Evaluation Of Air Purifier For Reducing Aerosol Exposure In The Ventilated Room

Indoor air quality imposes great influence on peoples' health. The experiments conducted by the foreign experts in 1990s showed that indoor particulate matter is a significant contributor to sick building syndrome (SBS). Nowadays, indoor air pollution and its effect on peoples' health have aroused universal attention. The conventional design of comfort HVAC system gives priority to the conditioning treatment, air-flow origination and building energy conservation rather than the dust concentration. Out of consideration for the expense and convenience, compared with the strategy of replacing the existing HVAC system, using the air cleaner to improve the partial indoor air quality appears to be an economical and reasonable solution.The research aims at two kinds of air cleaner in this dissertation: the first kind is the two-stage ESP; the second kind is designed to improve the air quality around the people. This research was conducted under two conditions (the window is open or not) in an office, the air flow origination, temperature and particle concentration distribution was analyzed when the air cleaner was put in different place and in different working condition by means of the field experiment test and the simulation software CFD.When the pollution source is in the room, the particle is mainly in the submicron grade. The experiment results indicate that the air supply velocity is the key factor influencing the filtration efficiency compared with place where the air cleaner located. The larger the face velocity is, the better filtration effect obtained and the easier to achieve steady state when the air supply velocity is within the value set in the instrument. Steady state simulation carried out when the pollution source was in different location. The results demonstrate the efficiency of the air cleaner is higher when the air supply velocity is low.When the pollution source comes from the outdoor air, the particle is mainly in the micron grade. Steady state simulation shows the final indoor air filtration effect depends on its self-filtration efficiency, recirculation air volume and the amount of the pollutant entered into the room. In general, the larger the supply air is, the lower particle concentration, the better filtration effect achieved. With regard to the personal air cleaner, the degree of strength of thermal plume is dominant factor influencing the filtration efficiency. Furthermore, the relatively lower air supply velocity may cause the phenomenon that the large particle suspends around the people, worsening the air quality. Calculation of the deposition rate of the different height shows that the working condition of the air cleaner imparts little influence on the deposition of the particle.