In this study used Computational Fluid Dynamic analysis to examine NOx reduction in hydrogen combustion, analyzing six conditions with varying air/fuel ratios, temperatures, and concentrations. Results were compared between two combustor shapes and previous experimental data. Findings showed increased air/fuel ratios decreased flame temperature and increased post-combustion O2. NOx emissions peaked at high temperatures and low O2. Numerical results aligned with previous experimental trends, validating the approach. Combustor shape differences, reflecting variations in fuel and air pipes, significantly affected flow rates and combustion positions. This reduced NOx emissions up to a certain air/fuel ratio, but excessive increases diminished this effect. The study highlights the complex relationship between combustor design, operating conditions, and NOx emissions. Further research is needed to optimize NOx reduction by considering pipe numbers and combustion locations. Future studies should explore various combustor geometries, fine-tune air/fuel ratios, and investigate additional parameters influencing NOx formation and reduction in hydrogen combustion systems.

PURPOSES : The purpose of this study was to evaluate the performance of a titanium dioxide (TiO2) asphalt surface treatment agent for reducing NOx on the roadside at laboratory and full scales. METHODS : To verify the NOx reduction performance of TiO2 and silicon-based resin-applied surface treatment agents at the lab scale, a bed flow photo reactor test (ISO standard) and a mixed tank photo reactor test designed to apply real-scale construction materials were conducted. Subsequently, the full-scale NOx reduction performance was verified using a full-scale demonstration facility, and the field construction capability of the TiO2 asphalt surface treatment agent was verified through actual road site application. RESULTS : The bed flow photoreactor and mixed tank photoreactor methods showed the same trend in the NOx removal performance. Evaluation of the NOx removal performance of the TiO2 surface treatment agent revealed that the NO removal rate was approximately 13% at the laboratory scale and 15% at full scale. CONCLUSIONS : Through this study, it was determined that the asphalt surface treatment agent applied with TiO2 will have a sufficient NOx reduction effect in an actual road site. In the future, it will be necessary to analyze the continuity of the effect according to traffic volume through continuous monitoring in the field.

선택적 촉매 환원법(SCR)은 질소산화물(NOx)을 저감하는 매우 효율적인 방법으로 알려져 있으며 발생된 질소산화물(NOx)을 질 소(N2)와 수증기(H2O)로 환원시키는데 촉매 작용을 한다. 질소산화물(NOx) 저감 성능을 결정하는 요소 중 하나인 촉매는 셀 밀도가 증가하 면 촉매효율이 증가하는 것으로 알려져 있다. 본 연구에서는 실습선 세계로호에 설치되어 있는 발전 기관의 배기가스 조건을 모사한 실 험장치를 통하여 100CPSI(60Cell)촉매의 부하에 따른 질소산화물(NOx) 저감 성능을 확인하고 세계로호에 설치되어 있는 25.8CPSI(30Cell) 촉 매의 기존 연구 자료와의 비교를 통해, 셀 밀도가 질소산화물(NOx)의 저감에 미치는 영향에 대하여 고찰하였다. 실험용 촉매는 셀 밀도만 변화를 주었고 형태는 벌집형(honeycomb), 조성물질은 V2O5-WO3-TiO2를 동일하게 사용하여 제작하였다. 실험결과 100CPSI(60Cell) 촉매의 질소산화물(NOx) 농도 저감율은 평균적으로 88.5%이며 IMO specific NOx 배출량은 0.99g/kwh로 IMO Tier III NOx 배출기준을 만족하였다. 25.8CPSI(30Cell) 촉매의 경우, 질소산화물(NOx) 농도 저감율은 78%, IMO specific NOx 배출량은 2.00g/kwh 이었다 두 촉매의 NOx 농도 저감 율과 IMO specific NOx 배출량을 비교하였을 때, 100CPSI(60Cell)촉매가 25.8CPSI(30Cell) 촉매보다, NOx 농도 저감율은 10.5% 높고 IMO specific NOx 배출량은 약 2배 적은 것을 확인하였다. 따라서 촉매의 셀 밀도를 높임으로써 효율적인 탈질효과를 기대할 수 있으며 향후 실선 테스트를 통하여 검증한다면 촉매의 부피 저감을 통한 제작 비용을 줄이고 협소한 선박 기관실을 효율적으로 사용하기 위한 실용적 인 자료로서 기대된다.

