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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

Experimental characterization of a bio-liquid fuel to be used as an additive for improving biodiesel combustion in cold weather conditions

Chowdhury, Abu Mahmud Iqbal 02 October 2015 (has links)
Improvement of biodiesel’s cold flow properties still remains one of the major challenges for using it as an alternative fuel in diesel engines. Therefore, the main objective of the present research was to use newly developed liquid biofuels, 3-hydroxyl fatty acid esters and ethers, as an additive for improving biodiesel cold weather properties. Test results revealed that blending with 10% 3-hydroxyl fatty acid esters (C4, C6, C8 and C12) improved biodiesel volatility, cloud point, flash point and kinematic viscosity without a significant loss in LHV. However, blending biodiesel with 3-hydroxyl fatty acid esters negatively affected the oxidation stability which was then found to improve by blending with 3-hydroxyl fatty acid ethers (1,3-DMO and 1,3-DMD). The latter novel fuel substance (1,3-DMO and 1,3-DMD) exhibited much higher evaporation rate compared to biodiesel and only slightly lower than that of decane, gasoline or ethanol. Moreover, the LHV of 1,3-DMO and 1,3-DMD was found to be almost equal to that of canola biodiesel, and higher than that of methanol and ethanol. These findings suggest that 1,3-DMO and 1,3-DMD have the potential to be used as additive to improve biodiesel cold weather combustion performance or as standalone fuels. / February 2016
2

En samverkan mellan högkapacitetstransporter och torrhamnar : Kartlagt utifrån triple bottom line / A synergy between High Capacity Transporting and Dry Ports : Charter based on triple bottom line

Larsson, Cajsa, Johansson, Lina January 2017 (has links)
Hållbarhet har blivit ett aktuellt ämne inom de flesta verksamheter och strävan är erhålla en ekonomisk vinning utan att äventyra naturresurser, människan och samhället. Verksamheters förmåga att distribuera gods säkert, snabbt och kostnadseffektivt är avgörande för internationell och inrikes handel och ekonomisk utveckling. Godstransporter är en stor källa till utsläpp av växthusgaser och därför är det viktigt att nya transportlösningar hittas för att minska de avtryck som godstransporter gör i en försörjningskedja. Användningen av så kallade högkapacitetsfordon, HCT-fordon, förväntas öka då möjligheten att köra lastbilar som överskrider EU:s dimensioner för längd, bredd och vikt kan medföra ökad effektivitet och reducerad miljöpåverkan. Även konceptet torrhamnar, det vill säga en anläggning med en terminal som drivs likt en hamn, kan användas för att konsolidera gods, avlasta hamnen och öka intermodaliteten hos godset. Intermodalitet innebär att godset fraktas från A till B med hjälp av en kombination av flera olika typer av fraktsätt, exempelvis sjö, tåg och lastbil.   Följande rapport kartlägger hur en samverkan mellan högkapacitetsfordon och torrhamnar skulle kunna se ut. Detta genomförs med hjälp av att utifrån hållbarhetsmodellen triple bottom line som avser de tre dimensionerna ekonomi-, miljö- och sociala effekter, identifiera styrkor och svagheter hos begreppen. Med hjälp en teoretisk litteraturstudie, en fallstudie av ETT-projektet, en observation av Skaraborg Logistics Center samt nio stycken intervjuer med experter inom området, analyseras effekterna av en samverkan mellan högkapacitetsfordon och torrhamnar.   Rapporten identifierar att bättre ekonomiska-, miljömässiga och sociala effekter nås om en torrhamn är kopplad till ursprungshamnen med järnväg snarare än med HCT-fordon. Ytterligare identifierad problematik där en torrhamn försörjs med HCT-fordon utgörs av de tillfälliga tillstånden för att få framföra de längre och tyngre lastbärarna. Analysen visar att för att uppnå en god effekt från en samverkan mellan HCT-fordon och torrhamnar krävs att varje begrepp ensamt uppnår de faktorer som krävs för god effekt.   Rapporten är avgränsad till att räkna allt gods som normalt gods, endast avse HCTtransporter på väg samt att förutsätta att svenska arbetsregler följs vid inrikes transporter på väg. Rapporten studerar inte detaljer kring potentiell utveckling inom tekniken, exempelvis säkerhetssystem, IT-system eller aerodynamik. / Sustainability has become a highly prioritized subject among most companies and the goal is to maintain financial value without jeopardizing nature's resources, neither human health nor the society. How safe, fast and cost efficient a company distribute their goods is crucial for international- and domestic trade as well as economic growth. Haulage is a great source of greenhouse gas emissions and therefore it is crucial that new solutions of transport are developed in order to reduce the negative footprint of haulage in a supply chain. The use of high capacity transporting (HCT) vehicles is assumed increase when the EU's dimensions for a truck’s length, width and weight are allowed. This exception from EN standards would lead to increased transport efficiency, economic efficiency and reduced impact on the environment. The logistical solution of dry ports, namely a port on inland, can be used to consolidate goods, unburden the port and increase intermodality within the goods. Intermodality is when goods is transported between its starting location to its end location using several different kinds of transport ways.  The following report maps how a synergy between high capacity vehicles and dry ports would look like. By using the triple bottom line sustainability model the report identifies strengths and weaknesses of the two concepts. The reports analysis is created from a theoretical literature study, a case study of the ETT project, an observation of Skaraborg Logistics Center and nine interviews with experts within the field. The report identifies that better economic, environmental and social effects are achieved if a dry port is connected to the port of origin by rail way rather than with HCT vehicles. Further identified problems is the temporary permit of conveying the longer and heavier vehicles. The analysis shows that in order to achieve a good effect from an interaction between HCT vehicles and dry ports, each term alone require that the necessary factors for good effect is fulfilled.  The reports limitations are to consider all goods being normal gods and only to consider HCT-vehicles, not HCT-haulage by rail way. The writers also make the assumption that Swedish rules of labor are applied on domestic transportations by road. The report does not study details within IT, security systems nor aerodynamic.
3

