Reactions of o-cresol and nitrocresol with nitrogen oxides (NOx) in sunlight and with ozone-nitrogen dioxide mixtures in the dark

1985 ◽  
Vol 19 (10) ◽  
pp. 968-974 ◽  
Author(s):  
Daniel. Grosjean
Keyword(s):  
Nitrogen Oxides ◽  
Nitrogen Dioxide

scholarly journals Air pollution by nitrogen oxides in Sarajevo from 2005 to 2010

2013 ◽  
Vol 3 (3) ◽  
pp. 250-254
Author(s):  
Suad Habeš ◽  
Zarema Obradović ◽  
Aida Ridžal ◽  
Asmir Aldžić
Keyword(s):  
Air Pollution ◽  
Nitrogen Oxides ◽  
Positive Result ◽  
Nitrogen Dioxide ◽  
Total Concentration ◽  
Nitrogen Monoxide ◽  
Atmospheric Conditions ◽  
Measuring Point ◽  
Limit Values ◽  
Research Show

Introduction: Air pollution occurs when the concentration of certain substances (pollutants) reaches a size which causes its toxicity, or in other words, begins to cause harm to human health, fl ora and wildlife.Methods: Measurements were performed in the period from 2005 to 2010, at the measuring point Bjelave-Sarajevo by the method of Griess-Saltzmann. It encompasses the following parameters: NO, NO2, NOx, measured concentrations of pollutants in the atmosphere reduced to normal atmospheric conditions of 293 K (Kelvin) and pressure of 101.3 kPa (kilopascal).Results: NO concentration in the period from 2005 to 2008 was above the permitted value, but the results of research in the period between 2009 and 2010, have shown that there was a decrease in NO concentration in the atmosphere. Measurements show that the concentration of this pollutant is currently declining, which is a positive result compared to the pollution of the atmosphere by nitrogen monoxide. Furthermore, the results of the research showed that the concentration of NO2 for the period of 2005 to 2010, is in the limited values, and that has a decreasing trend, which is also a positive result compared to the pollution of the atmosphere by nitrogen dioxide. Related to the total concentration of NOx in the atmosphere, the results of the research show that their representation corresponds to the limit values existing in the Rulebook on limit values for air quality.Conclusion: The results of the research for the pollution of the atmosphere by nitrogen oxides in the investigated area show that the amount of nitrogen oxides in the atmosphere is in constant decline.

Formation of Nitrogen Dioxide and Formaldehyde in a Medium Duty Diesel Engine With Oxygenated Fuels

2020 ◽  
Author(s):  
Denis Notheis ◽  
Uwe Wagner ◽  
Amin Velji ◽  
Thomas Koch
Keyword(s):  
Diesel Engine ◽  
Nitrogen Oxides ◽  
Nitrogen Dioxide ◽  
Diesel Fuel ◽  
Oxygen Radicals ◽  
Injection Timing ◽  
Boost Pressure ◽  
Fuel Ratio ◽  
Oxygenated Fuels ◽  
Operating Points

Abstract For modern Diesel aftertreatment systems the ratio of nitrogen dioxide (NO2) to nitrogen oxides emissions (NOx) is of great importance for the conversion of total NOx especially at low loads and low engine out exhaust temperatures. As known from previous studies the relative air-fuel ratio and so the increase of oxygen has a major impact on the in-cylinder formation of NO2. As the focus lies mainly on increasing the relative air-fuel ratio by increasing the boost pressure the influence of bounded oxygen in oxygenated fuels is not yet fully understood and is therefore in the focus of this papers. Bounded oxygen offers the potential to release oxygen radicals, which can increase NO2 formation from nitrogen monoxide (NO) at higher pressures according to the principle of Le Chatelier. At low pressures, however, released oxygen radicals can also lead to a reduction of NO2. Additionally, concerning the in-cylinder formation of NO2, the formation of formaldehyde (HCHO) is focused in this investigation, too. Especially for the oxygenated fuel like OME3–5 which can be interpreted as a compound of formaldehyde molecules the HCHO emission might increase. Although HCHO has not yet been regulated for vehicles, its carcinogenic properties require its reduction as far as possible. In this paper, investigations are presented which were carried out on a single-cylinder Diesel engine with different oxygenated fuels such as oxymethylene ether compounds (OME3–5) and 2-ethoxyethyl ether (2-EEE) and blends of these components with conventional Diesel fuel. The relevant exhaust gas components were measured using different analysis method for high accuracy and mutual validation. To analyze the effects of the fuel composition on nitrogen dioxide and formaldehyde formation the fuels are compared with pure Diesel fuel operation. Several operating points were investigated together while varying engine parameters such as relative air-fuel ratio, EGR rate, injection timing and injection pressure in a one-factor-time parameter study. Additionally, at a low load operating point a Design of Experiments (DoE) study was done to see the statistical impact and the main influencing parameters of the formation of NO2 and HCHO. Furthermore, other typical Diesel emissions like particulates, carbon monoxide and the total nitrogen oxides are investigated and compared. The investigations show an inconsistent behavior at different operating points for NO2. In most operating points a decrease of NO2 is visible, which was attributed to a decrease of the total NOx emission. Especially at higher relative air-fuel ratios and so high charge pressures the potential of oxygenated fuels to increase the NO2 to NOx ratio becomes apparent. Due to the very low particulates emissions which can be achieved with OME3–5 fuel, no restriction on low relative air/fuel ratios and higher EGR rates regarding the particulate emissions (smoke limit) exists. The HCHO emissions show different behavior in these restriction zones. At partial load, high EGR rates and low relative air-fuel ratios, HCHO emissions increase. In contrast, when the load is increased and the stoichiometric conditions are reached, the HCHO emissions decrease.