대기오염물질과 온실가스 배출량을 저감 시키기 위한 배기 후처리 장치에 대한 연구는 활발히 진행 중이지만 그 중 선박용 입 자상물질/질소산화물(PM/NOx) 동시저감 장치에서는 엔진에 미치는 배압 및 필터 담체 교체에 대한 문제가 발생하고 있다. 본 연구에서는 PM/NOx를 동시저감 할 수 있는 일체형 장치의 최적 설계를 위해 장치 내부 유동과 입·출구 압력을 통한 배압의 변화를 연구하여 적절한 기준을 제시하였다. Ansys Fluent를 활용하여 디젤미립자필터(DPF) 및 선택적촉매환원법(SCR)에 다공성 매체 조건을 적용하였고 공극률은 30 %, 40 %, 50 %, 60 % 및 70 %로 설정하였다. 또한, 엔진 부하에 따른 Inlet 속도를 경계 조건으로 7.4 m/s, 10.3 m/s, 13.1 m/s 및 26.2 m/s로 적 용하여 배압에 미치는 영향을 분석하였다. CFD 분석 결과, 장치의 입구 온도 보다 입구 속도에 따른 배압의 변화율이 크고 최대 변화율은 27.4 mbar였다. 그리고 모든 경계 조건에서의 배압이 선급 기준인 68 mbar를 초과하지 않았기 때문에 1800 kW 선박에 적합한 장치로 평가 되었다.

A porous photocatalyst concrete filter was successfully produced to remove NOx, by mixing TiO2 photocatalyst with lightweight aerated concrete. Ultra Fine Bubbles were used to form continuous pores inside the porous photocatalytic concrete filter, which was mixed via a bubble generation experiment. The optimal mixing condition was determined to be with 4% of the bubble generation agent B. NO removal specimens were prepared for various photocatalytic loading conditions, and the specimen containing 3% P-25 removed NO at a concentration of 1.03 μmol in 1 h. The NO removal rate of the porous photocatalytic concrete filter prepared in this study was 10.99%. This photocatalytic filter performance was more than 9 times the amount of NO removed by a general photocatalytic filter. The porous photocatalyst concrete filter for removing NOx developed in this study can be applied to various construction sites and the air quality can be solved by reducing NOx contributing to the formation of fine particles.

PURPOSES : NOx is a particle matter precursor that is harmful to humans. Various methods of removing NOx from the air have been developed. TiO2 and activated carbon are particularly useful materials for removing NOx, and the method is known as particulate matter precursor reduction. The removal of NOx using TiO2 requires sunlight for the photocatalytic reaction, whereas activated carbon absorbs NOx particles into its pores after contact with the atmosphere. The purpose of this study is to evaluate the NOx removal efficiency of TiO2 and activated carbon applied to concrete surfaces using the penetration method. METHODS : Surface penetration agents, such as silane-siloxane and silicate, were used. Photocatalyst TiO2 and adsorbent activated carbons were selected as the materials for NOx removal. TiO2 used in this study was formed by crystal structures of anatase and rutile, and plant-type and coal-type materials were used for the activated carbon. Each surface penetration agent was mixed with each particulate matter sealer at a concentration ratio of 8:2, and the mixtures were sprayed onto the surface. The NOx removal efficiency was evaluated using NOx removal efficiency equipment fabricated in compliance with the ISO 22197-1 standard. RESULTS : Anatase TiO2 showed a maximum NOx removal efficiency of 48% when 500 g/m² was applied. However, 500 g/m² of rutile TiO2 showed a NOx removal efficiency of up to 10%. When 700 g/m² of coal-based activated carbon and plant-based activated carbon was used, NOx removal efficiencies of up to 11% and 14%, respectively, were obtained. CONCLUSIONS : Rutile TiO2, a coal-based activated carbon, and plant-based activated carbon have lower NOx removal efficiencies than anatase TiO2. A lower amount of anatase TiO2 (500 g/m²), compared to the other spraying volumes, yielded the most significant NOx removal efficiency under optimal conditions. Therefore, it is recommended that 500 g/m² of anatase TiO2 should be sprayed onto concrete structures to improve the economic and long-term performance of these structures.

