scholarly journals A Numerical Study for Assessing the Risk Reduction Using an Emergency Vehicle Equipped with a Micronized Water System for Contrasting the Fire Growth Phase in Road Tunnels

2021 ◽  
Vol 11 (11) ◽  
pp. 5248
Author(s):  
Ciro Caliendo ◽  
Gianluca Genovese ◽  
Isidoro Russo
Keyword(s):  
Growth Phase ◽  
Numerical Study ◽  
Probabilistic Approach ◽  
Water System ◽  
Safety Measure ◽  
Cfd Modeling ◽  
Emergency Vehicle ◽  
Fire Growth ◽  
Short Period ◽  
Road Tunnels

We performed Computational Fluid Dynamics (CFD) modeling, and simulated a people evacuation process from a tunnel in the event of a fire, for evaluating the potentialities of using, as a temporary safety measure, an emergency vehicle equipped with a micronized water system for contrasting the fire growth phase. The structure investigated is a one-way road tunnel with only natural ventilation, and with a length less than 1000 m. The tunnel is assumed at present to be affected by refurbishment works for making it comply with the minimum safety requirements of the European Directive 2004/54/EC. In particular, it is considered that it has not yet been provided with hydrants, and with the sidewalks and the emergency exit which are still under construction. This means that users are forced to use the road carriageway for escaping from the tunnel if a fire occurs. The CFD findings have shown that the use of the micronized water system might lead to a significant improvement in the environmental conditions along the escape route since the tenability limits of temperature, radiant heat flux, CO and CO2 concentration were found to be better satisfied. Additionally, the visibility distance was shown to increase, even though it was found to be higher than the acceptable threshold value only in a few cases. However, the quantitative risk analysis based on a probabilistic approach, which was combined with a method currently used in Europe for assessing the risk due to the transit of only dangerous goods, shows that the final cumulative F-N curves related to the micronized water system always lie below those without the mentioned system, and in addition, they are always contained within the limits of the ALARP region. It is to be stressed that our paper might represent a reference in showing the effectiveness of the micronized water system as a temporary safety measure. However, it is desirable that the Tunnel Management Agencies accelerate the refurbishment works for making road tunnels definitively safer for users in a short period of time.

scholarly journals Kinetic control on the distribution of secondary precipitates during CO2-basalt interactions

2019 ◽  
Vol 98 ◽  
pp. 04006 ◽  
Author(s):  
Helge Hellevang ◽  
Domenik Wolff-Boenisch ◽  
Mohammad Nooraiepour
Keyword(s):  
Spatial Distribution ◽  
Crystal Growth ◽  
Numerical Study ◽  
Numerical Models ◽  
Probabilistic Approach ◽  
Kinetic Control ◽  
Secondary Mineral ◽  
Mineral Growth ◽  
Secondary Precipitates ◽  
Overall Kinetics

A combined experimental and numerical study was undertaken to better understand the spatial distribution of secondary mineral growth along a basalt column. The work demonstrated that few and large crystals formed at random locations. This can only be explained in terms of an overall control by mineral nucleation. The main implication is that a new probabilistic approach must be developed in order to get the overall kinetics and the distribution of crystal growth in the numerical models right.

Numerical Study of Smoke Control for Underground Platform in a High-Speed Railway Station

2012 ◽  
Vol 256-259 ◽  
pp. 2803-2812 ◽  
Author(s):  
Hua Yang ◽  
Richard Yuen ◽  
He Ping Zhang
Keyword(s):  
Urban Space ◽  
High Speed ◽  
Numerical Study ◽  
Exhaust System ◽  
Cfd Modeling ◽  
Smoke Control ◽  
Railway Station ◽  
High Speed Railway ◽  
Fire Engineering ◽  
Smoke Spread

Smoke control for the underground platform of a high-speed railway station was investigated. Nowadays, the development of high-speed railway in China is rapid. In order to economize valuable urban space and to realize the convenient interchange to the subway, some of the high-speed railway station platforms and transfer halls are set underground. It is difficult and uneconomic to achieve static ventilation in the underground platform. Therefore, The mechanical smoke control system is the most feasible and most reliable method to ensure the fire safety of the underground platform. How to protect the evacuation stairs free from the threat of fire-induced smoke is a major concern of smoke control in the underground platform. An underground island platform and underground waiting and transfer halls of an under construct high-speed railway station in south China are reconstructed in this paper. Three smoke control modes based on mechanical ventilation, namely mechanical air makeup, pressurized air supply for stairwell and air curtain, are numerically simulated by Computational Fluid Dynamics (CFD) method. The distribution of smoke, temperature, and CO in the platform and influences of them on evacuation staircases are computed and analyzed. The effect of fire location in smoke spread are explored in our research. This study based on CFD modeling enables the improvement of the design and operation of smoke control and exhaust system for underground high-speed railway station. The results are applicable to practical fire engineering designs for underground high-speed railway station platform.

scholarly journals Evaluation of Yangon city tap water quality and the efficacy of household treatment

2021 ◽  
Author(s):  
Shane Htet Ko ◽  
Hiroshi Sakai
Keyword(s):  
Water Quality ◽  
Tap Water ◽  
Water System ◽  
Central Business District ◽  
Quality Standard ◽  
Bottled Water ◽  
Coliform Bacteria ◽  
Carbon Reduction ◽  
E Coli ◽  
Short Period

