Designing a compact thermal air steriliser with recirculation for improved indoor environmental quality: Experimentation, modelling and simulation

Given the past various airborne viral infections like SARS-CoV-2, Nipah and tuberculosis, many different types of air sterilisers were developed. One less persuasive method is the dry-heating method's thermal deactivation of viruses and bacteria. Some clues were obtained from a literature search: many viruses can be deactivated by heating air to 60°C or above for a few seconds. This work uses a thermal air steriliser with wall heating and recycling features. A prototype has been developed, and its start-up time and fluctuations in long-term operation were studied. Simulation studies were also carried out using COMSOL Multiphysics software to identify the dead zones and high and low temperature zones in the recycle chambers of the apparatus. Optimum parameters were determined for the effective functioning of this air steriliser. The parameters obtained match the data received from the experimental study. The prototype for microbial deactivation was checked by measuring the optical density of the reagent medium containing outlet air from the prototype, and it indicated a microbial level of 0.001 units against two units for room air.