Development of a fast-response, high-resolution electrical mobility spectrometer

Panich Intra,Nakorn Tippayawong 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.1

A short electrical mobility spectrometer (EMS) for measuring aerosol size distribution has been developed and presented [Intra and Tippayawong, Korean J. Chem. Eng., 26, 1770, 2009]. In this work, further improvement of the short EMS into a fast-response, and high resolution instrument is presented. This was done by (i) improvement in particle charging, (ii) utilization of faster flow rate, and (iii) adoption of higher number of electrode rings. The so-called “long” EMS consists of three main parts: a particle charger, a long multi-channel size classifier column, and a multichannel electrometer. Performance of the long EMS was preliminarily tested using polydisperse, carbonaceous aerosol particles generated by a diffusion flame. Preliminary test results showed that the long EMS performed comparatively well, and gave faster response and higher resolution than the short EMS. It was a valuable aerosol instrument available for measuring size distribution of aerosol particles.

Comparative Study on Electrical Discharge and Operational Characteristics of Needle and Wire-Cylinder Corona Chargers

Intra, Panich,Tippayawong, Nakorn The Korean Institute of Electrical Engineers 2006 Journal of Electrical Engineering & Technology Vol.1 No.4

The electrical discharge and operational characteristics of needle and wire-cylinder corona charger based on current measurements for positive and negative coronas were evaluated and compared. A semi-empirical method was used to determine the ion concentrations in the charging zone and at the outlet of both chargers. Results from experimental investigation revealed that magnitudes of the charging current from the wire-cylinder charger were approximately 3.5 and 2 times smaller than those from the needle charger for the positive and negative coronas, respectively. The ion number concentrations at the outlet for positive corona of both chargers were higher than fur negative corona at the same voltage. Flow and electric fields in the charging zone of both chargers were also analyzed via numerical computation. Strong electric field strength zone was identified and led to high charging and particle deposition. Effect of particle deposition on the evolution of discharge current was presented. It was shown that ions loss inside the wire-cylinder charger was higher than the needle charger The particle deposited on the corona electrodes and on the grounded cylinder caused a great reduction in charging efficiency of both chargers.

Design and Evaluation of a High Concentration, High Penetration Unipolar Corona Ionizer for Electrostatic Discharge and Aerosol Charging

Intra, Panich,Tippayawong, Nakorn The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.5

The aim of this paper is to design and evaluate a high concentration, high penetration unipolar corona ionizer. The electrostatic characteristics in terms of voltage-current relationships of the present ionizer in the discharge zones for positive and negative coronas were discussed. Using ion current measurement, the concentration and penetration of ions were evaluated at corona voltages across the needle electrodes between 1 and 4 kV, flow rates between 1 and 5 L/min, and an operating pressure of 1 atm. In the discharge zone of the ionizer, the highest ion concentrations were found to be about $1.71{\times}10^{14}$ and $5.09{\times}10^{14}\;ions/m^3$ for positive and negative coronas, respectively. At the outlet of the ionizer, it was found that the highest ion concentration was about $1.95{\times}10^{13}$ and $1.91{\times}10^{13}\;ions/m^3$ for positive and negative coronas, respectively. The highest ion penetration for positive and negative coronas through the ionizer was found to be about 98 % and 33 %, respectively. The $N_it$ product for positive and negative coronas was also found to $1.28{\times}10^{13}$ and $7.43{\times}10^{13}\;ions/m^3s$, respectively. From the findings, this ionizer proved to be particularly useful as an aerosol charger for positive and negative charge before the detector in an electrical aerosol detector.

Approach to Characterization of a Diode Type Corona Charger for Aerosol Size Measurement

Intra Panich,Tippayawong Nakorn The Korean Institute of Electrical Engineers 2005 KIEE International Transactions on Electrophysics Vol.5C No.5

A semi-empirical method to determine the electrostatic characteristics of a diode type corona aerosol charger based on ion current measurement and electrostatic charging theory was presented. Results from mathematical model were in agreement with those from experimental investigation of the charger. Current-voltage characteristics, $N_{i}t$ product and charge distribution against aerosol size were obtained. It was shown that the space charge was significant and must be taken into account at high ion number concentration and low flow rate. Additionally, significant particle loss was evident for particles smaller than 20 nm in diameter where their electrical mobility was high. Increase in charging efficiency may be achieved by introducing surrounding sheath flow and applying AC high voltage. Overall, the approach was found to be useful in characterizing the aerosol charger.

