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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.
61

Long term effects of ammonia on piston ring materials for maritime combustion engines

Firsching, Matilda January 2024 (has links)
Due to climate changes and an increasing global temperature, the maritime transport sector has taken upon a mission to reduce their share of greenhouse gas emissions by 50% until 2050. Combustion engines used in ships mainly run on carbon-based fuels, but to achieve the reduction of emissions it is crucial to investigate the possibility of alternative fuels. Ammonia is an alternative fuel with a carbon free chemical composition that shows big potential, with several initiatives to put ammonia driven ship engines on the market in the near future. For ships to be able to run on ammonia fuel, the engine materials have to withstand the corrosive effect of ammonia whilst still ensuring that the motor runs properly. In this study, two piston ring materials are investigated with regards to long-term effects of exposure to ammonia solution. The piston ring materials investigated were comprised of a cast iron substrate covered with either a chromium ceramic coating or a with a cermet coating, the latter also coated with an aluminium-bronze based running in layer on top. The materials were submerged in 25% ammonia solution for different time intervals up to 12 weeks, with a solution change every fourth week. After exposure to ammonia, the materials were tribologically tested in a reciprocal sliding test rig. The surfaces, both inside and outside of the wear tracks, were analysed with SEM and EDS, as well as with CSI. The chromium ceramic coating did not seem to get affected by, or interact chemically, with the ammonia solution. Exposing the material to ammonia did not seemingly affect the tribological properties. However, two different behaviours were observed when analysing the cermet coated samples with a running-in layer of aluminium-bronze. These samples reacted with the ammonia solution in two different ways, resulting in the series being split into two. In both cases precipitates were formed, but the colour changes of the solutions differed for the series. The coatings were also worn differently, as in one case a flattening effect was observed throughout all time intervals, whereas in the other case the worn volume and track depth seemed to increase with exposure to ammonia solution.
62

Car(ing) for our environment? : Consumer eco-innovation adoption and curtailment behaviors: The case of the alternative fuel vehicle.

Jansson, Johan January 2009 (has links)
Determinants influencing consumer eco-innovation adoption and green curtailment behaviors in a travel context are at the center of this thesis. Previous research on green consumer behavior has uncovered that internalized personal attitudinal factors such as values, beliefs, and norms are influential in determining mainly non-consumption and post-purchase behaviors. This thesis extends the understanding of a moral basis of green consumer behavior by exploring the influences of attitudinal factors on both car curtailment behaviors, and on consumer adoption of a high involvement eco-innovation – the alternative fuel vehicle. The integrated influences of innovation specific characteristics, car habits, knowledge and social norms, are also examined. Furthermore, differences between AFV adopters and non-adopters are explored, and the notion of consumers performing purchase and curtailment behaviors for different reasons is utilized in the development of nuanced profiles of three distinct consumer groups. Four studies, which build on two quantitative data collections on adopters and non-adopters of AFVs in Swe­den, are included in this thesis. In the first study, similarities and differences among adopters and non-adopters of AFVs, and the effects of attitudinal factors (values, beliefs, and norms), knowledge, and sociodemo­graphics on the adoption decision are analyzed. The results show that knowledge and personal norms are strong predictors of AFV adoption and that the VBN theory is applicable in this context. The main implication from the study is that high-involvement green purchase deci­sions, such as eco-innovation adoption, can be viewed as morally based. In the second study, a set of determinants influencing both curtailment of car use and willing­ness to adopt a less environmentally harmful vehicle are analyzed. Biospheric values, per­sonal proenvironmental norms, and car habit strength are found to influence both types of behaviors in different ways. The main implication from this study is that green purchase deci­sions and curtailment behaviors within a specific context are determined by partly different factors but personal norm is a strong predictor of both types of behaviors. The third study extends the findings from the previous one in segmenting consumers on cur­tailment behaviors and proenvironmental purchases. Three distinct types of consumers emerge from the data. The Non-greens are found to exhibit the lowest levels of green attitudes and behaviors, and the strongest car habits. The Curtailers are distinguished by performing primar­ily reductionist behaviors, and by being the most willing to reduce negative environ­mental impact of car use. The Ecovators are found to be the most inclined to purchase eco-innovations and also display the greenest values. The study shows that green consumers are a heterogeneous group that can be separated on the basis of green curtailment behaviors and proenvironmental purchase decisions, and that there seems to be no inherent contradiction in being an early adopter of new green technology (such as the AFV) and also having high levels of proenviron­mental values, beliefs, and norms. In the final study, innovation specific characteristics and consumer innovativeness factors are integrated with normative and attitudinal determinants influencing AFV adoption. The results show that personal and social norms, consumer novelty seeking, and four perceived innovation characteristics influence the adoption decision. Differences between AFV adopters’ and non-adopters’ ratings of AFV specific attributes are also analyzed. The contribution of this study is the integration of VBN theory and the DOI framework and the empirical conclusion that eco-innovations need to deliver on both traditional and proenvironmental attributes in order to be perceived as attractive by consumers. In sum, this thesis demonstrates the importance of proenvironmental personal norms for consumer adoption of a high involvement eco-innovation such as the AFV.
63

