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Fossil fuel dependency in developed countries is worrisome due to the lack of energy security that traditional energy generation provides. In order to prevent future energy problems and to maintain a sustainable society, some countries are starting to develop renewable energy sources. In this research, biomass energy is introduced as a solution not only to reduce fossil fuel dependency, but also to improve municipal solid waste management. The purpose of this report is to construct a distributed power generation system combining the superheated steam gasification of solid waste and photovoltaic panels, and to verify the feasibility of generating power at the consumption site. It also focuses on optimizing the current waste superheated steam gasification system and compares the superheated steam gasification technology with other waste to energy technologies, such as downdraft air gasification and solid waste direct combustion. Finally, the report analyzes the economic, environmental and energetic viability of the above mentioned distributed generation system, which is located in a medium size mall surrounded by a community of 20,000 inhabitants. As a result, it was found that a distributed generation system composed by waste superheated steam gasification and photovoltaic panels is perfectly feasible, since its long term economic performance shows high profitability.

The authors proposed for new fuel between blending of jatropha methyl ester and n-tridecane. Biodiesel has an advantage in reducing emissions. Nevertheless, it has high viscosity and density and has poor spray characteristics compared to diesel fuel. The blending between n-tridecane would overcome the unwanted fuel properties. The n-tridecane and jatropha methyl ester were blended under three condition; JME25% (Jatropha Methyl Ester 25% and n-tridecane 75%), JME50% (Jatropha Methyl Ester 50% and n-tridecane 50%), and JME75% (Jatropha Methyl Ester 75% and n-tridecane 25%). The fuel properties were analyzed under biodiesel standardization from JIS K and ASTM D. FTIR analyzed also showed the characteristics of carbonyl peak that indicates as methyl ester. In the results, JME50% had met the requirements for fuel properties from biodiesel standardization.

Ignition, combustion and emissions characteristics of dual-component fuel spray were examined for ranges of injection timing and intake-air oxygen concentration. Fuels used were binary mixtures of gasoline-like component i-octane (cetane number 12, boiling point 372 K) and diesel fuel-like component n-tridecane (cetane number 88, boiling point 510 K). Mass fraction of i-octane was also changed as the experimental variable. The experimental study was carried out in a single cylinder compression ignition engine equipped with a common-rail injection system and an exhaust gas recirculation system. The results demonstrated that the increase of the i-octane mass fraction with optimizations of injection timing and intake oxygen concentration reduced pressure rise rate and soot and NOxemissions without deterioration of indicated thermal efficiency. Numerical investigation into the pressure rise rate reduction mechanism was also performed by use of a multi-component fuel model developed by the authors. The calculated result showed that the pressure rise rate was reduced due to the difference in the vapor concentrations between two components which have difference reactivity.

Auto-ignition and combustion processes of dual-component fuel spray were numerically studied. A source code of SUPERTRAPP (developed by NIST), which is capable of predicting thermodynamic and transportation properties of pure fluids and fluid mixtures containing up to 20 components, was incorporated into KIVA3V to provide physical fuel properties and vapor-liquid equilibrium calculations. Low temperature oxidation reaction, which is of importance in ignition process of hydrocarbon fuels, as well as negative temperature coefficient behavior was taken into account using the multistep kinetics ignition prediction based on Shell model, while a global single-step mechanism was employed to account for high temperature oxidation reaction. Computational results with the present multi-component fuel model were validated by comparing with experimental data of spray combustion obtained in a constant volume vessel. The results showed a good agreement in terms of spray tip penetration, liquid length, ignition delay and so on, for several kinds of dual-component fuels. Additional investigation into a combustion control methodology using dual-component fuel, which aims to mitigate combustion rate of premixed charge, was performed. Consequently, the feasibility of this approach was confirmed.

Research on alternative fuels is necessary to reduce CO2 emissions. Hydrotreated Vegetable Oil (HVO) of light fuel physically improves spray and combustion characteristics. Fatty Acid Methyl Ester (FAME) is an oxygenated fuel and its combustion characteristics are chemically improved, although its spray characteristics such as penetration and atomization are deteriorated. The purpose of this study is to understand the effects of blending HVO, which has carbon neutral (CN) characteristics, with FAME, which also has CN characteristics, on spray and combustion characteristics, and to further improve emission such as THC and Smoke. This report presents the effect of the combination of improved spray characteristics and oxygenated fuel on emissions. Spray characteristics such as penetration, spray angle and spray volume were investigated by shadowgraph photography. Also, combustion characteristics such as heat release rate and emission were investigated using a single-cylinder diesel engine. As a result, with blending of HVO and FAME, by increasing the percentage of HVO, lower the fuel density and kinematic viscosity, forming a low penetration and high dispersion spray. In addition, entrainment is promoted and the spray volume tends to increase. The emission performance was found to be significantly affected by chemical effects. Furthermore, blended fuel can reduce THC and Smoke emissions compared to gas oil, while keeping the same NOx levels. Therefore, blended fuel can improve emission performance without affecting the environmental impact, and is a promising alternative fuel to gas oil.

