A method to promote the efficiency of electrically enhanced filter is proposed, using photoelectric charging which is a very efficient way of charging small particles.
To understand the mechanism of photoelectric charging, particle charging of Silver by exposured to Ultraviolet has been investigated. The charge distributions turned out to be dependent on initial charge states.
Experiments were also performed to identify the effect of particle charge on filter efficiency. Highly monodisperse Silver particles (≤ 0.2㎛) charged to various levels by photoelectric charging, and their penetration through uncharged filter and electrically enhanced filter was measured with a condensation nucleus counter (CNC). In both uncharged filter and electrically enhanced filter, increases in filter efficiency were observed with increasing particle charge.
Single fiber efficiency of uncharged filter for charged particles compared to early experimental results. The measured values of filter efficiency were found higher than previous data in Brownian diffusion dominant region. New empirical expression including Peclet number is proposed. Single fiber efficiency of electrically enhanced filter is compared to theoretical prediction. Experimental data have a good agreement with the values calculated from theory in a weak electrical field. In a strong field, the disagreement between theory and real measurements happened, due to the complex structures of fibrous filter.
To prove the possibility of the method suggested as new removal system, experiments conducted in real conditions. Based on these results, it is concluded that the pre-charging of particles by Ultraviolet irradiation augmented performance of filter.
