The preignition oxidation chemistry of n-decane and n-dodecane in a pressurized flow reactor and their use as jet fuel surrogate components.

摘要

The U.S. Department of Defense (DoD) Directive 4140.43 mandated the use of JP-8 jet fuel as the universal military fuel where applicable. The specifications for JP-8 allow a broad range of thermophysical characteristics, such as chemical composition, distillation characteristics, and heat of combustion, which can be produced from multiple sources, such as petroleum and natural gas. In the evolution of advanced engines, simulations are becoming preferable to testing in developing systems. JP-8 is a complex fuel that contains hundreds of components, many with unknown chemistry, and proper simulations require resources beyond current computational abilities. To reduce these requirements, the use of surrogate fuels, mixtures containing 1-10 components that mimic the properties and behaviors of real fuels, has been recognized as a feasible approach for predicting combustion behavior. n-Decane and n-dodecane are major surrogate components for petroleum and natural gas derived jet fuels and are the targets of this study.;Neat n-decane and n-dodecane were oxidized in a pressurized flow reactor over the temperature regime from 550-830 K at a pressure of 8 atm and lean equivalence ratios. Samples were extracted and stable intermediates were analyzed utilizing a gas chromatograph with a flame ionization detector coupled to a mass spectrometer. To identify the branching pathways controlling autoignition, intermediate species produced during the oxidation of n-decane and n-dodecane were identified and quantified. The results showed that the major species produced from n-decane oxidation were carbon oxides, aldehydes, and alkenes. The oxidation of n-dodecane also produced cyclic ethers and lactones. The experimental results were compared to current chemical kinetic models. Suggested pathways for lactone production, which are not included in current models, are the cleavage of the peroxy bond in C4H7OOOH to yield dihydro-2(3H)-furanone and a hydroxyl radical, and the cleavage of the peroxy bond in C4H5OOOH to yield the unsaturated lactone, 2(3H)-furanone, and hydroxyl radical.;Overall, the research results will aid in the development and continued refinement of chemical kinetic models for n-decane and n-dodecane that will be employed for simulating combustion characteristics of gas turbines and CI engines while ultimately improving such traits as fuel efficiency, emissions, and power output.