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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Porovnání emisních norem u motorů JCB

RYŠAVÝ, Tomáš January 2018 (has links)
The aim of this diploma thesis is to compare the latest emission standards for JCB engines that are used in JCB telescopic loaders. The first part of this work is focused on the history of JCB, the development of JCB Loadall telescopic loaders and also deals with issues of emissions, their origin, effects on humans and the atmosphere. In addition, there are listed ways how to reduce emissions, both ways of reducing pollutants by designing the combustion chamber and reducing them by systems such as SCR (Selective Catalytic Reduction), DOC (Diesel Oxidation Catalyst), EGR (Exhaust Gas Recirculation) and particulate filters. Emission regulations are included as well. The second part of this work is focused on the actual measurement of the exhaust gas emissions of JCB engines with different technologies for their reduction. The measured values will be further processed and inserted into tables and graphs that will then be compared to each other.
2

Qualitative analysis of a regional public policy for air quality : A case study of Normandie, France / Kvalitativ analys av en regional offentlig policy för luftkvalitet : Fallstudie av Normandie, Frankrike

Avenas, Arthur January 2021 (has links)
Today, outdoor air quality occupies an important place into civic dialogue because of the many impacts of atmospheric pollution on health. Different legislations and strategies have thus been implemented across the world to improve outdoor air quality. Analysing and comparing the different strategies can help adopting the best practices in favour of air quality. In France, in particular, the national air quality policy is reflected at a regional scale through legislative documents called Atmosphere Protection Plans (PPAs). The analysis of such a document thus represents a powerful way to assess a regional air quality policy. Here, Normandie’s PPA has been analysed through a literature review, working meetings as well as qualitative interviews. The study highlighted that Normandie’s air quality policy had to answer a complex legislative ecosystem of international, national and local documents. The analysis also underlined that the questions of the perimeter of action of the policy and the targeted pollutants were as central as the measures implemented to improve air quality. The working meetings and the qualitative interviews led to consensus that Normandie’s air quality policy should target 3 atmospheric pollutants: nitrogen dioxide, particulate matter 10 and particulate matter 2.5. If road traffic has been identified as the major emitting source of the first, particulate matter emitting sources were pointed as varied and multi-sectoral. Finally, some measures of Normandie’s air quality policy appeared to be particularly efficient and advanced, such as agricultural measures. Yet, many difficulties were encountered when implementing several measures of the policy. The main difficulties were the lack of financial resources, the lack of project leader and the lack of technical expertise. More than a basic analysis of an air quality public policy, these results can also be perceived as a sharing of experience on how a region addresses air quality issues. Because a work of collection of best practices and best strategies to improve air quality is more than ever needed, further research can build on this study to elaborate a relevant air quality policy. / Luftkvaliteten visar den antropogena nedbrytningen av det naturliga tillståndet för luft. Detta ämne har spelat en allt viktigare roll i den offentliga debatten under de senaste decennierna, på grund av de olika effekterna som luftföroreningar har på hälsan. I denna masteruppsats har Normandies politik för luftkvalitet analyserats. I Frankrike regleras nationell luftkvalitetspolitik i regional skala genom lagstiftningsdokument som kallas Atmosphere Protection Plan (PPA). Analysen av detta dokument gör det möjligt att bedöma den regionala luftkvalitetspolitiken. Således har hela studien baserats på analysen av Normandies PPA.  Här har Normandies PPA analyserats genom litteraturöversikt, arbetsmöten och kvalitativa intervjuer. Först och främst belyste litteraturöversikten att Normandies PPA måste ta hänsyn till ett komplext lagstiftningsekosystem, allt från internationell till lokal skala. I synnerhet är Normandies PPA-huvudmål att uppnå de tröskelvärden som definieras av de europeiska direktiven.  I ett andra steg tillät en granskning av PPA från sex franska regioner att jämföra Normandies luftkvalitetspolitik med andra regioners politik. Under denna fas har såväl strukturer dokumenterats som de presenterade åtgärderna utvärderats med avseende på strukturerna och åtgärderna för de andra PPA. I synnerhet har återkommande kategorier och underavsnitt identifierats i de sex PPA. Dessutom tycktes motiveringen av applikationomkrets vara central, liksom de riktade atmosfäriska föroreningarna. På samma sätt tillät jämförelsen av åtgärderna för de sex PPA att identifiera de relevanta och banbrytande åtgärderna i Normandies PPA, som tillhör hamnsektorn och de sektorsövergripande åtgärderna. Omvänt verkade åtgärderna av Normandies PPA vara otillfredsställande inom industri- och transportsektorn.  En mer fördjupad analys genomfördes genom arbetsmöten och kvalitativa intervjuer. Flera frågor har bedömts, till exempel applikationomkrets och PPAs struktur. I synnerhet har man dragit slutsatsen att minskningen av applikationomkretsen som Normandie avsåg var relevant och förhindrade PPAs komplikationer. Dessutom påpekade deltagarna att om Normandies PPA-struktur var ganska tydlig, saknades fortfarande viktiga underavsnitt i Normandies PPA och de bör läggas till.  Arbetsmötena liksom de kvalitativa intervjuerna gjorde det också möjligt att ta upp frågan om de riktade föroreningarna och deras källor. Alla deltagare och intervjuade gick med på att rikta in NO2, PM10 och PM2.5 i Normandies PPA. Integrationen av SO2 och O3 har dock diskuterats mer, den första har endast släppts ut i skadlig mängd under industriella olyckor, och den andra var för svår att hantera eftersom den är en sekundär förorening. När det gäller utsläppskällorna visade studien att en hög atmosfärisk koncentration av NO2 främst berodde på vägtrafik. Utsläppskällorna PM10 och PM2.5 identifierades som mer varierade och flersektoriella.  Slutligen tillät de kvalitativa intervjuerna att avgöra vilka åtgärder av Normandies PPA som har slutförts eller inte, och att identifiera varför. Åtgärder inom jordbrukssektorn nämndes som de mest avancerade åtgärderna i Normandies PPA. Omvänt har två åtgärder övergivits helt, en inom hamnsektorn, den andra inom transportsektorn. Några skäl som förklarade varför alla åtgärder inte har genomförts var bristen på ekonomiska resurser, bristen på projektledare och bristen på teknisk expertis. Mer allmänt verkar det vara avgörande att involvera de olika intressenterna från varje utsläppssektor och sätta dem runt ett bord för att skapa effektiva åtgärder till förmån för luftkvaliteten.
3

