• 한국환경농학회지
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• 제26권1호
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• pp.1-6
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• 2007

본 연구에서는 바이오가스의 연소엔진을 이용한 에너지 전환시에 발생되는 $NO_x$와 CO의 배출특성을 분석하고 나아가 배출계수를 산정하고자 하였다. 바이오가스의 주성분인 메탄을 70%로 한 합성가스를 이용하여 실험한 결과 연소엔진의 표준상태에서 $NO_x$와 CO가 각각 4 ppm과 100 ppm의 배출농도를 나타내었고, 이는 1.29g/MMBtu와 30.86 g/MMBtu의 배출계수 값을 산정할 수 있었다. 바이오가스의 주성분인 메탄을 60%로 한 약간의 과잉공기의 상태에서는 $NO_x$와 CO가 각각 2 ppm과 200 ppm의 배출농도를 나타내었고, 이는 정격 조건에 비해 투입열량이 적어져 연소온도의 저하로 인하여 열적 반응에 의해 생성되는 $NO_x$는 줄고, CO는 증가함을 알 수 있었다. 미국 EPA의 배출계수를 비교하기 위하여 투입된 연료의 열량을 기준으로 비교해 볼 때 본 연구의 결과가 $NO_x$의 경우 근사한 값을 보여 주었고, 이는 국내 바이오 가스 연소시의 오염배출계수로 잘 적용 가능함을 보여 주었다. 본 연구에서 사용한 가스엔진이 오염배출 측면에서 대기 환경보전법상의 배출 허용기준 내에서 가동됨을 알 수 있었고, 가동조건에 따라 연소온도를 증가시킴으로서 CO의 발생을 저감시킬 수 있으리라 사료된다.

• 한국대기환경학회지
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• 제13권6호
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• pp.451-461
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• 1997

The soil NO flux measurements in Korea were made from 17 May 1997 to 16 June 1997 on grass land at Kunsan National University in southwestern Korea by using flow-through chamber technique. The experiment was conducted in an effort to determine the role of natural emissions of NO on rural atmospheric photochemistry, and to understand the soil NO emission mechanism with respect to soil parameters. Soil NO fluxes were measured every minutes and averaged in every 15 minutes as well as soil temperature. Soil samples were analyzed for $NO_3^-, NH_4^+$, and moisture in soil. Soil nitrate was not detected in most times, and total N-containing was limited in site soils. There was a optimum range of soil moisture and temperature for soil NO flux. The overall average of soil NO emission rates were found to be 1.30 $\pm 0.92 ngNm^{-2}s^{-1}$ (n=1219), and ranged from 0.01 ngNm^{-2}s^{-1}$ to 5.62 ngNm^{-2}s^{-1}$. Diurnal variation of soil NO emission was typical, which was in higher level during daytime, and was in lower level over the night. NO flux showed a strong soil temperature dependence $(r^2=0.78)$, but not with soil moisture and soil N-containing during this experimental period; NO fluxes increased exponentially as soil temperature increased. In order to assure the relevant relationship between soil NO flux and the soil parameters, long-term soil flux measurement on different types of land use should be planned and conducted continuously.

• 한국대기환경학회지
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• 제29권6호
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• pp.745-756
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• 2013

The purpose of this study is to evaluate representativeness of fuel-based emission factors. Twelve light-duty diesel vehicles which meet Euro-3 to 5 legislative emission limits were selected for emission tests. Second-by-second modal emission rates of vehicles were measured on a standard laboratory chassis dynamometer system. An off-cycle driving cycle was developed as a representative Korean real-world on-road driving cycle. Fuel-based emission factors were developed for short trip segments that involved in the selected driving cycle. Each segment was defined to have unit travel distance, which is 1 km, and characterized by its average speed and Relative Positive Acceleration (RPA). Fuel-based $NO_x$ emission factors demonstrate relatively good representativeness in terms of vehicle operation conditions. $NO_x$ emission factors are estimated to be within ${\pm}20%$ of area-wide emission factor under more than 40% of total driving situations. This result implies that the fuel-based $NO_x$ emission factor could be practically implemented into the on-road emission management strategies, such as a remote sensing device (RSD). High emitting vehicles as well as high emitting operating conditions heavily affect on the mean values and distributions of CO and THC emission factors. Few high emitting conditions are pulling up the mean value and biasing the distributions, which weaken representativeness of fuel-based CO and THC emission factors.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.129-136
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• 2003

Numerical study with momentum-balanced boundary conditions has been conducted to grasp chemical effects of added $CO_{2}$ and $H_{2}O$ to fuel- and oxidizer-sides on flame structure and NO emission behavior in $CH_{4}$/Air counterflow diffusion flames. The dilution with $H_{2}O$ results in significantly higher flame temperatures and NO emission, but dilution with $CO_{2}$ has much more chemical effects than that with $H_{2}O$. Maximum reaction rate of principal chain branching reaction due to chemical effects decreases with added $CO_{2}$. but increases with added $H_{2}O$. The NO emission behavior is closely related to the production rate of OH, CH and N. The OH radical production rate increases with added $H_{2}O$ but those of CH, N decrease. On the other hand the production rates of OR CH and N decrease with added $CO_{2}$. It is found that NO emission behavior is considerably affected by chemical effects of added $CO_{2}$ and $H_{2}O$.

