Global and local sensitivity analysis of the Emission Dispersion Model input parameters

PurposeThe objectives of this paper are the application of sensitivity analysis (SA) methods in atmospheric dispersion modeling to the emission dispersion model (EDM) to study the prediction of atmospheric dispersion of NO2 generated by an industrial fire, whose results are useful for fire safety applications. The EDM is used to predict the level concentration of nitrogen dioxide (NO2) emitted by an industrial fire in a plant located in an industrial region site in Algeria.Design/methodology/approachThe SA was defined for the following input parameters: wind speed, NO2 emission rate and viscosity and diffusivity coefficients by simulating the air quality impacts of fire on an industrial area. Two SA methods are used: a local SA by using a one at a time technique and a global SA, for which correlation analysis was conducted on the EDM using the standardized regression coefficient.FindingsThe study demonstrates that, under ordinary weather conditions and for the fields near to the fire, the NO2 initial concentration has the most influence on the predicted NO2 levels than any other model input. Whereas, for the far field, the initial concentration and the wind speed have the most impact on the NO2 concentration estimation.Originality/valueThe study shows that an effective decision-making process should not be only based on the mean values, but it should, in particular, consider the upper bound plume concentration.

Risk Index Method—A Tool for Building Fire Safety Assessments

The use of fire safety engineering and performance-based techniques continues to grow in prominence as building design becomes more ambitious, increasing complexity. National fire safety enforcement agencies are tasked with evaluating and approving the resulting fire strategies, which have similarly continued to become more advanced and specialist. To assist with the evaluation of fire strategies, this paper introduces a methodology dedicated to sustainable building fire safety level simulations. The methodology derives from ideas originally introduced in British Standard Specification PAS 911 in 2007 and combines a visual representation of fire strategies with a semi-quantitative approach to allow for their evaluation. The concept can be applied to a range of industrial fire safety assessments and can be modified for specific needs relative to different industries.

River Breezes in the Central Amazon: Cluster Analysis of Meteorological and Chemical Data Sets Collected by an Unmanned Aerial Vehicle

<p>Local atmospheric circulation induced by wide rivers in Amazonia can strongly affect the transport of urban, industrial, fire, and forest emissions. Herein, a copter-type unmanned aerial vehicle (UAV) operated from a boat was used to collect vertical profiles of meteorological parameters and chemical concentrations during Sep-Oct 2019 of the dry season. Sensor packages mounted on the UAV measured wind speed and direction together with concentrations of carbon monoxide (CO) and total oxidants (O<sub>x</sub>, defined as O<sub>3</sub> + NO<sub>2</sub>). Multivariate statistical analysis identified distinguishing patterns for meteorological variables. The occurrence of river breeze circulations was linked to meteorological conditions from in-situ measurement and satellite images. Vertical profiles of chemical concentrations both from in-situ measurements and large eddy simulations confirmed that under some conditions a river breeze can facilitate pollutant mixing perpendicular to the river orientation. The results of this study advance an urgent need to quantify the occurrence and the properties of river breeze circulations in respect to microscale chemical dispersion, air quality, and human health.</p>

Numerical Study of Spray-Induced Turbulence Using Industrial Fire-Mitigation Nozzles

A numerical investigation of the spray-induced turbulence generated from industrial spray nozzles is carried out to better understand the roles of the nozzle spray on the fires or explosions in different accidental scenarios. Numerical simulations are first validated against experimental data in the single nozzle case using the monodisperse and polydisperse assumption for droplet diameters. The polydispersion of the nozzle spray is proven to be necessary to correctly predict the gas and droplet velocities. The turbulent kinetic energy has dominant values inside the spray cone, decreases rapidly with the vertical distance from the spray nozzle, and is strongly affected by the spray droplet diameter. On the contrary, the integral length scale is found to have high values outside the spray cone. Two interacting sprays injected from different nozzles are then investigated numerically using the validated polydisperse model. The water sprays generated from such industrial nozzles can generate turbulence of high intensity in the near-nozzle region, and this intensity decreases with the distance from the nozzles. A better understanding of the turbulence generated by the spray system can be beneficial for the evaluation of several important phenomena such as explosion enhancement. The guideline values obtained from this investigation of single and double nozzles can be useful for large-scale numerical simulations.