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Articoli di riviste sul tema "Nitrogen oxides Environmental aspects"
1
Fialko, Nataliia, Raisa Navrodska, Malgorzata Ulewicz, Georgii Gnedash, Sergii Alioshko e Svitlana Shevcuk. "Environmental aspects of heat recovery systems of boiler plants". E3S Web of Conferences 100 (2019): 00015. http://dx.doi.org/10.1051/e3sconf/201910000015.
Testo completoAbstract (sommario):
The results of studies on improving the environmental characteristics of boiler plants of municipal heat-power engineering in the application of technologies for the deep recovery of heat from exhaust-gases of gas-fired boilers are presented. The data on the reduction of environment by reducing the amount and temperature of harmful emissions resulting from fuel combustion are given. The data are given for boiler plants equipped with complex heat-recovery systems characterized by cooling the exhaust-gases below the dew point of the water vapor contained in them. It is shown that the decrease in emissions is due to a decrease in fuel consumption in boilers due to the beneficial use of the heat of exhaust-gases in these systems and the dissolution of nitrogen and carbon oxides in the condensate, formed in the heat-recovery equipments. The analysis of improving the environmental safety of boiler plants when used in heat-recovery technologies of corrosion protection systems for chimneys has been performed. Anticorrosion protection is provided by preventing condensate formation in the exhaust-gas ducts of boiler plants when using technologies for the deep recovery of exhaust-gas heat. To prevent condensate formation, the method of pre-drying cooled exhaust-gases in a heat exchanger-preheater installed after heat-recovery equipment is used. It is also shown that the use of complex heat-recovery systems provides in the boiler plant additional water in the form of condensate formed during condensation of moisture from exhaust-gases. Receipt of this condensate is another ecological effect of heat-recovery, which allows reducing the consumption of natural water resources for supply municipal heat networks.
2
SOMESHWAR, ARUN V., JAY P. UNWIN, WILLIAM THACKER, LAUREL EPPSTEIN e BARRY MALMBERG. "Environmental aspects of wood residue combustion in forest products industry boilers". March 2011 10, n. 3 (1 aprile 2011): 27–34. http://dx.doi.org/10.32964/tj10.3.27.
Testo completoAbstract (sommario):
We conducted a comprehensive review of air emissions resulting from burning wood residues in industrial boilers and potential methods to control these emissions. This report compares average emissions with similar data published by the U.S. Environmental Protection Agency for the burning of fossil fuels coal, oil, and natural gas in industrial boilers. As compared with coal or oil combustion, wood combustion in boilers generally leads to lower emissions of trace metals, hydrochloric acid, sulfur dioxide (SO2), and nitrogen oxides (NOx); higher emissions of carbon monoxide, polyaromatic hydrocarbons, and total volatile organic compounds; and comparable emissions of particulate matter and polychlorinated dibenzo-dioxins and -furans (PCDDs/Fs) (both of which are highly dependent on the efficiency of the ultimate particulate matter control device). Most importantly, wood combustion is carbon dioxide-neutral, a distinct advantage over fossil fuel combustion. Firing wood in stoker units with sulfur-containing fuels, such as coal and oil, leads to a reduction in expected SO2 emissions because of the high carbon and alkali content of most wood ash, and cofiring wood with coal also has some benefits for NOx reduction. This report also discusses the generation and types of combustion ashes resulting from wood burning in mostly combination boilers in the United States and Canada, and provides an overview of ash management practices and the salient characteristics of such ashes relative to their trace metal, organic, and PCDD/F contents.
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Mikulandric, Robert, Drazen Loncar, Dejan Cvetinovic, Gabriel Spiridon e Daniel Schneider. "Improvement of environmental aspects of thermal power plant operation by advanced control concepts". Thermal Science 16, n. 3 (2012): 759–72. http://dx.doi.org/10.2298/tsci120510134m.
Testo completoAbstract (sommario):
The necessity of the reduction of greenhouse gas emissions, as formulated in the Kyoto Protocol, imposes the need for improving environmental aspects of existing thermal power plants operation. Improvements can be reached either by efficiency increment or by implementation of emission reduction measures. Investments in refurbishment of existing plant components or in plant upgrading by flue gas desulphurization, by primary and secondary measures of nitrogen oxides reduction, or by biomass co-firing, are usually accompanied by modernisation of thermal power plant instrumentation and control system including sensors, equipment diagnostics and advanced controls. Impact of advanced control solutions implementation depends on technical characteristics and status of existing instrumentation and control systems as well as on design characteristics and actual conditions of installed plant components. Evaluation of adequacy of implementation of advanced control concepts is especially important in Western Balkan region where thermal power plants portfolio is rather diversified in terms of size, type and commissioning year and where generally poor maintenance and lack of investments in power generation sector resulted in high greenhouse gases emissions and low efficiency of plants in operation. This paper is intended to present possibilities of implementation of advanced control concepts, and particularly those based on artificial intelligence, in selected thermal power plants in order to increase plant efficiency and to lower pollutants emissions and to comply with environmental quality standards prescribed in large combustion plant directive.
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Gis, Wojciech, Maciej Gis, Jacek Pielecha e Kinga Skobiej. "Alternative Exhaust Emission Factors from Vehicles in On-Road Driving Tests". Energies 14, n. 12 (11 giugno 2021): 3487. http://dx.doi.org/10.3390/en14123487.
Testo completoAbstract (sommario):
On-road driving tests are performed to determine the emission of harmful exhaust compounds from vehicles. These primarily include carbon dioxide, nitrogen oxides, and particle number. However, there is a lack of indicators that combine the first three substances that are the most important in assessing the environmental aspects of vehicles. The purpose of this article is to indicate the possibility of assessing emissions in real driving conditions from light-duty and heavy-duty vehicles of different categories. In order to do so, a portable emissions measurement system (PEMS) and an instrument for measuring the particle number were used. The tests were carried out on routes designed to comply with the requirements and regulations laid down in the European Union legislation. On-road emissions of carbon dioxide, nitrogen oxides and particle number have been determined. Factors have been determined as the multiplication of these compounds for each vehicle category in three phases of the test: urban, rural, and motorway. A new way of assessing emissions from vehicles using new factors has been proposed.
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Madejska, Beata. "Legal aspects of low-emission shipping in the light of provisions of “sulphur directive” adopted by the European Union". Polish Maritime Research 20, n. 4 (1 dicembre 2013): 87–94. http://dx.doi.org/10.2478/pomr-2013-0045.
Testo completoAbstract (sommario):
ABSTRACT Shipping emits a variety of air pollutants: sulphur dioxide (SOx), nitrogen oxides (NOx), carbon dioxide (CO2) and particulate matter PM. Air pollutant emissions from maritime transport can be transported over long distances and thus increasingly contribute to air quality problems. Key environmental regulations (international and European) coming into force in this decade address emissions of SOx, NOx, CO2 and PM to control and limit their impact in the atmosphere. In the European Union, accordingly to the legal regulations, in the sulphur emission control areas the required SOx content of fuel will be reduced from 1.5 % to 0.1 % beginning January 2015. Globally, from 2020 onwards, ships operating in all other European Sea areas will have to use fuels with sulphur content of 0.5 % or less.
