Esta Tesis Doctoral evalúa la norma UNE EN 14211:2006 -Método normalizado de medida de la concentración de dióxido de nitrógeno y monóxido de nitrógeno por quimiluminiscencia-, citada como referencia técnica en la Directiva 2008/50/CE sobre calidad del aire y una atmósfera más limpia en Europa.La citada norma establece ensayos y criterios que deben superar los analizadores de los contaminantes citados antes de su comercialización en la Unión Europea, lo que se conoce como ensayo de aprobación de tipo. La Tesis Doctoral elaborada estudia en profundidad esta nueva norma, llevando a cabo un estudio crítico que analiza los aspectos operativos y los criterios exigidos. En algunos casos se proponen modificaciones que pueden ayudar a mejorarla. Así mismo se sugiere aplicar procedimientos correctivos de los datos obtenidos en campo, que resultan afectados por determinados parámetros físicos (presión, temperatura y humedad), modelizables mediante el empleo de leyes físicas o ajustes empíricos. / This Doctoral Thesis aims at evaluating the norm EN 14211: Standard method for the measurement of the concentration of nitrogen dioxide and nitrogen monoxide by chemiluminescence, mentioned in the Directive 2008/50/EC as technical reference document.The above standard specifies performance parameters that the analyzers must comply with prior to being sold, what is known as "Type Approval Test", and field calibration and verification guidelines, neither of which was considered in the previous standards.The study of the new Standard has revealed that some points could be improved in order to achieve a higher degree of accuracy and precision in the concentration data of nitrogen oxides. The improvement proposals cover certain aspects of the tests related to the Type Approval Test and data corrective procedures empirically obtained or by means of physical laws which are affected by physical parameters such as pressure, temperature or humidity.

In order to meet the US EPA's National Ambient Air Quality Standards as set under the provisions of the Clean Air Act, states and regions throughout the United States are designing cap and trade programs aimed at reducing the emissions of the two dominant precursors for ozone, nitrogen oxides (NOx) and Volatile Organic Compounds (VOCs). While emission cap and trade programs are becoming more common, relatively few analyses have examined the air quality implications of moving emissions from one location to another (due to trading of emissions between facilities), from one sector to another (due to the use of technologies such as Plug-in Electric Hybrid Vehicles - PHEVs), and changing the temporal distribution of emissions (through emissions trading among facilities with different temporal profiles). This thesis will examine, in detail, the air quality implications of two emission cap and trade programs. The first program is a NOx trading program that covers Electricity Generating Units (EGUs) in the Northeastern United States. Results show that refining the temporal limits on this cap and trade program, by charging facilities more to emit NOx on days when ozone is most likely to form, has the potential to significantly reduce NOx emissions and ozone concentrations. Additionally, this research also shows that, for this region, the spatial redistribution of NOx emissions due to trading leads to greater ozone reductions than similar amounts of NOx emission reductions applied evenly across all facilities. Analyses also indicate that displacing emissions from the on-road mobile sector (vehicles) to the EGU sector through the use of PHEVs decreases ozone in most areas, but some highly localized areas show increases in ozone concentration. The second trading program examined in this thesis is limited to Houston, Texas, where a VOC trading program is focused on a sub-set of four Highly Reactive Volatile Organic Compounds (HRVOCs), which have been identified as having substantial ozone formation potential. Work presented in this thesis examined whether this trading program, in its current form or in an expanded form, could lead to air pollution hot spots, due to spatial reallocation of emissions. Results show that the program as currently designed is unlikely to lead to ozone hot spots, so no further spatial limitations are required for this program. Expanding the trading to include Other VOCs, fugitive emissions and chlorine emissions, based on reactivity weighted trading, is also unlikely to lead to the formation of ozone hot spots, and could create more flexibility in a trading market that is currently not very active. Based on these air quality modeling results, policy suggestions are provided that may increase participation in the trading market. These case studies demonstrate that use of detailed air analyses can provide improved designs for increasingly popular emission cap and trade programs, with improved understanding of the impacts of modifying spatial and temporal distributions of emissions. / text

