<p>This Degree Project has been done at Växjö University, department of bioenergy technology and discusses the released thermal power in wood pellets. The purpose of the project is to investigate if two new types of wood biofuels (pellets) are more or less reactive than the pellets previously investigated at Växjö University. To measure the released thermal power, an isothermal calorimeter with eight channels has been used. To see how the microbial activity is influenced, the pellets have been stored under various conditions with focus on temperature and metal.</p>

The first chapter of this dissertation examines welfare impacts of a combination of subsidies to alternative fuels (AFs) and alternative fuel vehicles (AFVs), and how they compare to gasoline taxes. The particular AF examined here is ethanol that is produced from agricultural products in a small open economy. The model in this paper characterizes a country or state where gasoline is the major source of fuel for automobiles, but that also produces and consumes ethanol as an AF. Gasoline combustion is polluting and its use equals the total amount of emissions produced. Thus, a gasoline tax here is the same as an emissions tax and is the most direct environmental instrument. However, increasing gasoline taxes for pollution purposes is often politically not feasible. Thus, this paper studies how closely subsidies to alternative fuels (AFs) and alternative fuel vehicles (AFVs) emulate abatement behavior from a unit gasoline tax in a simple three sector general equilibrium model, and in the presence of pre-existing labor taxes. The model can also be used to track the effects of each policy on outputs, exports, and fuel use. The analytical results of the model are then calibrated to data from the largest ethanol producing state in the U.S., namely Illinois. The paper finds that subsidies can achieve up to 64 percent of the welfare gains from the gasoline tax, if the uncompensated wage elasticity is low enough or the elasticities of substitution between the transportation goods is high enough. The second chapter estimates behavior of households who jointly make discrete decisions about vehicle ownership and continuous decisions about miles driven. The paper uses seven years of data from 1995-2001 for the 35 states and union territories of India. The estimated parameters will be used to calculate elasticities of each different type of vehicle for percentage changes in petrol price per unit distance travelled and in vehicle taxes. The paper also computes income and price elasticities for petrol consumption. Two types of vehicles predominant in India are cars and two-wheelers such as motorcycles, mopeds, and scooters. The latter type of vehicle is more fuel efficient than the former. However, patterns of vehicle ownership across the country reflect a growing number of cars relative to motorcycles. This paper investigates the impact alternative policies such as taxes on petrol or on cars have on efficient methods of vehicle emission abatement in India. In particular, the chapter estimates the effect of each such policy on vehicle choice and driving behavior, and how they in turn affect emissions. The main results are summarized as follows: First, continuous choice own-price elasticities are higher for 4w relative to 2w, given age, and for older vehicles relative to newer ones, within each category. Second, discrete choice own-price elasticities with respect to capital cost are higher for 2w relative to 4w. Moreover, older vehicles of each type are more sensitive to higher vehicle prices relative to their newer counterparts. Third, income elasticities for discrete vehicle choices are all positive and greater than unity. Thus, higher income encourages purchase of newer vehicles of each type. Moreover, usage of vehicles rises with income, conditional on the particular vehicle choice. Finally, the paper conducts simulations that alter the price per kilometer by adding either an additional gas tax, a distance tax or an emissions tax. Results show that a distance tax reduces vehicle kilometers traveled the most, followed by an emissions tax and lastly by the gas tax. However, local emissions are reduced the most by an emissions tax, followed by a distance tax and then by a gasoline tax. Even though it would be ideal to compare the results obtained in this paper to results generated using a micro-level data set, the estimates presented here are indicative of whether a distance tax or a gasoline tax is more effective for emissions abatement in India. The third chapter of this dissertation evaluates how information asymmetry in private automobile markets affects programs to accelerate vehicle retirement, also known as scrappage programs. We use a dynamic framework where agents have heterogenous preference for car quality. Cars can either be new, or used. While all new cars have the same quality, used cars can be of high- or low-quality. The quality of a car is perfectly correlated with emissions. The goal of a scrappage program is to induce car owners to voluntarily scrap low-quality used cars. One key result is that in the presence of adverse selection a subsidy that maintains an active resale market unambiguously makes all types of consumers better off. However, if this option of implementing the subsidy does not exist, then the only other way to induce effective scrappage in our framework is to shut down the used car market. Welfare implications suggest that it might be better not to do anything rather than have a scrappage program such as the latter. / text

In the north of Sweden lots of the soil is naturally contaminated by acid sulfate. When soil gets in contact with oxygen an oxidation process begins which releases elements that may be harmful to the surroundings. When the Botniabanan was built, soil had to be transported from the railroad area to deposit sites. This study was made to investigate the suspicions a landowner had regarding if his estate had been contaminated sulphide soil soil during the building of the Botniabanan. To do that four pits were dug in the area where the soil had been deposited. Then the soil was analyzed to see the content of sulfate, iron, organic matters and water. When the results was compared to other studies it showed that the content of sulfate and organic matters was to low to classify the soil as an acid sulfate soil.