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Bebkiewicz, Katarzyna, Zdzisław Chłopek, Hubert Sar e Krystian Szczepański. "Comparison of pollutant emission associated with the operation of passenger cars with internal combustion engines and passenger cars with electric motors". International Journal of Energy and Environmental Engineering 12, n. 2 (21 gennaio 2021): 215–28. http://dx.doi.org/10.1007/s40095-021-00382-4.
Testo completoAbstract (sommario):
AbstractEnergy consumption and pollutant emission aspects were ascertained for cars under traffic conditions: in cities, outside cities, on motorways and expressways, with the use of data from the inventory of emissions from road transport in Poland in 2018. The values of characteristics of energy consumption under model traffic conditions, as well as pollutant emissions and energy consumption of cars with internal combustion engines and cars with electric motors, constituted the basis for further analyses and conclusions about the characteristics of the vehicles under the study in terms of energy consumption and pollutant emissions. As a result of the research, it was found in the case of the use of electric drives, a very significant decrease in energy consumption—by 70% and the emission of non-methane volatile organic compounds—at the level of 90%. In the case of the emission of nitrogen oxides, there is a great advantage in relation to cars with compression-ignition engines, while the emission of nitrogen oxides from cars with spark-ignition engines is about two times lower. It was found that the emission of particulate matter for electric cars is about three times higher than for cars with compression-ignition engines and almost six times higher than for cars with spark-ignition engines. On the other hand, the impact on carbon dioxide emissions is small—less than 10%.
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Kowalski, Arkadiusz, e Robert Waszkowski. "Method of Selecting the Means of Transport of the Winning, Taking into Account Environmental Aspects". Applied Sciences 11, n. 12 (14 giugno 2021): 5512. http://dx.doi.org/10.3390/app11125512.
Testo completoAbstract (sommario):
The transport of the winning in deep mines, using the room and pillar mining system, is most often performed with bucket loaders and haul trucks. In the era of attempts to stop rapid climate change, it is crucial to choose the transport means for the winning both in terms of efficiency and cost-effectiveness and to consider its environmental aspect. Permissible levels of pollutant emissions in exhaust gases are defined for this type of means of transport by the EU Stage Standards. There is a discernible need to develop a multi-criteria method supporting the decision-making process, which should reward loaders and haul trucks that meet more stringent emission standards. The article proposes an innovative idea of taking environmental aspects into account when selecting loaders and haul trucks for excavated material transport tasks, so that the amount of pollutants emitted by them in exhaust gases, e.g., the sum of hydrocarbons and nitrogen oxides (HC+NOx), is also taken into consideration when assigning means of transport to particular tasks. Based on simulation studies for a specific case, it was found that a 20% reduction of HC+NOx emission is possible with only a 2% increase in the transport costs of the winning. For this purpose, an objective function was used formulated on the basis of two criteria: minimization of the transport cost of the winning and the level of pollutant emissions in the exhaust gases. Since dozens of mining machines are operated continuously in deep mines of non-ferrous metal ores, the application of the proposed method would significantly reduce the emission of pollutants in the used air coming out of ventilation shafts.
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Ciobanu, Gheorghe, Cornelia Ciobanu, Cornel Domuta, Nicolae Csep e Petru Burescu. "Environmental Consequences of Efficient Use of Nitrogen Fertilizers". Acta Agraria Debreceniensis, n. 1 (12 maggio 2002): 41–46. http://dx.doi.org/10.34101/actaagrar/1/3535.
Testo completoAbstract (sommario):
Nitrogen fertilizer represents major economic burden. For this reason, although the efficiency of nitrogen utilization varies highly, its actual use generally remains at low levels; these averaging between 25 and 50%. We set up an experiment at the Oradea Research Station, using 15N labeled fertilizers, in order to investigate the possibility of increasing N fertilizer efficiency in winter wheat under irrigation conditions.Fertilizers labeled with 15N allows us to individually determine its effect on yield formation, as well as the use efficiency of N from fertilizer following application rate and time. The amount of N derived from fertilizer as determined in straw and grain yield is high. When the labeled fertilizer is applied at tillering time, the values of this indicator rise when higher N levels we applied.In separate experiments, we investigated a series of aspects connected to chemical fertilizer regarding the determination of the type of fertilizer, optimum time and rates of application; all these as a function of the special pedoclimatic conditions.The results obtained in the field show that the effectiveness of N utilization in wheat is most variable and generally low, often ranging between 25 and 33%, owing to N loss within the system through leaching and NH3 volatilization.A readily achievable increase in efficiency of 5 percentage points would result in considerable savings, and can be brought about by reducing nitrogen losses. The added benefits to the environment in terms of reduced ground/water contamination and lowered nitrous oxide (N20) emissions would also be substantial.The figures for N fertilizer use efficiency (% N range from 35.5 to 72.6, the highest value being recorded with an N application of 120 kg/ha at tillering, when the previous crop was sunflower).INTRODUCTION
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Unwin, R. J. "Nitrogen cycling on the livestock farm". Proceedings of the British Society of Animal Production (1972) 1986 (marzo 1986): 45. http://dx.doi.org/10.1017/s0308229600015567.
Testo completoAbstract (sommario):
The environmental or polluting aspects of nitrogen in relation to livestock farms are gaseous losses to the atmosphere, nitrate leaching into water supplies and the eutrophication of surface waters. Gaseous losses of ammonia by volatilisation from organic materials and denitrification losses from soil as nitrogen and nitrous oxide have been at various times implicated in acid rain, photochemical smogs and effects on the ozone layer although the latter is now largely discounted. Nitrate leached from soil may pass rapidly into surface waters where it can affect quality for drinking or encourage algal blooms. Over porous strata nitrate may take many years to percolate downwards so as to pollute groundwater supplies. Restrictions may face livestock farmers in the arable areas of eastern England to restrict nitrate leaching from their land.
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Mahmud, Kishan, Dinesh Panday, Anaas Mergoum e Ali Missaoui. "Nitrogen Losses and Potential Mitigation Strategies for a Sustainable Agroecosystem". Sustainability 13, n. 4 (23 febbraio 2021): 2400. http://dx.doi.org/10.3390/su13042400.
