Experimental and CFD Simulations of the Aerosol Flow in the Air Ventilating the Underground Excavation in Terms of SARS-CoV-2 Transmission

Tomasz Janoszek,Jerzy Jaroszewicz,Andrzej Walentek,Zbigniew Lubosik,Lucjan Świerczek

doi:10.3390/en14164743

Tomasz Janoszek, Jerzy Jaroszewicz + Show 3 more

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https://doi.org/10.3390/en14164743

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Journal: Energies	Publication Date: Aug 4, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: Central Mining Institute, Medical University of Silesia

Abstract

The paper presents the results of experimental and model tests of transport of dispersed fluid droplets forming a cloud of aerosol in a stream of air ventilating a selected section of the underground excavation. The excavation selected for testing is part of the ventilation network of the Experimental Mine Barbara of the Central Mining Institute. For given environmental conditions, such as temperature, pressure, relative humidity, and velocity of air, the distribution of aerosol droplet changes in the mixture of air and water vapor along the excavation at a distance was measured at 10 m, 25 m, and 50 m from the source of its emission. The source of aerosol emission in the excavation space was a water nozzle that was located 25 m from the inlet (inlet) of the excavation. The obtained results of in situ tests were related to the results of numerical calculations using computational fluid dynamics (CFD). Numerical calculations were performed using Ansys-Fluent and Ansys-CFX software. The dimensions and geometry of the excavation under investigation are presented. The authors describe the adopted assumptions and conditions for the numerical model and discuss the results of the numerical solution.

Highlights

The COVID-19 pandemic has resulted in the long-term lockdown of people all over the world
The results of numerical simulations of the aerosol transport process carried out for a specific value of the air stream flowing through the analyzed section of the underground excavation are presented below
120,000 nm); Air density: 1.2 kgm−3 ; Gravity: 9.81 ms−2 ; Turbulence model: k-ε; Heat transfer model for particles; Air heat transfer model; Particle coupling model, i.e., the mixture of air and water vapor acts on the aerosol and the aerosol acts on the mixture; Friction force at the air/aerosol interface; Aerosol velocity injection—150 ms−1 ; Droplets were evaporated in a stream of air; Average temperature of the injected aerosol: 12 ◦ C; The number of droplets of each aerosol: 100 drops per second; Average relevant humidity: 86%; Average pressure: 97,800 Pa

Summary

Introduction

The COVID-19 pandemic has resulted in the long-term lockdown of people all over the world. Organization (WHO), including governments, have ordered people to keep a so-called social distance of approximately 2 m from each other in order to minimize the risk of infection with SARS-CoV-2, which is mainly spread through nose and mouth droplets. Based on the available literature and observations, it is likely that small particles containing the virus can be transported in the external environment at a considerable distance from the sources of emission, which is a type of aerosol transfer [1,2,3,4] It is not well researched whether the movements of air masses, humidity, and temperature will cause the droplets of the fluid to be transported further with the air over long distances and cause the social distancing policy to be insufficient. This problem largely affects the mining sector, where a complex network of underground excavations creates complex airflow paths

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