An analysis of consumer intention to purchase green vehicles in the South African market : a theory of planned behaviour perspective

Hamilton, Brett Joseph 12 1900 (has links)
Thesis (MBA)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: For companies, merely offering green products does not guarantee long-term market success (Hansen, Risborg & Steen, 2012). In many cases, consumers fail to act green despite stating that they intend to do so and having a positive attitude towards green behaviour. This is referred to as the attitude-action gap (Lane & Potter, 2007; Eckhardt, Belk & Devinney, 2010). What is required is a deeper understanding of the underlying reasons for green consumer behaviour, such as consumer values, in order to develop effective green marketing strategies (Hansen, 2008; Kim & Chung, 2011). The purpose of the research was to use Ajzen’s theory of planned behaviour (TPB) (1985) to study the link between the personal values of consumers and their attitudes and behaviour toward purchasing green vehicles in the South African market. It focused on alternative fuel vehicles (AFVs) and, more specifically, hybrid and electric-drive vehicles (HEVs and EVs), since these are the only type of AFV currently available in the South African market. In addition, it investigated the role that subjective norm (SN) and perceived behavioural control (PBC) has on the intention to purchase AFVs. The analysis failed to find a significant relationship between the four higher-order values (self-enhancement, self-transcendence, openness to change and conservation) and attitude. In the case of openness to change and conservation, this was not entirely unexpected, but a lack of a significant relationship between self-enhancement, self-transcendence and attitude was an interesting result, which warrants further investigation, as the use of the ESS Human Value Scale as measurement instrument could be brought into question. The analysis also found significant relationships between attitude, subjective norm, and perceived behavioural control and behavioural intention. Of the three constructs, attitude was found to have the most significant impact on behavioural intention. These findings are in support of modern literature and emphasise: 1. that consumers do not rely on their values when forming an attitude towards AFVs and, thus, the marketing of AFVs should not rely on value-driven marketing, 2. that attitudinal factors has the biggest influence on intention, 3. that the perceived support and encouragement of referent others are important considerations for individuals, and 3. that control factors also play a critical role when consumers decide whether to purchase an AFV or not. The marketing of AFVs should thus focus on these three factors, including shaping attitudes, emphasising the role of referent others and informing consumers about control factors.
64

Personal, interpersonal, and contextual influences on consumer preferences for plug-in electric vehicles: a mixed-method and interdisciplinary approach