Testo completoAbstract (sommario):
Nitrogen (N) in the agricultural production system influences many aspects of agroecosystems and several critical ecosystem services widely depend on the N availability in the soil. Cumulative changes in regional ecosystem services may lead to global environmental changes. Thus, the soil N status in agriculture is of critical importance to strategize its most efficient use. Nitrogen is also one of the most susceptible macronutrients to environmental loss, such as ammonia volatilization (NH3), nitrous oxide (N2O) emissions, nitrate leaching (NO3), etc. Any form of N losses from agricultural systems can be major limitations for crop production, soil sustainability, and environmental safeguard. There is a need to focus on mitigation strategies to minimize global N pollution and implement agricultural management practices that encourage regenerative and sustainable agriculture. In this review, we identified the avenues of N loss into the environment caused by current agronomic practices and discussed the potential practices that can be adapted to prevent this N loss in production agriculture. This review also explored the N status in agriculture during the COVID-19 pandemic and the existing knowledge gaps and questions that need to be addressed.
Tesi sul tema "Nitrogen oxides Environmental aspects"
1
Ahmed, Sauda. "Modeling of Ultrafine Particle Emissions and Ambient Levels for the Near Roadside Environment". PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3506.
Testo completoAbstract (sommario):
Various epidemiological studies have linked exposure to Ultrafine Particles (UFP; diameter< 100 nm) to adverse health impacts. Roadway traffic is one of the major sources of UFPs and heavily influences UFP concentrations in the nearby vicinity of major roadways. Modeling efforts to predict UFPs have been limited due to the scarcity of reliable information on emissions, lack of monitoring data and limited understanding of complex processes affecting UFP concentrations near sources.
In this study continuous measurement of ultrafine particle number concentrations (PNC) and mass concentrations of nitric oxide (NO), nitrogen dioxide (NO2) and PM2.5 was conducted near an arterial road and freeway at different seasons and meteorological conditions and integrated with traffic count data. PNC showed high correlation with NO (r=0.64 for arterial; 0.61 for freeway), NO2 (r=0.57 for arterial; 0.53 for freeway) and NOx (NOx=NO+NO2; r=0.63 for arterial; 0.59 for freeway) and moderate to low correlation with traffic volume (r=0.33 for arterial; 0.32 for freeway) and PM2.5 (r=0.28 for arterial; 0.23 for freeway); respectively; for both sites at 15 minute averages. The PNC-NOx relationship prevailed on a shorter term (15 min), hourly, and throughout the day basis. Both PNC and NOx showed comparatively higher correlation with traffic during the morning period but became lower during evening which can be attributed to the higher boundary layer and wind speeds. The variable meteorology in the evening affects both PNC and NOx concentrations in the same way and the correlation between NOx and PNC is maintained high both during morning (r=0.74 for arterial; 0.69 for freeway), and evening (r=0.62 for arterial; 0.59 for freeway) periods. Thus nitrogen oxides can be used as a proxy for traffic-related UFP number concentration reflecting the effect of both traffic intensity and meteorological dilution.
The PNC-NOx relation was explored for various meteorological parameters i.e. wind speed and temperature. It is found that NOx emission is temperature independent and can be used to reflect the effect of traffic intensity and meteorological dilution. Once the effect of traffic intensity and dilution is removed, the effect of temperature on PNC-NOx ratio becomes important which can be attributed to the variation in PNC emission factors with temperature.
The high morning PNC-NOx ratio found at the arterial road is a result of new particle formation due to lower temperature and low concentration of exhaust gases in the morning air favoring nucleation over condensation. This finding has important implication when calculating emission factors for UFP number concentrations. Thus it can be concluded that roadside concentration of ultrafine particles not only depends on traffic intensity but also on meteorological parameters affecting dilution or new particle formation. High concentrations of ultrafine particle number concentration close to a roadway is expected due to higher traffic intensity , as well as during low wind speed causing low dilution and low temperature conditions favoring new particle formation.
Finally a simplified approach of calculating particle number emission factor was developed using existing and easily available emission inventory for traffic related tracer gases. Using NOx emission factors from MOVES emission model, the emission ratio of PNC to NOx was converted to develop particle number emission factors. NOx was selected as the traffic related tracer gas since the number concentration of particles is closely correlated to NOx, NOx and particles are diluted in the same way and NOx emission factors are available for a variety of traffic situations. To ensure contribution of fresh traffic exhaust, the average of the difference of pollutant concentrations at high traffic condition and background condition was used to calculate PNC-NOX ratio. Using nitrogen oxides to define background and high-traffic conditions and MOVES emission factor for NOX to convert corresponding PNC-NOX ratio, an average emission factor of (1.82 ± 0.17) E+ 14 particle/ vehicle-km was obtained, suitable for summertime. When compared to existing particle number emission factors derived from dynamometer tests, it was found that there exits reasonable agreement between the calculated real world particle number emission factors and emission factors from dynamometer tests.
The calculated emission factor and R-Line dispersion model was tested in predicting near-road particle number concentrations. Although only 23% of the variability in PNC was explained by the dispersion model, 84.33% of the measurements fell within the factor of two envelope. This suggests that there is potential to effectively use these models and thus warrants more in-depth analysis. Finally, a simple map of PNC gradients from major roads of Portland was developed.
The results of this study helped identify proxy-indicators to provide reference values for estimating UFP concentrations and emissions that can be used for simple evaluation of particle concentration near major roadways for environmental and urban planning purposes and to assess expected impact of UFP pollution on population living near roadways exposed to elevated concentrations.
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Nordin, Anders. "On the chemistry of combustion and gasification of biomass fuels, peat and waste : environmental aspects". Doctoral thesis, Umeå universitet, Kemiska institutionen, 1993. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-110672.
Testo completo
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Crawford, Ian Stewart. "Catalytic reduction of nitric oxide by carbon monoxide or hydrogen over a Monel metal catalyst". Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09EN/09enc899.pdf.
Testo completo
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Thornton, Matthew Jaeger. "Modal vehicle activity on freeways and freeway onramps : an assessment of the oxides of nitrogen emissions impacts resulting from changes in vehicle operating mode due to ramp metering systems". Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20785.
Testo completo
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Lim, Guo Quan. "Evaluation of the Influence of Non-Conventional Sources of Emissions on Ambient Air Pollutant Concentrations in North Texas". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804841/.
