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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.
141

Design and Evaluation of Workwear for Protection Against Steam and Hot Water

Yu, Sihong Unknown Date
No description available.
142

Heat and mass transfer in combined convection.

Crotogino, Reinhold Hermann. January 1971 (has links)
No description available.
143

A three-dimensional mechanistic model of steam condensers using porous medium formulation

Al-johani, Mohammed S. 05 1900 (has links)
No description available.
144

Interdisciplinary Infusion in the Discipline Based Middle School Art Classroom

Breazeale, Mary 09 May 2015 (has links)
This research has a primary focus on the middle school setting and how schools, students, and art educators might benefit from an interdisciplinary art curriculum. In this thesis I outline how cross-curricular inclusions in art lessons have the potential to be a fantastic advocacy tool for fine arts departments. I also investigate the differences between interdisciplinary inclusions in the visual art classroom and arts integrated school models as well as the beneficial relationship that can exist between these two pedagogical approaches. Additionally, I examine through literary review and curriculum development, some of the positive and negative influence in academic subject areas and more importantly art disciplines. My final and primary aim in examining various methods of cross-curricular inclusion is to shed light upon the immense potential for student development via dynamic interdisciplinary art curriculum.
145

The formation and detachment of steam bubbles formed at submerged orifices in sub-cooled water

Arebi, Bashir H. January 1996 (has links)
No description available.
146

Förbränning av termokemiskt behandlade biobränslen : en studie av biomassa som genomgått en pyrolys-, torrefierings- eller steam explosionprocess

Lindberg, Karl January 2014 (has links)
EU har som mål att år 2020 ha minskat utsläppen av växthusgaser med 20 % och ökat andelen förnyelsebar energi till 20 %. I Sverige är andelen fossilt bränsle som förbränns ca 30 %. Denna studie syftar till att utreda om termokemiskt behandlade biobränslen kan ersätta de kommersiella fossila bränslena. Resultatet har nåtts med simulering i programvaran Fuelsim och insamling av experimentella data.  En simulering ska påvisa om syreberikning gynnar bränslena och experimentella data används för att se vilka problem som finns för respektive bränsle. Den biomassa som analyserats kommer från ett vedslag liknande gran eller tall som har genomgått processen mellansnabb pyrolys, torrefiering eller steam explosion. Ingen ekonomisk aspekt har tagits i beaktande vid utvärderandet av bränslena. Pyrolysprocessens produkt pyrolysvätska har flera utmaningar framför sig innan den kan ersätta befintliga oljor. Den är väldigt korrosiv, har en hög fukthalt och en kort lagringstid på sex månader. Pyrolysvätskan tycks gynnas av en syreberikning på 0,5 till 2 %. Pyrolyskoksen har potentialen att ersätta eller samförbrännas med kol i kolpulvereldadepannor. Pyrolysgasen innehåller en stor mängd CO2 vilket ger den ett lågt energiinnehåll. Både pyrolyskoksen och pyrolysgasen bör i första hand förbrännas i en fluidbäddspanna som är integrerad med pyrolysreaktorn eftersom pannanläggningen behöver värmen. Torrefieringsgasen är en biprodukt från framställningen av torrefierad biomassa. Problem med filtrering och kondensering av gasen medför att den bör sameldas med något annat bränsle för att återföra värmen till reaktorn. När den torrefierade biomassan pelleterats förbränns den lämpligast i storskaliga pannor såsom bubblande fluidbädd(BFB)-, eller cirkulerande fluidbädd(CFB)- eller rostpannor men även mindre pelletspannor är möjligt. Intrimning av bl.a. luftflöden är nödvändig vid samförbränning och även vid konvertering från annat bränsle för att uppnå en erforderlig förbränning. Simuleringsresultaten av steam explosion (SE) pellets visar potential som ersättare till både träpelleten och stenkolet. Baserat på simuleringen förbränns SE pellets lämpligast i CFB-, BFB- eller rostpannor. Ett begränsat utbud av experimentella data medför dock att bränslet inte kan utvärderas fullständigt. Studien visar att det inte är helt problemfritt att konvertera från ett kommersiellt bränsle till ett termokemiskt behandlat bränsle och att fler experimentella data behövs för att utvärdera bränslenas förbränningsegenskaper. / A goal set by The European Union is to reduce the emissions from greenhouse gases by 20 % and increase renewable energy with 20 % until year 2020.  Fossil fuels account for about 30 % of Sweden’s combusted fuel. The purpose of this study is to investigate if thermochemically treated biofuels can replace or be co-fired with commercial fuels. The results are gathered from experimental data and from the simulations made with the software Fuelsim.  A simulation will be made to determine whether oxygen-enrichment favors the fuels and experimental data is used to investigate if any combustion problems exist with these fuels. The biomass that have been analyzed comes mainly from pine wood or spruce wood trees which have been processed through either a fast pyrolysis, torrefaction or a steam explosion reactor. No economic aspect has been taken into account in the evaluation of the fuels. One of the pyrolysis process products is pyrolysis liquid which has several challenges ahead before it can replace existing oils. It is very corrosive, has a high moisture content and the storage time is limited to short period of six months. The pyrolysis liquid seems favored by an oxygen-enrichment of 0,5 to 2 % according to the simulation results. The pyrolysis char has the potential to replace or be co-fired with coal in a pulverized coal burner. Pyrolysis gas contains a large amount of CO2, giving it a low energy content. Both char and gas should primarily be combusted in a fluid bed boiler that is integrated with the pyrolysis reactor as boiler plant requires heat. The torrefaction gas is a by-product from the processing of torrefied biomass. Current problems with filtration and condensation of the gas entails that it should be co-fired with another fuel to return the heat to the torrefaction reactor. When the torrefied biomass has been pelletized it is preferably combusted within a large scale boiler such as bubbling fluid bed- (BFB), circulating fluid bed- (CFB) or grate boilers also smaller pellet boilers is possible. Fine adjustments of airflow etc. are required when co-firing or when converting from another fuel to achieve required combustion of the torrefied pellets. The steam explosion pellet simulation results shows that the potential to replace both wood pellets and coal. Based on the results combustion of steam explosion pellets is preferable in either a CFB-, BFB- or grate boiler. This fuel cannot be fully evaluated because of the limited range of experimental data. This study shows that it is problematic to convert from commercial fuels to a thermochemically treated fuel and more experimental data is needed to evaluate the fuels combustion characteristics.
147

