• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1222-1233
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• 1990

The formation and oxidation processes of soot particles in a diesel flame were investigated with a rapid compression machine. A cloud of soot particles was successfully visualized by means of the instantaneous laser shadow photographs technique and the equivalence ratio of the soot formation zone was estimated from a measured fuel concentration distribution in a nonevaporating spray. The temporal and spatial variation of soot concentration in the flame was also correlated with the rate of heat release. Soot particles appears first in a region near the flame tip when diffusion combustion period starts, and its concentration is a maximum at about the end of injection, then decreases due to oxidation. The reason for soot being formed in a fuel lean region near the flame tip is the evaporated fuel requires time to be pyrolized as it travels through the burning fuel rich zone towards the flame tip.

• Particle and aerosol research
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• v.8 no.3
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• pp.99-110
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• 2012

In the SCR (selective catalytic reduction) system which is used for controlling the NOx emission from the Diesel engines, the soot deposited on the catalysis causes degradation of the system performance. Numerical study was done to evaluate the performance of soot blower which is proposed as a method for removing the soot on the catalysis. The spray conditions and the effect of the compressed air from the AIG (air inlet gun) were analyzed numerically to evaluate the overall effective method of the soot blowing. The characteristics of the final velocity distribution and velocity waves across the inlet section of the catalysis were evaluated with respect to the geometries of the AIG outlets and pressure conditions. An experimental model was used to validate the results of the numerical calculation that is used for finding the effective removal blowing momentum transfer quantities of soot the inlet section of the catalysis, and it is proposed that the required minimum blowing momentum transfer quantities are over than 0.499 $kg/m{\bullet}t_{eff}$ in the current study.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.403-412
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• 2006

The effect of a wall temperature on the soot deposition process from a diffusion flame to a solid wall was investigated in a microgravity environment to attain in-situ observations of the process. The fuel for the flames was an ethylene ($C_2H_4$). The surrounding oxygen concentration was 35% with surrounding air temperatures of $T_a=600K$. In the study, three different wall temperatures. $T_w$=300, 600, 800K, were selected as major test conditions. Laser extinction was adopted to determine the soot volume fraction distribution between the flame and burner wall. The experimental results showed that the maximum soot volume fractions at $T_w$=300, 800 K were $8.8{\times}10^{-6},\;9.2{\times}10^{-6}$, respectively. However, amount of soot deposition on wall surface was decreased because of lower temperature gradient near the wall with increasing wall temperature. A numerical simulation was also performed to understand the motion of soot particles in the flame and the characteristics of the soot deposition to the wall. The results from the numerical simulation successfully predicted the differences in the motion of soot particles by different wall temperature near the burner surface and are in good agreement with observed soot behavior that is, the 'soot line', in microgravity.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.22-28
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• 2010

The Direct Quadrature Method of Moments (DQMOM) has been presented for the solution of population balance equation in the wide range of the multi-phase flows. This method has the inherently interesting features which can be easily applied to the multi-inner variable equation. In addition, DQMOM is capable of easily coupling the gas phase with the discrete phases while it requires the relatively low computational cost. Soot inception, subsequent aggregation, surface growth and oxidation are described through a population balance model solved with the DQMOM for soot formation. This approach is also able to represent the evolution of the soot particle size distribution. The turbulence-chemistry interaction is represented by the laminar flamelet model together with the presumed PDF approach and the spherical harmonic P-1 approximation is adopted to account for the radiative heat transfer.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.8
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• pp.907-914
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• 2005

Experiments at the Japan Microgravity Center (JAMIC) have investigated the interaction between diffusion flames and solid surfaces Placed neat flames The fuel for the flames was $C_{2} H_{4}$ The surrounding oxygen concentration was 35$\%$ with surrounding air temperatures of $T_{a}$ : 300K. Especially, the effect of wall temperature on soot deposition from a diffusion flame Placed near the wall has been studied by utilizing microgravity environment, which can attain very stable flame along the wall. Cylindrical burner with fuel injection was adopted to obtain two dimensional soot distributions by laser extinction method. In the experiment two different wall temperatures. $T_{w}$=300, 800 K, were selected as test conditions The results showed that the soot distribution between flame and burner wall was strong1y affected by the wall temperature and soot deposition increases with decrease in wall temperature. The comparison among the values lot two different wall temperatures suggests that the change in thermophoretic effect is the most dominant factor to give the change in soot deposition characteristics.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.87-92
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• 2005

