providing a safe and clean environment for passengers, the improved tunnel ventilation can also achieve better energy saving as the air flow rate is optimized.

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Verification of Mathematical Description of Changes in Air Temperature and Humidity in Headings Ventilated with Auxiliary Ventilation System/Weryfikacja Metematycznego Opisu Zmian Temperatury I Wilgotności Powietrza W Wyrobiskach Przewietrzanych Lutniciągiem Tłoczącym Z Dadatkowym Wentylatorem O Zmienianej Prędkości Obrotowej

Archives of Mining Sciences ◽

10.2478/amsc-2014-0039 ◽

2014 ◽

Vol 59 (2) ◽

pp. 529-551 ◽

Cited By ~ 1

Author(s):

Bernard Nowak ◽

Jan Piątek

Keyword(s):

Flow Rate ◽

Ventilation System ◽

Volumetric Flow Rate ◽

Climatic Conditions ◽

Specific Humidity ◽

Graphical Form ◽

Algebraic Equations ◽

Dead End ◽

Calculation Results ◽

The Mathematical Model

Abstract The article presents verification of the mathematical model which was developed in earlier works, describing, through distributions of temperature, specific humidity, and flow rate of both fresh and exhaust air in the dead end headings ventilated with forcing duct line ventilation system, the climatic conditions existing in those headings. On the route of the considered duct line, an additional fan with a variable rotational speed was installed in order to avoid recirculation of the air between the inside of the duct line and the heading. The task of this auxiliary fan is an increase in the volumetric flow rate of fresh air at the mine face. The above-mentioned verification was based on a comparison of the calculation results obtained from the numerical solution of ordinary differential equations of the first order and algebraic equations with the results of measurements carried out in the selected mine heading. Wide comparative material was obtained by changing the location of the auxiliary fan in the duct line for a given heading length, and the heading length itself. 14 research variants were obtained in this way, in which, in addition to the already mentioned temperatures and humidity of the air, also the rotor speeds of the auxiliary fan were compared. The results of calculations and measurements have been presented in a graphical form. Their comparison was carried out using statistical methods.

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Numerical study on the effect of shaft position on natural smoke exhaust in tunnels with one closed portal

E3S Web of Conferences ◽

10.1051/e3sconf/202019405061 ◽

2020 ◽

Vol 194 ◽

pp. 05061

Author(s):

GENG Pengqiang ◽

WANG Zihao ◽

WENG Miaocheng ◽

LIU Fang

Keyword(s):

Temperature Distribution ◽

Heat Release ◽

Release Rate ◽

Numerical Study ◽

Fire Dynamics ◽

Fire Dynamics Simulator ◽

Fire Source ◽

Tunnel Fire ◽

Ceiling Temperature ◽

Longitudinal Distance

.This paper uses Fire Dynamics Simulator (FDS) to study the effect of the longitudinal distance from the shaft to the fire source on the natural smoke exhaust of the tunnel fire with one closed portal, and analyzes the temperature distribution of the smoke and the shaft’s smoke exhaust efficiency. The results show that when the shaft is located downstream of the fire source (Ds<0), with the increase of the distance from the shaft to the fire source, the smoke exhaust efficiency decreases first and then stabilizes at a fixed value. At this time, the ceiling temperature attenuation’s coefficient at upstream of the fire source is only related to the heat release rate of the fire source (HRR). When the shaft is located upstream of the fire source (Ds>0), the smoke exhaust efficiency increases slightly with the increase of the distance from the shaft to the fire source, but the overall value is relatively small. When HRR is fixed, the shaft located downstream of the fire source has a higher smoke exhaust efficiency. As the distance between the shaft and the fire source increases, the plug phenomenon decreases.

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Building a bridge between industry and theory on the example of a new ventilation system

EPJ Web of Conferences ◽

10.1051/epjconf/201921301001 ◽

2019 ◽

Vol 213 ◽

pp. 01001 ◽

Cited By ~ 1

Author(s):

Kazimierz Peszyński

Keyword(s):

Mathematical Modelling ◽

Velocity Distribution ◽

Flow Velocity ◽

Cross Section ◽

Flow Rate ◽

Rectangular Cross Section ◽

Ventilation System ◽

Volumetric Flow Rate ◽

Ventilation Ducts

The paper presents the possibilities of simplified determination of the air volumetric flow rate in ventilation ducts. This problem occurred during the tests of local losses in the elements of a new ventilation system based on ducts with a rounded rectangular cross-section. The presented method requires mathematical modelling of the flow velocity distribution in the ducts. The paper presents four models of the velocity distribution. The necessity of using so many models resulted from the wide coverage of the tested sections: Amax/Amin= 46.88.

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