Active Versus Passive Flow Control in UVC FILTERs for COVID-19 Containment.

Ultraviolet radiation as a germicide is widely used in the health field and even in domestic hygiene. Here, we propose an improvement in low-cost portable units of filtration for indoor air, which is based on ultraviolet radiation. In the current technology, to carry out an air filtration with a suspension of aerosols in which there is a likely concentration of pathogens, whether viral, bacterial or molds, the air is forced to pass as close as possible to the ionizing radiation source (near field). Since the optical mass is very small, the desired effect can be achieved in a considerably short time, deactivating the infective potential of these biological agents. The proposal of this work is the regulation of the flow or speed control of passage through these filters by passive elements instead of by electronic control systems. For this, two devices have been designed, simulated, and built, obtaining similar net pathogen inactivation rates under different flow rates. The passive flow control device has demonstrated higher performance in terms of flow rate and lower cost of production since they do not require electronics and are produced with fewer diodes. This passive device has also shown a lower projection of maintenance cost, lower energy consumption rate (higher efficiency), and longer projection of useful life.