Numerical Evaluation of the Efficiency of an Indoor Air Cleaner under Different Heating Conditions

Abstract

For an efficient indoor air purification, it is important to know the detailed airflow distribution in the room. A series of numerical simulations are carried out for five heating regimes using an air–air heat pump, capillary mat on the ceiling, capillary mat on the walls, heated floor, and radiator. The most homogeneous temperature field is obtained for the case with the heated floor. The highest velocity is obtained for the air–air heat pump, while the lowest is obtained for the capillary mat on the ceiling. A portable air cleaner based on the prototype device is introduced into the model and its influence on the velocity and temperature distributions is calculated. Our simulations additionally consider is the transport of an infectious aerosol and its purification inside the air cleaner. The time dependency of the concentration is exponential, and the purification rate depends on the air cleaner’s orientation and heating regime. The efficiency is higher for a purifier with flow in the upwards direction compared to in a horizontal one. In the experimental part, an NaCl solution is dispersed into the air, and the efficiency of purification in the case of the air–air heat pump is evaluated by measuring the time-dependent particle concentrations. These experimental results corroborate the numerical model.

Computational Fluid Dynamics-Based Calculation of Aerosol Transport in a Classroom with Window Ventilation, Mechanical Ventilation and Mobile Air Purifier

“…Based on the transient observations presented so far, we can derive several correlations and interactions between various effects discussed in this section. Our results mainly confirm the findings of investigations conducted by other authors (see [14][15][16][17][18]21,22]), we also show that an air purifier leads to a significant reduction in the aerosol concentration in the room air. We extend the existing knowledge by highlighting the additional impact of transient, intermittent window ventilation.…”

“…They observed an overall reduction in the infection risk in all investigated scenarios where the air purifier was active, although zones with high local concentrations were found. Assuming different heating settings in a small chamber, Sabanskis et al [16] confirmed the strong sensitivity of the filtering efficiency of a mobile air purifier to the positions of both the aerosol source and the filtration device. Duill et al [17] conducted a thorough study to investigate a classroom setting using different air purifier types, with one type operated at two different locations.…”

Evaluation of Surrogate Aerosol Experiments to Predict Spreading and Removal of Virus-Laden Aerosols

“…However, if this is not feasible, Küpper et al showed that placing APs in the corner of a room is still effective if there is no disturbance for the air flow at the intake and outlet [37]. Aerosol spreading has also been described numerically to spatially resolve aerosol spreading, i.e., for a more precise evaluation of room mixing, prediction of infection risk, or the optimized positioning of filtering devices [38][39][40][41][42][43]. Most of these considerations mainly cover unsteady situations.…”