Catalytic combustion of gasified waste

Kusar, Henrik January 2003 (has links)
This thesis concerns catalytic combustion for gas turbineapplication using a low heating-value (LHV) gas, derived fromgasified waste. The main research in catalytic combustionfocuses on methane as fuel, but an increasing interest isdirected towards catalytic combustion of LHV fuels. This thesisshows that it is possible to catalytically combust a LHV gasand to oxidize fuel-bound nitrogen (NH3) directly into N2without forming NOX. The first part of the thesis gives abackground to the system. It defines waste, shortly describesgasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns thedevelopment and testing of potential catalysts for catalyticcombustion of LHV gases. The objective of this work was toinvestigate the possibility to use a stable metal oxide insteadof noble metals as ignition catalyst and at the same timereduce the formation of NOX. In paper II pilot-scale tests werecarried out to prove the potential of catalytic combustionusing real gasified waste and to compare with the resultsobtained in laboratory scale using a synthetic gas simulatinggasified waste. In paper III, selective catalytic oxidation fordecreasing the NOX formation from fuel-bound nitrogen wasexamined using two different approaches: fuel-lean andfuel-rich conditions. Finally, the last part of the thesis deals with deactivationof catalysts. The various deactivation processes which mayaffect high-temperature catalytic combustion are reviewed inpaper IV. In paper V the poisoning effect of low amounts ofsulfur was studied; various metal oxides as well as supportedpalladium and platinum catalysts were used as catalysts forcombustion of a synthetic gas. In conclusion, with the results obtained in this thesis itwould be possible to compose a working catalytic system for gasturbine application using a LHV gas. <b>Keywords:</b>Catalytic combustion; Gasified waste; LHVfuel; RDF; Biomass; Selective catalytic oxidation; NH3; NOX;Palladium; Platinum; Hexaaluminate; Garnet; Spinel;Deactivation; Sulfur; Poisoning
4

