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Electrical Mobility Spectrometer Modeling and Design

Saifi, Reza | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 44928 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Saeedi, Mohammad Saeed; Sani, Mahdi
  7. Abstract:
  8. Aerosol measurement is used in different fields such as nanotechnology and materials science, environmental air pollution monitoring and air quality measurements, combustion and engine exhaust, inhalation toxicology and medical studies. One of the most prevalent methods for aerosol measurement uses electrical mobility. An electrical mobility spectrometer (EMS) is used to classify particles ranging from 10 – 1000 nanometers, under the influence of an electric field. There are two electrodes in EMS between which the aerosol and sheath air flow. Charged particles in the aerosol and sheath enter the device from one end and are subjected to an electric field. Passing through the annulus, particles depending on their specific mobility are collected on the electrode ring(s). The size distribution is obtained by measuring electrical signals from the rings usually using electrometers.
    The accuracy of this distribution is influenced by flow condition, the geometry of EMS, electric field and the number of electrode rings. While ramping the electric field and using one electrode ring can give particle distribution, using multiple electrode rings in a constant electric field can also provide the particle size distribution. In this work, a multi channel EMS has been studied using computational fluid dynamics. Fluent commercial code has been used to predict the flow pattern, electric field, and particle trajectories to optimize different parameters such as the ratio of sheath to aerosol flow rates, number of electrode rings, width of each electrode ring and the optimum electric field to have the best particle distribution and the lowest amount of particle escapes or loss
  9. Keywords:
  10. Aerosols ; Electrical Mobility ; Electrical Mobility Spectrometer (EMS) ; Aerosol Measurement

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