A numerical investigation of the interactions between adjacent cooling tower plumes

Bornoff, Robin B. January 1997 (has links)
Cooling tower plume rise, dilution and dispersion is investigated using a numerical model. Both single and double sources are considered. The main aim of the investigation is concerned with comparison of the computational results to existing wind tunnel experimental data as well as simple empirical rise height formula. Analysis of the interaction of adjacent sources, and subsequent rise augmentation compared to that of a single source, is a central theme of the work. A full-scale hybrid mechanical cooling tower is modelled as a surface mounted cuboid block 20 m high with an internal development duct of 10 m diameter. Both jet and moderately buoyant plume type sources are studied. Two exit velocity ratios are also considered. An oncoming atmospheric boundary is modelled with an associated logarithmic velocity profile and profiles of turbulence kinetic energy and length scale. Two double source orientations, tandem and side-by-side with respect to the oncoming cross wind, are studied. Physical symmetry is utilised and so only half of the domain is modelled. Both the small-scale (wind tunnel) and full-scale were modelled. The small-scale work used combinations of a low Reynolds number k-e turbulence model and both hybrid and QUICK discretisation schemes. The high Reynolds numbers encountered in the fullscale allowed the use of a number of different turbulence models, namely the standard k-e model, the RNG k-e model and a differential flux model, combined again with the hybrid and QUICK discretisation schemes. The results of a number of sensitivity tests showed that plume rise in this case was not sensitive to the turbulence model constant C3 or to source turbulence levels. A decrease in the turbulent Prandtl number led to a marked increase in the turbulent diffusion of the thermal plume. Horizontal plume spreading was underpredicted in both small and full-scales compared to the experimental data. Plume rise and dilution was, in the majority of cases, predicted accurately compared to both the experimental data and also to rise heights given by simple empirical relationships. Generally, the choice of discretisation scheme was a more important factor than choice of turbulence model. Interaction of side-by-side plumes was dominated by the interaction of the rotating vortex pairs within the plumes. A tandem source arrangement led to early merging and efficient rise enhancement. Merging into a single type plume occurred sooner with an decrease in exit velocity ratio, R.
148

