• Journal of the Korean Society of Combustion
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• v.6 no.1
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• pp.20-28
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• 2001

Self flue gas recirculation flow is an effective method for low NOx emission in a regenerative low NOx burner. The object of this study is to analyze self flue gas recirculating flow by varying the jet velocity of the combustion air. Fuel and air flow rates are fixed and combustion air jet nozzle diameters are 13, 6.5 and 5mm. The stoichiometric line is obtained from the concentration of fuel using the acetone PLIF technique. It is found that self flue gas recirculating flow is entrained into that line using the two color PIV technique. As the jet velocity of combustion air is increased, the flue gas entrainment rate into the stoichiometric line is increased. This result suggests that NOx emission can be reduced due to the effects of flue gas lowering the flame temperature.

• Journal of ILASS-Korea
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• v.23 no.3
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• pp.136-148
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• 2018

Major countries have tighten their NOx regulation of diesel passenger cars. In the case of the EU, the regulation has been toughen up to 6.25 times since 2000. Despite the regulation the NOx concentration of the ambient has not been reduced proportionally. As these issues, to reduce NOx emission practically, Korea and the EU introduced the real-world driving emission (RDE) regulation and the test method that will be applied after 2017. In this paper, for the regulation to make a soft landing in Korea, 6 diesel passenger cars which met Euro 6a~6d regulation and were equipped with LNT/SCR were tested at a chassis dynamometer with environmental chamber applying the off-cycles (FTP, US06, SC03, HWFET and CADC) and several ambient conditions (-7 and $14^{\circ}C$) as well as certification modes (NEDC, WLTC@ $23^{\circ}C$). The result of the test showed that the ambient temp. and the engine load as a test mode impacted the NOx emission of the cars while the vehicles with SCR emitted NOx lower than with LNT. Additionally, to propose an effective RDE test method, the above result was compared with the results of the other papers which tested RDE using the same cars.

• Journal of the Korean Society of Combustion
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• v.14 no.4
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• pp.17-24
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• 2009

Reburning is one of the most useful technologies for reducing nitric oxide in economically and technically. The reburning process was demonstrated as an effective NOx reduction method through injection of a secondary hydrocarbon fuel. An experimental study has been conducted to evaluate the effect of biomass reburning on NOx and CO formation in a light oil flamed combustion furnace. Reburning tests on NOx reduction of air-carried rice husk powder as the reburn fuel and light oil as the main fuel were performed in flames stabilized by a co-flow swirl and fuel staged burner, which was mounted at the front of the furnace. The results included flue gas emissions and temperature distribution in the furnace for several kinds of experimental conditions. It was observed clearly that NOx concentrations in the exhaust have considerably decreased due to effect of biomass reburning. The maximum NOx reduction rate was 42% when the reburn fuel fraction was 0.18. The CO emissions were kept under 42 ppmv in all experimental tests. And this paper makes clear that in order to decrease NOx concentration in the exhaust when the biomass reburning system is adapted, the control of some factors such as reburn fuel fraction and reburn zone fraction is very important.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.179-189
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• 2008

The performance of Lean NOx Trap (LNT) based on the catalysts of Pt/K/Ba/$\gamma-Al_2O_3$ with proprietary washcoat formulation is studied using a bench flow reactor system. To investigate the effect of temperature and gas hourly space velocity (GHSV) on the nitrogen oxides (NOx) trapping capacity as well as NOx breakthrough time and final ratio of $NO_2$ to NO of LNT, series of adsorption isotherms are carried out with simulated exhaust gases of the lean burn engines. Since typical operation of LNT requires periodic regeneration with a short rich excursion, where the stored or trapped NOx is released and subsequently reduced to $N_2$, the effect of the duration of lean and rich phase and type of reductants on the NOx conversion is investigated. NOx storage capacity and breakthrough time obtained from adsorption isotherms shows a volcano-type dependence on the temperature with a maximum NOx storage capacity occurring $350^{\circ}C$ and with a maximum breakthrough time occurring $400^{\circ}C$ at all GHSVs investigated in this study. Also, maximum ratio of $NO_2$ to NO is obtained at $400^{\circ}C$ with a GHSV of $75,000\;hr^{-1}$ Lean/rich cycle of 100 s lean and 5 s rich used with a concentration of 1.33% of $H_2$ and 4% of CO in the rich phase is found to be optimum at operating temperature of $350^{\circ}C$ and a GHSV of $50,000\;hr^{-1}$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.4
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• pp.171-181
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• 1977

This paper is aiming at calculating NOx concentration, which is one of the harmhul components of emission from the gasoline engine, formed in the combustor through the presess of combustion. Instantaneous temperature and concentration of each components for each division can be determined by the solution of simulatneous equation of reaction equation and equation of energy conservation, inputting the estimated temperature with a considerably wide rage of temperature. After determining instantaneous temperature and instantanous concentration of each components, the nonequilibrium calculation is performed based on the reaction kinetics in order to determine NOx concentration. To summarize the result abtained from the above method ;through the passage of NO concentration, NO concentration is the highest in the first division and it is gradually decreasing through the following divisions In the final division, NO concentation is the lowest.