Testo completoAbstract (sommario):
Emissions of air pollutants from non-conventional sources have been on the rise in the North Texas area over the past decade. These include primary pollutants such as volatile organic compound (VOC) and oxides of nitrogen (NOx) which also act as precursors in the formation of ozone. Most of these have been attributed to a significant increase in oil and gas production activities since 2000 within the Barnett Shale region adjacent to the Dallas-Fort Worth metroplex region. In this study, air quality concentrations measured at the Denton Airport and Dallas Hinton monitoring sites operated by the Texas Commission on Environmental Quality (TCEQ) were evaluated. VOC concentration data from canister-based sampling along with continuous measurement of oxides of nitrogen (NOx), ozone (O3), particulate matter (PM2.5), and meteorological conditions at these two sites spanning from 2000 through 2014 were employed in this study. The Dallas site is located within the urban core of one of the fastest growing cities in the United States, while the Denton site is an exurban site with rural characteristics to it. The Denton Airport site was influenced by natural gas pads surrounding it while there are very few natural gas production facilities within close proximity to the Dallas Hinton site. As of 2013, there were 1362 gas pads within a 10 mile radius to the Denton Airport site but there were only 2 within a 10 mile radius to Dallas Hinton site. The Dallas site displayed higher concentrations of NOx and much lower concentrations of VOC than the Denton site. Extremely high levels of VOC measured at the Denton site corresponded with the increase in oil and gas production activities in close proximity to the monitoring site. Ethane and propane are two major contributors to the measured VOC concentration, suggesting the influence of fugitive emissions of natural gas. In Dallas, the mean and maximum values of ozone had decreased since 2000 by about 2% and 25%, respectively. Similarly NOx decreased by 50% and 18% in the mean and maximum values. However, the mean VOC value showed a 21% decrease while the maximum value increased by about 46%. In Denton, the change in percentage of ozone and NOx were similar to Dallas but the mean VOC concentration increased by about 620% while the max value increased 1960%. Source apportionment analysis confirmed the findings by identifying the production of natural gas to be the primary source of VOC emissions in Denton, while traffic sources were more influential near the Dallas site. In light of the recent proposal by EPA to revise the ozone standard, the influence of these new unconventional sources should be further evaluated.
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Shihady, Steven. "TREATMENT OF NITROGEN OXIDES BY CHLORELLA VULGARIS ALGAE IN PHOTOBIOREACTORS". DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1284.
Testo completoAbstract (sommario):
The effectiveness of algae to treat NO2and NO in simulated flue gas was tested using Chlorella vulgaris in photobioreactors (PBRs) using NOxconcentrations between 30 ppm to 780 ppm. NOxdissolved and reacted in water to form NO3-and NO2-in the PBR growth medium, providing a nitrogen source that the algae readily assimilated for cell synthesis. Three 20-L photobioreactors were inoculated with a pure culture of C. vulgaris prepared in Bristol growth medium and algae were grown in the PBRs at 25°C and pH of 7.0 in a modified Bristol medium that did not contain nitrogen compounds. The C. vulgaris grew substantially using NO3-/NO2-as its nitrogen source for cell synthesis. The NO3-and NO2-were formed through the dissolution and oxidation/reduction of NOxfrom the simulated flue gas. Algal growth by assimilation of NO3-and/or NO2-allowed for continual dissolution of NOx, resulting in NOxremoval rates from the gas phase of up to 97%, with residual nitrogen of up to 7 mg-N/L in solution. Algae grew from an initial cell density of 3.1 x 105cells/L to cell densities of up to 1.85 x 107cells/mL and dry weights of up to 243 mg/L. Cell nitrogen content varied from 4-8%. PBR to treatment of gaseous NOxwas analyzed in terms of mass transfer rates, chemical kinetics, and biological growth.
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Walecka-Hutchison, Claudia. "Nitrogen dynamics in diesel biodegradation : effects of water potential, soil C:N ratios, and nitrogen cycling on biodegradation efficacy". Diss., The University of Arizona, 2005. http://hdl.handle.net/10150/191274.
Testo completoAbstract (sommario):
Respirometric experiments were performed to evaluate the role of nitrogen in aerobic diesel biodegradation. Specific objectives included 1) evaluating the effects of water potential induced by various nitrogen amendments on diesel biodegradation rates in arid region soils, 2) comparing concurrent effects of C:N ratios and soil water potential on diesel degradation rates, and 3), measuring gross rates of nitrogen cycling processes in diesel-contaminated soil to determine duration of fertilizer bioavailability. In all studies, increasing nitrogen fertilization resulted in a decrease in total water potential and correlated with an increase in lag phase and overall reduction in microbial respiration. Highest respiration and estimated diesel degradation was observed in the 250 mg N/kg soil treatments regardless of diesel concentration, nitrogen source, or soil used, suggesting an inhibitory osmotic effect from higher rates of nitrogen application. The depression of water potential resulting in a 50% reduction in respiration was much greater than that observed in humid region soil, suggesting higher salt tolerance by microbial populations of arid region soils. Due to the dependence on contaminant concentrations, use of C:N ratios was problematic in optimizing nitrogen augmentation, leading to over-fertilization in highly contaminated soils. Optimal C:N levels among those tested were 17:1, 34:1, and 68:1 for 5,000, 10,000 and 20,000 mg/kg diesel treatments respectively. Determining nitrogen augmentation on the basis of soil pore water nitrogen (mg N/kg soil H₂0) is independent of hydrocarbon concentration but takes into account soil moisture content. In the soil studied, optimal nitrogen fertilization was observed at an average soil pore water nitrogen level of 1950 mg N/kg H₂0 at all levels of diesel contamination. Based on the nitrogen transformation rates estimated, the duration of fertilizer contribution to the inorganic nitrogen pool at 5,000 mg/kg diesel was estimated at 0.9, 1.9, and 3.2 years in the 250, 500, and 1000 mg/kg nitrogen treatments respectively. The estimation was conservative as ammonium fixation, gross nitrogen immobilization, and nitrification were assumed as losses of fertilizer with only gross mineralization of native organic nitrogen contributing to the most active portion of the nitrogen pool.
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Samoylov, Alexander V. "Improvement of the efficiency of vehicle inspection and maintenance programs through incorporation of vehicle remote sensing data and vehicle characteristics". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50410.
Testo completoAbstract (sommario):
Emissions from light-duty passenger vehicles represent a significant portion of total criteria pollutant emissions in the United States. Since the 1970s, emissions testing of these vehicles has been required in many major metropolitan areas, including Atlanta, GA, that were designated to be in non-attainment for one or more of the National Ambient Air Quality Standards. While emissions inspections have successfully reduced emissions by identifying and repairing high emitting vehicles, they have been increasingly inefficient as emissions control systems have become more durable and fewer vehicles are in need of repair. Currently, only about 9% of Atlanta area vehicles fail emissions inspection, but every vehicle is inspected annually. This research addresses explores ways to create a more efficient emissions testing program while continuing to use existing testing infrastructure. To achieve this objective, on road vehicle emissions data were collected as a part of the Continuous Atlanta Fleet Evaluation program sponsored the Georgia Department of Natural Resources. These remote sensing data were combined with in-program vehicle inspection data from the Atlanta Vehicle Inspection and Maintenance (I/M) program to establish the degree to which on road vehicle remote sensing could be used to enhance program efficiency. Based on this analysis, a multi-parameter model was developed to predict the probability of a particular vehicle failing an emissions inspection. The parameters found to influence the probability of failure include: vehicle characteristics, ownership history, vehicle usage, previous emission test results, and remote sensing emissions readings. This model was the foundation for a proposed emissions testing program that would create variable timing for vehicle retesting with high and low failure probability vehicles being more and less frequently, respectively, than the current annual cycle. Implementation of this program is estimated to reduce fleet emissions of 17% for carbon monoxide, 11% for hydrocarbons, and 5% for nitrogen oxides in Atlanta. These reductions would be achieved very cost-effectively at an estimated marginal cost of $149, $7,576 and $2,436 per-ton-per-year for carbon monoxide, hydrocarbons, and nitrogen oxides emissions reductions respectfully.
