Research On The Real World Performance Of The Particulate Air Filter For General Ventilation In Air Handling Unit

With the problems about outdoor air pollution and human living environment quality getting obvious,the topic of indoor particle pollution has triggered quite a lot of concern. Particulate air filters for general ventilation are widely used in industrial and civil air-handling units and they play an important role in controlling the transport of particles, improving indoor air quality and reducing particulate matters exposure. The performance data signs of air filter are obtained from performing tests on standard test rig and can not represent real world performance in the actual operation environment. So the research on the real world performance of particulate air filters for general ventilation in air-handling units is important.At the beginning of the subject, factors that influence the air filter performance were analyzed through summarizing classical single fiber filtration theoretical model. The characteristics of atmospheric aerosol, particle size differences between atmospheric aerosol and synthetic test dust and the influence of dust loading on the performance of common air filters and electrets filters were discussed. The dynamic model about filtration performance of air filter under dust loading stage was established.And monitoring test rig for air filter in AHU which meets ASHRAE Guideline 26-2008 and ISO/CD 29462 standard was designed and assembled. The test system is high automatic data collection and analyzing system. Particle counter zero efficiency, system zero efficiency and so on were tested, they all meet the standard requirements. In addition, error about experiment system was analyzed.With the help of real-time monitoring system for air filters in AHU, four air filters were tested. It was found that test results were more variable in real world changeable environment compared to controllable laboratory environment. Besides, electrostatic filter suffered degradation in efficiency in real world test because air relative humidity, chemical reactions, charge impairment or screen occurred between aerosol particles and fibers which lead to fiber charge decay. Comparison efficiency between untreated efficiency and discharged electrostatics filter media sample, it was found that high initial efficiency of electrostatic fiber filter depends on its strong electrostatic effects. The pressure drop changing trend of tested filters depends on their features and particle size of challenged aerosols. As the real world environment factors that influence performance of tested filter are uncontrollable and variable, established dynamic model for predicting air filter efficiency during loading stage can not agree with the test results very well. This research is of importance for understanding and analysis on the performance signs of air filters.