• Journal of environmental and Sanitary engineering
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• v.21 no.1 s.59
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• pp.44-51
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• 2006

This study was conducted to investigate air quality in the underground parking lot of department store. Sampling sites were selected to the three sites in one department store. Measuring instrument started from November 3rd, 2005 to November 9, 2005. Target air quality parameters include a number of criteria pollutants such as NOx, $O_3$. The purpose of this study was to find out the present condition of indoor air quality in underground parking space of department store. Through the field measurement, the current situation and the behavior of contaminants were investigated and then was compared with the advice standards. The result of this study was as follows; The Average density of NOx gas and $O_3$ gas was maintained below the indoor air advice standards. The Average density of NOx gas and $O_3$ gas was highly measured during the weekend than during the week day. Average density of NOx gas and $O_3$ gas was highly measured at daytime than that of afternoon. Average density of NOx gas was highly measured in the center area than the other area. Average density of $O_3$ gas was highly measured at the entrance than the other area. NOx gas concentration was maintained below 0.3ppm, an average for 1 hours, as defined in the parking space law. $O_3$ gas concentration was maintained below 0.08ppm, an average for 1 hours, as defined in the parking space law.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.485-490
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• 2010

MILD (Moderate and Intense Low Oxygen Dilution) combustion is a technique which is able to reduce NOx formation and to uniform temperature distribution in the furnace by recirculating the exhaust gas to the fresh air and fuel. This study focuses on finding optimal condition of MILD combustor by changing equivalence ratio with fuel and air flow. The present experiment employs six thermocouple sensors in the furnace, and two concentration probes of NOx and CO at the exhaust exit pipe respectively. The MILD combustion phenomena have been observed at the condition of equivalent ratios of 0.71~0.73, and the temperature uniformity, NOx and CO concentration are also examined at the MILD combustion condition.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.332-339
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• 2005

The environmental regulations in the world has been reinforced and many nations has devoted themselves to the development of cost-effective technology. Selective catalyst reduction(SCR) and selective non-catalyst reduction (SNCR) processes are mainly used to treat nitrogen oxidants generated from fossil-fuel combustion. One of these typical technologies for reduction of do-NOx is SNCR process has increased continuously because of the low cost for building and maintenance. Nevertheless the researches on the application to real scale plant by the reductant like Urea are rarely studied. In this paper, an experimental investigations were performed on the SNCR process in the industrial waste incineration plant. With no reducing agent, the concentration of NOx stayed in around 180 ppm $(O_2\;12\%)$ with the exhausting temperature of $950^{\circ}C$ and changed within the range of 20 ppm to remain relatively consistent. When $10\;wt\%)$ of a solution was added, the efficiency of denitrification reached above $61.4\%$ with the NSR of 2.0 and the exhausting temperature of $950^{\circ}C.$ When the concentration of the urea solution was set to $10\;wt\%$ and the sprinkling to four nozzles, the reaction temperature was reduced to about $50~100^{\circ}C$ with a mixture of $10\;wt\%\;CH_3OH\;and\;5wt\%\;Na_2CO_3$ in $40\;wt\%$ of the solution. The NOx removal efficiency increased to $78.4\%,$ achieving a broader and expansive range of reaction temperatures than the addition of an unmixed pure solution.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.540-546
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• 2006

Effects of organic and inorganic additives on the SNCR reaction of NOx were investigated in a pilot scale flow reactor with a variation of operating parameters. NOx reduction efficiency increased with the increase of a residence time and an initial NOx concentration. NOx reduction reaction by urea solution started to appear about 850 and then reached to maximum value around $970^{\circ}C$. NOx reduction efficiency also increased with the increase of NSR (Normalized Stoichiometric Ratio) up to 2.0. Addition of ethanol and phenol as an organic additives shifted the optimum temperature window to lower region with decreasing the maximum NOx reduction efficiency. This might be due to the side reaction of hydrocarbon in ethanol structure. NaOH addition widened the temperature window and enhanced the NOx reduction efficiency about 10％ due to the chain reaction of NaOH and the reduction of $N_2O$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.32-37
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• 1999

The superposing effect of SPCP(Surfoce Induced Plasma Chemical Process) and corona discharge has been studied for rerroval of NOx from industrial flue gases. NOx rermval rates by SPCP, corona discharge and superposing discharge were monitored and compared. Parameters were the concentration and the flow rate of gas, frequency and the type of discharge. Experirrental results showed that NOx removal rate by sUIffPOSing discharge was 10-15[%] higher than that by the other two modes. The higher NOx. rermval rate was observed with the lower frequency of upper electrode in the combined reactor and with the higher frequency of lower electrode. 'The maximum obtainable NOx. rerroval rate by SPCP (18 [W]) and corona discharge (8.5 [W]) was 80[%] and 10[%], respectively. With the combination of the two modes, however, 90[%] of NOx removal rate was observed with the discharge power of 14 [W].14 [W].