Catalytic combustion of gasified waste

Kusar, Henrik January 2003 (has links)
<p>This thesis concerns catalytic combustion for gas turbineapplication using a low heating-value (LHV) gas, derived fromgasified waste. The main research in catalytic combustionfocuses on methane as fuel, but an increasing interest isdirected towards catalytic combustion of LHV fuels. This thesisshows that it is possible to catalytically combust a LHV gasand to oxidize fuel-bound nitrogen (NH3) directly into N2without forming NOX. The first part of the thesis gives abackground to the system. It defines waste, shortly describesgasification and more thoroughly catalytic combustion.</p><p>The second part of the present thesis, paper I, concerns thedevelopment and testing of potential catalysts for catalyticcombustion of LHV gases. The objective of this work was toinvestigate the possibility to use a stable metal oxide insteadof noble metals as ignition catalyst and at the same timereduce the formation of NOX. In paper II pilot-scale tests werecarried out to prove the potential of catalytic combustionusing real gasified waste and to compare with the resultsobtained in laboratory scale using a synthetic gas simulatinggasified waste. In paper III, selective catalytic oxidation fordecreasing the NOX formation from fuel-bound nitrogen wasexamined using two different approaches: fuel-lean andfuel-rich conditions.</p><p>Finally, the last part of the thesis deals with deactivationof catalysts. The various deactivation processes which mayaffect high-temperature catalytic combustion are reviewed inpaper IV. In paper V the poisoning effect of low amounts ofsulfur was studied; various metal oxides as well as supportedpalladium and platinum catalysts were used as catalysts forcombustion of a synthetic gas.</p><p>In conclusion, with the results obtained in this thesis itwould be possible to compose a working catalytic system for gasturbine application using a LHV gas.</p><p><b>Keywords:</b>Catalytic combustion; Gasified waste; LHVfuel; RDF; Biomass; Selective catalytic oxidation; NH3; NOX;Palladium; Platinum; Hexaaluminate; Garnet; Spinel;Deactivation; Sulfur; Poisoning</p>
5

Solar pyrolysis of biomass at laboratory scale / Pyrolyse solaire de biomasse à une échelle de laboratoire

Zeng, Kuo 01 April 2016 (has links)
L’énergie solaire concentrée est utilisée comme source de chaleur dans le but de mener des réactions de pyrolyse de la biomasse. Cela permet d’améliorer l’énergie contenue dans la matière première en stockant l’énergie solaire sous une forme chimique. Grâce à de hautes températures et à des vitesses de chauffe élevées, d’avantage de gaz pyrolytiques, avec un produit calorifique inférieur (PCI) élevé, peuvent être produit par la pyrolyse solaire directe.Les expériences effectuées dans ce travail montrent l’effet des paramètres de la pyrolyse solaire sur les quantités de produits, leur composition et leurs propriétés. Le PCI total des gaz augmente fortement (il est multiplié par 5) lorsque la température augmente (de 600°C à 1200°C), et lorsque la vitesse de chauffe augmente (de 5°C/s à 50°C/s. L’association de la température et de la vitesse de chauffe amplifie leurs effets lorsqu’ils sont tous deux à de hautes valeurs. Le charbon et le goudron collectés ont été analysés et caractérisés. Le facteur d’augmentation énergétique obtenu est d’environ 1.5 quelle que soit la température. Dans un second temps, un modèle non linéaire, en deux dimensions, et utilisant la CFD pour résoudre les bilans de masse et de chaleur, a été développé pour la pyrolyse solaire. Les coefficients stœchiométriques, déterminant la fraction massique du goudron primaire convertie par la réaction en gaz et en goudron secondaire, ont été déterminés à différentes températures et à différentes vitesses de chauffe. Les évolutions des produits finaux et des pertes de masse de la biomasse sont amplifiées par la température et par la vitesse de chauffe. / Concentrated solar energy provides heat to drive biomass pyrolysis reactions, which upgrades the feedstock energy by storing solar energy in chemical forms (bio-gas, bio-oil and bio-char). Thanks to high temperature and fast heating rate, more pyrolytic gas with high lower heating value (LHV) can be produced by direct solar pyrolysis. Experiments have highlighted the effect of solar pyrolysis parameters on products yields, composition and properties. The total gas LHV dramatically increases (5-fold) with increasing temperature (from 600°C to 1200°C) and sample heating rate (from 5°C/s to 50°C/s), which is mainly due to variations in the CO and H2 yields. The interaction between temperature and heating rate enhances at both high ranges. The maximum gas products LHV (14 589 kJ/kg of beech wood) was obtained at 2000°C and 450°C/s heating rate. The collected char and tar were analyzed and characterized, which emphasizes the temperature and heating rate effects. And the energy upgrade factor is determined as about 1.5 independent of temperature. At the same time, a 2D unsteady CFD particle model (simplified assumption using first-order Arrhenius type reactions) with heat and mass transfers was developed for solar pyrolysis. Numerical model predictions are in good agreement with experimental observations. Stoichiometric coefficients about the mass fraction of primary tar converted by the reaction to gas and secondary tar were determined at different temperatures and heating rates for the first time. The evolution of the final products and mass losses of biomass are enhanced with temperature and heating rate increase.

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