An Interactive Biological Contaminant and CO₂ Exposure Dose Calculation Tool

Univ Coimbra, ADAI, Department of Mechanical Engineering, Rua Luís Reis Santos, Pólo II, 3030-788 Coimbra, Portugal

Abstract

An interactive computational tool based upon the differential equation modeling the time evolutions of the concentrations of both CO2 and a bio contaminant in an indoor uni-zone compartment was developed to support teaching and training activities during the COVID-19 pandemic. It uses the finite differences formulation, calculating the concentration change along equally spaced sampling time instants. The calculation tool has been developed in the LabView programming software, benefitting from its good graphical display tools. It was designed to allow the change of the governing parameters during the simulation of cases, allowing an immediate perception of the effect of the introduced changes. It takes into account the impact of the following variables: emission rate of bio contaminant source, half-life time of bio contaminant, efficiency of protective mask wearied by the emitter, efficiency of protective mask worn by the receiver, fresh air flow rate, volume of the room, number of occupants in the room and respective corpulence data and metabolic rate, flow rate of an indoor installed air cleaner device and individual one-pass purification efficiency. For a previously defined duration running test, the tool displays the time evolutions of the concentrations of CO2 and the bio contaminant and the time history of the dose inhaled by a receiver with and without a protective mask. The results presented in the paper refer to a parametric study where the air exchange rate, the use of protective masks, and an air cleaning device were changed in a typical classroom with 20 occupants.