Review of new requirements for smoke ventilation system for road tunnels in NFPA 502 published in 2020

2020 ◽  
pp. 16-25
Author(s):  
Борис Борисович Колчев ◽  
Андрей Владимирович Пехотиков ◽  
Игорь Иванович Ильминский ◽  
Павел Алексеевич Чернышов ◽  
Оксана Владимировна Фомина
Keyword(s):  
Ventilation System ◽  
Significant Discrepancy ◽  
Limited Access ◽  
Fire Extinguishing ◽  
Release Capacity ◽  
Road Tunnels ◽  
Air Intake ◽  
Air Flow Velocity ◽  
Heat Release Capacity

Одним из нормативных документов, содержащих основные требования к системам противодымной вентиляции автодорожных тоннелей, является NFPA 502 «Standard for Road Tunnels, Bridges and Limited Access Highways». Стандарт обобщает накопленный опыт, полученный в результате экспериментальных исследований, проводимых как в США, так и за их пределами. В августе 2019 г. была опубликована его новая редакция (2020 Edition), в которой значительно изменился подход к определению требуемых параметров противодымной вентиляции, основанной на продольной схеме. The article presents an analysis of the new edition of NFPA 502 “Standard for Road Tunnels, Bridges, and Limited Access Highways” regarding the method for determining the critical value of the longitudinal air flow velocity generated by smoke ventilation based on longitudinal scheme. The classification of road tunnels introduced by NFPA 502 is described, taking into account the occupancy of tunnels by vehicles during rush hour, as well as the length of the tunnel. The data concerning protection of tunnel by fire protection systems taking into account the introduced classification are presented. There are analysed the schemes of smoke ventilation, including longitudinal, semi-transverse and transverse, containing different number of concentrated and distributed smoke receiving and air intake devices introduced by NFPA 502. There is described the effect of trapping air from under the smoke layer, that is called as “Plugholing” effect in the standard. The data on heat release capacity from fire source are presented taking into account various types of burning vehicles, as well as the equipment of tunnel with automatic fire extinguishing systems. There is performed the comparison of results of the calculated determination of critical velocity, determined by the dependencies of NFPA 502 in 2017 and 2020 editions. The significant discrepancy in required values is found.

scholarly journals Method of the boiler room ventilation system efficiency experimental determination

2020 ◽  
pp. 71-81
Author(s):  
O. Voznyak ◽  
◽  
Yu. Yurkevych ◽  
M. Kasynets ◽  
N. Spodyniuk ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Ventilation System ◽  
Experimental Studies ◽  
Regulatory Requirements ◽  
Air Jets ◽  
Boiler Room ◽  
Room Ventilation System ◽  
Air Flow Velocity ◽  
Air Exchange

The issue of the normative air exchange ensuring in the premises of the boiler houses is extremely important. The article presents the results of theoretical and experimental studies of air velocity determination in the distribution of air by round and compact jets in the boiler room. Graphical and analytical dependences are given. The research results substantiate the higher accuracy of the average air flow velocity determination in small boiler rooms. The aim of the work is to develop a method for experimental determination of the efficiency of the ventilation system in the boiler room; to increase of the accuracy of the average velocity determination of the round and the compact air jets in the plane of the supply nozzle to ensure the normative air exchange of the boiler room and to substantiate of the calculation method. The characteristics and patterns of development of round and compact air jets in the premises are established and the calculated dependences are obtained. It is substantiated that the application of the proposed method will significantly increase the accuracy of air exchange determination in the boiler rooms to ensure the required value in accordance with regulatory requirements. Recommendations for the practical determination of the calculated values to ensure proper ventilation of the boiler rooms are given.

scholarly journals SIMULATION TESTS OF EXTINGUISHING PROCESS USING MIST NOZZLES WITH APPLICATION OF HYBRID FIRE MODEL

2016 ◽  
Vol 22 (4) ◽  
pp. 573-583 ◽  
Author(s):  
Jerzy GAŁAJ ◽  
Marek KONECKI ◽  
Ritoldas ŠUKYS
Keyword(s):  
Heat Flux ◽  
Computer Model ◽  
Input Data ◽  
Elementary Cell ◽  
Characteristic Parameters ◽  
Computational Cell ◽  
Fire Model ◽  
Fire Extinguishing ◽  
Unique Approach

