Development and performance test of a micromachined unipolar charger for measurements of submicron aerosol particles having a log-normal size distribution

Park, Dong‐Ho; Kim, Yong Ho; Lee, Sang Goo; Kim, Chul; Hwang, Jungho; Kim, Yong Jun

doi:10.1016/j.jaerosci.2010.02.007

Cited by 19 publications

(10 citation statements)

References 22 publications

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“…The extrinsic charging efficiency is, however, higher for the 1.5 L/min flow rate than for the 0.3 L/min flow rate as a result of charged particle loss in the prototype. Park et al (2010) designed and evaluated the performance of a micromachined unipolar charger in terms of particle loss and charging characteristics. The fabrication of the bottom plate began by patterning a 1 mm-thick thermallygrown silicon oxide layer on a 4 in silicon wafer having 100 -crystalline plane.…”

Section: Corona Discharge Chargersmentioning

confidence: 99%

An Overview of Unipolar Charger Developments for Nanoparticle Charging

Intra

Tippayawong

2011

Aerosol Air Qual. Res.

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Charging of nanoparticles is an important process in aerosol sizing. A unipolar charger is one of the most important upstream components in aerosol particle sizing and measurement systems by electrical mobility analysis. The aim of particle charging for an electrical mobility analyzer is to impose a known net charge distribution on the aerosol particles for each size. Charger performance depends on the extrinsic charging efficiency and stable operation. A well-designed unipolar charger should provide high extrinsic charging efficiency and stability that can be accurately determined for any given operating conditions. Depending on the mechanisms used to generate the ionized gas, the chargers can be classified into: (i) a corona discharge chargers, (ii) a radioactive chargers, and (iii) a photoelectric chargers. In this article, a brief overview on the development of existing unipolar aerosol chargers for nanoparticles is presented. Descriptions of the operating principles as well as detailed physical characteristics of these chargers, including the corona discharge, ionizing radiation, and photoelectron emission, are given.

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Section: Corona Discharge Chargersmentioning

confidence: 99%

An Overview of Unipolar Charger Developments for Nanoparticle Charging

Intra

Tippayawong

2011

Aerosol Air Qual. Res.

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“…Unipolar diffusion chargers, based on electrical corona discharge, are therefore a preferred option. Unipolar diffusion chargers exist in a large variety of designs and some of them were explicitly developed for miniaturized nanoparticle measurement devices (Qi et al 2008;Park et al 2010). Commercial, portable devices that are based on unipolar diffusion charging to determine nanoparticle concentrations include the NanoCheck (Grimm Aerosoltechnik) and the NanoTracer (Philips Aerasense; Marra et al 2010), which both determine number concentration and mean particle size based on the assumption of unimodal lognormal size distributions.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Description of Experimentally Determined Charge Distributions of a Unipolar Diffusion Charger

Kaminski

Kuhlbusch

Fißan

et al. 2012

Aerosol Science and Technology

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The charge distributions of an improved opposed flow unipolar diffusion charger were measured using a tandem differential mobility analyzer (DMA) set up in a size range of approximately 20-400 nm. The charger is intended to be used in a portable aerosol sizer to measure particle size distributions. The determined charge distributions were represented by lognormal distributions, and a set of equations and coefficients was developed to calculate the charge distributions. These equations can be easily implemented in software for size distribution measurements. The agreement between the mathematically derived and measured charge distributions is very good, with regression coefficients R 2 > 0.96. The investigations showed that approximately 55% of 20-nm particles remain uncharged, while up to 25 elementary charges need to be considered for multiple charge correction of 400-nm particles. Comparison with the Fuchs theory delivered satisfying agreement with the measured average charge levels, but charge distributions cannot be described by the Fuchs theory, likely caused by the charger geometry.

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“…Fig. 8 shows that the average charges of NaCl particles were similar to those of soot particles, but lower than the ones presented in Park et al (2010). We expected that with the long term use of the MUC, particles had deposited on the wall surfaces of the MUC, thereby resulting in a decrease of particle residence time that would also cause the decrease of particle charging time.…”

Section: Performance Evaluation Of Muc With Test Flame Soot Aerosolsmentioning

confidence: 73%

“…In our previous work, Park et al (2010), a MUC was developed based on a micro-electromechanical systems (MEMS) process, and its performance was tested for submicronsized NaCl aerosol particles generated from a lab-scale tube furnace. The schematic of the MUC is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The spacing between the ground electrode of the top plate and the silicon tip of the bottom plate during aerosol charging was 200 mm. For details of the fabrication procedure, see Park et al (2010). If an electrometer is used, the MUC can be applied to make a rough estimate of the total number concentration for a specific situation; for example, when the real-time detection of the transient response of engine exhausted particles is needed.…”

Section: Introductionmentioning

confidence: 99%

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