Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
An Approximate Dispersion Model of Nitrogen Compounds in the Atmosphere with Chemical Reaction
Submission Author:
Edson Chiaramonte , RS
Co-Authors:
Edson Chiaramonte, Renato Letizia Garcia, sergio meth
Presenter: Edson Chiaramonte
doi://10.26678/ABCM.COBEM2023.COB2023-1034
Abstract
The dispersion of chemical compounds emitted into the atmosphere from point sources has drawn the attention of states and society. The release into the atmosphere of nitrogen compounds (NOx) and volatile organic compounds (VOC) in the presence of solar radiation generates the so-called photochemical smog. The development of a dispersion estimation model that represents different emission scenarios (for example, an industrial source, or an urban scenario with vehicular emissions) is the objective of this work. This model would be very useful to evaluate the consequences of atmospheric pollution. This work presents an approximate model that describes the dispersion of compounds emitted from a chimney of a thermoelectric power plant. It estimates the mixture of gases emitted by the chimney. The model uses the method of combining a series of “puffs” in the form of a rectangular prism, with homogeneous concentration (box models). The “puffs” are released with a constant displacement time. Advection and dispersion phenomena are separated from chemical reaction mechanisms at each displacement time. The model, which estimates the phenomena of advection and diffusion, uses an analytical solution of the diffusion equation, for the total amount of emitted mass. This model estimates the dilution of the “puff”, by the atmospheric air, at each displacement time. Diffusion coefficients are estimated from atmospheric parameters. In this work, a set of chemical reactions is presented only for Nitrogen compounds (NOx), which produce Ozone gas by photochemical reactions in the lower atmosphere. This set of chemical reactions generates a system of coupled ordinary equations for the concentrations of the components. The work shows a comparison between the numerical solution model of the system and an analytical solution model that makes a first order approximation for each ordinary equation for the concentration component. The results of this comparison are presented for a day of high solar radiation and unstable atmosphere. For this dispersion situation, the approximate model showed a result close to the numerical model and a much shorter processing time.
Keywords
atmospheric dispersion, Chemical Reaction, box models
