Development and Performance Evaluation of a Flying Electrostatic Precipitator

• Main Authors: Jun-Hao Su, 蘇峻豪
• Other Authors: Tsrong-Yi Wen
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/b8qdq8

碩士 === 國立臺灣科技大學 === 機械工程系 === 107 === Exposure to an environment that has a high-concentrated aerosol particle has been confirmed to be harmful to human health. According to the literatures, when the concentration of aerosol particle increases, the rate of going to the clinic because of respiratory diseases increases. Hence, when a sudden incident in which a large number of aerosol particles are produced, such as fires, a device that is capable of removing those particles efficiently and effectively is expected to be developed. This thesis proposes a concept, “flying electrostatic precipitator (flying ESP),” that combines an ESP (high collection efficiency) and a drone (high mobility) to collect those particles directly on top of it regardless of traffic and terrain. ESP collects particles based on the principle of electrohydrodynamics. The passing particles are charged by corona discharge. Then these charged particles move to the collecting electrode by the effect of induced electrostatic force when passing through the collector. Because the electrodes of the ESP are either thin or parallel to the direction of the airflow, the pressure drop of the ESP is much smaller than that of the bag filter. Besides, the collection efficiency of an ESP does not increase over the dust accumulation. Taking the advantage of low pressure drop, particles can pass a flying ESP because of the airflow generated by the natural convection that is caused by combustion, without using external fans. However, the charger of the traditional two-stage ESP generates the ionic wind that is perpendicular to the incoming airflow. If the incoming airflow is low enough, the ion wind can significantly impede the incoming airflow, reducing the chance of particles entering the ESP (by pass). Thus, this thesis proposes the semi two-stage ESP to make the ionic wind direction not completely perpendicular to the incoming airflow. The results showed that the semi two-stage ESP can guide about 11.8% particles into the ESP more than the traditional two-stage ESP can. Additionally, because the flying ESP collects particles while moving, this thesis also discusses the characteristics of collection efficiency as the ESP works in moving state. The results showed that the collection efficiency increases exponentially with the increasing of the repelling voltage. The moving distance of the semi two-stage ESP does not affect the collection efficiency. Nevertheless, when the repelling voltage is over 5 kV, the collection efficiency is not affected even the vibrational acceleration is 5g (moving velocity at 0.22 m/s). When the repelling voltage is below 2 kV, the particles on the collecting electrode can fall off as long as the vibration acceleration is higher than 3g. With a high vibration acceleration and a low repelling voltage, the collection efficiency can be significantly influenced, up to 20% loss of the collection efficiency. In summary, when ESP operates in a moving state, it is not necessary to consider the influence of the moving distance for the collection efficiency. However, when ESP operates at a low repelling voltage, the particles on the collecting plate can be coming off due to vibration, lowering the collection efficiency. The collection efficiency decreases with the increasing of the vibration.