Simulation of Hydrogen Generation from Methane Partial Oxidation in a Plasma Fuel Reformer

A model for the chemistry in a plasma fuel reformer or plasmatron has been developed. The plasma fuel reformer is set up to produce syngas (hydrogen and carbon monoxide gas mixture) from partial oxidation of hydrocarbons. The behavior of methane as fuel has been investigated to characterize and simulate the plasmatron performance. The goal of this work has been improved understanding of the physical/chemical processes within the reactor. The simulation tool used was CHEMKIN 3.7, using the GRI methane combustion mechanism. The Partially Stirred Reactor application (PASR) simulates random mixing by a frequency mixing parameter, which is directly dependant of the system fluid dynamic properties. The fuel reformer was designed as a reactor where combustion is initiated by an electric discharge due to ohmic heating of the arc region. From discharge observations, energy estimations and model simulations, it was found that the electric arc initiates combustion by locally raising the temperature and then propagating the reaction by heat and mass transfer/mixing to the surroundings. Simulation results demonstrated that there is an optimum characteristic mixing time for each residence time, depending on the initial temperature reached at the arc. It was also found that for given power input into the system, the more spread the energy is, or the more mass is heated to a moderate temperature, the better the calculated performance

High-Speed Flow and Fuel Imaging Study of Available Spark Energy in a Spray-Guided Direct-Injection Engine and Implications on Misfires

The spark energy transferred under the highly stratified conditions during late injection in a spray-guided spark-ignition direct-injection (SG-SIDI) engine is not well characterized. The impact of high pressures, temperatures, velocities, and variations in local fuel concentration along with temporal and/or spatial variations on spark performance must be better characterized. Previous spark ignition studies have not addressed the full range of conditions that are present in SG-SIDI engines. Therefore, high-speed particle image velocimetry (PIV) experiments are conducted to characterize the spark energy dependence for a wide range of well-defined homogeneous fuel–air equivalence ratios (W50–2.9) and average air velocities (0–8m/s) in an optical SG-SIDI engine. Amoderate dependence of spark energy on equivalence ratio is shown to exist with average values of spark energy increasing by 21 per cent for the equivalence ratio range of W50–2.3. Air injection into the motored engine is used to prepare well-defined flow conditions without the complications of fuel concentration gradients that are present during fuel injection. This allows the study of the effects of velocity, shear strain rate, and vorticity on spark energy. The spark energy increases with velocity at the spark plug. This observation is consistent with findings reported in the literature for low-pressure conditions. A linear increase is shown between shear strain rate and spark energy, while vorticity and spark energy are only weakly correlated. Simultaneous high-speed PIV, planar laser-induced fluorescence, and spark-discharge electrical measurements are also performed in the optical SG-SIDI engine to measure flow properties and fuel concentrations under late injection. Operating parameters are chosen to be near peak indicated mean effective pressure performance, but they occasionally provide a random misfired or partial burned cycle. Misfired cycles occur under stoichiometric-to-lean mixtures and low velocities near the spark plug. The lower spark energies observed under these conditions are in agreement with the observationsmade under well-controlled mixture and flow conditions reported in this study. All mixture conditions found in misfiring and partially burning cycles are within the ignitability range and fall within the general population of all, predominantly well-burning, cycles. There is no predominant impact of shear strain rate and vorticity under late injection operation on misfires and partial burns.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86771/1/Sick7.pd

Design of a distributed hybrid electric propulsion system for a light aircraft based on genetic algorithm

Hybrid aircraft is a new attempt for next-generation aircraft, they are environmentally friendly and highly efficient. This paper proposes a new type of hybrid electric propulsion system for light aircraft, which integrated distributed propulsion concept and more electric aircraft concept together to improve aircraft performance. Based on the mission requirements and unique system configuration, all components, including engine, generator and motors are intelligently selected. The sizing problem can be divided into two parts. The power source part applied a non-dominated sorting genetic algorithm to choose components and simultaneously minimized total weight and fuel consumption. The rest of the system used a conventional genetic algorithm, which minimized weight and guaranteed that all selected motors can output enough power. In the end, by applying a simple deterministic energy management strategy, the new system achieved a 12% fuel consumption reduction