The mass balance equation is utilized for theoretical analysis and experimental verification of the indoor PM2.5 concentration within residential buildings equipped with air cleaners. This study delves into the impact of various factors such as the positioning of air cleaners, Clean Air Delivery Rate (CADR), and the volume of the room on the non-uniform mixing model of air purification systems through meticulously designed experiments. Furthermore, an exponential function relationship between Effective Air Cleaning Ratio (EACR) and the air exchange rate of the air cleaner’s circulation is derived. When the air cleaner is positioned at the central position, the calculated EACR is 0.8. When placed against the wall, the calculation result is 0.76. In contrast, when situated in the corner, the indoor PM2.5 distribution is unbalanced due to the air flow delivered by the air cleaner, the EACR is only 0.74. To obtain the purification capacity of air cleaner in actual environments, an empirical correlation between EACR, room volume, and the nominal CADR is established based on experimental results. Practical application The placement of an air cleaner is a critical factor that directly influences its Clean Air Delivery Rate (CADR), resulting in a notable discrepancy between its laboratory-rated and actual performance for controlling indoor PM2.5 concentrations. The rated CADR value is insufficient for predicting actual removal effectiveness, the actual purification performance must account for practical room conditions, including room volume and airflow patterns. To obtain the purification capacity of air cleaner in actual environments, an empirical correlation between EACR, room volume, and the rated CADR is established based on experimental results. This study can provide a basis for effectively controlling indoor PM2.5 levels.
Xie et al. (Thu,) studied this question.