• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1152-1157
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• 2004

Temporal behavior of the laser induced incandescence (LII) signal is often used for soot particle sizing, which is possible because the cooling behavior of a laser heated particle is dependent on the particle size. In present study, LII signals of soot particles are modeled using two non-linear coupled differential equations deduced from the energy- and mass-balance of the process. The objective of this study is to see the effects of particle size, laser fluence on soot temperature characteristics and cooling behavior. Together with this, we focus on validating our simulation code by comparing with other previous results. Results of normalized LII signals obtained from various laser fluence conditions showed a good agreement with that of Dalzell and Sarofim's. It could be found that small particles cool faster at a constant laser fluence. And it also could be observed that vaporization is dominant process of heat loss during first 100ns after laser pulse, then heat conduction played most important role while thermal radiation had little influence all the time.

• Journal of the Korean Society of Combustion
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• v.3 no.1
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• pp.31-39
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• 1998

The local instantaneous flame temperature and soot concentration in a D. I. diesel engine were measured using a two-color method. The proposed method based on the continuous spectra! radiation from the soot particles in the flame is applicable to industrial Diesel engines without major modifications of their main characteristics because of simplicity and relative ease of application. Measurements were performed at two locations inside the combustion chamber of a D. I. diesel engine. Effects of different engine speeds and loads, fuel injection timings, combustion chamber shapes on flame temperature and KL factor, which is qualitatively proportional to soot concentrations, were examined. Flame temperature change were observed with increasing engine speed and load. The higher the flame temperature is, the lower the KL factor is.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.9
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• pp.3007-3014
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• 1996

The instantaneous flame temperature and soot formation and oxidation in a D.I. diesel engine are measured using a two-color method. The proposed method based on the continuous spectral radiation from the soot particles in the flame is applicable to industrial diesel engines without major modifications of their main characteristics. Measurements are performed at one location inside the combustion chamber of a D.I. diesel engine. Effects of different engine speeds and loads on flame temperature and KL factor which is an index of soot concentration were examined. Little temperature change were observed with increasing rpm, while increased with loads. The higher the flame temperature is, the lower the KL factor is.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.173-182
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• 1997

The instantaneous flame temperature and soot formation and oxidation in a D. I. diesel engine are measured by using a two-color method. The proposed method based on the continuous spectral radiation from the soot particles in flames is applicable to industrial diesel engines without major modifications of their main characteristics. Measurements are performed at one location inside the combustion chamber of a D.I. diesel engine. Effects of different engine speeds and loads on flame temperature and KL factor which is an index of soot concentrations were examined. A little temperature change were observed with increasing engine speed, while increased with loads. The higher the flame temperature is, the lower the KL factor is.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1065-1073
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• 2006

The unturned carbon in fly ash, recently occurred in the coal-fired Yong Hung power station, caused some problems in ash utilization and boiler efficiency. This paper describes the analysis of unburned carbon and six coals, some tests performed at Yong Hung Boiler, and the results of combustion modification for the reduction of unburned carbon in fly ash. From the physical and chemical analysis of unburned carbon in fly ash, most particles were turned out to be hollow cenosphere and agglomerated soot particles. The sooting potential from six coals used in the plant were investigated with CPD(Chemical Percolation Devolatilization) model. The results showed that the higher potential was presented to Peabody, Arthur, Shenhua coals rather than other coals. It was necessary to measure the coal flow rates at each coal feeding pipe for four burner levels since they affect the extent of mixing of soot with oxidant, in turn, the oxidation rate of soot particles. The unbalance in coal flow rate was found in several coal pipes. We successfully reduced unturned carbon in ash by increasing the excess air and changing the SOFA's yaw angle.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.45-50
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• 1997

An experimental study on LII signal images from soot particles in a flame has been carried out in order to investigate the effect of the incident laser characteristics. By changing the wavelength of the incident laser beam, the LII signal was saturated at smaller laser power with 532 nm than 1,064 nm. This implies that the larger absorption coefficient of soot particles at 532 nm would influence the LII signal characteristic. Using the deconvolution technique, the projected LII line images were coverted to reconstruct the local LII signals inside the beam. The results show that the LII images at ICCD camera result from the integration of LII signal across the laser beam.

• Proceedings of the KIEE Conference
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• 1984.07a
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• pp.226-229
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• 1984

A novel high intensity charging device has been developed for the control of the submicron particles, such as the diesel soot particulates, which are very hard to charge highly by any means of the conventional charging device. Having new corona electrodes of a multineedle disk with the corona field-control electrodes in the outer-cylinder electrode, extremely intense and stable coronas on there sharp points expanding both radially and axially are established in the corona charging region between the multi-corona -needles and an outer-cylinder electrode. As a result, the maximum corona field intensity and current density of the charging device of the standard one on soot load in laboratory tests have been 8.5KV/cm(E=$2V_m$/D(1nD/d)) and $6.5{\mu}A/cm^2$ which enhance greatly the charging of soot particles about several 100 times higher than those obtained in conventional cylinder precipitators.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.113-121
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• 2002

The distribution of volume fraction, mean diameter and number density of soot particles are measured quantitatively in a co-flow ethylene diffusion flame using a simultaneous LII/LIS measurement technique. The LII/LIS system and the measured values are, respectively, calibrated and evaluated by comparing to the informations obtained from laser light. extinction/scattering experiments, LII signal shows some sensitivity to the laser light intensity when laser power density exceeds a certain value(threshold). It is also found that there is an optimal laser intensity and a delay time in order to obtain the best result using the simultaneous LII/LIS measurement technique.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.157-163
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• 2006

A new technique utilizing LII signal for the measurement of flow velocities of laminar diffusion flames has been investigated. Soot particles in ethylene diffusion flames are heated by a modulated Ar-ion laser beam. LII signals and their phase angles are measured using a lock-in amplifier at the different flame heights and the axial flow velocity are obtained from the measured phase angle delay. The measured velocities are similar to those from LDV measurements under the same operating conditions. The effects of laser power, LII signal wavelength, and modulation frequency are not sensitive to the velocity measurement. However, the choice of an optical chopper blade type could affect the measurement result. The use of a 6/5 chopper blade showed the better result that is possibly due to the square shape of modulated laser beam. This study successfully demonstrated that axial flow velocities of laminar diffusion flames can be measured by a new technique utilizing LII signal, which does not need particle seeding unlikely to LDV or PIV techniques.

• Journal of the Korean Society of Combustion
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• v.23 no.1
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• pp.1-7
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• 2018

The effect of LII interference on the measurement of LIF signals from PAH in a diffusion flame has been investigated. Argon-ion laser at 488 nm was vertically or horizontally polarized, and irradiated to the centerline of the flame at varying flame height. Signals from PAH-rich regions measured at 515 nm were mostly LIF signals, however, signals from soot-rich regions were determined to be mixed with Mie scattering signals and/or LII signals. Signals measured 1 mm above the excitation height were mostly LII signals from soot particles. The results show that a quantitative determination of the LIF's contribution to the measured signals would be difficult as long as the experimental setup described here is used for the regions where PAHs and soot particles exist together.