Design and evaluation of a catalytic stripper with a plate electrical aerosol classifier

Abstract. The catalytic stripper (CS) for removing volatile particles is a critical unit within the measurement system. However, the penetration efficiency of small size particles is currently significantly lower than large particles in CS. Therefore, further improving the penetration efficiency of small size particles is of significant research interest. This study aims to enhance the penetration efficiency of small size particles by reducing the thermophoretic loss. For this purpose, a CS equipped with a plate-type electrical aerosol classifier (EAC) was designed and developed, and its performance was evaluated. The particles are prevented from depositing on the tube wall by applying an electric field force to them in the opposite direction to the thermophoretic force they are subjected to, which ultimately serves the purpose of further improving the particle penetration efficiency. The experimental results demonstrated that the CS achieved a removal efficiency (RE) higher than 99.9 % at a flow rate of 1.5 L/min or lower. At a sample flow of 0.3 L/min and a temperature of 350 °C, the penetration efficiency of CS+EAC without voltage was evaluated. Combined with the CS+EAC voltage-penetration efficiency curve, applying -112 V on the EAC, the penetration efficiency was further improved under the same experimental conditions, and the smaller the particle size, the greater the improvement. Compared to the 0 V, the improvement rate for 15 nm at -112 V was 24.4 %, while that for 23 nm was 18.9 %. Further experimental results show that the EAC can remove particles smaller than 10 or 23 nm by further increasing the voltage. This capability enables rapid particle classification and facilitates high temporal resolution measurements of particle number concentrations across different size intervals.