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This paper shows a general development process for aircraft gas turbine combustors. As a first step for developing the preliminary combustor design program, several combustor sizing methodologies using reference area concepts are reviewed. There are three ways to determine the reference area; 1) combustion efficiency approach, 2) pressure loss approach, 3) velocity assumption approach. The current study shows the comparisons of the calculated results of combustor reference values from the pressure loss and velocity assumption approaches. Further works are required to add iterative steps in the program using more reasonable values of pressure loss and velocities, and to evaluate the sizing results using data for actual combustor performance and sizes.
가스터빈용 희박 예혼합 연소기 내부에 와류 발생기(vortex generator)를 장착하여 그에 따른 연료/공기혼합 및 NOx 배출 특성 변화를 조사하였다. 이를 위해 수치해석적 방법을 채택하여 연소기내 유동특성, 연료/공기 혼합도, 배기가스(NOx), 화염형상을 분석하였다. 와류 발생기를 장착한 경우, 연소기 내부에서 와류 발생기에 의한 나사산 형상으로 인해 와류가 형성되며 이는 연소기 전면부까지 유지되었다. 또한 연소기 내부 면적 차로 인해 압력섭동이 발생하였다. 이와 더불어 연소기 전면부 기준 상류지역의 연료와 공기의 혼합도가 증가됨으로서 연료 과농지역이 감소하게 되며 이로 인해 전반적인 NOx 발생량의 감소 효과를 볼 수 있었다. 화염 형상의 변화로부터 와류 발생기의 영향으로 선회수는 다소 감소할 것으로 예상되며, 이는 와류 발생기로 인한 유속의 반복적 증감에 의한 결과라고 판단된다.
The oxy-fuel combustion is CO₂ capture technology that uses mixture of pure O₂ and recirculated exhaust as oxidizer. Currently some Oxy-fuel power plants demonstration project is underway in worldwide. Meanwhile research project for converting 125 MWe Young-Dong power plant to 100 MWe oxy-fuel power plants is progress. In this paper, 1 D process analytical approach was applied for conducting process design and operating parameters sensitivity analysis for oxy-fuel combustion of Young-Dong power plant. As a result, appropriate gas recirculation rates was 74.3% that in order to maintain normal rating superheater, reheater steam temperature and boiler heat transfer patterns. And boiler efficiency 85.0%, CPU inlet CO₂ mole concentration 71.34% was predicted for retrofitted boiler. The oxygen concentration in the secondary recycle gas is predicted as 27.1%. Meanwhile the oxygen concentration 22.4% and moisture concentration 5.3% predicted for primary recycle gas. As the primary and secondary gas recirculation increases, then heat absorption of the reheater is tends to increases whereas superheater side is decreased, and also the efficiency is tends to decrease, according to results of sensitivity analysis for operating parameters. In addition, the ambient air ingression have a tendency to lead to decline of efficiency for boiler as well as decline of CO₂ purity of CPU inlet.
Recently, controlling nitrogen oxides(NOx) emission is actually very important task to protect human against environmental pollution. NOx is known as a precursor for photochemical smog, contributes to acid rain and causes ozone depletion. The goal of this study is verifying the effects of reburning, SNCR with air staging hybrid system on NOx reduction. In this article reports the experimental result according to the several experimental cases. It is divided into four sections. Experimental case 1 section was tested about reburning process. Studying the impact that reburn fuel fraction in the reburning zone has on characteristic of NOx reduction. Air staging and hybrid reburning/air staging effects were considered in experimental case 2 part. The effects of air staging on the gas temperature distribution and heat flux were studied. At case 3 part, SNCR process was considered. And finally, reburning, SNCR and air staging hybrid system were studied at case 4. By comparison the effectiveness with several De-NOX processes, we can find the advantage of reburning, SNCR and air staging hybrid system.
The purpose of this paper is to investigate the effect of equivalence ratio on the combustion and emission characteristics of a compression ignition engine fueled with biodiesel. In this research, a single-cylinder direct injection engine with 373.3 cc of displacement volume was tested on DC dynamometer. In order to investigate the effect of biodiesel equivalence ratio on combustion characteristics, the experiments were conducted at various equivalence ratios and injection pressures of 40~120 MPa. For investigating engine performance, lambda meter was connected and equivalence ratios was varied from 0.6 to 1.0. In addition, the exhaust emissions such as oxides of nitrogen(NOx), hydrocarbon(HC) and carbon monoxide(CO) were measured by exhaust gas analyzer under the various air/fuel ratios. The experimental results show that maximum IMEP was measured at the 0.8 of equivalence ratio. Furthermore, NOx emission was rapidly decreased as the increase of equivalence ratio. However soot emission was significantly increased according to the increase of equivalence ratio.
A numerical analysis was performed to predict the thermo-fluid dynamic characteristics of hydrazine monopropellant reaction in the thruster combustor and nozzle. A 1-D porous model was introduced to simulate catalytic reaction by iridium in the combustor while 2-D axisymmetric analysis was applied to predict the nozzle flow. The chemical species and temperature variations were predicted by changing the injection pressure and mass flow rate and their results were validated by comparison with limited experimental data. The thrust variation with injection pressure could be estimated using the current 1-D combustor modeling.
The regenerative burner system, which has 20 years" history since the Japanese initiative project High Performance Industrial Furnaces in 1993 has been shown to provide significant reduction in energy consumption (up to 60%), downsizing of the equipment (about 30%) and lower emissions (about 30%), while maintaining high thermal performance of the system. Energy savings translate to reduction of CO2 and other greenhouse gases to the environment. Besides, the application of regenerative burner as an energy-saving technique has been gradually played an important role in industrial furnaces. In this paper recent advances on High Temperature Air Combustion Technology(HiTAC) including Cost Down type are reviewed.
Numerical analysis was performed to investigate the NOx formation pathways on gas turbine conditions using OpenFOAM. Validation is done against measurement data for mean flow and scalar fields of Sydney swirl flame, SM1. The standard k-e model was employed to reproduce mean turbulent flow field and turbulence-chemistry interaction was modelled by partially stirred reactor approach with GRI 3.0 mechanism. In this study NOx formation pathways including Zeldovich, nitrous oxide and prompt were investigated for gas turbine conditions. Results were compared to the experimental data of high-pressure jet-stirred reactor operating on lean-premixed methane/air.
There is a strong need for carbon-free and low NOx gas turbine power plants. In order to keep up with this global need, major gas turbine manufacturers are making great efforts to develop low NOx combustion technologies that can afford a high fraction of hydrogen. The purpose of this paper is to review the trends of research and development for low NOx hydrogen gas turbines carried out by major gas turbine manufacturers and research institute. Technical issues that should be considered for hydrogen combustion under wide gas turbine operating conditions will be briefly summarized, and then state-of-the-art development status for premixed-type hydrogen gas turbine combustor will be followed.
Simulation is performed to analyze the characteristics of turbulent spray combustion in a diesel engine condition. An extended Conditional Moment Closure (CMC) model is employed to resolve coupling between chemistry and turbulence. Relevant time and length scales and dimensionless numbers are estimated at the tip and the mid spray region during spray development and combustion. The liquid volume fractions are small enough to support validity of droplets assumed as point sources in two-phase flow. The mean scalar dissipation rates (SDR) are lower than the extinction limit to show flame stability throughout the combustion period. The Kolmogorov scales remain relatively constant, while the integral scales increase with decay of turbulence. The chemical time scale decreases abruptly to a small value as ignition occurs with subsequent heat release. The Da and Ka show opposite trends due to variation in the chemical time scale. More work is in progress to identify the spray combustion regimes.