Reduction of NOx Emissions in a Single Cylinder Diesel Engine Using SNCR with In-Cylinder Injection of Aqueous Urea

Timpanaro, Anthony 01 January 2019 (has links)
The subject of this study is the effect of in-cylinder selective non-catalytic reduction (SNCR) of NOx emissions in diesel exhaust gas by means of direct injection of aqueous urea ((NH2)2CO) into the combustion chamber. A single cylinder diesel test engine was modified to accept an electronically controlled secondary common rail injection system to deliver the aqueous urea directly into the cylinder during engine operation. Direct in-cylinder injection was chosen in order to ensure precise delivery of the reducing agent without the risk of any premature reactions taking place. Unlike direct in-cylinder injection of neat water, aqueous urea also works as a reducing agent by breaking down into ammonia (NH3) and Cyanuric Acid ((HOCN)3). These compounds serve as the primary reducing agents in the NOx reduction mechanism explored here. The main reducing agent, aqueous urea, was admixed with glycerol (C3H8O3) in an 80-20 ratio, by weight, to function as a lubricant for the secondary injector. The aqueous urea injection timing and duration is critical to the reduction of NOx emissions due to the dependence of SNCR NOx reduction on critical factors such as temperature, pressure, reducing agent to NOx ratio, Oxygen and radical content, residence time and NH3 slip. From scoping engine tests at loads of 40 percent and 80 percent at 1500 rpm, an aqueous urea injection strategy was developed. The final injection strategy chosen was four molar ratios, 4.0, 2.0, 1.0 and 0.5 with five varying injection timings of 60, 20, 10, 0, and -30 degrees after top dead center (ATDC). In addition to the base line and aqueous urea tests, water injection and an 80-20 water-glycerol solution reduction agent tests were also conducted to compare the effects of said additives as well. The comparison of baseline and SNCR operation was expected to show that the urea acted as a reducing agent, lowering NOx emissions up to 100% (based on exhaust stream studies) in the diesel exhaust gas without the aid of a catalyst. The data collected from the engine tests showed that the aqueous urea-glycerol solution secondary had no effect on the reduction of NOx and even resulted in an increase of up to 5% in some tests. This was due to the low average in-cylinder temperature as well as a short residence time, prohibiting the reduction reaction from taking place. The neat water and water-glycerol solution secondary injection was found to have a reduction effect of up to 59% on NOx production in the emissions due to the evaporative cooling effect and increased heat capacity of the water.

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