• 한국대기환경학회지
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• 제29권3호
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• pp.307-316
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• 2013

The sensitivity of ozone to $NO_x$ and volatile organic compounds (VOCs) emission rates under different ventilation rates and $NO_2-to-NO_x$ emission ratios in a street canyon is investigated using a chemistry box model. The carbon bond mechanism IV (CBM-IV) with 36 gaseous species and 93 chemical reactions is incorporated. $NO_x$ and VOCs emission rates considered range from 0.01 to $0.30ppb\;s^{-1}$ with intervals of $0.01ppb\;s^{-1}$. Three different ventilation rates and three different $NO_2-to-NO_x$ emission ratios are considered. The simulation results show that the ozone concentration decreases with increasing $NO_x$ emission rate but increases with increasing VOCs emission rate. When the emission ratio of VOCs to $NO_x$ is smaller than about 4, the ozone concentration is lower in the street canyon than in the background. On average, the magnitude of the sensitivity of ozone to $NO_x$ emission rate is significantly larger than that to VOCs emission rate. As the $NO_x$ emission rate increases, the magnitude of the sensitivity of ozone to $NO_x$ and VOCs emission rates decreases. Because the ozone concentration is lower in the street canyon than in the background, the increased ventilation rate enhances ozone inflow from the background. Therefore, the increase in ventilation rate results in the increase in ozone concentration and the decrease in the magnitude of the sensitivity of ozone to $NO_x$ and VOCs emission rates when the emission ratio of VOCs to $NO_x$ is smaller than about 4. On the other hand, the increase in $NO_2-to-NO_x$ emission ratio results in the increase in ozone concentration because the chemical ozone production due to the $NO_2$ photolysis is enhanced. In the present experimental setup, the contribution of the change in $NO_2-to-NO_x$ emission ratio to the change in the sensitivity of ozone to $NO_x$ emission rate is larger than that of the change in ventilation rate.

• 수산해양기술연구
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• 제12권1호
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• pp.1-6
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• 1976

To investigate the relation of $NO_x$ emission and consumption rate in a direct injection diesel engine with a multihole nozzle under same fuel consumption and rpm, a naphthyl ethylenediaming method on NO, emission and Tektronix oscilloscop on the indicator diagrams have been used. Comparisons of the $NO_x$ emission and fuel consumption rate made on various conditions have led to the fllowing results. 1. The higher the injection pressure in the later injection time the lower $NO_x$ emission and the fuel consumption rate have been attained. 2. By the change of nozzle hole diameter under the same injection pressure, the $NO_x$ emission was much more lowered in the small diameter than large one, but fuel consumption rate was in inverse proption to the $NO_x$ emission. 3. The effect of injection spray angle, $\frac{1_n}{d_n}$ on $NO_x$ emission, fuel consumption rate under same injection time and injection pressure was neglectable.

• 한국대기환경학회지
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• 제31권6호
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• pp.562-572
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• 2015

$NO_x$ emissions from diesel vehicles have been regarded as a main cause of high $NO_2$ concentration in metropolitan area. Recent studies have shown that the on-road $NO_x$ emissions of diesel vehicles are quite higher than the emission limits specified with the pre-defined test method for emission certification. To reduce air pollutants effectively, the discrepancy of emissions in certification and real-driving conditions should be tackled. In this study, the real-driving emissions have been estimated with portable emission measurement system (PEMS). The results of this study have shown that the on-road $NO_x$ emissions from diesel vehicles have been decreased as the introduction of stricter emission regulation, EURO-6, but additional reduction should be still required and robust technologies should be applied to control $NO_x$ in real-driving conditions. RDE-LDV (Real Driving Emission - Light Duty Vehicles) test method being developed in the European Union can represent excessive on-road $NO_x$ emissions of diesel vehicles as applied emission technologies and can be a solution to remove discrepant $NO_x$ emissions between certification and Korean real-driving conditions. Among the $NO_x$ reduction technologies for EURO-6 diesel vehicles, selective catalytic reduction (SCR) system has shown the better performance than lean $NO_x$ trap (LNT) system to control on-road $NO_x$ emissions. Implementing RDE-LDV will require vehicle manufacturers to adopt the more effective $NO_x$ reduction technology in real driving conditions.