Kormos, Christine 02 May 2016 (has links)
Widespread adoption of plug-in electric vehicles (PEVs) can help to achieve deep reductions in global greenhouse gas emissions; however, the degree to which this potential will be realized depends on consumers’ decisions to purchase these vehicles over conventional ones. To provide comprehensive insight into the psychological and contextual influences on consumer vehicle preferences, three studies were performed using a mixed-methods approach. Study 1 employed a survey and stated choice experiment to explore: 1) the explanatory power of the three psychological variables from Ajzen’s (1991; 2005) theory of planned behaviour in predicting PEV purchase intentions among new vehicle buyers from British Columbia, and 2) the influence of hypothetical variations in financial and non-financial incentives on estimated PEV preference, with the goal of informing the design of provincial policy measures. Vehicle preferences were most strongly influenced by purchase price and point-of-sale incentives – with a roughly 4% forecasted increase in PEV new vehicle market share under a $5,000 purchase rebate – as well as by attitudes about PEVs (especially concerning personally-relevant PEV benefits), perceived behavioural control, and social norms. In Study 2, a latent class choice model was used to integrate survey and choice experiment data to characterize consumer classes based on vehicle preferences, demographic characteristics, and psychological variables. Findings revealed profiles of five distinct preference-based segments and demonstrated that the inclusion of psychological covariates can improve the fit of such latent class models. Study 3 extended these findings through a controlled message framing experiment that evaluated the impact of psychological distance on PEV purchase intentions. Results demonstrated that messages emphasizing both personally-relevant and societally-relevant PEV benefits increased related purchase intentions compared to the control group. Taken together, these findings may be useful in the development of PEV policies as well as targeted marketing and communications strategies aimed at supporting a transition to PEVs within Canada. / Graduate / 0451 / 0621 / 0709 / christine.kormos@gmail.com
65

Desempenho de motor Ciclo diesel em bancada dinamométrica utilizando Biodiesel etílico de soja / Performance of engine cycle diesel in dynamométer using mixtures diesel/biodiesel

Castellanelli, Márcio 27 July 2006 (has links)
Made available in DSpace on 2017-07-10T19:25:07Z (GMT). No. of bitstreams: 1 Marcio Castellanelli.pdf: 1580041 bytes, checksum: b88f98c62541a81dbb056e3bbb1905a3 (MD5) Previous issue date: 2006-07-27 / Ahead of the forecast of scarcity of the oil, the ethyl ester (biodiesel) if has presented as an excellent alternative fuel option for engines cycle diesel. The characteristics of biodiesel are similar of diesel in terms of viscosity and the calorific power, being able to be used without adaptations in the engines. For accomplishment of this work, a motor cycle was used diesel, of direct injection with four cylinders, without adaptations. The engine was connected to a dynamometer and systems of acquisition of data auxiliary for the register of the necessary data. The performances of torque, power and brake specific fuel consumption for the following mixtures had been evaluated: B2, B5, B10, B20, B50, B75 and B100. The best registered performance was given with the B20 mixture. / Diante da previsão de escassez do petróleo, o éster etílico (biodiesel) tem se apresentado como uma excelente opção de combustível alternativo para motores ciclo diesel. As características do biodiesel são semelhantes as do diesel em termos de viscosidade e poder calorífico, podendo ser utilizado sem adaptações nos motores. Para realização deste trabalho, utilizou-se um motor ciclo diesel, de injeção direta com quatro cilindros, sem adaptações. O motor foi acoplado a um dinamômetro e sistemas de aquisição de dados auxiliares para o registro dos dados necessários. Avaliaram-se os desempenhos de torque, potência e consumo específico de combustível para as seguintes misturas: B2, B5, B10, B20, B50, B75 e B100. O melhor desempenho registrado deu-se com a mistura B20.
66

Desempenho de motor Ciclo diesel em bancada dinamométrica utilizando Biodiesel etílico de soja / Performance of engine cycle diesel in dynamométer using mixtures diesel/biodiesel