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Cochlan, William Patrick. "Nitrogen uptake by marine phytoplankton : the effects of irradiance, nitrogen supply and diel periodicity". Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/30628.
Testo completoAbstract (sommario):
Diel patterns of nitrogen (NO₃⁻, NH₄⁺, urea) uptake were
investigated in natural assemblages of phytoplankton from
neritic and oceanic environments off the coast of British
Columbia. This is the first study to report nitrogen uptake
rates and extensive measurements of ambient NH₄⁺ and urea
concentrations in these waters. Calculated rates of N uptake, 15
based on ¹⁵N incorporation into particulate matter during time course experiments, were maximal during the day and minimal at night. Besides the obvious effects of irradiance, the amplitude of the periodicity in uptake rate was influenced by phytoplankton community composition, ambient nitrogen concentration, forms of nitrogen available, and depth of sampling. Uptake of nitrogen during the night and in artificial darkness were measurable proportions of daytime and light uptake rates, with the importance of dark uptake generally increasing with increasing N limitation. This is the first study of diel urea uptake by marine phytoplankton in the field. The ratios of dark to light urea uptake over a diel cycle were more similar to those of NO₃⁻than those of the other reduced N form, NH₄⁺.
Rates of NO₆⁻ and urea uptake by phytoplankton in the shallow and deep chlorophyll layers of the Strait of Georgia were measured over a gradient of irradiances and results of these experiments could be fitted with a hyperbolic function similar to the Michaelis-Menten equation. Half-saturation constants (KLT) for light-dependent uptake of urea and NO₃⁻
ranged from 0 to 14% of the surface irradiance and dark uptake was a variable, but often substantial (> 50%) portion of the total (light + dark) uptake.
The uptake response of nitrate-replete and -starved populations of the picoflagellate, Micromonas pusilla (Butch.) Manton et Parke, to urea, NH₄⁺ and NO₃⁻ perturbations was determined by both ¹⁵N accumulation and nutrient disappearance
from the culture medium. Maximum specific uptake rates (Vmax) of NH₄⁺ were 0.13 h⁻¹, more than 2 times the Vmax of NO₃⁻ or urea (ca. 0.05 h⁻¹). The half-saturation constants (Ks) for urea, NH₄⁺ and NO₃⁻ were within ± 0.1 µg-at N•L⁻¹ of each other; the average value of 0.41 µg-at. N•L⁻¹ is within the range reported for small, oceanic diatoms. NO₃⁻ uptake was completely inhibited following NH₄⁺ addition (1-10 µg-at. N•L⁻¹), whereas urea addition resulted in only a 28% reduction in NO3- uptake. Starved cultures of M. pusilla exhibited variable uptake of NH₄⁺ and urea as a function of time, with an initial "surge" uptake response. This is the first laboratory study of N uptake by an eucaroyotic picoplankter and demonstrates that many of the transient uptake responses reported for diatoms, with which it competes in the field, are common to this picoplankter.
Diel periodicity of nitrogen uptake and assimilation were measured in N-replete batch cultures of M. pusilla and also in N-limited cyclostat cultures (14L:10D) at three growth rates corresponding to ca. 75, 50 and 25% of it's maximal growth rate. Nitrate uptake was continuous and independent of the
L:D cycle in the cyclostat cultures at the lowest dilution rate, but NO₃⁻ uptake rates exhibited pronounced periodicity in the batch and higher dilution rate cultures, a response similar to that seen in previous studies of cyclostat cultures of some diatoms. Diel patterns in cell division, mean cell volume, potential uptake rates and internal pools of NO₃⁻ were also observed and are discussed with respect to the nutritional status of the cells. The effect of irradiance on the uptake of NH₄⁺ and NO₃⁻ by M. pusilla was also described by Michaelis-Menten kinetics; with increasing N limitation the importance of light for nitrogen uptake decreased and dark uptake increased from 5-20% to 21-39% of NO₃⁻ and NH₄⁺ uptake rates, respectively, at saturating irradiance.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
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Hengnirun, Somgiat. "A computer simulation model for manurial nitrogen management : environmental aspects (MANIMEA)". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40357.
Testo completoAbstract (sommario):
The MANIMEA $ rm ( underline{MA}nurial underline{NI}trogen underline{M}anagement{:} underline{E}nvironmental underline{A}spects)$ model is a one-dimensional dynamic model that simultaneously simulates nitrogen transformations (volatilization, net mineralization-immobilization, and denitrification), nitrogen transport (runoff and leaching), plant uptake, and adsorption in homogeneous, unsaturated soils. The simulated system is divided into two components: the applied manure layer and the soil. The model describes the transformation processes occurring in both components separately. It is also capable of accounting for both micro and macroporous flows. In addition, the simulation can be done for time steps shorter than 1 day.The model was developed to be interactive and user-friendly and was constructed on a modular basis using Microsoft FORTRAN PowerStation$ sp circler$ as a compiler. It can be run on an IBM$ sp circler$ or IBM compatible microcomputer with a minimum requirement of a 386 microprocessor with 4 MB RAM. This model was developed as a nitrogen management-oriented model. However, it can also be used to gain further understanding of nitrogen processes for research and teaching purposes.
The accuracy of the stimulation was enhanced by taking into account moisture and temperature variation and distribution in the soil. The SWACROP and the HEAT programs were integrated into the MANIMEA model to generate transient moisture and temperature profiles, respectively. The Numerical Method Of Lines (NMOL) technique, which implements finite difference method, was used to numerically solve the partial differential equations in the model.
Generally, the results generated by the MANIMEA model using the parameters from literature agreed with the results obtained by analytical solutions and from experiments. It was found that the model is highly sensitive to the volatilization and net mineralization rate constants $(K sb{v}$ and $K sb{m}).$ The study showed that the MANIMEA model can be implemented to evaluate nitrogen transformations, transport, and plant uptake for a wide range of climatic and soil conditions and organic type of wastes. Such a tool can contribute to the protection of our environment through a better management of organic nitrogen fertilizer and a better understanding of the nitrogen processes.
Libri sul tema "Nitrogen oxides Environmental aspects"
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Picard, David J. Emission inventory of sulphur oxides and nitrogen oxides in Alberta. Calgary: Acid Deposition Research Program, 1987.
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Jaakkola, Antti. Typen oksidien päästöt Suomessa 1980- ja 1990- luvuilla. Helsinki: Ympäristöministeriö, Ympäristön- ja luonnonsuojeluosasto, 1986.
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O'Donnell, C. Nitrogen oxides monitoring at Rathmines: Assessment of levels in an inner suburb of Dublin city. Wexford: E.P.A., 1996.
