Design and Construction of a Scanning Mobility Particle Sizer (SMPS) to Determine Particle Size Distribution of Aerosolerosols

In this study, the Scanning Mobility Particle Sizer (SMPS) was constructed and used to determine the particles size distribution of submicron aerosols. SMPS Spectrometer is widely used as the standard method to measure airborne particle size distributions. This particle sizer is also routinely used to make accurate nanoparticle size measurements of particles suspended in liquids. The SMPS consists of the constant output atomizer, the particle charge neutralizer, Differential Mobility Analyzer (DMA) and Condensation Particle Counter (CPC). Each part of this system was designed and constructed separately and then primary experiments were done. In the next step assembling of all devices was done to create a SMPS system. In this system, the Polydispersed aerosols were created from the atomizer inside the diffusion drier tube to eliminate their humidity. The polydispersed aerosols exiting the drier were passed through the neutralizer to obtain a known charge distribution. Then the aerosol stream was classified by the DMA at a selected voltage to extract a known particle diameter. The exiting particles from the DMA were led to the CPC in order to count particles number and to measure the size distribution. Calibration of SMPS performance by monodispersed particles with 100 nm size. This method is independent of the refractive index of the particle or fluid and has a high degree of absolute sizing accuracy and measurement repeatability. High-resolution data up to 250 channels, broad size range (from 1 nm to 1,000 nm), fast measurements (complete size distributions in 10 minutes) and wide concentration range from 1 to 107 particles/cm3 are some advantages of this instrument over the existing systems.