| Summary: | 碩士 === 國立交通大學 === 環境工程系所 === 105 === Two-stage electrostatic precipitators (ESPs) are commonly used in restaurants as exhaust gas treatment equipment, but only few studies have investigated the theoretical and experimental collection efficiency. A commercial two-stage ESP was tested in this study. Test items include: collection efficiency of fine particles at different flow rates, concentration of ozone by-products, and changes of collection efficiency of fine particles with time.
When increasing the flow rate from 4 CMM to 30.75 CMM, the mass median aerodynamic diameter (MMAD) of generated oil fume decreased from 0.44 µm to 0.2 µm and PM2.5 collection efficiency also decreased from 96.3 % to 43.9 %. A long time exposure test also conducted at the flow rate of 10 CMM in this study, after 141 hours of exposure, 104.7g of particles were collected in ESP and the corresponding PM2.5 collection efficiency decreased from 91 % to 61 %.
In order to build the collection efficiency model, two-stage ESPs are seen as a series connection of ionizing section and collector section, and the collection efficiency of each part are calculated separately. According to the model result, collection efficiency of the two-stage ESP is inversely proportional to the operating flow rate. The model was compared with experimental data. Result shows that model can fit experimental data quite well, error at all operating flow rate is less than 10 %.
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