針尖放電型靜電集塵器收集效率的研究

Abstract

The multipoint-to-plane electrostatic precipitator (MPPESP) is one type of ESP devices used for the sampling and the control of nanoparticles and sub-micron particles with the advantages of low pressure drop and high particle collection efficiency. Several empirical equations for predicting the particle collection efficiency are available in the literature but most of them are only applicable to wire-to-plate ESPs. For ESPs with different discharge electrodes, the empirical equations are different since the ion concentration and electric fields are different. In this thesis, a predictive method is developed to calculate the particle migration velocity and the particle collection efficiency equation η(%) of MPPESPs in the form as η(%) ={1-exp⁡{-[β_1 (〖N_De〗^(β_2 ) )+β_3 (N_De )+β_4 ] } }×100% in which β1, β2, β3 and β4 are regression coefficients, which equal 6.122, 0.7289, -3.273 and 0.5821, respectively and NDe is the Deutsch number determined by the particle migration velocity. Good agreement is obtained between the present model predictions and experimental particle collection efficiencies obtained from the literature. Present experimental results showed that the collection efficiency of the present MPPESPs decreases with an increasing air flow rate and a decreasing applied voltage and the ion current decreases with an increasing point-to-plane spacing, an increasing needle tip radius, a decreasing point-to-point spacing, a decreasing needle length. Good agreement is obtained between the present model predictions and experimental particle collection efficiencies obtained from the literature and the present study. Therefore present model can be used to facilitate the design of efficient MPPESPs for nanoparticle and sub-micron particles removal.

The multipoint-to-plane electrostatic precipitator (MPPESP) is one type of ESP devices used for the sampling and the control of nanoparticles and sub-micron particles with the advantages of low pressure drop and high particle collection efficiency. Several empirical equations for predicting the particle collection efficiency are available in the literature but most of them are only applicable to wire-to-plate ESPs. For ESPs with different discharge electrodes, the empirical equations are different since the ion concentration and electric fields are different. In this thesis, a predictive method is developed to calculate the particle migration velocity and the particle collection efficiency equation η(%) of MPPESPs in the form as η(%) ={1-exp⁡{-[β_1 (〖N_De〗^(β_2 ) )+β_3 (N_De )+β_4 ] } }×100% in which β1, β2, β3 and β4 are regression coefficients, which equal 6.122, 0.7289, -3.273 and 0.5821, respectively and NDe is the Deutsch number determined by the particle migration velocity. Good agreement is obtained between the present model predictions and experimental particle collection efficiencies obtained from the literature. Present experimental results showed that the collection efficiency of the present MPPESPs decreases with an increasing air flow rate and a decreasing applied voltage and the ion current decreases with an increasing point-to-plane spacing, an increasing needle tip radius, a decreasing point-to-point spacing, a decreasing needle length. Good agreement is obtained between the present model predictions and experimental particle collection efficiencies obtained from the literature and the present study. Therefore present model can be used to facilitate the design of efficient MPPESPs for nanoparticle and sub-micron particles removal.