Castellanelli, Márcio 27 July 2006 (has links)
Made available in DSpace on 2017-05-12T14:48:30Z (GMT). No. of bitstreams: 1 Marcio Castellanelli.pdf: 1580041 bytes, checksum: b88f98c62541a81dbb056e3bbb1905a3 (MD5) Previous issue date: 2006-07-27 / Ahead of the forecast of scarcity of the oil, the ethyl ester (biodiesel) if has presented as an excellent alternative fuel option for engines cycle diesel. The characteristics of biodiesel are similar of diesel in terms of viscosity and the calorific power, being able to be used without adaptations in the engines. For accomplishment of this work, a motor cycle was used diesel, of direct injection with four cylinders, without adaptations. The engine was connected to a dynamometer and systems of acquisition of data auxiliary for the register of the necessary data. The performances of torque, power and brake specific fuel consumption for the following mixtures had been evaluated: B2, B5, B10, B20, B50, B75 and B100. The best registered performance was given with the B20 mixture. / Diante da previsão de escassez do petróleo, o éster etílico (biodiesel) tem se apresentado como uma excelente opção de combustível alternativo para motores ciclo diesel. As características do biodiesel são semelhantes as do diesel em termos de viscosidade e poder calorífico, podendo ser utilizado sem adaptações nos motores. Para realização deste trabalho, utilizou-se um motor ciclo diesel, de injeção direta com quatro cilindros, sem adaptações. O motor foi acoplado a um dinamômetro e sistemas de aquisição de dados auxiliares para o registro dos dados necessários. Avaliaram-se os desempenhos de torque, potência e consumo específico de combustível para as seguintes misturas: B2, B5, B10, B20, B50, B75 e B100. O melhor desempenho registrado deu-se com a mistura B20.
67

Analysis of Alternative Fuels in Automotive Powertrains

Gunnarsson, Andreas January 2009 (has links)
<p>The awareness of the effect emissions have on the environment and climate has risen in the last decades. This has caused strict regulations of greenhouse gas emissions. Greenhouse gases cause global warming which may have devastating environmental effects. Most of the fuels commercially available today are fossil fuels. There are two major effects of using fuels with fossil origin; the source will eventually drain and the usage results in an increase of greenhouse gases in the atmosphere. Fuels that are created from a renewable feedstock are often referred to as alternative fuels and under ideal conditions they are greenhouse gas neutral, meaning that the same amount of greenhouse gases is released during combustion as the source of the fuel have absorbed during its growth period. This evaluation method is known as a well-to-wheel analysis which besides emissions also evaluates energy efficiencies during both the production and the combustion phases.</p><p>By evaluating results of well-to-wheel analyses along with fuel properties and engine concept characteristics, this report presents which driving scenario that is suitable for different powertrain configurations. For example, vehicles operating in high populated areas, as cities, have a driving scenario that includes low velocities and multiple stops while vehicles in low populated areas often travel long distances in higher speeds. This implies that different powertrains are suitable in different regions. By matching favorable properties of a certain powertrain to the properties important to the actual driving scenario this report evolves a fuel infrastructure that is suitable in Sweden.</p>
68

Analysis of Alternative Fuels in Automotive Powertrains

Gunnarsson, Andreas January 2009 (has links)
The awareness of the effect emissions have on the environment and climate has risen in the last decades. This has caused strict regulations of greenhouse gas emissions. Greenhouse gases cause global warming which may have devastating environmental effects. Most of the fuels commercially available today are fossil fuels. There are two major effects of using fuels with fossil origin; the source will eventually drain and the usage results in an increase of greenhouse gases in the atmosphere. Fuels that are created from a renewable feedstock are often referred to as alternative fuels and under ideal conditions they are greenhouse gas neutral, meaning that the same amount of greenhouse gases is released during combustion as the source of the fuel have absorbed during its growth period. This evaluation method is known as a well-to-wheel analysis which besides emissions also evaluates energy efficiencies during both the production and the combustion phases. By evaluating results of well-to-wheel analyses along with fuel properties and engine concept characteristics, this report presents which driving scenario that is suitable for different powertrain configurations. For example, vehicles operating in high populated areas, as cities, have a driving scenario that includes low velocities and multiple stops while vehicles in low populated areas often travel long distances in higher speeds. This implies that different powertrains are suitable in different regions. By matching favorable properties of a certain powertrain to the properties important to the actual driving scenario this report evolves a fuel infrastructure that is suitable in Sweden.
69

