Jeong-Uk Kim’s research while affiliated with Yonsei University and other places

Pleated filter bags have received a considerable amount of attention due to their higher filtration area compared to that of cylindrical filter bags. They can be used to increase both the filtration efficiency and dust holding capacity, as it is possible to decrease the filtration velocity when using the same amount of exhaust gas. However, the effective filtration area of pleated filter bags remains uncertain, despite the fact that it is an important design parameter in pulse-jet bag house systems. The effective filtration area of a pleated filter bag is determined in this study by assuming the effective filtration area (50%, 60%, 70% and 100% of the theoretical filtration area) and comparing its filter cleaning characteristics with those of a cylindrical filter bag. The filtration characteristics of a pleated filter bag with optimal geometry were investigated under the conditions of a filtration velocity of 1.2 m/min and a dust concentration of 10 g/m³. As a result, we found that the pleated filter bag assessed here had an effective filtration area of approximately 50 to 60%, in contrast to the theoretical filtration area, due to the dead space caused by filter pleating. In addition, particle clogging in the outer pleating section of the pleated filter bag significantly affected the decrease in the effective filtration area.

The electret filter is a potential component to remove airborne particles due to its high collection efficiency and low pressure drop. However, its filtration performance is gradually decreased by exposure to organic solvents, which limits the application of electret filters. The effect of ethanol exposure on the filtration performance of polypropylene electret filters was investigated experimentally to clarify the charge decay phenomenon in this study. Experimental results revealed that filter performance is strongly dependent upon the challenged mass and existing state of an ethanol solvent. The filter performance was drastically degraded by exposure to ethanol droplets generated from a solution with ethanol concentrations above 30%; however, it was maintained during exposure to ethanol vapors. This tendency was also seen in the surface potentials of the exposed filter media. In addition, we found that the critical challenging amount of ethanol droplets was in the vicinity of 0.045 g/cm² to neutralize a tested electret filter in this study. Copyright 2015 American Association for Aerosol Research

Ceramic filters are quite an efficient component for hot gas filtration due to their high collection efficiency and high thermal durability. Among the various steps to fabricate a ceramic filter, sintering is one of the most important processes. In this study, disk-type ceramic filters were prepared at various sintering temperatures, and the effect of sintering temperature on physical/chemical properties and filtration performance were investigated. We found that the sintering temperature strongly influenced the physical and chemical properties as well as the filtration performance of a ceramic filter. The adhesive force among powders and the oxidation degree of Si species are more important parameters to determine the mechanical strength of a ceramic filter than other physical properties. Filters prepared at sintering temperatures lower than 1450 °C have low mechanical strength due to insufficient binding energy among powders, and filters prepared at sintering temperatures higher than 1500 °C also have low mechanical strength due to the oxidation of SiC to SiO2. However, ceramic filters sintered at 1350 °C and 1400 °C achieve a better filter quality factor than other filters, even though they have lower mechanical strength. Therefore, both mechanical strength and filter quality factor should be considered to choose a better ceramic filter.

The silicon carbide (SiC) ceramic filter is the most favorable component to remove particulate matter from hot flue gas due to its high filtration efficiency and high thermal durability. The effect of SiC powder size on the physical properties and filtration performance to prepare high-performance granular ceramic filter media was investigated in this study. Disk-type filter media were prepared by mixing ceramic components followed by physical compression and sintering. The porosity and average pore diameter in the filter media increased with increasing powder size. However, the mechanical strength decreased with increasing powder size, while it increased with increasing physical compressive force. The filter performance factor, qFM was introduced to evaluate the ceramic filter properties, and the SiC50 filter was the best of the ceramic filters prepared in this study. We also found that diffusion was a dominant collection mechanism for particles smaller than 0.7 μm, and direct interception and inertia were dominant collection mechanisms for particles larger than 0.7 μm in the SiC50 filter based on a single collector efficiency model. In addition, the predicted collection efficiencies showed reasonably good agreement with the experimental ones.Copyright 2014 American Association for Aerosol Research

The filtration performance of filter media fabricated by foam coating technology is highly dependent upon their pore sizes. Therefore, we investigated the effect of the mixing ratio of combined coating components (PTFE emulsion, a foam stabilizer, a foaming agent, and a thickener) and operating parameters (feed rate of coating solution, air flow rate, mixing speed, and cooling temperature) on the bubble size distribution of generated foams in a foam generator. The mean bubble size and bubble size distributions were observed through microscopic observations with an optical microscope. We found that viscosity was the most critical parameter in preparing a coating solution, and the entire series of operating parameters as mentioned above influenced the bubble size in a foamed solution. The bubble size decreased with an increasing ratio of thickening agent up to 1.8%, mixing speed, and with decreasing solution feed rate, and cooling temperature. Furthermore, we had a minimum bubble size for the condition of air flow rate at 200 mL/min. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2062–2067, 2013