It is the need of the hour to reduce the pollutants which poison our atmosphere and harm our health. The diesel engines are the most efficient IC engines in the world today, but paradoxically, they are also the engines which create the largest amounts of NOx, the pollutant that is most difficult to control with the existing technologies. In fact, the existing technologies are unable to meet the increasingly stringent standards for NOx. Even in bio-diesels, which in the future may be adopted as an important alternative fuel, NOx is the major pollutant. Thus not having a safe and stable method for NOx removal from the diesel exhaust stream is a cause for concern. In this thesis, there has been an attempt to address this issue by means of non-thermal plasma and catalysts. In this thesis, first the performance of the three sources was evaluated individually, along with two different HV electrodes, a helical wire and a straight wire. Secondly, the efficiencies of these three different types of sources were compared. Thirdly, a catalyst (Red Mud) and an adsorbent (NaZSM5) were cascaded with the plasma reactor to enhance the performance of the NOx removal process with the AC source as it gave the best results. All the experiments were performed with real diesel engine exhaust. The conclusions drawn from the experiments are as follows: The helical electrode consumes much lower power than the straight electrode. Therefore it is energy efficient. It also causes corona inception at lower voltages due to the strong non-uniformity of its electric field. The drawbacks of the helical electrode are an excess production of NO2 .it also does not work with the HFAC source, because at high frequency, the voltage doesn’t build up owing to the presence of only a dielectric medium of 2 mm thickness between the two electrodes. The performances of the 3 sources were compared. The HVAC unit gave the best NOx removal, followed by the MPC and finally, the HFAC source. The differences in efficiencies were related to both the magnitude of the peak voltage achieved by each device and the time period. It was also seen that when the voltage was high, a better efficiency can be achieved with lower power consumption. The comparison of the sources leads us to conclude that the high voltage AC source can be used as an economic alternative for NOx control. This is because a standard AC unit is easily available at higher voltages, and contains less electrical or mechanical complexity, whereas a pulsed source is comparatively expensive and complex. The NaZSM5 zeolite showed excellent removal at room temperature as an adsorbent when cascaded after the AC source, by reducing the NO2 levels consistently. The Red Mud showed reasonable catalytic activity at 400 C with the AC source. It was also efficient in compensating for the increase in the NO2 and CO concentration in the plasma atmosphere. Hence, both Red Mud and ZSM 5 are good candidates for a hybrid plasma-adsorbent or plasma-catalyst system. The combination better NOx/CO removal is the AC energization coupled with spiral electrode with either ZSM-5 or red mud. Scaling up the plasma/ plasma- catalyst system for handling higher flow rates will be the main task next. A method to optimize the source and load matching for better power transfer to the plasma reactor from the different sources also need to be developed. The design of the compact high frequency AC source must be upgraded for higher powers.

Darbe tirta tiekiamo oro temperatūros, deginių recirkuliacijos ir degalų savybių įtaka suslėgimu uždegamo homogeninio oro – bioetanolio mišinio degimo procesui, variklio darbo ir deginių emisijos rodikliams. Nustatytos variklio darbo homogeniniu oro – bioetanolio mišiniu maksimalios apkrovos zona, kurią riboja slėgio didėjimo greitis ir susidarantis detonacinis degimas. Gautieji rezultatai varikliui veikiant bioetanoliu, lyginti su rezultatais gautais varikliui veikiant baziniais degalais – benzinu. Dyzeliniam varikliui dirbant homogeniniu oro ir bioetanolio mišiniu, keičiant tiekiamo oro temperatūrą, naudojant deginių recirkuliaciją ir įmaišant 20 % reaktyvinių degalų, azoto oksidų emisijos lieka dešimtis kartų mažesnės negu tradicinio dyzelinio variklio. Slegiamo homogeninio oro – bioetanolio mišinio užsiliepsnojimui valdyti pirmą kartą panaudoti reaktyviniai degalai. / It was found that the intake air temperature, exhaust gas recirculation and fuel properties have the influence on the combustion characteristics of homogeneous air – bioethanol mixture, engine performance and emissions. The operating region was found at which critical rate of pressure rise was unacceptably high and engine worked at “knocking” combustion. In order to assess the combustion process in homogeneous charged compression ignition (HCCI) mode fuelled with the air – bioethanol mixture, it was compared whit the combustion process in HCCI mode fuelled with the air – gasoline mixture. When the diesel engine works in HCCI mode fuelled with air – bioethanol mixture, the nitrogen oxides can be reduced more than 10 times compared with normal diesel operation. For the first time, to control the autoignition of compressed homogeneous air and bioethanol mixture, the JET A1 fuel was simultaneously added in to combustible mixture in this study.