Experimental Investigation Of Use Of Canola Oil As A Diesel Fuel

Ozdemir, Ali 01 September 2008 (has links) (PDF)
In this study, canola oil has been selected for the test on a diesel engine and its suitability as an alternative fuel has been examined. To decrease the high viscosity of canola oil, the effect of temperature on viscosity has been researched. Then the fuel delivery system has been modified to heat canola oil before injecting the oil into the combustion chamber. Also, ethanol has been tested as an additive by blending with canola oil. An experimental setup has been installed according to standards to carry out tests. The set up has been controlled with a computer to take measurements more precisely and to perform experiment automatically. Experimental investigations have been conducted on a four cylinder, direct injection diesel engine. Full load-variable speed tests have been conducted to evaluate engine performance parameters. In addition 13 mode ESC test cycle has been performed to determine the exhaust emissions. Engine performance and emissions characteristics of canola oil and canola-ethanol blend containing 30% ethanol have been compared with those of baseline diesel fuel. Experimental results show that engine performance decreased for canola oil. Addition of ethanol into canola oil has been noticed to improve performance a little with respect to pure canola oil. Although, maximum performance has been obtained with diesel fuel, minimum specifics energy cost is obtained with canola oil. It has been observed that hydrocarbon (HC) emissions decrease with canola oil, blending ethanol with canola oil increase HC emissions and maximum values are read for diesel fuel. Carbon monoxide (CO) emissions have been observed to be the highest for canola oil but blending ethanol has a decreasing effect on CO emissions. As for particulate matter (PM), use of canola oil has been seen to be more pollutant than diesel but adding ethanol in canola reduces PM emissions significantly.
70

Avaliação de misturas de óleos vegetais na produção de biodiesel: caracterização físico-química e reológica. / Evaluation of mixtures of vegetable oils in biodiesel production: physical-chemical and rheological characterization.

