Experimental assessment of low temperature plasma devices for bacterial aerosol inactivation in the air duct of HVAC systems

In light of growing concerns about indoor air quality and the transmission of pathogens, this study aims to evaluate the effectiveness of low temperature plasma (LTP) devices in inactivating bacterial aerosols in the air duct of HVAC systems, exploring methods to enhance air purification efficiency. This research employed experimental methods to explore the deactivation effects of LTP on common bacteria such as E. coli and Bacillus subtilis, focusing on the role of air parameters such as the airflow rate, relative humidity, and temperature in influencing the device's performance. Notably, the study determined that an operational voltage of 3000 V for the LTP device, combined with conditions of low airflow, low humidity, and high temperature, significantly enhances the inactivation of bacterial aerosols, achieving an 82% inactivation rate at a negative ion concentration of 2.4 × 1011 ions per m3 and a wind speed of 3 m s-1. Despite the generation of ozone and ultraviolet light as by-products, their concentrations were found to be within safe limits for human exposure. In addition, this study identified an effective inactivation range, alongside an optimal arrangement for the airflow direction within ducts, to maximize the sterilization efficiency of the LTP device. Given these promising results, the study advocates for the integration of LTP technology into the air duct of HVAC systems of public buildings to improve air quality and reduce the risk of airborne disease transmission.