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Abstract Performance evaluation of an air purifier in a controlled chamber environment to assess its effectiveness under varying airflow conditions (within chamber, i.e. recirculation fan (RF) and ceiling fan (CF)) using smoke and salt particles was conducted. Clean Air Delivery Rate (CADR) of an air purifier (AP) was measured following the Association of Home Appliances and Manufacturers (AHAM AC-1:2013) standard, with values of 500 ± 10 m 3 h −1 for smoke, 471 ± 7 m 3 h −1 for ammonium sulphate, and 488 ± 9 m 3 h −1 for potassium chloride particles, closely aligned with the certified (as per GB/T 18801:2015 standard) CADR of 520 m 3 h −1 . These measured values against certified values validated the testing facility and the methodology used for its measurement capabilities. Deposition rate (natural decay) analysis revealed significant size-specific variations, for smoke particles of diameter ≤ 1 and 2 µm, the deposition rates vary from 0.68 to 0.89 h −1 under calm condition (when RF and CF were in off position) to 5.33–7.59 h −1 for turbulent conditions (when RF and CF were on). Ammonium sulphate particles showed a size-dependent (0.5–5 µm) increase in deposition rates, ranging from 0.30 to 3.54 h −1 under calm conditions to 0.84–6.90 h −1 under turbulent conditions. Similarly, potassium chloride particles exhibited deposition rates ranging from 0.48 to 1.72 h −1 under calm conditions, increasing to 0.72–4.14 h −1 under turbulent conditions. Study revealed that size-specific particle removal efficiency of AP varied with particle diameter, effectively removing smaller particles (< 1 µm) under calm conditions due to enhanced Brownian diffusion and effective filtration. While, larger particles exhibited higher removal through inertial impaction and gravitational settling. Under turbulent conditions, increased particle resuspension resulted in lower removal efficiencies across all particle types than calm conditions. These findings emphasize the importance of refining the CADR evaluation standards by incorporating size-specific efficiency metrics and assessing performance under dynamic airflow conditions. Additionally, this study suggests that manufacturers should provide CADR specifications for multiple fan speed settings, enabling for more accurate performance assessments allowing consumers to choose devices that best suit their requirement. Graphical abstract
Kumar et al. (Sat,) studied this question.