FELIX, Poliana Harlanne Dantas. 04 July 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-07-04T12:58:55Z No. of bitstreams: 1 POLIANA HARLANNE DANTAS FELIX - DISSERTAÇÃO PPGEA 2011..pdf: 17920132 bytes, checksum: 3142a61f99f446543cb00d431fc4f602 (MD5) / Made available in DSpace on 2018-07-04T12:58:55Z (GMT). No. of bitstreams: 1 POLIANA HARLANNE DANTAS FELIX - DISSERTAÇÃO PPGEA 2011..pdf: 17920132 bytes, checksum: 3142a61f99f446543cb00d431fc4f602 (MD5) Previous issue date: 2011-02 / Capes / Os óleos vegetais têm-se mostrado como alternativa promissora para a substituição dos combustíveis derivados de petróleo em motores de ciclo diesel. Um dos problemas enfrentados na atualidade é a alta viscosidade do biodiesel gerado a partir do óleo de mamona. Objetivou-se então, neste trabalho estudar as caracterizações físicas e físico-químicas dos óleos vegetais (mamona, algodão e soja), e de suas misturas em 10 formulações (formulação 1: 80% mamona + 10% soja + 10% algodão; formulação 2: 50% mamona + 40% soja + 10% algodão; formulação 3: 65% mamona + 25 % soja + 10% algodão; formulação 4:65% mamona + 25% soja + 10% algodão; formulação 5: 65% mamona + 10% soja + 25% algodão; formulação 6: 50% mamona + 25% soja + 25% algodão; formulação 7: 60% mamona + 20% soja + 20% algodão; formulação 8: 70% mamona + 27% soja + 3% algodão; formulação 9: 55% mamona + 30% soja + 15% algodão; formulação 10: 55% mamona + 15% soja + 30% algodão), e a obtenção do biodiesel desses óleos e misturas. Após serem submetidos a uma reação de transesterificação, os referidos óleos podem ser utilizados como aditivos ou até mesmo no futuro, como um substituto do óleo diesel convencional. Os óleos de mamona, algodão e soja foram obtidos por prensagem mecânica. A metodologia para obtenção de biodiesel foi realizada pela rota metílica. Para as caracterizações físico-químicas foram determinados o índice de acidez, saponificação, peróxido, iodo e teor de água. Para caracterizações físicas foram determinadas a viscosidade e a densidade em temperaturas (28,40,50,60)°C. Os valores obtidos nas análises físico-químicas para os óleos vegetais (soja, algodão e mamona), foram respectivamente: teor de água de 0,06, 0,07 e 0,36 b.u., índice de saponificação de (163, 180,180)mgKOH/g, índice de iodo de 10 gl/lOOg, índice de acidez de (0,4 ,0,4, 0,5) mgKOH/g, índice de acidez dos biodiesel (0,5, 1,1 6,5) mgKOH/g; índice de refração de 1,466, 1,451, 1,470. As misturas apresentaram propriedades similares ao diesel, além de favorecer a redução da viscosidade do biodiesel puro, através das misturas de óleos vegetais, promovendo maior eficiência no escoamento. O biodiesel proveniente das misturas O, f5 e f6 foi o que obteve as características físicas e tisico-quimicas mais adequadas para uso como combustível alternativo. / Vegetable oils have been shown as a promising alternative for the replacement of petroleum fuels in diesel engines. One of the problems today is the high viscosity of biodiesel generated from castor oil. The objective, then, in this work to study the physical characterizations and physical-chemical properties of vegetable oils (rapeseed, cotton and soybeans), and their mixtures in 10 formulations (formulation 1: 80% castor oil + 10% soy + 10% cotton; formulation 2: 50% castor oil + 40% soy + 10% cotton; formulation 3: 65% castor oil + 25% soy + 10% cotton, castor formulation 4:65% + 25% soy + 10% cotton, 5 formulation: 65% castor + 10% soy + 25% cotton, 6 formulation: 50% castor oil + 25% soy + 25% cotton, 7 formulation: 60% castor oil + 20% soy + 20% cotton; formulation 8: 70% castor oil + 27% soybean + 3% cotton; formulation 9: 55% castor oil + 30% soy + 15% cotton, 10 design: 55% castor oil + 15% soy + 30% cotton), and the attainment of these oils and biodiesel blends. After being subjected to a transesterification reaction, these oils can be used as additives or even in the future as a substitute for petroleum diesel. The oils of castor, cotton and soybeans were obtained by mechanical pressing. The methodology used to produce biodiesel from methanol was carried out along the route. For the physical-chemical characterizations were determined acid vaiue, saponification, peroxide, iodine and water content. Physical characterizations were determined for the viscosity and density at temperatures (28,40,50,60) ° C. The values obtained in the physical and chemical analysis for vegetable oils (soybean, cotton and castor) were: water content of 0.06, 0.07 and 0.36 bu, saponification index (163, 180.180) mgKOH / g, iodine value of 10 gl/100g index, acidity (0.4, 0.4, 0.5) mgKOH / g, acid value of biodiesel (0.5, 1.1 6.5) mgKOH / g, refractive index of 1.466, 1.451, 1.470. The mixtures showed similar properties to diesel, besides favoring the reduction of viscosity of pure biodiesel, through mixtures of vegetable oils, promoting greater efficiency in the flow. Biodiesel blends from f3, f5 and f6 is what got the physical and physicochemical more suitable for use as an alternative fuel.

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