Evaluation of the Performance in Charging Efficiencies and Losses of Ultrafine Particles Ranging in Sizes from 15 to 75 nm in a Unipolar Corona-based Ionizer

Intra Panich,Wanusbodeepaisarn Paisarn,Siri-achawawath Thanesvorn 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2

For this study, a unipolar corona-based ionizer was constructed and experimentally evaluated for charging effi ciencies and losses of ultrafi ne particles in the size range of 15–75 nm at diff erent corona voltage, ion trap voltage and particle fl ow rate. The corona voltage was applied to the ionizer between 2.0–3.0 kV. The discharge currents increased from 0.16 nA to 4.23 μA and the ion number concentration increased from 6.27 × 10 9 to 1.36 × 10 14 ions/m 3 . Increasing the corona voltage lead to a higher discharge current and ion number concentration in the ionizer. The best intrinsic charging effi ciency of the ionizer was about 92.15–99.33% for particle diameters ranging from 15 to 75 nm, and occurred at corona voltage, ion trap voltage and particle fl ow rate of about 3.0 kV, 100 V, 0.6 L/min, respectively. At a given corona voltage, the extrinsic charging effi ciency increased as the particle fl ow rate increased. The best extrinsic charging effi ciency ranged from 14.93 to 57.70% for particle diameters increasing from 15 to 75 nm, and occurred at corona voltage, ion trap voltage and particle fl ow rate of about 2.6 kV, 100 V, and 1.5 L/min, respectively. In the present ionizer, the highest electrostatic loss was observed for particles with a diameter of about 45 nm, and it was about 88.03% at a corona voltage of 3.0 kV and an ion trap voltage of 200 V. Finally, the highest diff usion loss of about 22.66% was seen to occur with singly charged particles with a diameter of 15 nm at the particle fl ow rate of about 0.6 L/min.

Demonstration of a Modular Electrostatic Precipitator to Control Particulate Emissions from a Small Municipal Waste Incinerator

Intra, Panich,Yawootti, Artit,Tippayawong, Nakorn The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.1

Incineration is conceptually sound as a waste treatment technology. There is, however, concern over its emissions when it is improperly designed and operated. An electrostatic precipitator is one of the most commonly used devices to control particulate emissions from boilers, incinerators and some other industrial processes. In this work, a modular electrostatic precipitator with sizing of $1m{\times}1m{\times}1m$ was developed for removal of particulate matter from the exhaust gases of a small waste incinerator. Its design was based on a simple wire-and-plate concept. The corona discharge wires were connected to a positive high-voltage pulse generator, while the collection plates were grounded. The high-voltage pulse generator was used to produce the corona discharge field between the individual discharge wire and the collection plate. The particulate-laden exhaust gas flow was directed across the corona discharge field. The charged particles were deflected outward and collected on the plate. The collection efficiency was evaluated as a mass loading ratio between the difference at the inlet and the outlet to the particulate loading at the inlet of the precipitator. The collection efficiency of this modular electrostatic precipitator design was approximately 80 %.

Corona Discharge Characteristics and Particle Losses in a Unipolar Corona-needle Charger Obtained through Numerical and Experimental Studies

Intra, Panich,Yawootti, Artit,Rattanadecho, Phadungsak The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