In urban areas, emissions of nitrogen oxide radicals (NOx ≡ NO + NO2) to the atmosphere from anthropogenic activities such as fossil fuel combustion contribute to poor air quality through the production of ozone and particulate matter. Soils are also a significant global source of NOx, but at downind forest environments the deposition of transported reactive nitrogen can be much more important than local emissions. Data from a government monitoring network in the Toronto area from 2000-2007 was used to explore the impact of long-term trends in NO2 and other ozone precursors on local ozone levels. Non-linear chemistry and the influence of meteorology explained why reductions in precursor levels during this period did not lead to significant improvements in ozone. Data from this network was also used to investigate the ability of a satellite-borne spectrometer to represent spatial patterns of ground-level NO2 in the same region. Selection biases, resulting from the need to discard satellite data on cloudy days, were shown to affect locations differently and were most severe at a receptor site. The sum of all reactive nitrogen oxides including NOx is known as NOy. A custom-built instrument for high precision and time resolution measurements of reactive nitrogen oxides was tested under various lab and field conditions, and used in field work where direct biosphere-atmosphere exchange of NOy was measured by eddy covariance above two comparable North American mixed forests (Haliburton Forest Wildlife Reserve and the University of Michigan Biological Station). While these forests were found to be small net sources of NOx, they were subject to elevated rates of NOy deposition overall, driven by the transport of polluted air from upwind source regions. Wet deposition measurements were used to show that dry deposition contributed a significant fraction of total deposition during the observation periods.

In urban areas, emissions of nitrogen oxide radicals (NOx ≡ NO + NO2) to the atmosphere from anthropogenic activities such as fossil fuel combustion contribute to poor air quality through the production of ozone and particulate matter. Soils are also a significant global source of NOx, but at downind forest environments the deposition of transported reactive nitrogen can be much more important than local emissions. Data from a government monitoring network in the Toronto area from 2000-2007 was used to explore the impact of long-term trends in NO2 and other ozone precursors on local ozone levels. Non-linear chemistry and the influence of meteorology explained why reductions in precursor levels during this period did not lead to significant improvements in ozone. Data from this network was also used to investigate the ability of a satellite-borne spectrometer to represent spatial patterns of ground-level NO2 in the same region. Selection biases, resulting from the need to discard satellite data on cloudy days, were shown to affect locations differently and were most severe at a receptor site. The sum of all reactive nitrogen oxides including NOx is known as NOy. A custom-built instrument for high precision and time resolution measurements of reactive nitrogen oxides was tested under various lab and field conditions, and used in field work where direct biosphere-atmosphere exchange of NOy was measured by eddy covariance above two comparable North American mixed forests (Haliburton Forest Wildlife Reserve and the University of Michigan Biological Station). While these forests were found to be small net sources of NOx, they were subject to elevated rates of NOy deposition overall, driven by the transport of polluted air from upwind source regions. Wet deposition measurements were used to show that dry deposition contributed a significant fraction of total deposition during the observation periods.

