Electric air cleaner composed of nonthermal plasma reactor and electrostatic precipitator

Recent concerns of environmental protection encourage the use of a compact indoor air cleaner and various types of electrostatic precipitators (ESPs) have been manufactured. Although a wide range of airborne particles can be collected effectively with an ordinary ESP using a positive DC corona, it is difficult to remove gaseous compounds such as tobacco smoke which induces submicron particles and an offensive odor. In the present paper, the authors investigated the collection of submicron particles and the decomposition of acetaldehyde (CH/sub 3/CHO) using a commercial ESP and a nonthermal plasma reactor because the offensive odor of tobacco smoke is mainly caused by acetaldehyde molecules. For an ESP, the authors evaluated the particle-size dependent collection efficiency using a monodispersed aerosol because little investigations have been conducted in this area. As for acetaldehyde decomposition, more than 90% of decomposition efficiency was obtained with the use of the nonthermal plasma under dry air. However, the decomposition efficiency was deteriorated under humidified conditions. The higher collection efficiency was achieved for a particle size of 0.6 /spl mu/m than that of 0.3 /spl mu/m although the overall over collection efficiency exceeded more than 99%. The combination of ESP and nonthermal plasma technologies leads to the breakthrough of the conventional indoor electronic air cleaner technology.