A hybrid model consisting of a modified TAB (Taylor Analogy Breakup) model and DVM (Discrete Vortex Method) is proposed for numerical analysis of the evaporating spray phenomena in diesel engines. The simulation process of the hybrid model is divided into three steps. First, the droplet breakup of injected fuel is analyzed by using the modified TAB model. Second, spray evaporation is calculated based on the theory of Siebers' liquid length. The liquid length analysis of injected fuel is used to integrate the modified TAB model and DVM. Lastly, both ambient gas flow and inner vortex flow of injected fuel are analyzed by using DVM. An experiment with an evaporative free spray at the early stage of its injection was conducted under in-cylinder like conditions to examine an accuracy of the present hybrid model. The calculated results of the gas jet flow by DVM agree well with the experimental results. The calculated and experimental results all confirm that the ambient gas flow dominates the downstream diesel spray flow.[PUBLICATION ABSTRACT]

We analyzed the vapor-phase distribution and behavior of each component in multi-component fuel (MCF). Evaporation characteristic of MCF was researched by laser-induced fluorescent (LIF) method. A pulsed Nd-YAG laser was used as incident light, and an experiment was performed in a constant-volume vessel so that optical measurement could be possible. MCF was injected through electronically controlled common rail injector into the vessel. I-octane (C 8 H 18 ), n-dodecane (C 12 H 26 ) and n-hexadecane (C 16 H 34 ) were selected to be low boiling point (LO-B.P.), mid boiling point (MI-B.P.) and high boiling point (HI-B.P.) components, respectively, and Fuel A , Fuel B and Fuel C , made by compounding those components at different mass fractions, were used as MCF. Experimentation was performed under the conditions that injection pressures were 42MPa, 72MPa and 112MPa, respectively, ambient gas density was 15kg/m3 and ambient gas temperature was 700K. The spatial vapor-phase distribution, dispersion process of mixture, and vaporphase homogeneity were researched. It was ascertained that the vapor-phase of MCF showed stratified distribution and the dispersion of mixture was improved in proportion to the mass fraction of the LO-B.P. component.

It is expected that the analysis of the evaporation process for multicomponent fuels such as actual fuels like gasoline and diesel gas oil could be performed to assess more accurately the mixture preparation field inside the cylinder of D.I.S.I engines and diesel engines. In this paper, we suggested the importance of this multicomponent fuel consideration relating to the mixture formation and combustion characteristics from the basis of their own fuel physical and chemical properties. Then, we introduce a treatment for the phase change of a multicomponent solution through the formation of two-phase regions with the basis of chemical-thermodymical liquid-vapor equilibrium. Next, we analyze the distillation properties of a multicomponent fuel as well as the evaporation process of a multicomponent single droplet by use of the chemical-thermodymical analysis. And, we propose a simple estimation scheme for the evaporation process of a multicomponent fuel spray, where the quasi-two phase region is considered. Then, the mixture formation process in the spray was calculated for multicomponent fuel by KIVA-II code. The spray-wall interaction process was also modeled by considering the superheating degree of the surface for the liquid spray droplets based on several experimental results in order to take into account the change in boiling phenomena at the liquid-solid interface during the impingement and post impingement process.

This work investigates the soot formation process in diesel jet flame using a detailed kinetic soot model implemented into the KIVA-3V multidimensional CFD code and 2D imaging by use of time-resolved laser induced incandescence (LII). The numerical model is based on the KIVA code which is modified to use CHEMKIN as the chemistry solver using Message Passing Interface (MPI). This allows for the chemical reactions to be simulated in parallel on multiple CPUs. The detailed soot model used is based on the method of moments, which begins with fuel pyrolysis, followed by the formation of polycyclic aromatic hydrocarbons, their growth and coagulation into spherical particles, and finally, surface growth and oxidation of the particles. The model can describe the spatial and temporal characteristics of soot formation processes such as soot precursors distributions, nucleation rate and surface reaction rate. The experiments by use of laser induced incandescence were conducted using a constant volume combustion vessel which simulated diesel engine conditions. The distribution of soot volume fraction and particle diameter in diesel jet was revealed by time-resolved LII measurements, and qualitative agreement was obtained between the experimental and simulation results. The experimental results show that the smaller particles are made up of majority of soot formation region in the jet at the early time of the start of soot formation, which become larger around the periphery of the soot formation region with transition to the diffusion combustion phase, and rapidly transform the large particle after the end of injection. Also, simulation results show that the soot particles are formed to surround the soot precursor formation region and to extend downstream. It was also found that the dominant soot growth process differs by the region in the fuel jet. The particle inception is fast around the central region of the jet, and C₂H₂ surface reaction rate becomes higher toward the periphery of the jet.