Fine particulate matter control performance of a new kind of suspended fan filter unit for use in office buildings

Abstract

Fine particulate matter (PM2.5) pollutants threaten the productivity and health of workers in office buildings. Additional indoor filtration cleaners are needed for PM2.5 control in most cases. Portable air cleaners (PACs) designed for household use may not be applicable to relatively large office spaces because of their low clean air delivery rate (CADR) and energy inefficiency. We developed a new kind of suspended fan filter unit (SFFU) for use in office buildings. A polypropylene (PP) filter or intense field dielectric (IFD) filter was installed in the SFFU for filtration. We compared the PM2.5 control performance of the SFFU with the performance of five kinds of popular PACs on the market. The CADRs generated by the SFFU (360–650 m3/h) were 1.2–3.9 times the rates of the PACs (165–300 m3/h). The average energy efficiency (CADR/electrical power) of the SFFU with a PP filter (15.8 (m3/h)/W) was 2.0 times higher than that of the PACs (5.3 (m3/h)/W). The energy efficiency was increased by another 9% with the use of an IFD filter. The long-term performance of the IFD filter may be unsatisfactory at the current stage. After half a month of operation (8 h per day), the filtration efficiency of the IFD filter in the SFFU dropped to 80–85%. After a month of operation, the efficiency dropped further to 60–65%. The results of this study are particularly significant for commercial spaces (office buildings, shopping malls, etc.) where high CADRs are needed and where energy performance is more critical than in consumer applications.