Analysis of Virus Sanitization Alternatives and Optimization of a Thermal Air Purifier for SARS-CoV-2

Abstract

Air sanitization acquired renewed interest during the COVID-19 outbreak, especially in hospital rooms and intensive care units. In this work, mathematical analysis was done of the convenience of sanitizing the air of whole rooms or personalized isolation tents. Centralized air sanitization was found to have low effectiveness due to three reasons: 1) the constant virus emission from patients; 2) the practical upper limits of air recycle flowrates; 3) the low value of the minimum infective dose of SARS-CoV-2. Personalized air sanitization was the best option. Virus inactivation by thermal effect was then revisited, and a steady-state model was formulated for an efficient and personalized thermal sterilizer. An analytical solution was obtained for temperature and virus concentration in different parts of the sterilizer. Cell temperature was found to be the main variable for sterilization due to the Arrhenius-like form of the kinetic constant of virus deactivation. An objective cost function was written and subjected to conditions of minimum patient ventilation rate and minimum virus removal effectiveness. Numerical optimization gave an optimal design with the intrinsic advantages of thermal sanitization, i.e., simplicity, robustness, minimum maintenance and high sanitization rate.