• 공업화학
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• 제20권6호
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• pp.675-680
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• 2009

SM탄(인도네시아산)을 이용하여 NOx 배출 특성을 조사하였다. 실험은 석탄 거치 후 승온하며 연소하는 방법과 승온 후 석탄을 주입하는 방법을 이용하였다. 산소희박 분위기에서는 배출 NOx가 연소온도와 반비례의 관계를 나타내었으며 이는 fuel N이 강한 환원 분위기에서 $N_{2}$로 전화되기 때문인 것으로 나타났다. 또한 주입 가스량 증가 시에는 산화 분위기에 의해 fuel N이 NO로 산화되어 total fuel NO가 증가하는 경향을 나타내었다. 제조 온도에 따른 char의 연소시 발생되는 NO의 분석으로 total fuel N, volatile-N, char-N이 각각 NO로 전화되는 부분으로 구분될 수 있었으며 실험결과 본 연구에 사용된 SM탄은 total NOx의 대부분이 volatile-N에 기인하는 것으로 나타났다.

• 한국대기환경학회지
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• 제25권5호
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• pp.369-381
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• 2009

The objective of this study was to simulate surface air pollutants and to examine reliability of mobile emission for CMAQ system using an observation-based approach in the Seoul Metropolitan Area. Accurate assessment of emissions from mobile source is one of the most debatable parts in the entire emissions inventory process. For this study, we evaluated the official emission inventories of Volatile Organic Compounds (VOCs) and nitrogen oxides ($NO_x$) using an observation-based approach. In this paper, we achieved VOCs/CO and $NO_x$/CO ratios derived from ambient measurements taken from June to August of 2005 in early morning (07:00~08:00). And we compared them with those derived from the emission inventory. Based on these ratios and on the assumption that official inventory of CO emissions is reasonably accurate, mobile emissions of $NO_x$ seem to be slightly overestimated and VOCs emissions significantly underestimated. The results of simulations using modified emission of mobile source were in closer agreement with the observation results except NO. Predicted NO values based on revised $NO_x$ emissions were considerably lower than the observed values. Using modified emission inventories brings the modeled values into closer agreement with observed ozone levels in Seoul. Especially in case of CO, $NO_x$ and VOCs emission, the modified values were suitable for simulating ozone levels in Seoul and Gyeonggi. However, ozone values predicted using the modified emissions were higher than the observed and predicted values based on original emissions. According to the 95 percentile ozone concentrations, emission revised by CO, $NO_x$ and VOCs from mobile source was the best for predicting high concentration.

• 한국환경과학회지
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• 제17권12호
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• pp.1413-1419
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• 2008

The Kyoto Protocol, that had been in force from February 16, 2005, requires significant reduction in $CO_2$ emissions for all anthropogenic sources containing transportation, industrial, commercial, and residential fields, etc, and automotive emission standards for air pollutants such as particulate matter (PM) and nitrogen oxides $(NO_x)$ become more and more tight for improving ambient air quality. This paper has briefly reviewed homogeneous charge compression ignition (HCCI) combustion technology offering dramatic reduction in $CO_2,\;NO_x$ and PM emissions, compared to conventional gasoline and diesel engine vehicles, in an effort of automotive industries and their related academic activities to comply with future fuel economy legislation, e.g., $CO_2$ emission standards and corporate average fuel economy (CAFE) in the respective European Union (EU) and United States of America (USA), and to meet very stringent future automotive emission standards, e.g., Tier 2 program in USA and EURO V in EU. In addition, major challenges to the widespread use of HCCI engines in road applications are discussed in aspects of new catalytic emissions controls to remove high CO and unburned hydrocarbons from such engine-equipped vehicles.

• Journal of Korean Society for Atmospheric Environment
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• 제11권E호
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• pp.31-43
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• 1995

Natural emissions of NOx from soils were measured at an agricultural corn field during 3 weeks of growing season in summer (from May to June) 1995. This experiment was conducted in an effort to characterize the role of soil NOx on tropospheric ozone formation in rural atmosphere, and understand the natural NOx emission mechanism with respect to soil parameters. NO fluxes were ranged from 3.1 ng Nm$^{-2}s^{-1}$ to 259.0 ng Nm$^{-2}s^{-1}$, and average NO flux during experimental period was found to be 47.6 $\pm$ 50.6 ng Nm$^{-2}s^{-1}$ with 732 number of data. Diurnal variation of NO flux was shown clearly with daytime maximum and nighttime minimum. NO fluxes were correlated with soil temperature. Exponential soil temperature dependency of NO fluxes was found with 0.0160$^{circ}C^{-1} of k and r^2=0.508$, which agrees well to the value estimated at corn fields in eastern United States. The significant increases of NO fluxes from agricultural soil were detected after applying N fertilizers to soil. THe mechanisms attributed to this are enhanced biological nitrification and denitrification. In the view of rural ozone formation, the roles of natural NO emissions are very essential, especially in NOx - limited region such as southern United States.