The article presents a computer model of the fire extinguishing process using mist nozzles. A previously developed hybrid fire model was used for this purpose. Assumptions and relationships were given to represent a math­ematical model of extinguishing process, which comprises a unique approach to the determination of sprinkling area in an elementary cell of field fire model. A description of simulation tests of the model was given for several different input data, differing by mean diameters of droplets. This enabled a study of their effects on such output parameters as received heat flux, temperature and rate of its growth. For one selected computational cell located on the axis of the nozzle at floor level having the coordinates [10, 10, 1], the obtained results were presented in the form of heat flux and temperature. To simplify the analysis, characteristic parameters of particular curves were listed in the table. Conclusions formulated on the basis of results obtained during tests were specified at the end of work. They confirmed the expected regularity assuming that the extinguishing process was more effective in the case of droplets of a smaller diameter and greater sprinkling intensity. This allows assessing the degree, to which these stream parameters affect the extinguishing effectiveness.

Influence of the Pressure Load in the Efficiency of a Longitudinal Ventilation System in Road Tunnels

2009 ◽  
Author(s):  
Mo´nica Galdo-Vega ◽  
Carlos Santolaria-Morros ◽  
Jesu´s Manuel Ferna´ndez Oro ◽  
Katia Maria Argu¨elles-Di´az
Keyword(s):  
Momentum Transfer ◽  
Ventilation System ◽  
Operating Conditions ◽  
Traffic Density ◽  
Moderate Pressure ◽  
Pressure Gradients ◽  
Operational Parameters ◽  
Satisfactory Description ◽  
Longitudinal Ventilation ◽  
Road Tunnels

The longitudinal ventilation system (LVS) efficiency in road tunnels is conditioned by geometric and operational parameters. Typical geometric parameters are the length of the tunnel, its slope and the transversal section. All these factors are generally fixed and thus not modifiable in the regular operation of the facility. On the other hand, operational parameters, like the working fans layout, the environmental conditions or the traffic density are case-sensitive and susceptible to influence the baseline performance of the ventilation system. In the present study, different pressure gradients, established between inlet and outlet location of the jet fan influence, are analyzed. This static resistance is shown to have a significant impact on the momentum transfer established between the jet expansion and the bulk flow inside the tunnel. For moderate pressure gradients, the jet discharged from fan is relativity well-mixed, allowing to reach uniform flow conditions in the streamwise direction. When the adverse pressure gradients become severe, the high-velocity flow is blocked, unable to mix out in the inter fan spacing and losing spanwise uniformity. At critical conditions, large recirculation areas can be developed within primary flow structures, generating turbulence and important energy losses, and even inducing reverse flow at the tunnel exit. The extreme operating conditions of a longitudinal ventilation system in a road tunnel have been studied using a 3D numerical simulation. Preliminary analysis for grid sensitivity and election of an accurate turbulence closure were performed to guarantee a valuable modeling. Following, systematic computations over a cluster of PC’s were executed using the well-tested Fluent code. RANS modeling with RSM scheme allowed a satisfactory description of three-dimensional vortical structure in the recirculation zones, especially for adverse pressure gradients. At this point, numerical results have provided a comprehensive overview of the mechanism associated to the momentum transfer of the jet expansion, comparing the performance for zero-pressure gradients with those observed for adverse conditions. Also, this paper gives valuable information about practical limits of the LVS, advancing operational conditions that compromise the ventilation efficiency.

scholarly journals Measurements and fire simulation models in road tunnels

2018 ◽  
Vol 196 ◽  
pp. 04077 ◽  
Author(s):  
Peter Danišovič ◽  
Juraj Šrámek ◽  
Michal Hodoň ◽  
Ján Glasa ◽  
Peter Weisenpacher ◽  
...  
Keyword(s):  
Ventilation System ◽  
Simulation Models ◽  
Project Schedule ◽  
Road Tunnel ◽  
Safety Equipment ◽  
In Situ Experiment ◽  
Emergency Event ◽  
Road Tunnels ◽  
Tunnel Safety

Ventilation system of road tunnel is one of the most important parts of the tunnel safety equipment, especially in view of the emergency event in the tunnel with fire. Last year we presented the testing and the first in situ measurements of our project entitled “Models of formation and spread of fire to increase safety of road tunnels”. With regard to our project schedule we performed also the second in situ experiment. Other part of this paper deals with computer simulations of fires of a selected Slovak road tunnel.

scholarly journals An OpenFOAM simulation of the natural ventilation system in a university chemical laboratory

