Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
2 results
Search Results
Item Nanocomposite and Soluble Energetic Additives for Burning Enhancement of Hydrocarbon Fuels(2017) Guerieri, Philip Michael; Zachariah, Michael R; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Metallizing liquid fuels and propellants to improve performance of energy conversion and propulsion systems has been of interest for decades but past attempts to do so using micron-sized metal powders demonstrated inefficient combustion and low burning rates of modified hydrocarbons. “Nanofuels” composed of energetic nanoparticles like nanoaluminum suspended in liquid fuels have slowly emerged in scientific research over the last two decades with promising results. Increased burning rates, lower ignition delays, and high suspension stabilities compared to slurry fuels of micron-sized particles have been demonstrated; however, the effects of various energetic nanoparticles on the combustion of hydrocarbons remain poorly understood while particle agglomeration remains a performance-limiting problem. The research in this dissertation identifies strategies for inclusion of aluminum into hydrocarbons which promote combustion performance in a free-droplet burning experiment developed herein. Considering the low burning rates which plagued micron particle-based slurry fuels, specific attention is paid to characterizing and understanding effects on droplet burning rate constants. Classical characterization of this metric based on the D-squared-law for isolated droplet combustion is found to be unsuitable with heterogeneous energetic additives and thusly an original scheme for experimental approximation of burning rate constant is set forth. Several beneficial strategies for aluminum inclusion and burning rate enhancement are studied including co-addition of nanoaluminum with the gas generator nitrocellulose (NC), dissolution of Al-containing molecules including organometallic clusters into hydrocarbons, and burning rate enhancements realized with oxygen-carrying nanoparticle co-additives. Arguably the most impactful strategy identified however is the preassembly of active nanoparticles into NC-bound clusters or controlled agglomerates, termed “mesoparticles” (MPs), by electrospray which drastically improves droplet burning rate increases and nanofuel suspension stabilities observed compared to nanofuels of unassembled nanoparticles. Mechanisms of the various additives studied are probed with a variety of diagnostic techniques and burning rate enhancements are linked to physical effects of droplet disruptions on the diffusion-limited burning droplet system. The MP architecture causes a feedback loop between physical disruptions by gas liberation from droplets, transport of active additives into the flame where they react, and promotion of further gas evolution repeating and accelerating this process.Item Supercritical Fluid Extraction of Hydrocarbons from the Marcellus Shale by Using CO2(2014) Jarboe, Palma Jean; Candela, Philip; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Supercritical carbon dioxide was used to extract n-aliphatic hydrocarbons from samples of Marcellus shale, and to evaluate recovery as a function of sample matrix particle size (sieve size). Results show that supercritical CO2 has the potential to liberate diesel-range n-aliphatic hydrocarbons from high-maturity shale at estimated in situ pressure and temperature conditions. Total quantity of resolvable n-aliphatic hydrocarbons ranged from approximately 0.3 - 12 milligrams of hydrocarbon per gram of total organic carbon. No significant differences in extracted hydrocarbons were observed between crushed samples of different sieve sizes (1000 - 500 µm, 250 - 125 µm, and 63 - 25 µm). However, some increase in hydrocarbon extraction efficiency was seen as a function of exposed surface area. Additionally, a slight positive correlation was also observed between hydrocarbon recovery and S1 (free oil content) warranting further investigation.