Abstract Yangon was one of the first cities in Asia to establish a tap water system. However, the city's water supply infrastructure now lags far behind those of other regions as a consequence of political instability over the last six decades. The installation of disinfection facilities in the tap water system and the enactment of the Myanmar National Drinking Water Quality Standard (MNDWQS) were accomplished only recently during the short period of democratic government. Due to the lack of reliable published information, the suitability of the tap water for drinking remains unclear to city residents. The quality of tap water and bottled water in the central business district was examined to assess compliance with the MNDWQS. The results showed that 95% of tap water delivered to homes was contaminated with Escherichia coli or coliform bacteria. Only 14% of bottled water was free of E. coli and coliform contamination. The efficacy of household treatment devices was tested, and ceramic purifiers (CPs) and reverse osmosis (RO) devices were found to be highly (>99%) effective for E. coli elimination. RO devices performed better in terms of dissolved organic carbon reduction at 60% compared with 43% reduction with CPs.

THERMAL-WAVE PROPAGATION PHENOMENON IN THIN FILMS HEATED WITH LASER HEAT SOURCE

2004 ◽  
Vol 04 (04) ◽  
pp. 435-445 ◽  
Author(s):  
SHUICHI TORII ◽  
WEN-JEI YANG
Keyword(s):  
Thin Film ◽  
Heat Source ◽  
Thermal Wave ◽  
Numerical Study ◽  
Numerical Technique ◽  
Internal Heat ◽  
Time History ◽  
Internal Heat Source ◽  
Hyperbolic Heat Conduction ◽  
Short Period

A numerical study is performed on the effect of laser radiation on the propagation phenomenon of a thermal wave in a very thin film subjected to a symmetrical heating on both sides. Laser heating is modelled as an internal heat source. The non-Fourier, hyperbolic heat conduction equation is solved by a numerical technique based on MacCormack's predictor-corrector scheme. Consideration is given to the time history of heat transfer behaviour before and after symmetrical collision of wave fronts from two sides of a film. It is disclosed that (i) if the absorption coefficient of the laser increases, temperature overshoot causes in a very thin film within a very short period of time, and (ii) the overshoot and oscillation of thermal wave depend on the frequency of the heat source time characteristics. This trend becomes minor in a thick film.

Structural Modification of a Power Plant’s River Water Intake to Minimize Ice Blockage

2013 ◽  
Author(s):  
Frank Michell ◽  
Marcela Politano ◽  
Jeffrey Stallings ◽  
Yushi Wang
Keyword(s):  
Water Intake ◽  
Cooling System ◽  
Numerical Study ◽  
Water System ◽  
Warm Water ◽  
Mitigation Measures ◽  
Second Phase ◽  
Sediment Control ◽  
Circulating Water ◽  
Ice Accumulation

Ice blockage of a power plant’s water intake is of paramount importance since it can lead to an unplanned shutdown of the intake compromising water supply and plant operation. American Electric Power’s (AEP) Conesville Power Plant historically controlled ice accumulation at the river intake by routing to the intake a portion of the warm water return from the condenser on the only operating “once-through” unit’s circulating water system. The unit operating with this once-through cooling system was retired at the end of 2012; thus, the plant lost the use of the condenser outlet/warm water return deicing flow at the river intake. A numerical study was conducted to evaluate design alternatives to alleviate ice accumulation at the river intake. A numerical model to predict the ice transport and accumulation at the river intake was developed and used to understand the main phenomenon leading to intake blockage. The effectiveness of mitigation measures was evaluated with the model. A mitigation plan consisting of intake modifications to be implemented during several phases is presented. In the first phase, large pipe openings are cut in the walls separating intake pump wells of previously retired units at the facility. In the second phase, a number of sediment control vanes previously placed in front of the intake are removed to facilitate downstream ice transport. A third phase, if needed to be implemented, involves removing additional sedimentation control vanes and cutting holes in the pump wells on the operating units. The paper describes the model, discusses numerical results and presents the field experience after implementation of phase one.

A short period oscillation in a water/oil/water system

1991 ◽  
Vol 40 (2) ◽  
pp. 149-153 ◽  
Author(s):  
Hitoshi Suzuki ◽  
Yoshimi Tsuchiya ◽  
Tatsuyuki Kawakubo
Keyword(s):  
Water System ◽  
Short Period ◽  
Period Oscillation ◽  
Oil Water

A Numerical Study for the Solution of Time Fractional Nonlinear Shallow Water Equation in Oceans

2013 ◽  
Vol 68 (8-9) ◽  
pp. 547-553 ◽  
Author(s):  
Sunil Kumar
Keyword(s):  
Analytical Solution ◽  
Shallow Water ◽  
Homotopy Perturbation Method ◽  
Numerical Study ◽  
Shallow Water Equation ◽  
Water System ◽  
General Characteristic ◽  
Convergent Series ◽  
Shallow Water Flows ◽  
Shallow Water System

In this paper, an analytical solution for the coupled one-dimensional time fractional nonlinear shallow water system is obtained by using the homotopy perturbation method (HPM). The shallow water equations are a system of partial differential equations governing fluid flow in the oceans (sometimes), coastal regions (usually), estuaries (almost always), rivers and channels (almost always). The general characteristic of shallow water flows is that the vertical dimension is much smaller than the typical horizontal scale. This method gives an analytical solution in the form of a convergent series with easily computable components, requiring no linearization or small perturbation. A very satisfactory approximate solution of the system with accuracy of the order 10-4 is obtained by truncating the HPM solution series at level six.

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