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.

Energijos kainų didėjimas ir ekonomikos augimo sulėtėjimas bei didėjančios vartotojų išlaidos energijos prekėms ir paslaugoms kelia vis didesnį pasaulio valstybių susirūpinimą. Darbe analizuojamas naftos ir gamtinių dujų kainų daromas poveikis Lietuvos realiam BVP ir šilumos bei transporto degalų kainoms. Darbe siekiama įvertinti naftos ir gamtinių dujų kainų daromą poveikio mastą Lietuvos ekonomikai ir vartotojams bei išanalizuoti galimas šio masto tendencijas ateityje. Pirmoje darbo dalyje susisteminti pagrindiniai ekonominėje literatūroje aptariami keliai, per kuriuos kintančios energijos kainos daro įtaką šalių makroekonomikoms ir vartotojams. Palyginami skirtingais laikotarpiais tyrusių ekonomistų darytos išvados bei atskleidžiamas kintantis požiūris į energijos kainų pokyčių daromą įtaką ekonomikai. Antroje dalyje pateikiami kitų autorių atlikti susisteminti tyrimų rezultatai analizuojama tema ir pristatomi darbe atlikto tyrimo eiga ir metodika. Pateikiama pagrindinių makroekonominių rodiklių ir energijos kainų kitimo tendencijų analizė. Trečioje dalyje aptariami gauti tyrimo rezultatai ir pagrindinės išvados. Pateikiamos rekomendacijos ir siūlymai, kaip sumažinti skiriamas išlaidas energijos produktams ir paslaugoms. Atlikus tyrimą, matomas statistiškai reikšmingas naftos ir gamtinių dujų kainų poveikis Lietuvos BVP ir šilumos bei transporto degalų kainoms. / Energy prices, the economic slowdown, rising energy prices and consumers spends on energy goods and services is a growing concern around the world. The paper analyzes the oil and natural gas prices affect on the real GDP of Lithuania and the heat and transport fuel prices. The paper aim is to evaluate the impact of oil and natural gas prices on Lithuania's economy and consumers spends, and to analyze the potential imapct in the future. In the first part reviews the main ways in which changing energy prices affect the macroeconomics and consumers spends, discussed in the economic literature. There are compared different views about energy price changes and their impact on the economy. There are analyzed the other authors empyrical studies in the second part and presented the methodology of research in this paper. Carried out a comparative analysis of the trend of the main macroeconomic indicators and energy prices. The third part deals with the results and findings. Also drawn up recommendations and proposals on how to reduce the spending on energy products and services. It is seen a statistically significant oil and natural gas prices impact on Lithuania‘s GDP and the heat and transport fuel prices.

Liquefied natural gas (LNG) is stored at a cryogenic temperatures ≤ -160°C and around atmospheric pressure to insure the minimum storage volume in tanks. The demand for LNG has been increasing as a primary source of energy. Therefore, there is significant interest in the construction of LNG tanks to achieve low cost and safe storage. Three systems are typically used to store LNG: single containment, double containment, and full containment. Concrete is used in these containment systems, and consequently, understanding concrete behavior and properties at cryogenic temperatures is important. The research documented in this thesis deals with computational analysis of the behavior of concrete subjected to cryogenic temperatures. The analysis focuses on the effect of aggregate sizes, coefficient of thermal expansion, volume fraction, and the shape of aggregate on damage of concrete subjected to cryogenic temperatures. The analysis is performed by developing a computational model using the finite element software ABAQUS. In this model, concrete is considered as a 3- phase composite material in a meso-scale structure: mortar matrix, aggregate, and interfacial transmission zone (ITZ). The Concrete Damage Plasticity model in ABAQUS is used to represent the mortar and ITZ phases of concrete. This model has the advantage of accounting for the effect of temperature on material properties. The aggregate phase is modeled as a linear-elastic material. The model parameters are selected based on comprehensive literature review of material properties at different temperatures. The finite element results provide very useful insight on the effects of concrete mixture design and properties on resistance to damage. The most important factor that affected damage development was the difference in the coefficient of thermal expansion between the mortar and aggregates. Models in which the mortar and aggregate had close values of positive coefficients experienced less damage. The model with irregular shape particles experienced more localized damage than the model with circular shape particles. The model was successful in demonstrating the effect of using air entrained concrete in reducing damage. The damage results predicted by the model for air entrained and non-air entrained concrete are validated by comparing them with experimental data from the literature. The analysis validated the capabilities of the mode in simulating the effect of reduction in temperature on damage. The modeling results and the findings from the literature review were used to put forward recommendations regarding the characteristics of concrete used in LNG storage.

No description available.

People respond to incentives—people make decisions by comparing the costs and benefits of a particular action. When either the costs or benefits change, behavior also changes. My dissertation focuses on estimating the impact of two different behaviour-altering taxes on household consumption. In the first section, I conduct an empirical examination of a hypothetical "fat tax" on household food consumption in Canada. The simulation results suggest that when fat tax revenues are recycled as lump-sum transfers to households, this policy would be the most efficient and progressive scenario from both economic and health perspectives. In the second section, I examine the impact of British Columbia's (BC) recently implemented carbon tax on household energy use from an aggregate perspective. I find no significant impact of the BC carbon tax on residential natural gas consumption. The third section is a further investigation of the BC carbon tax on household natural gas consumption varied by their environmental ideology. The results suggest that the impact of the carbon tax is more effective for non-environmentally conscious households than for other households.