In this paper, the unipolar corona-needle charger was developed and its capabilities were both numerically and experimentally investigated. The experimental corona discharges and particle losses in the charger were obtained at different corona voltage, aerosol flow rate and particle diameter for positive and negative coronas. Inside the charger, the electric field and charge distribution and the transport behavior of the charged particle were predicted by a numerical simulation. The experimental results yielded the highest ion number concentrations of about $1.087{\times}10^{15}ions/m^3$ for a positive corona voltage of about 3.2 kV, and $1.247{\times}10^{16}ions/m^3$ for a negative corona voltage of about 2.9 kV, and the highest $N_it$ product for positive and negative coronas was found to about $7.53{\times}10^{13}$ and $8.65{\times}10^{14}ions/m^3$ s was occurred at the positive and negative corona voltages of about 3.2 and 2.9 kV, respectively, and the flow rate of 0.3 L/min. The highest diffusion loss was found to occur at particles with diameter of 30 nm to be about 62.50 and 19.33 % for the aerosol flow rate of 0.3 and 1.5 L/min, respectively, and the highest electrostatic loss was found to occur at particles with diameters of 75 and 50 nm to be about 86.29 and 72.92 % for positive and negative corona voltages of about 2.9 and 2.5 kV, respectively. The numerical results for the electric field distribution and the charged particles migration inside the charger were used to guide the description of the electric field and the behavior of charged particle trajectories to improve the design and refinement of a unipolar corona-needle charger that otherwise could not be seen from the experimental data.

Investigation on the Electrical Discharge Characteristics of a Unipolar Corona-Wire Aerosol Charger

Intra, Panich,Yawootti, Artit,Vinitketkumnuen, Usanee,Tippayawong, Nakorn The Korean Institute of Electrical Engineers 2011 Journal of Electrical Engineering & Technology Vol.6 No.4

In the present study, a simple corona-wire charger for unipolar diffusion charging of aerosol particles is designed, constructed, and characterized. Experimental characterizations of the electrostatic discharge in terms of current-voltage relationships of positive and negative coronas of the corona-wire charger are also presented and discussed. The charging current and ion concentration in the charging zone increased monotonically with corona voltage. The negative corona showed higher current than the positive corona. At the same corona voltages, the current in the discharge zone is about 600 times larger than the charging current. The ion number concentrations ranged within approximately $5.0{\times}10^{10}$ to $1.24{\times}10^{16}$ and $4.5{\times}10^{12}$ to $2{\times}10^{16}$ ions/$m^3$ in the discharge and charging zones, respectively. A numerical model is used to predict the behavior of the electric potential lines. Numerical results of ion penetration through the inner electrode are in good agreement with the experimental results.

Experimental characterization of a short electrical mobility spectrometer for aerosol size classification

Panich Intra,Nakorn Tippayawong 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6

A prototype of a short column electrical mobility spectrometer (EMS) for size measurement of aerosol particle was design, constructed, and experimentally characterized. The short EMS consists of a particle charger, a size classifier column, and a multi-channel electrometer. Its particle size resolution is derived from a 10 channel electrometer detector. The short EMS is capable of size measurements in the range between 10 nm to 1,000 nm with a time response of about 50 s for full up and down scan. Particle number concentration in which the short EMS can measure ranges from 1011 to 1013 particles/m3. The operating flow rate of the short EMS is set for the aerosol flow rate of 1.0- 2.0 l/min and the sheath air flow rate fixed at 10.0 l/min. The inner electrode voltage of the classifier can be varied between 500-3,000 VDC. The short EMS operates at sub-atmospheric pressure, typically at 526 mbar. Validation of the short EMS performance was performed against a scanning electron microscope (SEM). Good agreements were obtained from comparison between sizes determined from the short EMS classifier and the SEM analysis. Signal current from the detector was also analyzed to give rise to number concentration of particles. Experimental results obtained appeared to agree well with the theoretical predictions.

Development of a PM2.5 sampler with inertial impaction for sampling airborne particulate matter

Panich Intra,Artit Yawootti,Usanee Vinitketkumnuen,Nakorn Tippayawong 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.8

A simple and low cost PM2.5 impactor for sampling airborne particulate matter was developed, designed and evaluated. The design was an assembly of an acceleration nozzle and an impaction plate. Particles with sufficient inertia were unable to follow air streamlines and impacted on the plate. Smaller particles followed the streamlines, avoided being captured by the plate and could then be collected on a downstream filter. Analytical and numerical models were formulated to predict collection efficiency, flow fields and vectors, and particle trajectories in the impactor. The modeling suggested that an optimal operational domain exists for the PM2.5 impactor. A prototype was then built and tested. The collected particles on the impaction plate and downstream of the PM2.5 impactor were analyzed by using scanning electron microscopy. Experimental results agreed well with the theoretical predictions. Testing of the PM2.5impactor prototype showed promising results for this airborne particulate matter sampler.