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In this work, the evolution of the InGaN layer growth on the ridge shaped GaN was studied. A mass transport model was presented to simulate the epitaxy process of the InGaN layer. The model consisted of two consecutive components, gas-phase diffusion process and surface diffusion process. The mean lifetime of adatoms on epitaxial surface was associated with their reaction rate in this model. An InGaN layer on ridge shaped GaN, including (0002) and {112¯2} facets, was grown by metal organic chemical vapor deposition to confirm the mass transport model. Gradient indium content distribution and inhomogeneous thickness of the InGaN layer were observed. Simulation of the InGaN layer growth process was performed by finite difference method with the mass transport model. By analyzing the results from calculations and experiments, the origins of the InGaN layer characteristics were attributed to the two diffusion components in the growth process. Surface diffusion resulted in the inhomogeneous thickness and gas-phase diffusion chiefly led to the gradient indium content. In addition, the adatoms reaction rate on epitaxial surface determined their mean lifetime as speculated by the analysis. The demonstration of the growth process of InGaN layer offers valuable insight in obtaining high efficiency white light emitting diodes by selective area growth technology.

A single-pulse shock tube study of the pyrolysis of two different concentrations of Chinese RP-3 jet fuel at 5 bar in the temperature range of 900–1800 K has been performed in this work. Major intermediates are obtained and quantified using gas chromatography analysis. A flame-ionization detector and a thermal conductivity detector are used for species identification and quantification. Ethylene is the most abundant product in the pyrolysis process. Other important intermediates such as methane, ethane, propyne, acetylene, butene, and benzene are also identified and quantified. Kinetic modeling is performed using several detailed, semidetailed, and lumped mechanisms. It is found that the predictions for the major species such as ethylene, propene, and methane are acceptable. However, current kinetic mechanisms still need refinement for some important species. Different kinetic mechanisms exhibit very different performance in the prediction of certain species during the pyrolysis process. The rate of production (ROP) is carried out to compare the differences among these mechanisms and to identify major reaction pathways to the formation and consumption of the important species, and the results indicate that further studies on the thermal decomposition of 1,3-butadiene are needed to optimize kinetic models. The experimental data are expected to contribute to a database for the validation of mechanisms under pyrolytic conditions for RP-3 jet fuel and should also be valuable to a better understanding of the combustion behavior of RP-3 jet fuel.

Diesel engines are widely used for propulsion on large ships, which has the undesired characteristic of generating large amounts of harmful emissions. To reduce these emissions, some alternative fuel was developed and used in a marine diesel engine. In this study, an experiment was carried out on a 6-cylinder turbocharged direct-injection marine diesel propulsion engine. A small proportion blend of biodiesel-diesel was used, aimed at exploring the emission characteristics and emission reduction mechanism for diesel propulsion engines. The results show that the high oxygen content of biodiesel blend is crucial for inhibiting the formation of particulate matter (PM) and reducing the formation of total unburned hydrocarbon (THC) and carbon monoxide (CO), which reduces the emission of harmful gases. At the same time, the number of particles (PN) has also decreased. However, the rapid burn rate of biodiesel was found to reduce brake thermal efficiency (BTE), resulting in an increase of fuel consumption and exhaust gas temperature (EGT), which can promote the formation of nitrogen oxides (NO x). More carbon dioxide (CO 2) is released due to the increased fuel consumption. The emission characteristics of the biodiesel blend and diesel fuel are discussed in this work.

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A basic understanding of the high-temperature pyrolysis process of jet fuels is not only valuable for the development of combustion kinetic models but also critical to the design of advanced aeroengines. The development and utilization of alternative jet fuels are of crucial importance in both military and civil aviation. A direct coal liquefaction (DCL) derived liquid fuel is an important alternative jet fuel, yet fundamental pyrolysis studies on this category of jet fuels are lacking. In the present work, high-temperature pyrolysis studies on a DCL-derived jet fuel and its blend with the traditional RP-3 jet fuel are carried out by using a single-pulse shock tube (SPST) facility. The SPST experiments are performed at averaged pressures of 5.0 and 10.0 bar in the temperature range around 900–1800 K for 0.05% fuel diluted by argon. Major intermediates are obtained and quantified using gas chromatography analysis. A flame-ionization detector and a thermal conductivity detector are used for species identification and quantification. Ethylene is the most abundant product for the two fuels in the pyrolysis process. Other important intermediates such as methane, ethane, propyne, acetylene, and 1,3-butadiene are also identified and quantified. The pyrolysis product distributions of the pure RP-3 jet fuel are also performed. Kinetic modeling is performed by using a modern detailed mechanism for the DCL-derived jet fuel and its blends with the RP-3 jet fuel. Rate-of-production analysis and sensitivity analysis are conducted to compare the differences of the chemical kinetics of the pyrolysis process of the two jet fuels. The present work is not only valuable for the validation and development of detailed combustion mechanisms for alternative jet fuels but also improves our understanding of the pyrolysis characteristics of alternative jet fuels.

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