Experiments at the Japan Microgravity Center(JAMIC) have investigated the interaction between diffusion flames and solid surfaces placed near flames. The fuel for the flames was $C_2H_4$. The surrounding oxygen concentration was 35% with temperatures of $T_a$=300. Especially, the effect of wall temperature on soot deposition from a diffusion flame placed near the wall has been studied by utilizing microgravity environment, which can attain very stable flame along the wall. Cylindrical burner with fuel injection was adopted to obtain two dimensional soot distributions by laser extinction method. In the experiment two different wall temperatures, $T_w$=300,800K, were selected as test conditions. The results showed that the soot distribution between flame and burner wall was strongly affected by the wall temperature and soot deposition increases with decrease in wall temperature. The comparison among the values for two different wall temperatures suggested that the change in thermophoretic effect is the most dominant factor to give the change in soot deposition characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.60-69
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• 2003

The simplified two-color method is proposed which can estimate the temperature distribution and the soot density of the whole flame with the image analysis of the high-speed photographs. The factors influenced on its processing were examined, for example, the selection of the wave length, the kind of films, the preparation of the calibration curve between the radiance of flame and the luminance temperature. The simplified two-color method reported in this paper can be used as a tool for the improvement of the combustion process in direct injection diesel engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1348-1354
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• 2002

We investigate the flame behavior and spatial distribution of OH, PAHs and soot in a confined buoyant diffusion flame with decrease of the coflowing air flow rate. Direct photographs and Schlieren images represent that flame is Ally occupied by blue flame and becomes unstable, which is partially detached to the fuel nozzle tip in a near extinction flame under extremely reduced oxidizer condition. Laser induced fluorescence profiles clearly shows that OH is still generated in near-extinction flame, although intensity becomes weak with decreasing air flow rate. But soot scattering image cannot be seen any more in an oxidizer deficient ambience and simultaneously the PAHs are widely distributed downstream. These results are due to that a decrease of oxygen concentration in the combustion chamber leads to a temperature drop of flame, as a consequence, to a delay in soot growth and to a expanding of the PAHs, as soot precursors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.5
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• pp.596-603
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• 2003

Present study has been conducted to see the relative effects of adding N: to fuel-side and air-side on flame structure, soot formation and NOx emissions. Experiments were carried out to ascertain to what degree chemical kinetics and/or molecular transport effects can explain the differences in soot formation and NOx emission by studying laminar diffusion flames. Direct photograph was taken to see the flame structure. CARS techniques was used to get the flame temperature profiles. And spatial distribution of soot could be obtained by PLII method. CHEMKIN code was also used to estimate the global residence time to predict NOx emissions at each condition. Results from these studies indicate that fuel-side dilution is more effective than air-side dilution in view of NOx emissions. However, air-side dilution shows greater effectiveness over fuel-side dilution in soot formation. And turbulent mixing and heat transfer problems were thought to be considered in practical applications.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.51-59
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• 2005

Co-flow laminar diffusion flames' temperature has been studied experimentally for ethylene$(C_2H_4)$ using a co-flow burner in order to investigate the characteristics of diffusion flame's temperature distribution. The temperature distributions in the flame were measured by rapid insertion of a R-type thermocouple. The measurement area was divided into three zones. 1st area was expect to created PAH zone, Il nd area was expect to form soot zone, which is known to generate most soot volume fraction, and III rd area was expect to from soot oxidization zone. Also The temperature along the flame y-axis as a fuel quantity was measured. As a results, we have measured temperature neglecting the effect of soot particles attached to the thermocouple junction, which is close to the nozzle and upstream zone has a unstable flow in co-flow diffusion flame and acquires that the flame y-axis temperature has a uniform temperature in the generated soot volume fraction zone(II nd).