2020 ◽  
Vol 167 ◽  
pp. 04003
Author(s):  
M Córdova-Suárez ◽  
O. Tene-Salazar ◽  
F. Tigre-Ortega ◽  
S. Carrillo-Ríos ◽  
D. Córdova-Suárez ◽  
...  
Keyword(s):  
Working Conditions ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Operating Conditions ◽  
Climate Data ◽  
Chemical Laboratory ◽  
Indoor Airflow ◽  
Air Intake ◽  
Air Speed ◽  
Closed Environment

The indoor airflow with a natural ventilation system was numerically calculated using the laminar and turbulent approach. In the chemical laboratory of the Technical University of Ambato, the computational code OpenFoam demonstrated an ability to numerically predict flow patterns. The design contemplated the natural ventilation system considering the laboratories’ working conditions not only in summer, but also in a winter week. These two operating conditions are calculated on a fully open and closed environment. For a room with a capacity of 20 people, the climate data average values were recorded at 14.0 ° C, 81.7%, 1.7 m /s for temperature, relative humidity, and wind speed, respectively. Furthermore, the demonstration has shown that the homogeneous occupancy air speed average is was 0.7 m / s with a facade air intake of 1.0 m / s 0.6 m / s in the room valid for the exchange of air and evacuation of pollutants. The maximum pressures were found in the lower part of the laboratory. This prevents the modification of the thermo-hygrometric conditions.

scholarly journals Innovative HVAC System Using an Integrated Greenhouse for a Virtual Low Energy Office Building

2019 ◽  
Vol 111 ◽  
pp. 04011
Author(s):  
Catalin Lungu ◽  
Florin Baltaretu
Keyword(s):  
Natural Ventilation ◽  
Energy Use ◽  
Ventilation System ◽  
Office Building ◽  
Treatment Unit ◽  
Heating And Cooling ◽  
Venturi Effect ◽  
Innovative System ◽  
Air Intake ◽  
Air Humidification

In this paper the authors describe a HVAC innovative system using an integrated greenhouse for heating and cooling an office building. The ventilation system allows natural (night) or mechanical ventilation and the passive cooling during the summer, including cold storage in the building structure and the PCM plywood and the refrigeration energy use during the day. Natural ventilation occurs when the wind or the Venturi effect, created by the « hat » that supports the photovoltaic panels, is strong enough; otherwise, a variable speed exhaust fan mounted on top of the building is used. The plants inside the greenhouse can produce O2 under certain conditions necessary for refreshing the ventilation air. The environment of the greenhouse allows air humidification naturally, without the use of humidifiers. If the greenhouse is sufficiently insulated in winter, it can be used in the ventilation process: the air intake from offices through the greenhouse, humidified and enriched in O2 (premixed, if necessary, with fresh air) reaches the general air treatment unit, and then sent back. The process is similar in the summer, but without recirculation, due to the humidity of the air extracted from offices. Stale air humidification enhances the thermal transfer process from the desiccant collector.

scholarly journals Oxygen Distribution and Air Leakage Law in Gob of Working Face of U+L Ventilation System

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Xiaowei Zhai ◽  
Bo Wang ◽  
Shangrong Jiang ◽  
Weixia Zhang
Keyword(s):  
Oxygen Concentration ◽  
Spontaneous Combustion ◽  
Ventilation System ◽  
Burial Depth ◽  
Air Leakage ◽  
Coal Spontaneous Combustion ◽  
Working Face ◽  
Air Intake ◽  
And Control ◽  
The Relationship

In order to prevent and control coal spontaneous combustion effectively in the gob of U+L working face, the 30105 working face of Hanglaiwan mine was taken as the research object. The relationship models between oxygen concentration and burial depth of the two tunnels in the gob of U+L working face were established. The distribution of oxygen in the gob of the working face of U+L ventilation system was studied by field observation combined with numerical simulation. The results show that the air leakage in the gob is serious. There are a number of fluctuation areas where the oxygen concentration first decreases and then increases in the air intake side of the gob. The oxygen concentration peaked at 100m, 175m, and 245m, respectively, from the intake side of the gob. In the same position of the gob depth, the air leakage intensity on the intake side is generally higher than that on the return side, and the oxygen concentration on the intake side of the gob is slower than the return side. Oxygen concentration maintains at 5.09% when the depth of gob reaches 400m. Measures to prevent coal spontaneous combustion should be strengthened in the air intake side.

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