Identifier

etd-07092009-230134

Degree

Doctor of Philosophy (PhD)

Department

Chemical Engineering

Document Type

Dissertation

Abstract

Fuels used in future high-speed jet aircraft will act as coolants to absorb excess heat produced by the engine, exposing the fuel to elevated temperatures and pressures beyond the fuel’s critical point before entering the combustion environment. Fuels used in this capacity are subject to pyrolysis reactions in the supercritical environment, forming polycyclic aromatic hydrocarbons (PAH) and eventually carbonaceous solids, a disastrous effect for aircraft operation. Thus, it is important to understand how different components of jet fuel will react in the supercritical pyrolysis environment, particularly if their reactions will lead to PAH and/or carbonaceous solids. To better understand these reactions, the model fuel 1-methylnaphthalene, an aromatic component of jet fuel, has been investigated in order to determine the supercritical pyrolysis conditions that form PAH and carbonaceous solids. Experiments have been performed at temperatures ranging from 550 to 650 °C, pressures from 50 to 110 atm, and residence times from 70 to 200 seconds in a supercritical fluid flow reactor. The products have been analyzed by high pressure liquid chromatography (HPLC) with diode-array ultraviolet-visible detection (UV) in series with mass spectrometry (MS), as well as gas chromatography with flame ionization detection and mass spectrometry. Over thirty PAH products have been identified, seventeen of which have never before been reported as products of 1-methylnaphthalene pyrolysis or combustion. A 9-ring PAH product, benzo[cd]phenanthro[1,2,3-lm]perylene, has been identified for the first time as a product of any fuel. The structures of all of the products identified from supercritical 1-methylnaphthalene pyrolysis reveal that in this environment, the two-ring aromatic unit remains intact. Reaction pathways explaining the formation of each product species and yield profiles of the products species at varying temperatures and pressures are presented. All PAH product yields were found to increase with respect to both increasing temperature and pressure, and the largest PAH exhibited dramatic increases in yields at conditions where the onset of solids formation was observed. The conversion of 1-methylnaphthalene conformed to a global first-order kinetic reaction rate, and the pressure-dependent and temperature-dependent parameters of the reaction rate have been calculated with respect to conversion of the reactant.

Date

2009

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Mary Julia Wornat

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