In recent models of semiconductor manufacturing clean rooms, air washers are used to remove airborne gaseous contaminants such as NH3, SOx and organic gases introduced from outdoor air into clean room. Meanwhile, there is a large quantity of exhaust air produced from clean room. It is desirable to recover heat from exhaust air and use it to reheat outdoor air. In the present study, an experiment was conducted to investigate heat recovery, particle collection, and gas removal in a heat recovery type air washer system for semiconductor manufacturing clean rooms.

Abstract Dielectric barrier discharge (DBD) in air, which has been established for the production of large quantities of ozone, is more recently being applied to a wider range of aftertreatment processes for HAPs (hazardous air pollutants). Although DBD has high electron density and energy, its potential use as precharging nano and submicron sized particles, is not known. In this work, we measured V‐I (voltage‐current) characteristics of DBD and estimated the collection efficiency of particles with bimodal distribution by DBD type 2‐stage ESP (electrostatic precipitator). To examine the particle collection with various applied voltage waveforms of DBD, nano size particles of NaCl (20∼100 nm) and DOS (50∼800 nm) were generated by an electrical tube furnace and an atomizer, respectively. Particle collection efficiencies of all the cases increased with increase of DBD electric power that the results corresponded to product of V by I whose magnitudes were the largest in triangular voltage waveform.

The purpose of this work is to develop a new type of particle collection filter using electrical discharge technology. The new filter must be high efficiency and applicable to air conditioner to use for household, so we suggested the new type filter. The new type filter has a distinctive feature except characteristic of ESP, a thickness of collecting electrodes is thicker than that of existing type ESP. When particles come into the filter, the particles will collide with side surfaces of the collecting electrodes. At the same time of particle collision with side surface, the particles are charged by the collision and collected by electrical force. Therefore, we called this type "Ion Impactor". We optimized condition of thickness of collecting electrodes and applied voltage using six sigma method because thickness of collecting electrodes and applied voltage are very important to improve the collection efficiency. We analyzed distribution of electric field line, the electric field lines were uniformly distributed on the side surface of the collecting electrodes. From this analysis, we can see the improvement of the particle collection efficiency. We made the ion impactor type filter on a large scale to equip to the air conditioner, and measured the particle collection efficiency. For the 0.1∼0.2㎛ range particle, the collection efficiency was higher than that of existing type ESP by 30%. The collection efficiency of the 0.3∼0.4㎛ range particle was higher by 12%.

In order to develop combination air filters for air conditioners, 2 types of charging section were constructed. One was the wire-plate type and the other was the scroll type. Each charging section was combined with the same electrostatic polypropylene (PP) media. NaCl aerosol particles with geometric mean diameter of 0.05∼0.16㎛, geometric standard deviation of 1.6∼1.9 and total number concentration of 1,700∼24,000 particles/㎤ were used to determine collection efficiencies of the combination air filters for air conditioners with respect to particle size. It was shown that the scroll type combination air filter has greater collection efficiencies and lower pressure drops than the wire-plate type one does.