Removal of airborne particles by a tubular particle-removal device using UV/photoelectron method

A new tubular particle-removal device based on the principles of charging of particles by ions and collecting by electrical force is developed and its performance is evaluated. In this device, negative ions of a high concentration are generated from continuously supplied photoelectrons emitted from the surface of an Au/ITO (Indium Tin Oxide) thin film irradiated by UV light. This removal method is called UV/photoelectron method. Airborne particles fed into the device are designed to encounter the ions, and to be attracted to a cylindrical positive electrode of which the outer wall of the device is composed. Measurements using submicron aerosol particles show that over 90% of the particles of 0.06-0.12 μm in diameter are collected by the device when the operating flow rate is below 1 1 min−1 However, removal efficiency depends on particle size, aerosol flow rate and electric field strength in the device. To investigate theoretically the removal efficiency, numerical calculation of particle behavior is made in which simultaneous charging of particles by negative ions and particle transport by air flow, Brownian diffusion and Coulomb force are taken into account. The results calculated successfully reproduce the dependence of the results measured on the operating conditions of the device.