• 한국토양비료학회지
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• 제44권6호
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• pp.1232-1238
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• 2011

아산화질소 ($N_2O$)는 가장 중요한 지구온난화 가스 중의 하나로 농업용으로 시용한 비료의 생물학적인 변환에 의한 것이 가장 큰 배출 원인으로 알려져 있다. 우리나라 농경지로부터 아산화질소의 간접배출 특성 및 배출량을 밝히기 위해 2007부터 2010년 까지 4년간 경남지방의 농업용관정의 지하수 질소성분들을 분석한 결과, 총 질소의 경우 평균 6.91, 질산태질소는 $5.06mg-N\;L^{-1}$이었다. 용존 아산화질소의 농도는 평균 $14.2{\mu}g-N\;L^{-1}$, 중앙값은 $7.8{\mu}g-N\;L^{-1}$, 최고값은 $169.6{\mu}g-N\;L^{-1}$로 분포하였다. 지하수 중의 총 질소나 질산태질소의 농도는 연도나 시기별로 큰 차이가 없었으나 용존 아산화질소 농도는 연도별로는 2009년에 시기별로는 8월이 가장 낮은 결과를 보였다. 우리나라 지하수 중의 $N_2O$-N 농도와 $NO_3$-N 농도비는 평균값이 0.0034, 중앙값이 0.0018이며, 95% 이상이 IPCC 가이드라인의 default 값인 0.015 이하에 분포하고 있어 IPCC가 1996 가이드라인의 농경지 지하유출에 의한 간접배출계수 ($EF_{5-g}$) 0.015 $N_2O-N/NO_3-N$가 우리나라의 환경보다 너무 높게 선정된 것임을 알 수 있었다. 따라서 IPCC의 $EF_{5-g}$ default 값인 0.015 $N_2O-N/NO_3-N$ 대신 우리나라 농경지 지하수 중의 $N_2O$-N와 $NO_3$-N 농도비의 평균값인 0.0034 $N_2O-N/NO_3-N$을 농경지 질소의 지하유출에 의한 아산화질소 간접배출량 평가를 위한 국가고유 배출계수 ($EF_{5-g}$)로 제시코자 하며, 따라서 농경지에서 수계유출에 의한 아산화질소 전체의 간접 배출계수 ($EF_{5-g}+EF_{5-r}+EF_{5-e}$)는 현재 우리나라의 국가 배출량평가에 사용되는 IPCC default값 0.025 $N_2O-N/NO_3-N$ 대신 0.0134 $N_2O-N/NO_3-N$를 제시코자 한다. IPCC의 수계 간접 배출계수인 0.025 $N_2O-N/NO_3-N$을 적용하여 평가한 2008년 우리나라 농경지에서 질소의 수계유출에 의한 아산화질소 배출량은 1,801,576톤 ($CO_2$-eq)이었으나 본 연구에서 제시한 배출계수인 0.0134 $N_2O-N/NO_3-N$을 적용할 경우 964,645톤 ($CO_2$-eq)으로 835,931톤 ($CO_2$-eq)의 온실가스 배출 감축효과를 얻을 수 있었다. 하지만 본 연구에서 제시한 배출계수는 질소 유출경로 중 가장 비중이 큰 지하침출에 의한 배출계수인 $EF_{5-g}$ 뿐으로 우리나라 농경지 아산화질소 간접배출량의 올바른 평가를 위해서는 앞으로 시용된 질소 중 수계를 통한 외부 유출 비율에 관한 default 값인 $Frac_{LEACH}$ (30%), 표면수 유출계수인 $EF_{5-r}$ (0.0075 $N_2O-N/NO_3-N$), 그리고 하천변을 통해 유출되는 계수인 $EF_{5-e}$ (0.0025 $N_2O-N/NO_3-N$ )에 관한 추가적인 연구가 수행되어야 할 것이다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.263-266
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• 2012

The characteristics of mild combustion and pollutant emission were investigated computationally with supplied air stream temperature and dilution rate in jet flame. The air was diluted with main combustion products. As dilution rate increased at fixed air temperature, the temperature distribution of burner inside was uniformed and the maximum mole fraction of CO and NO was decreased. In addition, emission indices for NO, CO, and $CO_2$ were compared with air temperature and dilution rate.