Diss. (sammanfattning) Linköping : Univ., 2004. / Härtill 5 uppsatser.

Understanding the quality of the air we breathe is critical in quantifying the impact that atmospheric chemistry has on health. Poor air quality increases the risk of heart and lung diseases as well as having a detrimental effect on climate, ecology and the built environment. The burning of fossil fuels and plant matter (biomass burning) creates large quantities of gases and particulate matter that impact air quality and the air we breathe. Biomass burning is estimated to contribute 400 Tg of non-methane organic compounds, 40 Tg of methane and 7.1 Tg of nitrogen oxides to the atmosphere each year. This thesis aims to better understand the role of biomass burning on air quality and tropospheric chemistry. The in depth analysis presented here addresses of the impact of boreal biomass burning in North America on air quality, in particular, carbon monoxide (CO) and ozone (O3). By using a number of different modelling techniques along with data collected from a field campaign and satellites the transport and chemistry of biomass burning emissions were analysed and quantified. The first research chapter of the thesis used the GEOS-Chem atmospheric chemistry transport model to interpret aircraft measurements of CO in biomass burning outflow taken during the 2011 BORTAS-B campaign over Canada. The model has some skill reproducing the observed variability, but has a positive bias for observations < 100 ppb and a negative bias for observations > 300 ppb. It was found that observed CO variations are largely due to fires over Ontario, with smaller and less variable contributions from fossil fuel combustion from eastern Asia and NE North America. To help interpret observed variations of CO an effective physical age of emissions (¯A) metric was developed. It was found that during BORTAS-B the age of emissions intercepted over Halifax, Nova Scotia is typically 4–11 days, and on occasion as young as two days. The analysis shows that ¯A is typically 1–5 days older than the associated photochemical ages inferred from co-located measurements of different hydrocarbons. It is argued that a robust observed relationship between CO and black carbon aerosol during BORTAS-B (r² > 0.7), form the basis of indirect evidence that aerosols co-emitted with gases during pyrolysis markedly slowed down the plume photochemistry during BORTAS-B with respect to photochemistry at the same latitude and altitude in clear skies. The second research chapter focuses on O3 production downwind from boreal biomass burning. Using the GEOS-Chem model, the O3 chemistry within a biomass burning plume from a fire on 17 July 2011 in mid-Canada was examined. The model shows a significant positive bias (~20 ppb) in reproducingO3 mixing ratios over North America for July 2011 when compared to observations. Reducing NO emissions from lightning and fossil fuel by 50% and 54% respectively reduced this bias to ~10 ppb. The cause of the remaining bias is uncertain. Using a novel technique with the model, the centre of the biomass burning plume was tracked and O3 concentrations and chemistry was extracted from the centre of the plume. The biomass burning enhanced O3 concentrations throughout the plume by between 1 – 20 ppb when compared with the same plume path with no biomass burning. The plume was characterised as being NOx-rich for the initial four days of transport. The sensitivity of the O3 chemistry to different emissions was calculated and it was found that the O3 is initially highly sensitive to NO emissions from biomass burning and then to NO emissions from fossil fuels as it travels across an urban area surrounding Quebec City. The O3 net production was found to initially decrease with an increase in NO but increase further downwind. The final research chapter of the thesis uses long-term satellite observations to evaluate natural variability in CO concentrations over the North Atlantic. 15 years of MOPITT CO column observations were used along with modelled CO from the GEOS-Chem model. The model was evaluated against the MOPITT overpass and shows a negative bias of between -8% and -24% over the northern mid-latitudes with the largest bias seen in spring. The model has a large positive bias (8% – 40%) over the Amazon,West Africa and Indonesia through all seasons. Using Empirical Orthogonal Function (EOF) analysis on the MOPITT and GEOS-Chem CO columns shows the largest mode of variability seen in the North Atlantic to be the oxidation of methane for winter and spring, biomass burning during summer and fossil fuel combustion from East Asia during autumn.

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