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Gschwandtner, Gerhard. Comparison of historic SOb2s and NOx emission data sets: Project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1988.
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Braun, Elizabeth. Reactive nitrogen in the environment: Too much or too little of a good thing. Paris: UNEP DTIE, Sustainable Consumption and Production (SCP) Branch, 2007.
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Khodakov, I︠U︡ S. Oksidy azota i teploėnergetika: Problemy i reshenii︠a︡. Moskva: OOO "ĖST-M", 2001.
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Shareef, S. A. Fired heaters: Nitrogen oxides emissions and controls : project summary. Research Triangle Park, NC: U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory, 1988.
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Gutt, Elissa. Building on 30 years of Clean Air Act success: The case for reducing NOx air pollution. Boulder: Environmental Defense, 2000.
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Management, Wisconsin Bureau of Air. Nitrogen oxide emissions in Wisconsin: Final report : an assessment of effects, costs for reduction and recommendations for action. Madison, Wis. (Box 7921, Madison 53707): The Bureau, 1992.
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Jenkins, Gilbert. Nitrogen in fossil fuels worldwide and nox emissions. [England: s.n., 1992.
Cerca il testo completoCapitoli di libri sul tema "Nitrogen oxides Environmental aspects"
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Srivastava, H. S. "Nitrogen Oxides and Nitrogen Nutrition in Plants". In Environmental Stress: Indication, Mitigation and Eco-conservation, 121–34. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-015-9532-2_11.
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Németh, T. "Long-term N-fertilization calibration experiments — environmental aspects". In Nitrogen Economy in Tropical Soils, 371–77. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1706-4_36.
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Hakeem, Khalid Rehman, Muhammad Sabir, Munir Ozturk, Mohd Sayeed Akhtar e Faridah Hanum Ibrahim. "Nitrate and Nitrogen Oxides: Sources, Health Effects and Their Remediation". In Reviews of Environmental Contamination and Toxicology, 183–217. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/398_2016_11.
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Mills, Aaron L. "Qualitative and Quantitative Aspects of the Modern Nitrogen Cycle". In Advances in Environmental Microbiology, 31–63. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-10777-2_2.
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Hakeem, Khalid Rehman, Muhammad Sabir, Munir Ozturk, Mohd Sayeed Akhtar e Faridah Hanum Ibrahim. "Erratum to: Nitrate and Nitrogen Oxides: Sources, Health Effects and Their Remediation". In Reviews of Environmental Contamination and Toxicology, E1. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-51243-3_15.
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Nichols, Albert L. "Designing a Trading Programme for Emissions of Nitrogen Oxides in the Northeastern United States". In Environmental Policy Between Regulation and Market, 171–97. Basel: Birkhäuser Basel, 1997. http://dx.doi.org/10.1007/978-3-0348-9012-0_8.
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Tagliavini, M., D. Scudellazi, B. Marangoni e M. Toselli. "Nitrogen fertilization management in orchards to reconcile productivity and environmental aspects". In Fertilizers and Environment, 161–70. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1586-2_27.
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Shaviv, A. "Plant response and environmental aspects as affected by rate and pattern of nitrogen release from controlled release N fertilizers". In Progress in Nitrogen Cycling Studies, 285–91. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-011-5450-5_48.
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Ferouani, Abdel Karim, Fatiha Lassouani, Chawki Ougherb, Souhila Askri e Mostefa Lemerini. "Contribution of the Spatio-temporal Evolution of Reduced Electric Field on the Conversion of Nitrogen Oxides". In Recent Advances in Environmental Science from the Euro-Mediterranean and Surrounding Regions (2nd Edition), 383–88. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-51210-1_61.
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Pettorelli, Nathalie. "Satellite remote sensing, environmental quality, and human health and wellbeing". In Satellite Remote Sensing and the Management of Natural Resources, 120–32. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198717263.003.0009.
Testo completoAbstract (sommario):
This chapter reviews how satellite data can provide key information relevant to efforts to improve human health and wellbeing. It first discusses how satellite remote sensing can be used to track, predict, and manage vectorborne disease such as malaria, dengue fever, and trypanosomiasis. The second section of this chapter focuses on the use of satellite data to monitor air quality, looking at how satellites can help (1) track air pollution associated with the release of harmful substances into the atmosphere through human activities, such as nitrogen oxides, carbon monoxide, and chlorofluorocarbons (CFCs); (2) detect and forecast outbreaks of airborne substances that trigger an allergic reaction, such as pollen grains; (3) assess emissions from volcanic eruptions; and (4) monitor dust storms in space and time. The third part of this chapter explores how satellite data can be used to report on water quality, detailing how these data can be used to predict and manage harmful algae blooms and to study eutrophication. The fourth section addresses satellite remote sensing in the context of human wellbeing, highlighting how satellite data can be used to estimate economic welfare and poverty, and how this information can be used to test various hypotheses pertaining to the role of greenness in determining various aspects of our physical and mental health.
Atti di convegni sul tema "Nitrogen oxides Environmental aspects"
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Andreini, A., B. Facchini, L. Mangani e F. Simonetti. "Development and Validation of a 1-D Tool for Thermoacoustic Instabilities Analysis in Gas Turbine Combustors". In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51248.
Testo completoAbstract (sommario):
In the last years, the more restrictive environmental legislations have constrained gas turbine manufacturers to the development of new low-emission combustors. Lean Premixed technology has become a necessary standard to meet emissions requirements and allowing an heavy reduction of nitrogen oxides emission. This kind of technology, due to the use of lean premixed mixtures, is severely affected by thermoacoustic phenomena which cause damages to combustor components and consequently reduce the overall gas turbine life of a factor of two or more. Specifically, premixed flames pose the threat of pressure oscillations. This phenomenon is the effect of the strong interaction between combustion heat-release and fluid dynamics aspects. In order to investigate thermoacoustic instabilities, a mono-dimensional code was developed and validated. It takes into account only longitudinal frequencies and it is thought to be highly modular to modify or add blocks, corresponding to different thermoacoustic models. The tool is based on a lumped-parameter approach, which consists in considering constant mean flow quantities over each fundamental straight duct element and a nodal point at each duct interface. For each interface, where an acoustic impedance could be present, the linearized fluctuating mass, momentum and energy equations are solved including entropic waves. To validate such tool, several tests, referring to actual test rigs and experimental gas turbine combustor geometries, were performed. The results show a general agreement with empirical data and other numerical results reported in literature in terms of resonance frequencies, stability and modal shapes, both for no flame and fluctuating heat release cases.
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Tanoura, Manazumi, Kenji Muta, Kohtaro Fujimura e Kimishiro Tokuda. "Detection of nitrogen oxides by high-resolution near-infrared absorption spectroscopy". In Environmental Sensing III, a cura di Maurus Tacke e Winfried Stricker. SPIE, 1997. http://dx.doi.org/10.1117/12.274776.
