Experimental study of the relationship between initial single-pass efficiency and structural parameters of honeycomb adsorption filters

Abstract

An adsorption filter is the main functional component of a portable air cleaner. However, it is not easy to predict the adsorption efficiency of honeycomb adsorption filters using existing methods. Some of the required parameters are difficult to measure, in particular the hydraulic diameter of the adsorbent. In addition, some of the structural factors of honeycomb adsorption filters that affect the efficiency are not considered. Therefore, the relationship between the initial single-pass efficiency and the structural parameters was studied experimentally using benzene at concentrations of 0.4–3 ppm and 2.5–20-mesh activated carbon. The void ratio ranged from 0.293 to 0.919, and the face air velocity was 0.1–1.8 m/s. The air temperature was 25 °C, and the relative humidity was 40%. The results showed that the method can achieve acceptable precision when the void ratio is used instead of the hydraulic diameter of the granular adsorbent in the empirical equation for calculating the initial single-pass efficiency. Other necessary parameters in the empirical formula are the face air velocity and thickness. Moreover, the adsorbent shape and filling rate affect the initial single-pass efficiency, but an acceptable accuracy can be obtained without considering them in the empirical formula. Using a skeleton with loosely arranged cells can reduce the single-pass efficiency. In addition, the adsorption efficiency of a thin honeycomb adsorption filter with a total efficiency of less than approximately 30% can be considered to be the same along the flow channel, regardless of the effects of changes in the concentration.