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Storage of biomass is often associated with problems such as heat development, drymatter losses and reduction of fuel quality. The rise in temperature can potentiallycause a risk of self-ignition in the fuel storage. Moreover, emissions from storage pilescan cause health problems in the surrounding. The dry matter losses and reduction offuel quality can have economical effects. The aim of this thesis project is to developguidelines on how to store large amount of biomass at Vattenfalls heat and powerplants in an optimal way. Storage trials at Idbäckens CHP were done in order to studythe effect of storage on fuel quality, dry matter losses and temperature development.Two storage trials were performed over six weeks with waste wood chips and stemwood chips stored in about 4.5 m high outdoor piles. A trial over four days in whichwaste wood chips was placed on a heated surface was evaluated. A study to test thepossibility of using waste heat to dry waste wood chips was performed.Small but not negligible dry matter losses were observed in both of the piles of storedmaterial. The largest weekly losses were found during the first week of storage and adeclining behavior could thereafter be seen. The accumulated losses during six weeksof storage were 2.0 % and 1.7 % respectively, for waste wood and stem wood. Storageduring six weeks of waste wood and newly chipped stem wood did not cause anymajor deterioration of the fuel quality as such, beside the substance losses.No drying effect could be seen in the heated surface trial. The surface became warm,about 50°C, but it was not sufficient to dry the chips. The conclusion is that it is notpossible to dry large amount of chips on a heated surface with the design used hereand during four days.The overall conclusion is that in order to minimize the dry matter losses the materialshould be handled according to the LIFO (last in first out) principle. Wheneverpossible, try to purchase fuel that has been stored for a while since the more easilydegraded compounds has already been degraded through microbial activity. There is apossibility that the largest losses has already occurred. Furthermore, try also tocomminute the material (reduce the particle size) at the plant and as close in time tocombustion as possible.

The quality of asphalt depends on quality and type of components. The e main characteristic of asphalt is the composition – binder content and aggregate graduation. There are developed many methods for the evaluation of asphalt content. This work analyzes the methods of asphalt content determination. Also there are compared to methods: solvent extraction and ignition method. For the evaluation of these methods the researches of 50 samples have been made. The samples were taken from the asphalt pavement and others were made in laboratory. When results of research were analyzed by principles of statistics. The conclusions and recommendations are presented at the end of the research paper.

The need to ignite within a very short time the aircraft engines led to many studies. However, the ignition process is not yet fully understood. Many experimental studies are based on obtaining ignition probability at different points and in different average flow conditions but few have focused on the study of a single ignition event. The reason for the lack of full understanding is transient nature of the the ignition process, which depends on many physical parameters, before, during and after the deposition of spark energy. The purpose of this study is to develop the tools necessary to understand unique events by simultaneously measuring multiple parameters that affect the ignition process. A new technique of measurement, two-dimensional laser-induced plasma spectroscopy (2D-LIPS) was developed for the spatially resolved concentration gradients of species and energy in a laser-induced plasma. This technique is based on the use of two cameras, each provided with an interference filter centered on a transition atomic emission. This technique provides the initial size of plasma containing the minimum fuel concentration, thereby justifying the success/failure of an event. It was first validated in a mixing layer of air/nitrogen mixture to determine and resolve the spatial uncertainty of the technique. It was then applied to an aviation fuel injection system. The flow of air, preheated to 200_C, was set at 10 g/s and drops of dodecane having a Sauter mean diameter between 30 and 40 _m were inserted. This injector has a aerodynamic instability type Precessing Vortex Core around 550 Hz, measured by 2D-PIV on the droplets at 20 kHz. Simultaneous measurements 2D-LIPS and 2D-PIV at 20 kHz have established a scenario of ignition. A minimum concentration of dodecane and a minimum size of plasma are necessary but not sufficient for a successful ignition. The strength of PVC also appears to play a role in the fate of the initial nucleus. The study proposes to establish conditional probabilities of ignition using measurements by 2D LIPS. It is shown that for ignition tests having an unconditioned probability of 33% show a conditional probability of 88% through the 2D-LIPS measurements.