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Bainier, Francis, Pascal Alas, Florian Morin e Tony Pillay. "Two Years of Improvement and Experience in PEMS for Gas Turbines". In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56138.
Testo completoAbstract (sommario):
Due to environmental regulations, Nitrogen oxides (NOx), Carbon Monoxide (CO) and Sulfur Dioxide (SO2) emissions are key issues for gas turbine plants. Regulators are becoming more and more involved and they often require complete and real-time emission information. The measurements can be done with gas analyzers, this technology is called CEMS: Continuous Emissions Monitoring System. An alternative method [1][2] is to use a calculation based on the turbine instrumentation. This technology is called PEMS: Predictive Emissions Monitoring System. But these technologies do not provide all the information required by the regulator. GRTgaz, the main gas transmission company in France managing 44 turbines spread over 27 stations across France, has decided to monitor its emissions by PEMS for many years. Two years ago, GRTgaz developed successfully its own PEMS equations, organized answers to regulators around this technology and decided to spread the technology across its gas turbine fleet. The complete intellectual path followed is described in the paper GT2014-25242. This 2016 3-part paper describes the PEMS project steps forward. In the first part of the paper, a review is done of the PEMS equations used at GRTgaz for NOx and CO concentrations. The various lean premixed combustion turbines differ in terms of combustion design, control and instrumentation. These differences are analyzed considering their influence on combustion and their impact on the PEMS results accuracy. In order to comply with regulators requirements a calibration of the PEMS results is done every quarter. The results of the first 2 stations equipped with PEMS are described in this first part. The second part of the paper introduces the smoke developed and the neutral air flow to complete the real time calculation required by the regulators: SO2 concentration and the mass flowrates for NOx, CO and SO2. The final calculation integrates the mass flowrate in order to elaborate the total mass emitted into the atmosphere over different time periods. The last part deals with developing personnel involvement, managing the data and compiling the results given to regulators. These aspects were more difficult to implement than expected. The importance of these aspects should not be underestimated because the scientific credibility of PEMS cannot be confirmed without them.
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Zolata, Hasan, Cesar Celis, Vishal Sethi, Riti Singh e David Zammit-Mangion. "A Multi-Criteria Simulation Framework for Civil Aircraft Trajectory Optimisation". In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38237.
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Over the past few years, great concern has been raised about the impact of commercial aviation on the environment. In a Business As Usual approach, the expected growth in air traffic is going to affect climate change even more unless mitigation policies are devised and implemented. Although there is a tendency to focus on long-term technological solutions and breakthroughs, short-term improvements applicable to existing aircraft/engine configurations are also very important to fully realise the benefits of new technologies. Aircraft trajectory optimisation presents the opportunity to effectively reduce fuel consumption and pollutants emitted providing a feasible short-term strategy to be applied to the existing aircraft fleet. The present study focuses on preliminary results obtained using a multi-disciplinary aircraft trajectory optimisation simulation framework. Three in-house computational models are implemented in the framework to model the aircraft and engine performance, as well as to predict the level of gaseous emissions produced. A commercially available optimiser is integrated within the framework to analyse and optimise single flight path elements (e.g., climb), as well as the entire flight profile. For the purpose of this study, the climb and the whole flight profile are divided in four and eight segments respectively. Trajectory optimisation processes are then carried out in order to minimise three different objective functions: flight time, fuel burned, and mass of oxides of nitrogen (NOx) emitted. The results of the trajectory optimisation processes performed confirm the validity, effectiveness, and flexibility of the methodology proposed. In future, it is expected that these types of approaches are utilised to efficiently compute complete, optimum and ‘greener’ aircraft trajectories, which help to minimise the impact of commercial aviation on the environment. Other computational models that simulate several other aspects such as aircraft and engine noise, weather conditions and contrails formation, among others, need to be also included in the optimisation processes.
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Ligang Zheng, Shuijun Yu e Minggao Yu. "Prediction of nitrogen oxides from coal combustion by using response surface methodology". In 2012 International Conference on Computer Distributed Control and Intelligent Environmental Monitoring (CDCIEM 2012). IEEE, 2012. http://dx.doi.org/10.1109/cdciem.2012.126.
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Bainier, Francis, e Florian Havard. "Setting Up and Managing a PEMS Mathematical Formula to Fully Respond to the Expectations of the Regulator". In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25242.
Testo completoAbstract (sommario):
Due to environmental regulations, Oxides of nitrogen (NOx) and carbon monoxide (CO) are important issues for gas turbine plants. Regulators are becoming more and more involved and they often require overall and real-time emission information. These measurements can easily be done with gas analyzers. This technology is called CEMS: Continuous Emissions Monitoring System. With CEMS, regulators easily understand proofs such as calibration and certificate. However, this technology is expensive to buy and to maintain. An alternative method is to use a calculation based on the turbine operation. This technology is called PEMS: Predictive Emissions Monitoring System. Although PEMS is less expensive than CEMS, setting up and managing a PEMS mathematical formula to fully respond to the expectations of the regulator is more complicated than using CEMS. This paper describes an approach to set up an equation for PEMS which can be accepted by regulators. Before starting PEMS research, expectations must be established. What are the expectations of the regulator? What are the users’ expectations? Yes, do not forget the goals of the unit operators. It is not sufficient to provide answers for regulator at the lowest cost. A responsible user is also concerned about the environmental aspect and this fact will help your in the future. GRTgaz, the main gas transmission company in France managing 44 turbines spread over 25 stations across France, has decided to answer these questions before starting research. The answers to these questions make up the first part of this 4-part paper. The second part of the paper is a review of publications and literature. Since no applicable PEMS exist for all types of combustion turbines, analyzing empirical and theoretical formulas leads to the important parameters and the link between them. The third part is dedicated to turbines. A lean premixed combustion system and its regulation are described. Also in this part, the available measured parameters are listed in regards to their combustion influence and their accuracy. The fourth part deals with the establishment of equations and their tests in regards to the goals. The last part presents the implementation of the equations on the units. If tools and knowledge are available, the conclusion point out that achieving a PEMS requires a good evaluation and understanding of the expectations of the regulator, not only in the present day but also what they will and could be.
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Tejwani, Gopal D. "Transmittance and Radiance Computations for Rocket Engine Plume Environments". In ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47406.