Recently air pollution is becoming a global environment issue. Especially, the smoke from engines and boiler systems, which burn fossil fuels directly, is an extremely serious issue. For this reason, IMO is tightening regulations for the control of NOx and SOx. Therefore, in this study, the NOx reduction effect of emulsified oil mixed with 10% of water was tested after applying the emulsified oil to an industrial boiler burner using Bunker-C oil. The study showed that the exhaust gas oxygen concentration of emulsified oil was nearly 1.3% high and this was identified by the effect of dissolved oxygen contained in water. Also, based on the standard oxygen concentration(4%), the average and maximum NOx reduction rates were 28.53% and 30.23% respectively, which means the reduction efficiency was very high.

The fuel used in this study, DMM is an oxygen additive containing 42.5% oxygen by weight and dissolved in diesel fuel, also known as methyl alcohol or Dimethoxymethane (CH3-O-CH2-O-CH3). DMM, which is a colorless liquid, shows chemical characteristics of gas-liquid and is also used as a diesel fuel component. In this study, five mixtures were added to the common diesel fuel at DMM addition rates of 2.5, 5, 7.5, 10 and 12.5% by volume. A single cylinder, four strokes, DI diesel engine was used as the test engine. Experimental data were also collected at 24 engine speed-load conditions operating in steady state. The purpose of this experiment was to study the effect of the addition ratio of oxidized fuel mixed in diesel fuel on engine power and exhaust performance. When compared with the common diesel fuel, the exhaust of Smoke was substantially reduced in all DMM mixing ratios. These results indicate that DMM can be an effective blend of diesel fuel and is an environmentally friendly alternative fuel. This study also shows that smoke and NOx emissions can be reduced at the same time through the application of oxygen fuel and EGR.

본 연구에서는 기존 상용 SCR 촉매보다 비표면적, 경량성 및 온도 응답성이 우수한 SCR 촉매의 개발을 목적으로 바나듐과 텅스텐의 함량과 바인더의 첨가량을 달리하여 Metal foam 형태의 지지체에 코팅하여 SCR 촉매를 제조한 후, 실험실 규모의 마이크로 상압반응기상에서 공간속도별로 NOx 저감 성능을 측정하였다. 촉매의 특성은 Porosimeter, SEM(scanning electron microscope), EDX(energy dispersive x-ray spectrometer) 및 ICP(inductively coupled plasma), 실체현미경(Stereomicroscope) 기기를 이용하여 분석하였다. 연구 결과 NOx 저감 성능은 공간속도가 증가할수록 감소하였고, 바나듐과 텅스텐의 함량이 3.5 wt.% 일 때 가장 우수한 것으로 확인하였다. 또한, 바인더 첨가량이 많을수록 NOx 저감 성능이 감소하는 것으로 나타났는데, 이는 촉매 표면상의 활성점수가 바인더에 의해 점유되어 감소된 것에 따른 것으로 판단된다. 또한 표면 코팅 상태 분석을 통하여 바인더의 첨가량이 적절히 조절 되어야 함을 알 수 있었다.

