Micro-Electrostatic precipitation uses combining impulses and dc voltage in order to charge and remove fine, sub-micron particles efficiently. Short impulses are expected to increase the precipitation efficiency and to reduce power consumption

MacGregor, S. J.

Mermigkas, A. C.

Timoshkin, I. V.

University of Strathclyde Institutional Repository

Strathprints Institutional RepositoryMermigkas, A. C. and Timoshkin, I. V. and MacGregor, S. J. (2012) Micro electrostatic precipitation for air treatment. In: 6th Environmental and Clean Technology Conference, 2012-06-21, Grand Central Hotel. , This version is available at http://strathprints.strath.ac.uk/56812/Strathprints is  designed  to  allow  users  to  access  the  research  output  of  the  University  of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may  not  engage  in  further  distribution  of  the  material  for  any  profitmaking  activities  or  any commercial gain. You may freely distribute both the url (http://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge. Any  correspondence  concerning  this  service  should  be  sent  to  Strathprints  administrator: strathprints@strath.ac.ukA. C. Mermigkas, I. V. Timoshkin, S. J. MacGregor  Department of Electronic and Electrical Engineering  University of Strathclyde, 204 George Street, Glasgow, G1 1XW,  Micro-electrostatic precipitation for air treatment           athanasios.mermigkas @strath.ac.uk 2nd year PhD student Charge airborne particles using non-thermal plasma (corona) discharges   Typically 50 Hz AC or DC stress is used   Precipitate charged particles using electrostatic forces on collection electrode Problem Statement Exposure to particulate matter less than 2.5ȝm in diameter (PM2.5) can cause health problems [1,2].   There is no evident safe level found for PM2.5 [2]  Attempts are made to reduce overall levels of exposure.    Electrostatic precipitation can be used for PM control.  Minimum in ESP efficiency for 0.1-2.5ȝm particles [3].  New approach: the use superposition of ns impulses and DC voltage to charge and remove Electrostatic precipitation  One way transient time - 125ns   System is designed to generate 250ns impulses.  Reactor design Single stage tests: Flour particles Average % of particles collected on the grounded cylinder in the first histogram with DC + Impulse energisation (10 pps) and in the second one with DC only.  Each bar represents an average of 5 individual 2 min tests ¾ There is precipitation of particles without any voltage due electrostatic electrisation of particles (~50%).  ¾ DC only voltage increase efficiency of precipitation at ~75%  ¾ Impulses superimposed on DC always improves efficiency increasing ~85% compared to the DC case.  ¾ Energy consumption: 16.2 ȝWh / pulse or 0.6075 Wh / m3 of treated air.  ¾ Charge injected: 3.52 ȝC / pulse.   9 Particle spectrometer Grimm 1.109 is used for detection of fine particles.  9 Spectrometer measures airborne particles in sizes ranging from 0.25 ȝP to >32 ȝP in 31 different size channels in real-time.  Single Stage tests: H600 dolomite powder Future work  A powder resistivity measuring device has been designed in order to  correlate ESP efficiency with resistivity of dusts.   Smoke will also be used as it has all its particles inside the PM2.5 range and its distribution is more uniform during the measurement time.   A scaled-up version of the reactor is intended to be tested later on. [1] J. G. Ayres, ³/RQJ term exposure on air pollution: effect on PRUWDOLW\´ Committee On the Medical Effects of Air Pollutants, 2009, COMEAP report, pp. 1-4, [Online]. Available: http://www.dh.gov.uk/ab/COMEAP/DH_108151  [2] D. Laxen, S. Moorcroft, B. Marner, K. Laxen, P. Boulter, T. Barlow, R. Harrison, M. Heal, ³302.5 in the 8.´ SNIFFER, Edinburgh, UK, Final report, Project ER12, Dec. 2010. [Online]. Available:http://www.sniffer.org.uk/Webcontrol/Secure/ClientSpecific/ResourceManagement/UploadedFiles/PM25%20Report%20Final%20%2820Dec10%29.pdf  [3] K. Parker, ³(OHFWULFDO operation of electrostatic SUHFLSLWDWRUV´ The Institution of Electrical Engineers, 2003, pp. 16. Types of impulses used INLETAIR FLOW WITH PARTICLESHV IMPULSESCORONA DISCHARGE PLASMAGROUNDEDCOLLECTION ELECTRODEINLETAIR FLOW WITH PARTICLESHV DCCORONA DISCHARGE PLASMAEXHAUSTGROUNDEDCOLLECTION ELECTRODEOUTLETVoltage impulse, 25 kV peak Current impulse, a 4 mA peak DC energisation: positive voltage  above corona ignition voltage 1) Sub-ȝs impulses: 2) ȝs impulses:  ~ 25 kV amplitude   ~ 175 ȝs wide  9 At 50 pps and with the use of an HV diode to avoid negative overshoot, they take the form as shown in the oscillogram: ¾ It was established that the micro-ESP technology provides a high precipitation efficiencies for fine, less than 2.5 micrometer (PM2.5), airborne particles: up to 81-97%. Efficiencies of ~100% have been achieved for environmental particles larger than 2.5 ȝP.  ¾Energy consumption: 6.95 ȝWh / pulse or 1.3 Wh / m3 of treated air.  ¾Charge injected: 1.81 ȝC / pulse  Cylindrical topology : compact design of small-scale indoor air-cleaning applications.  Positive energisation is used in micro-ESP process in order to avoid excessive ozone and nitrogen oxides production.  Air flow of 16 L / min used  Sub ± Microsecond impulses were used on top on DC voltage in a single stage reactor. In the double ± stage precipitator  1st stage ± Charging: ȝs impulses - wire acts as a HV electrode   2nd stage ± Collecting: DC Voltage ± smooth rod acts as HV electrode Environmental tests with double-stage precipitator Vertical axis ± normalised number of  particles [N(t)/Nmax(t)] Horizontal  axis ± time interval (interval = 6s) Points that are 0 are not shown in logarithmic scale. 2nd stage (17kV DC, 72.8 ǋƧ) Precipitation efficiency at   (A) +11 kV dc and +24-kV-impulse energization, (B) +15 kV dc and +26-kV-impulse energization, (C) +16 kV dc and +32-kV-impulse energization.   (Circles) DC energization only.  (Triangles) Superposition of dc voltage and HV impulses (50 pps) Micro-Electrostatic precipitation Uses combining impulses and dc voltage in order to charge and remove fine, sub-micron particles efficiently.   Short impulses are expected to increase the precipitation efficiency and to reduce power consumption. 1st stage (25kV ǋs impulses @ 50 pps ) Both stages ¾ With only the first stage energised ~ 10 % of the particles pass through, with only the second they fall to ~ 1 %, while with both stages only ~ 0.1 % of the particles passes through  ¾ Impulse stage energy consumption: 2.6 ȝWh / pulse or 0.4875 Wh / m3 of treated air  ¾ DC stage energy consumption: 1.2376 W  ¾ Charge injected: 0.513 ȝC / pulse 

Micro electrostatic precipitation for air treatment

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Micro electrostatic precipitation for air treatment

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