• 한국연소학회지
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• 제4권1호
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• pp.27-38
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• 1999

We constructed a wire-cylinder type pulsed corona discharge system for $NO_x$ removal, which was operated in room temperature. A emission spectrometer was built with a boxcar averager and monochrometer equipped with photo-multiplier tube detector. The sensitivity of the emission spectrometer was greatly improved by synchronizing the emission spectrometer with pulsed corona discharge system using a triggered spark-gap switch. $N_2$ spectrum($c^3{\Pi}_u{\rightarrow}X^1{\Sigma}_g{^+}$) was measured in the range of 300 - 450 nm and oxidizing OH radical emission($A^2{\Sigma}^+{\rightarrow}X^2{\Pi}$) was measured in case $N_2$ was supplied with water bubbling. As wet gas composition of inlet $N_2$ supplied in the discharge system increased, the intensity of OH emission was increased and saturated at wet gas composition 50%. We also investigated additive effect of $C_2H_4,\;H_2O,\;H_2O_2$ on the intensity of OR emission and $NO/NO_2/NO_x$ reduction and analysed the related reaction mechanism in corona discharge process. $H_2O_2$ additive increased the intensity of OH emission and $NO/NO_x$ reduction.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.878-883
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• 2001

The effects of external excitation with various frequencies and amplitudes on the flame behavior and pollution emission characteristics from a laminar jet flame are experimentally investigated. Measurements of $NO_{x}$ emission indices($EINO_{x}$), performed in unconformed and vertical lifted flame at resonance frequency by strong excitation, have been conducted experimentally. It was also conducted to investigate the effects of excited frequency on $NO_{x}$ emissions with a various frequency ranged 0Hz to 2kHz. From the vertical lifted flame like turbulent of the excited jet with resonance frequency was shown that the dependence of $NO_{x}$ emission could be categorized into three groups: Group 1 of intermediate flame length and relative narrow flame volume yielding low $NO_{x}$ emission, Group 2 of short flame length but large flame volume yielding high $NO_{x}$ emission and Group 3 of long flame length with low temperature contours yielding high $NO_{x}$ emission.

• 한국수소및신에너지학회논문집
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• 제28권2호
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• pp.220-224
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• 2017

Nitrogen dioxide ($NO_2$) is an important urban pollutant in Korea. Expecially, diesel vehicles are responsible for the most traffic rated nitrogen oxide ($NO_X$) emission, including nitric oxide (NO) and nitrogen dioxide ($NO_2$). Though nitrogen oxide ($NO_X$) emission from vehicle was applied a strict enforcement of emission standard, the specific $NO_2$ fraction in $NO_X$ ($NO_2/NO_X$) from various types of diesel vehicles was not understood. In order to investigate the fraction of $NO_2/NO_X$, the vehicle emission study was carried out at the facility of Transport Pollution Research Center (TPRC), National Institute of Environmental Research (NIER), Korea. Three different types of diesel vehicles(VAN, SUV, passenger) were tested on the NIER driving mode. The result of $NO_2/NO_X$ ratio was over 0.1 for all test vehicles and the highest $NO_2$ emission was observed at the van vehicle. The observation was showed that the emission trend of $NO_2/NO_X$ for passenger and SUV vehicles were inversely proportional. Also, as the emission standard has been strengthen, the emission rate of $NO_2$ has been decrease.

• 한국화재소방학회논문지
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• 제18권2호
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• pp.34-40
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• 2004

층류 비예혼합 분류 화염에서 다양한 주파수와 강도로 외부에서 유동장에 자극을 주었을 때 화염의 배출특성과 거동에 대해서 실험적으로 조사하였다. 먼저 일정한 관 공명 주파수에서 가진 강도를 가변시켜 난류화염 된 부상화염에서 질소산화물 배출 지수($EINO_x$)를 측정하였다. 또한, 가진 강도가 일정한 상태에서 주파수를 0 Hz에서 높은 주파수인 2 KHz까지 다양한 주파수 조건으로 가진된 한 경우에도 질소산화물의 배출지수를 측정하였다. 큰 가진 강도의 관공명 주파수로 가진된 경우 부상된 난류화염에서 $NO_x$ 배출 특성은 다음과 같이 크게 세 가지 형태의 특성을 보였다. Group I의 화염에서는 공간적인 섭동이 크며 비교적 화염길이가 길고 높은 $NO_x$ 배출 특성을 보였으며 Group II에서는 상대적으로 짧은 길이와 좁은 폭의 화염거동에 낮은 $NO_x$배출 특성을 보였다. Group III에서는 약간 긴 화염길이에 매우 큰 화염체적으로 상당한 높이까지 시ㆍ공간적으로 섭동이 큰 운동양태로 부상되는 거동과 가장 높은 $NO_x$ 배출 특성을 보였다.