폐 RHDM(Residue Hydrodemetallation) 촉매상에 침적된 비활성화 성분인 탄소, 황 을 고온배소 처리하여 제거한 후, 과량 침적되어 있는 바나듐은 초음파 교반기에서 5~15wt% 옥살산 수용액을 이용하여 50℃, 5분 조건하에 바나듐 추출량을 조절함으로써 NOx 저감을 위한SCR(Selective Catalytic Reduction) 촉매로의 적용 가능성을 확인하고자 하였다. 폐촉매와 단계별 처리된 RHDM 촉매를 대상으로 상압반응기상에서 NOx 저감 효율을 측정하였고, 촉매의 성분분석은 ICP, C & S analyzer 및 XRF를 이용하여 분석하였다. 10wt% 옥살산 수용액으로 바나듐을 침출한 촉매가 가장 안정적이었으며 높은 NOx 저감 효율을 보였다. 이를 메탈폼 형태의 지지체에 워시코팅한 촉매는 상용 SCR 촉매와 동등 수준의 NOx 저감 효율을 나타내었다. 따라서 폐 RHDM 촉매의 처리 조건 조정에 관한 후속 연구를 통하여 각 적용처에 적합한 SCR 촉매로의 이용 가능성은 충분할 것으로 사료된다.

본 연구에서는 무격막식 전기분해 처리된 해수를 산화제로하는 NO 산화반응의 특성에 대해 실험적으로 살펴보았다. 폐순환 정전류 전기분해 시스템을 통해전해 시간이 길어질수록 전해수의 유효 염소농도와 온도, 염소산 이온의 비율이 증가함을 확인하였다. 전해수가 채워진 버블링 반응기에서 전해수의 유효염소농도와 온도에 비례하여 NO2로 산화되는 NO의 양이 증가하였다. 또한 산화되어 생성된 NO2는 전해수에 용해되어 HNO3- 이온으로 존재함을 확인하였다.

In the present study, potassium and caesium doped Ag/ catalysts were synthesized by simple wet impregnation method and evaluated for selective catalytic reduction (SCR) of NOx using methane. TEM analysis and diffraction patterns demonstrated the finely dispersed Ag particles. BET surface measurements reveal that the prepared materials have moderate to high surface area and the metal amount found from ICP analysis was well matching with the theoretical loadings. The synthesized K-Ag/ and Cs-Ag/ catalysts exhibited a promotional effect on deNOx activity in the presence of and . The long-term isothermal studies at under oxygen rich condition showed the superior catalytic properties of the both alkali promoted samples. The crucial catalytic properties of materials are attributed to NO adsorption properties detected by the NO TPD.

The influence of sulfate on the selective catalytic reduction of on the Ag/ catalyst was studied when was used as a reducing agent. Various preparation methods influenced differently on the activity. Among the methods, cogelation precipitation gave best activity. When sulfates were formed on the surfaces of samples prepared by impregnated and deposition precipitation, activity was enhanced as long as suitable forming condition is satisfied. The major sulfate formed in Ag/ catalyst was the aluminum sulfate and it seems that this sulfate acted as a promoter. When Mg was added to the Ag/ catalyst it promoted activity at high temperature. Intentionally added sulfate also enhanced activity, when their amount was confined less than 3 wt%.

In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated for a direct injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenated blended fuel which has seven kinds of mixed ratio. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission have been investigated. Ethylene glycol mono-n-butyl ether(EGBE) contains oxygen component 27% in itself, and it is a kind of effective oxygenated fuel of mono-ether group that the smoke emission of EGBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in a diesel engine. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel and cooled EGR method.

Due to the global warming problem, diesel engine is becoming an one of the most promising solutions for vehicles in the world. Compared to spark-ignition engines, diesel engines generally have lower unburned hydrocarbon and carbon monoxide, but they also produce still higher levels of NOx and smoke emissions even though using a common-rail injection system. To reduce the diesel emissions, DOC and DPF system have been developed to comply with tighten diesel emission regulations. This paper describes the NOx and smoke emission characteristics of current diesel vehicle with a post injection and plasma after-treatment system. Emissions tests were performed according to New European Driving Cycle mode. Results from these tests show that NOx and smoke emissions with Urea post injection and plasma treatment system is 72% lower than that without the system in the NEDC mode.