INFLUENCE OF THE DESIGN AND OPERATIONAL CONDITIONS ON THE AIRFLOW AND MASS TRANSFER PHENOMENA INSIDE A PORTABLE WIND TUNNEL USED TO ESTIMATE ODORANT COMPOUNDS MEASURED OVER PASSIVE LIQUID SURFACES

Name: Matheus de Araújo Siqueira
Type: PhD thesis
Publication date: 29/08/2022
Advisor:

Namesort descending Role
Bruno Furieri Co-advisor *

Examining board:

Namesort descending Role
Bruno Furieri Co advisor *
Igor Braga de Paula External Examiner *
Jane Meri Santos Advisor *
Neyval Costa Reis Jr. Internal Examiner *

Summary: The emissions to the atmosphere by liquid passive area sources, that is, extensive
liquid surfaces swept by the atmospheric flow in which occurs the emission of a certain
chemical, like the tanks and lagoons in wastewater treatment plants are significative
sources of odorant compounds, such as the H2S and the acetic acid. The health effects
of these gaseous compounds include eye and throat irritation, and nausea. Different
equipments are being used to perform a direct estimation of the emission of the odorant
compound on passive surfaces. However, it is well known in the literature that the
use of different equipments for the same source is conducing to different estimation
results. In general, these equipments are open-bottomed boxes in which is fluxed a
clean gas in its inside that enters in contact with the gas-liquid interface and carries
the odorant compound, to be posterior sampled at the equipment outlet and analyzed.
Thereafter, the results provided by these equipments are straightly connected with the
airflow and mass transfer phenomena on its inside. So, to properly assist the answer
of the question of which equipment is more adequated to estimate the emission rate
of an odorant compound in passive area sources it is first required to understand the
airflow and how the mass transfer phenomena occur on its inside occurs. In this way,
the present work objectives to analyze, using numerical simulations, the airflow and
mass transfer phenomena inside one the of equipments used in the direct estimative
of odorant compounds, namely the portable wind tunnel. The turbulent effects were
incorporated using the κ −ω SST model. The finite volume method was used via the
ANSYS Fluent software to numerically solve the involved equations. The analysis of
the streamlines, profiles, vectors, and contours of the velocity, turbulent kinetic energy,
and concentration showed that the flow inside the device is quite complex and 3D, with
several recirculation zones and thus reversed flow. This feature of the flow have a direct
impact on the volatilization process. Nevertheless, the results showed that the geometry
configuration of the equipment has a direct impact on the airflow and thus on its mass
transfer phenomena, in this way, it seems that small changes in its geometry could lead
to an improvement of the flow in its inside.

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