With increasing concerns about the harmful effects of conventional liquid fossil fuel emissions, natural gas has become a very attractive alternative fuel to power prime movers and stationary energy conversion devices. This research studies the injection and ignition numerically for natural gas (mainly methane) as a fuel applied to diesel engine. Natural gas injector and glow plug ignition enhancement are two of the most technical difficulties for direct injection natural gas engine design. This thesis models the natural gas injector, and studies the characteristics of the internal flow in the injector and natural gas jet in the combustion chamber during the injection process. The poppet valve model and pintle valve model are the first reported models to simulate the natural gas injector to improve the traditional velocity and pressure boundary conditions. This thesis also successfully models the glow plug assisted natural gas ignition and combustion processes by developing a glow plug discretized model and a novel virtual gas sub-layer model. Glow plug discretized model can describe the transient heat transfer, and adequately represents the thin layers of heat penetration and the local temperature difference due to the cold gas jet impingement. The virtual gas sub-layer model considers complicated physical processes, such as chemical reaction, heat conduction, and mass diffusion within the virtual sub-layers without significantly increasing computational time and load. KIVA-3V CFD code was chosen to simulate the fluid flow. Since the KIVA-3V is designed specifically for engine research application with conventional liquid fuels, many modifications have been implemented to facilitate this research.

With increasing concerns about the harmful effects of conventional liquid fossil fuel emissions, natural gas has become a very attractive alternative fuel to power prime movers and stationary energy conversion devices. This research studies the injection and ignition numerically for natural gas (mainly methane) as a fuel applied to diesel engine. Natural gas injector and glow plug ignition enhancement are two of the most technical difficulties for direct injection natural gas engine design. This thesis models the natural gas injector, and studies the characteristics of the internal flow in the injector and natural gas jet in the combustion chamber during the injection process. The poppet valve model and pintle valve model are the first reported models to simulate the natural gas injector to improve the traditional velocity and pressure boundary conditions. This thesis also successfully models the glow plug assisted natural gas ignition and combustion processes by developing a glow plug discretized model and a novel virtual gas sub-layer model. Glow plug discretized model can describe the transient heat transfer, and adequately represents the thin layers of heat penetration and the local temperature difference due to the cold gas jet impingement. The virtual gas sub-layer model considers complicated physical processes, such as chemical reaction, heat conduction, and mass diffusion within the virtual sub-layers without significantly increasing computational time and load. KIVA-3V CFD code was chosen to simulate the fluid flow. Since the KIVA-3V is designed specifically for engine research application with conventional liquid fuels, many modifications have been implemented to facilitate this research.

After the restriction of different halogenated fire suppressants by the Montreal Protocol, there is an urgent need to identify environmentally friendlier alternatives. In particular, several efforts have been conducted to find substitutes of Halon 1301 (CF_(3)Br) which was considered the best in its class, not only because of its superior extinguishing performance, but also due to its relatively low toxicity. Different options have been proposed over the last decade. However, no single compound has been found to meet all of the exigent criteria. Further progress in this research requires fundamental combustion knowledge that can help us understand the unique performance of Halon 1301, to prevent this search from becoming a tedious trial-and-error process. To this end, the present work aids in the search of fire suppressants alternatives by improving the flame inhibition mechanism understanding, starting with CF_(3)Br, which serves as a benchmark for new fire suppressants. Then, a case study of two of the most currently used fire suppressants, C_(2)HF_(5) (HFC-125) and C_(2)HF_(7) (HFC-227), is presented and compared with CF_(3)Br performance. For these analyses, a systematic analytical methodology was used to examine the effect of fire suppressants on ignition and laminar flame propagation of C_(1)-C_(3) alkanes premixed mixtures, as good representatives of flammable gas fires (Class B fires). This methodology integrates model formulations and experimental designs in order to examine both chemical kinetics and thermal effects on fire suppressants at different stoichiometric conditions. Modeling predictions were based on a detailed chemical kinetics mechanism which was assembled from a new, well-studied H_(2), C_(0)–C_(5) hydrocarbon mechanism from NUI Galway and recent CF_(3)Br and HFC fire suppressant chemistry from NIST. Experimental study involved the use of a shock tube (for ignition analysis) and a freely expanding flame speed bomb (for laminar flame speed analysis). Most of the experimental data provided in this work are the first measurements of their kind for the compounds and mixtures explored in this thesis. These measurements are extremely valuable since they can be used as a metric for model validation which represents one of the objectives of this work. Current analyses indicate that the combustion properties of halogenated compounds cannot be generalized and depends on different factors. On one hand, the presented results showed that all the tested fire suppressants can decrease the laminar flame speed of the examined C_(1)-C_(3)alkanes premixed flames; however, in some cases they can act as ignition promoters. In order to understand these behaviors, sensitivity analyses were conducted showing that halogenated species, resulting from the fire suppressants decomposition, can participate in both promoting and inhibiting reactions that compete to give a net effect. Identification of the key reaction responsible for such effects was conducted. Then, improvements on the fire suppressant chemistry can be done by modifying the corresponding Arrhenius parameters of such important reactions. This work not only provides fundamental knowledge of halogenated flame inhibition mechanisms, but also serves as the basis for more accurate chemical kinetics mechanisms that can be used for better predictions over a wide range of conditions.