An experimental investigation of dropwise and filmwise condensation of low pressure steam in tube banks

Cuthbertson, Grant January 1999 (has links)
Research to date has highlighted a number of conditions where dropwise condensation may offer heat transfer enhancements over filmwise condensation. Previous studies have shown at pressures above or around atmospheric, dropwise condensation offers significant benefit over filmwise. However, some of this research suggests that as the system pressure is reduced below atmospheric, the benefits of dropwise condensation diminish rapidly, to the extent that, at pressures around 50mbar the benefits of dropwise over filmwise are minimal. This thesis details a series of experiments which were conducted to investigate the heat transfer and pressure drop distributions in tube bundles during both dropwise and filmwise condensation of steam. The primary objective of the work was to determine the design implications associated with switching the mode of condensation of a electricity generating steam turbine condenser from the current filmwise mode, to dropwise. Experimental data were obtained from a new purpose build apparatus containing seventy-five, 150mm long titanium tubes, arranged in an in line configuration of five columns and fifteen rows. Dropwise and filmwise data were recorded from each row at test cell inlet pressures down to 50mbar using both pure steam and steam air mixtures. Filmwise heat transfer data indicated that, under most conditions, heat transfer coefficients were generally in agreement with those obtained by previous workers. Heat transfer data obtained during dropwise condensation suggested that the benefits of dropwise condensation are not significantly diminished at low pressure, and that, unlike filmwise condensation, inundation has little or no effect in a fifteen row bundle. The data also indicated that the pressure drop characteristics and effects of air are, within experimental error, identical during both modes of condensation and in line with models and theories proposed by previous workers.
149

Microfluidics for Steam Assisted Gravity Drainage and Petroleum Applications

de Haas, Thomas 11 July 2013 (has links)
Petroleum research is responsible for making previously unusable reservoirs economically viable and for limiting the environmental impact of petroleum development. Microfluidics, the study of fluid flow at the micro-scale, is predominantly used to study biological phenomena. Adapting microfluidics to study petroleum requires the use of materials and methods not commonly used. This thesis focuses on applying microfluidics to the study of petrochemical fluid flow at high-pressure and high-temperature. The first problem addressed is the study of fluids during alkaline steam assisted gravity drainage (alkaline SAGD). The addition of an alkaline additive is found to improve the bitumen production rate by 35-67%. Secondly, two high-pressure, high-temperature, solvent resistant microfluidic interfaces for glass chips are designed to be operated up to 140 bar and 70 degrees Celsius. Lastly, a novel method for fabricating solvent resistant microfluidic devices from Teflon film is demonstrated by measuring the viscosity of toluene-heavy oil blends.
150

Microfluidics for Steam Assisted Gravity Drainage and Petroleum Applications

de Haas, Thomas 11 July 2013 (has links)
Petroleum research is responsible for making previously unusable reservoirs economically viable and for limiting the environmental impact of petroleum development. Microfluidics, the study of fluid flow at the micro-scale, is predominantly used to study biological phenomena. Adapting microfluidics to study petroleum requires the use of materials and methods not commonly used. This thesis focuses on applying microfluidics to the study of petrochemical fluid flow at high-pressure and high-temperature. The first problem addressed is the study of fluids during alkaline steam assisted gravity drainage (alkaline SAGD). The addition of an alkaline additive is found to improve the bitumen production rate by 35-67%. Secondly, two high-pressure, high-temperature, solvent resistant microfluidic interfaces for glass chips are designed to be operated up to 140 bar and 70 degrees Celsius. Lastly, a novel method for fabricating solvent resistant microfluidic devices from Teflon film is demonstrated by measuring the viscosity of toluene-heavy oil blends.

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