No description available.

The routing of the Trans-Anatolian Pipeline plays an important role in the future energy security of the European Union. The natural gas pipeline is planned to run from the natural gas fields in the Caspian Sea through Turkey. This project is a case study for a Geographic Information System (GIS) least-cost route analysis of a section of the proposed pipeline in Western Turkey. The route analysis comprised of weighting multiple types of criteria in a compiled risk assessment map that was analyzed by a least-cost algorithm to display the least hazardous route through the study area. Multiple varieties of criteria were considered such as, lithology, slope of terrain, environmental and social risk factors, e.g. proximity to natural reserves and urban centers, to provide the least hazardous route through the region. The derived least cost paths were more efficient than the proposed route in the relative cost associated with each route.

It had been shown that the transport properties of CMS membranes varies as a function of H₂S exposure making the conditioning protocol an important step in identifying the steady state properties of CMS membranes. In this study the conditioning of CMS membranes with H₂S was studied for the determination of the acid gas steady state transport properties. The conditioned steady state has been shown to be the same state for both an extended conditioning protocol using high pressure mixed gas and a rapid conditioning protocol using pure H₂S. The rate of conditioning does vary between the two conditioning protocols as the rapid conditioning protocol takes 48 hours less to reach the conditioned steady state. The results of this study also show that oxygen doping during the formation of the CMS membrane affects the final, conditioned steady state transport properties.

Baigiamajame magistro darbe nagrinėjama „Lapių“ buitinių atliekų sąvartyno biodujų jėgainė. Analizės metu ištirti jėgainės technologiniai pajėgumai, išgaunamų biodujų kiekiai, kokybė, nustatytas jėgainės efektyvumas. Remiantis Lietuvoje galiojančiais teisės aktais ir gautais analitiniais rezultatais darbe nagrinėjami trys galimi biodujų panaudojimo scenarijai. Tradiciniai biodujų panaudojimo būdai (šilumos ir elektros energijos gamyba) lyginami su galimybe biodujas tiekti į gamtinių dujų tinklus. Pristatomi nagrinėtų scenarijų analitiniai rezultatai. Atliekamas visų scenarijų ekonominis pagrindimas. Pagal pasirinktus kriterijus vertinamas ekonominių rodiklių jautrumas. Teikiami pasiūlymai projekto finansiniam gyvybingumui didinti. Išnagrinėjus tris minėtus scenarijus, atlikus ekonominį vertinimą bei jautrumo analizę yra apibendrinami baigiamojo darbo rezultatai, formuluojamos ir pateikiamos baigiamojo darbo išvados. Darbą sudaro 18 skyrių. Darbo apimtis 82 psl. be teksto priedų, 19 lentelių, 34 paveikslai, 44 bibliografiniai šaltiniai. Atskirai pateikiami darbo priedai. / In the final major theses „Lapių“ landfill biogas plant was analysed. Analysis results showed biogas plant‘s technical capabilities, the amount and quality of produced biogas, plant‘s efficiency was identified. According to Lithuania‘s legal acts and research results three possible biogas usage scenarios were chosen to be analysed. Traditional biogas usage ways (production of heat and electricity) are compared with possibility to supply biogas to natural gas networks. The results of analysis of possible scenarios are introduced. All scenarios are based on economic. Economic indicators are valued by chosen criteria. Suggestions made to improve projects financial vitality. After examining all three scenarios, after economical and sensitivity evaluation, results of final thesis are summarized and final conclusions are made. In the final major theses are 18 chapters. Scope of work 82. text, 19 tables, 34 pics, 44 bibliographic entries.

This thesis presents estimates of marine gas hydrate distribution and concentration obtained from various geophysical methods. The study area is located in the accretionary prism of the Northern Cascadia subduction zone, offshore Vancouver Island. Canada. The primary objective of this study was to assess the applicability of a suite of geophysical methods in estimating marine gas hydrate distribution and concentration. The measurements tested are downhole log electrical resistivity and seismic velocity, multi-channel seismic (MCS) velocity, and seismic amplitude vs. offset (AVO) of a gas hydrate-related bottom-simulating reflection (BSR). The downhole log data are from Integrated Ocean Drilling Program Expedition 311, along a transect of four wells, and the seismic data are from a conventional 2-D MCS line along the well transect. Gas hydrate distribution and concentration estimates along the well transect exhibit high spatial variability, both from site to site, and within any given site. On average. estimates from electrical resistivity measurements give 5-15% gas hydrate pore space saturation. whereas velocity-based estimates are 15-25%. Some intervals in both cases show concentrations over 40%. Nonlinear Bayesian inversion of seismic AVO data yields a gas hydrate concentration estimate of 0-23% of the pore space. These results lead to the conclusion that resistivity and velocity data are effective tools for estimating marine gas hydrate concentration. The main uncertainty in the resistivity analysis is the in situ pore fluid salinity, whereas the main uncertainty in the velocity study is the magnitude of the bulk sediment velocity increase associated with gas hydrate occurrence (related to how gas hydrate forms). It is shown here that AVO of a gas hydrate BSR is not a useful method to estimate marine gas hydrate concentration. The method lacks the shear-wave velocity resolution necessary to add useful constraints to what is already known from compressional-wave velocity information.