Comparison of k-ε models in gaseous release and dispersion simulations using the CFD code FLACS

Moen, Alexander; Mauri, Lorenzo; Narasimhamurthy, Vagesh D.

doi:10.1016/j.psep.2019.08.016

Cited by 76 publications

(19 citation statements)

References 26 publications

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“…The grid-based resolution in FLACS, unlike other commercial simulation tools, relies on the so-called porosity/distributed resistance (PDR), where sub-grid geometry is represented as area and volume porosities (denoting the degree of "openness" for each grid cell), instead of resolving individual obstacles by a grid. Moen, A. et al [27] conducted a comparative study of k-ε models in impinging hydrogen jet dispersion scenarios using the CFD code FLACS. The simulation results were compared with the Schlieren photographs from experiments in Reference [28].…”

Section: Flacs-hydrogen Codementioning

confidence: 99%

Numerical Simulation of Hydrogen Leakage from Fuel Cell Vehicle in an Outdoor Parking Garage

Shen

Zheng

et al. 2021

WEVJ

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It is significant to assess the hydrogen safety of fuel cell vehicles (FCVs) in parking garages with a rapidly increased number of FCVs. In the present work, a Flame Acceleration Simulator (FLACS), a computational fluid dynamics (CFD) module using finite element calculation, was utilized to predict the dispersion process of flammable hydrogen clouds, which was performed by hydrogen leakage from a fuel cell vehicle in an outdoor parking garage. The effect of leakage diameter (2 mm, 3 mm, and 4 mm) and parking configurations (vertical and parallel parking) on the formation of flammable clouds with a range of 4–75% by volume was considered. The emission was assumed to be directed downwards from a Thermally Activated Pressure Relief Device (TPRD) of a 70 MPa storage tank. The results show that the 0.7 m parking space stipulated by the current regulations is less than the safety space of fuel cell vehicles. Compared with a vertical parking configuration, it is safer to park FCVs in parallel. It was also shown that release through a large TPRD orifice should be avoided, as the proportion of the larger hydrogen concentration in the whole flammable domain is prone to more accidental severe consequences, such as overpressure.

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Section: Flacs-hydrogen Codementioning

confidence: 99%

Numerical Simulation of Hydrogen Leakage from Fuel Cell Vehicle in an Outdoor Parking Garage

Shen

Zheng

et al. 2021

WEVJ

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“…m lv represents the interphase mass transfer rate. Previous studies have shown that the Realizable k-ε model has good applicability for the numerical simulation of dense-phase gas-releases [21,22]. Therefore, the turbulence model was set as the Realizable k-ε model in this study.…”

Section: Governing Equations and Boundary Conditionsmentioning

confidence: 99%

Numerical Study on Flow and Release Characteristics of Gas Extinguishing Agent under Different Filling Pressure and Amount Conditions

Pan

et al. 2021

Processes

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The fire-extinguishing system is an indispensable fire-protection facility on the aircraft. In order to guide weight reduction of the aircraft’s fixed gas fire-extinguishing system by improving its release efficiency, so as to improve fuel economy and reduce carbon emissions, the influence of filling pressures and filling amounts on the release efficiency of gas extinguishing agent along pipelines were studied based on numerical simulations. The release process of the fire-extinguishing system was analyzed. The effects of the filling pressure and filling amount of Halon 1301 agent on the release characteristics, such as release time, mass flow rate, and gasification ratio, were studied. Results show that the release process can be divided into three major phases, which are firstly the initial rapid filling of the pipeline, secondly the concentrated release of the liquid extinguishing agent, and thirdly the gas ejection along the pipeline. The second phase can also be subdivided into two stages: the outflow of the liquid extinguishing agent from the bottle, and the release of the residual liquid extinguishing agent along the pipeline. The release characteristics of the fire-extinguishing agent were obviously affected by the filling pressures and filling amounts. When the filling pressure was relatively low (2.832 MPa), increasing the filling pressure can significantly increase the mass flow rate, shorten the release time, and reduce the gasification ratio of the extinguishing agent during the release processes. Under the same filling pressure, with the increase of the filling amount of the extinguishing agent, the release times and the gasification ratio showed a linear increase trend, while the average mass flow rates showed a linear decrease trend.

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“…There are many methods to assess the impact of an explosion, such as the Multi-energy method, the TNT equivalent method, the Baker-Strehlow method, and CFD simulations. (van den Berg and Lannoy, 1993;Qiao and Zhang, 2010;Qi et al, 2019;Chen et al, 2020;Zhang et al, 2020;Horvat, 2018;Moen et al, 2019). The multi-energy method is widely used in the two-dimensional model, which comprehensively considers the turbulence acceleration and gas activity.…”

Section: Introductionmentioning

confidence: 99%

Towards limiting potential domino effects from single flammable substance release in chemical complexes by risk-based shut down of critical nearby process units

Sun

Wang

Yang

et al. 2021

Process Safety and Environmental Protection

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The explosion load is a significant escalation factor possibly influencing the potential occurrence of domino accidents in chemical plants. It is not economical to install explosion isolation systems (e.g., extinguishing barrier) for all equipment or process units across a chemical plant. Although shutting down all equipment or process unit can prevent an explosion, it may also cause further economic losses. To prevent domino accidents, the process unit that needs to be shut down accurately should be selected, and the normal operation of other units needs to be ensured. A method to select the process unit to be isolated based on the Dimensioning Accidental Load (DAL) is proposed. By calculating the occurrence probability and consequences of the accident scenarios, the DAL of the surrounding units is determined. DAL is used as the impact intensity of the accident unit on the surrounding units. The probit model is used to calculate the damage probability of surrounding units. The case analysis results show that the method of selecting the process unit to be isolated based on DAL quantifies the impact intensity of the exploded unit on surrounding units from probability and consequence. Under the premise of meeting the acceptable risk criteria, the method can determine which units should be shut down and which units can operate normally when a release accident occurs. While preventing domino accidents, economic losses caused by the shutdown of all process units are reduced and a theoretical basis for accident prevention and safe operation of the plant is provided.

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Comparison of k-ε models in gaseous release and dispersion simulations using the CFD code FLACS

Cited by 76 publications

References 26 publications

Numerical Simulation of Hydrogen Leakage from Fuel Cell Vehicle in an Outdoor Parking Garage

Numerical Simulation of Hydrogen Leakage from Fuel Cell Vehicle in an Outdoor Parking Garage

Numerical Study on Flow and Release Characteristics of Gas Extinguishing Agent under Different Filling Pressure and Amount Conditions

Towards limiting potential domino effects from single flammable substance release in chemical complexes by risk-based shut down of critical nearby process units

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