Testo completoAbstract (sommario):
Rocket engine exhaust plume is generally thermal in character arising from changes in the internal energy of constituent molecules. Radiation from the plume is attenuated in its passage through the atmosphere. In the visible and the infrared region of the spectrum for clear-sky conditions, this is caused mainly through absorption by atmospheric molecular species. The most important combustion-product molecules giving rise to emission in the IR are water vapor, carbon dioxide, and carbon monoxide. In addition, the high temperature plume reacting with the surrounding atmosphere may produce nitrogen oxides, in the boundary layer, all of which are strongly emitting molecules. Important absorbing species in the atmosphere in the engine plume environment are H2O, CO, CO2, CH4, N2O, NO, and NO2. Under normal atmospheric conditions, the concentrations of O3, SO2, and NH3 are too small to produce any significant absorption. Essentially the problem comprises of the propagation of radiation from a hot gas source through a long cool absorbing atmosphere thus combining aspects of atmospheric and combustion gas methods. Since many of the same molecular species are responsible for both emission and absorption, the high degree of line position correlation between the emission and absorption spectra precludes the decoupling of the optical path into isolated emitter and absorber regions and multiplying the source band radiance by the absorber band transmittance in order to arrive at the transmitted radiance spectrum. Also, very strong thermal gradients may be encountered. All this suggests that a layer-by-layer computation is called for. The pathlength through the plume and the atmosphere is assumed to go through a certain number of layers, each of which is considered to have all molecular species in local thermodynamic equilibrium at constant temperature and pressure within the layer. Radiative transfer problems can be visualized as a set of parallel layers orthogonal to the line of sight, each with an input radiance from the previous layer and an output radiance to the subsequent layer. The MODTRAN (MODerate resolution TRANsmission) code is ideally suited for layer-by-layer absorption/emission calculations for atmospheric molecular species. We have utilized MODTRAN 4.0 computer code, implemented on a Power Mac G3, for the radiance and transmittance computations. The MODTRAN code has been adapted for the engine plume radiance computations. If the plume composition and flowfield parameters such as the temperature and pressure values are known along the line of sight by means of the experimental measurements or (more likely) CFD simulations, one can compute the radiance from any plume with high degree of accuracy at any desired point in space. Emission and absorption characteristics of several atmospheric and combustion species have been studied and presented in this paper with reference to the rocket engine plume environments at the Stennis Space Center. In general transmittance losses can not be neglected for any pathlength of 2 m or more. We have also studied the effect of clouds, rain, and fog on the plume radiance/transmittance. The transmittance losses are severe if any of these occur along the line of sight. Preliminary results for the radiance from the exhaust plume of the space shuttle main engine are shown and discussed.
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Hetz, Andrew A., e David J. Shotts. "Nitrogen Oxides Control Selection for a Utility Combined Cycle Power Plant". In 1987 Joint Power Generation Conference: GT Papers. American Society of Mechanical Engineers, 1987. http://dx.doi.org/10.1115/87-jpgc-gt-3.
Testo completoAbstract (sommario):
Recently, the combined cycle gas turbine has become a leading candidate among generating alternatives. Under the Clean Air Act, all utility-scale gas turbines must undergo air quality permitting before construction. Owners of these turbines must satisfy the requirements of either the federal Non-attainment program or the Prevention of Significant Deterioration program, depending on the air quality of the region. Both programs require that an analysis of applicable pollutant controls be included in the permit application. This paper presents a determination of the best available control technology for nitrogen oxide emissions from two proposed combined cycle gas turbines. Each possesses a 210 MW generating capability: 145 MW are produced by a GE MS-7001F gas turbine and 65 additional megawatts by a heat recovery steam generator and steam turbine. Detailed analyses of economic, environmental, and energy impacts are given for two technologies: selective catalytic reduction and steam injection. The study concludes that steam injection to meet the Environmental Protection Agency’s New Source Performance Standards provides the most effective means of control for nitrogen oxides. Other means of nitrogen oxides control are eliminated on the basis of technical feasibility.
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Sudarev, A. V., Y. I. Zakharov, E. D. Vinogradov, S. Vesely e G. Poslushny. "Gas Turbine Units for Pipeline Compressor Stations: Environmental Update Problems". In ASME 1994 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/94-gt-497.
Testo completoAbstract (sommario):
The exhaust of nitrogen oxides into atmosphere is the most stringent environmental challenge in the operation of gas pipeline gas turbine plants. In 1991–1993 NITI EM along with EKOL retrofitted over 170 GTK-10 and GT-750-6 type gas turbine combustors of the “Tyumentransgas” and “Transit” (Czech Republic) gas transmission enterprises. Operations were carried out directly at the gas pumping stations. Emissions of the retrofitted units are within a range of 135–175 mg/Nm3 of oxides of nitrogen (NOx) referred to 15% O2 and carbon monoxide (CO) content of the exhaust gases does not exceed 100 mg/Nm3, at 15% O2.
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Gao, Tongyang, Shui Yu, Kelvin Xie, Marko Jeftic, Meiping Wang e Ming Zheng. "The Estimation of Nitrogen Oxides Reduction Potential Through Enhanced Heat Release Analysis". In ASME 2016 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icef2016-9440.
Testo completoAbstract (sommario):
An enhanced heat release analysis method is proposed to investigate the NOx emission reduction potential in diesel low temperature combustion and the combustion of premixed ethanol ignited by diesel injections. The heat release analysis from the in-cylinder pressure is a commonly applied diagnostic tool to gain insights in various aspects of combustion, such as start of combustion, ignition delay, combustion phasing, and combustion duration. However, these parameters are more qualitative than quantitative when they are correlated to engine efficiency and emissions. The results are often inconsistent at different engine operating conditions, such as different intake pressure levels, EGR rates and engine loads. In this work, the authors proposed a new parameter named as peak of combustion acceleration, which is the maximum of the first derivative of the heat release rate over an engine cycle. It was observed that the peak of combustion acceleration had a close correlation with the emissions of smoke and NOx at different engine loads and in the combustion of both diesel LTC and premixed ethanol ignited by diesel injections. With the test engine platform, the NOx emission reduced to lower than 50 ppm when the peak of combustion acceleration was less than 25 for diesel LTC and 35 for premixed ethanol ignited by diesel injections. The detailed cylinder pressure sampling and treatment processes were described in this paper. The impact of cycle to cycle variation in the cylinder pressure on the calculation of the peak of combustion acceleration was discussed. The peak of combustion acceleration and the corresponding engine crank angle from each individual engine cycle were calculated and the statistic performance of these parameters was evaluated. The comparison indicated an acceptable consistency between the results from individual engine cycle and from the averaged engine cycles. The proposed peak of combustion acceleration can be potentially integrated in the engine control as an indication of the NOx reduction potential.
Rapporti di organizzazioni sul tema "Nitrogen oxides Environmental aspects"
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Rosocha, L. A., A. W. Miziolek, M. J. Nusca, J. S. Chang e J. T. Herron. Reactions of oxides of nitrogen (NO{sub x}) leading to the formation of nitric acid (HNO{sub 3}) in non-thermal plasmas (NTPs). White paper for the Strategic Environmental Research and Development Program (SERDP) (Compliance Project CP-1038: Development of non-thermal plasma reactor technology for control of atmospheric emissions). Office of Scientific and Technical Information (OSTI), agosto 1998. http://dx.doi.org/10.2172/334238.
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