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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

Study of puffing and micro-explosion during the evaporation of Arabian light oil droplets

Restrepo-Cano, Juan 12 1900 (has links)
Although the suspended droplet evaporation and combustion have been studied for decades, fundamental research pertaining to the stochastic phenomena of complex multicomponent mixtures is extremely rare. In this work, an experimental suspended droplet study of Arabian light oil was held to study the frequency of puffing and micro-explosion phenomena during the evaporation/pyrolysis process. The experiments were conducted at three different evaporation temperatures (350 C, 440 C, and 570 C), chosen in accordance with the TGA profle obtained. The suspended droplet experiments were conducted on a furnace with optical access and a gas controlled-preheating system. The droplet size was optically registered at 500 fps by a LaVision Imager Pro HS high-speed camera coupled with a magnification lens Nikon AF-S Micro Nikkor 105 mm. Furthermore, a computer-vision data postprocessing program was developed to identify contours and measure the size of the objects in the frame in order to register the temporal evolution of the droplet size. Additionally, a new approach for characterizing the droplet vaporization of complex multi-component fuels is proposed. This method allowed us to study the continuum (ideal evaporation) and stochastic processes separately, by following the profile of the average normalized square diameter ((D=D0)2) and quantifying the breakup intensity (β) of each stochastic event. Based on the behavior of (D=D0)2, two consecutive stages were identified at every temperature investigated, the swelling and the regression stage. At 350 ◦C and 440 ◦C, the evaporation was finally controlled purely by the diffusion evaporation, whereas at 570 ◦C a pure diffusion stage was not spotted. Instead, a second swelling was registered, where an amorphous carbonaceous structure was formed. Due to the pyrolysis of the heavy hydrocarbons dominated the process. The stochastic events involved during the evaporation were successfully identified and classified in breakup modes depending on their β. Additionally, the effect of the temperature on the breakup events was assessed. Showing that the number of breakup events increased exponentially with temperature.
2

An investigation of the combustion of oil sand derived bitumen-in-water emulsions

Kennelly, Timothy Robert 01 May 2009 (has links)
Dwindling conventional oil resources has caused exploration efforts to focus elsewhere. Bitumen from oil sands has emerged as one of the primary unconventional oil resources in use today. Quadrise Canada Corporation has harnessed this unconventional oil by developing their bitumen-in-water emulsion known as MSAR (Multi-Phase Superfine Atomized Residue). Fuel-in-water emulsions are linked to a combustion phenomenon known as micro-explosion, which are associated with an increase in combustion efficiency and decrease in harmful emissions. A study has been conducted of the MSAR fuel to help advance the optimization and modeling of its use in spray combustors so as to best harness the potential. Quantitative and qualitative data has been obtained during combustion experiments of the fuel that will attribute to this end. Additionally, a simplified statistical model is presented based on the governing equations to describe the atomization that occur as a result of micro-explosions of the MSAR fuel as well as a simple model to represent internal force needed for a micro-explosion to occur. The results of this study continue to reinforce the understanding that micro-explosions cannot be attributed to one overriding physical principal, but rather are th result from variations in turbulent, dynamic, and thermal forces.

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