Relationship between lightning activity and tropospheric nitrogen dioxide and the estimation of lightning-produced nitrogen oxides over China

2017 ◽  
Vol 34 (2) ◽  
pp. 235-245
Author(s):  
Fengxia Guo ◽  
Xiaoyu Ju ◽  
Min Bao ◽  
Ganyi Lu ◽  
Zupei Liu ◽  
...  
Keyword(s):  
Nitrogen Oxides ◽  
Nitrogen Dioxide ◽  
Lightning Activity

scholarly journals Low-Speed Marine Diesel Engine Modeling for NOx Prediction in Exhaust Gases

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4442
Author(s):  
Branko Lalić ◽  
Andrijana Poljak ◽  
Gojmir Radica ◽  
Antonija Mišura
Keyword(s):  
Diesel Engine ◽  
Nitrogen Oxides ◽  
Nitrogen Dioxide ◽  
Nitrogen Oxide ◽  
Fuel Consumption ◽  
Compression Ratio ◽  
Fuel Injection ◽  
Nitrogen Monoxide ◽  
Exhaust Emissions ◽  
Injection Timing

Knowing the process of generating exhaust emissions and the determination of influential parameters are important factors in improving two-stroke slow-speed marine engines, particularly for further reductions in fuel consumption and stringent regulations on the limitation of nitrogen oxide emissions. In this article, a model of a marine low-speed two-stroke diesel engine has been developed. Experimental and numerical analyses of the nitrogen monoxide formations were carried out. When measuring the concentration of nitrogen oxides in the exhaust emissions, the amount of nitrogen dioxide (NO2) is usually measured, because nitrogen monoxide is very unstable, and due to the large amount of oxygen in the exhaust gases, it is rapidly converted into nitrogen dioxide and its amount is included in the total emission of nitrogen oxides. In this paper, the most significant parameters for the formation of nitrogen monoxide have been determined. Model validation was performed based on measured combustion pressures, engine power, and concentrations of nitrogen oxides at 50% and 75% of maximum continuous engine load. The possibilities of fuel consumption optimization and reduction in nitrogen monoxide emissions by correcting the injection timing and changing the compression ratio were examined. An engine model was developed, based on measured combustion pressures and scavenging air flow, to be used on board by marine engineers for rapid analyses and determining changes in the concentration of nitrogen oxides in exhaust emissions. The amount of nitrogen oxide in exhaust emissions is influenced by the relevant features described in this paper: fuel injection timing and engine compression ratio. The presented methodology provides a basis for further research about the simultaneous impact of changing the injection timing and compression ratio, exhaust valve opening and closing times, as well as the impact of multiple fuel injection to reduce consumption and maintain exhaust emissions within the permissible limits.

scholarly journals Mechanism of the oxidation of nitric oxide with oxygen

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Józef Głowiński ◽  
Józef Hoffmann ◽  
Marcin Wilk
Keyword(s):  
Nitric Oxide ◽  
Nitrogen Oxides ◽  
Nitrogen Dioxide ◽  
Gas Phase ◽  
Oxidation Reaction ◽  
Nitrogen Monoxide ◽  
Fast Reactions

Abstract Very fast reactions of forming higher nitrogen oxides set out an equilibrium framework for the course of the reaction of nitrogen monoxide oxidation. The slow course of reaction of nitrogen monoxide with oxygen permanently violates the created equilibria. In particular, the equilibrium of the oxidation reaction of nitrogen monoxide with nitrogen dioxide. The contribution of this reaction to the transformation of nitrogen monoxide in the conditions of nitrogen trioxide removal from the gas phase was estimated.

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