• 대한기계학회논문집
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• 제19권2호
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• pp.559-567
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• 1995

The combustion process within a porous inert medium (PIM) burner is numerical studied. A detailed chemical reaction scheme including thermal and prompt NO$_{x}$ reactions is used to predict the formation and destruction of pollutants such as NO$_{x}$ and CO. The reaction paths for NO$_{x}$ formation are divided to quantify the amount of NO$_{x}$ formed through thermal NO$_{x}$ reaction or through prompt NO$_{x}$ reaction. Emission index is calculated to compare the actual mass of NO$_{x}$ or CO produced through the combustion of unit mass of fuel. It is found NO formation in PIM burner is confined in flame zone and formation is suppressed due to heat loss at down-stream of the flame. Higher production of NO through prompt NO reaction path is observed due to the higher concentration of fuel derivative species and its higher diffusion at flame front. For all equivalence ratios, CO emission within PIM burner is lower than that from the one-dimensional freely-propagating flame. PIM burner flame has better NO$_{x}$ emission index from .psi. = 0.75 to .psi. = 1.1. to .psi. = 1.1.

• 한국수소및신에너지학회논문집
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• 제11권1호
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• pp.1-9
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• 2000

The goals of this research are to understand the $NO_x$ emission in direct injected diesel engine with premixed hydrogen fuel. Hydrogen fuel was supplied into the test engine through the intake pipe. Amount of hydrogen-supplemented fuel was 70 percent basis heating value of the total fuel. The effects of exhaust gas recirculation(EGR) on $NO_x$ emission were studied. The exhaust gas was recirculated to the intake manifold and the amount of exhaust gas was controlled by the valve. The major conclusions of this work include: (i) the tested engine was run without backfire under 70 percent hydrogen fuel supplemented; (ii) the peak cylinder pressure was decreased with increase of EGR ratio due to the decrease of oxygen concentration in an intake pipe; and (iii) $NO_x$ emission was decreased by 77% with 30% EGR ratio. Therefore, it may be concluded that EGR is effective method to lower $NO_x$ emission in hydrogen fueled diesel engine.

• 한국대기환경학회지
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• 제28권6호
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• pp.656-665
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• 2012

Recently, yearly production of SRF (Solid Recovered Fuel) as an alternative fuel has been rapidly increasing because of the limited waste disposal, rise in oil prices and reduction of greenhouse gas emission. However, SRF using facilities are excluded from the National Air Pollutant Emission Estimation because SRF using facilities are not yet included among the SCC (Source Classification Code). The purpose of this research was to estimate the emission and emission factor of SRF using facilities' PM and $NO_x$, in order to investigate whether or not they are included in the National Air Pollutant Emission Estimation. The emission factors of SRF using facilities' PM and $NO_x$ are calculated as 0.216 kg/ton, and 3.970 kg/ton, and the emission was estimated based on the yearly total SRF usage of 2011. The results above was 18.7% for PM and 12.8% for $NO_x$ emissions from combustion facility (SCC2) in manufacturing industry combustion (SCC1) of CAPSS. If CAPSS estimate the emission by adding SCC on unlisted SRF in case of Boiler (SCC3) fuel, both PM and $NO_x$'s emissions would increase by 15.8% and 11.3% compare to the emissions for the existing combustion facility. As a result, emissions caused by SRF should be considered when calculating the National Air Pollutant Emission Estimation. In addition, further researches to develop emission factor and improve subdivided SCC should be done in the future, for the accurate and reliable estimation of National Emission.