• Journal of the Korean Society of Combustion
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• v.22 no.2
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• pp.42-49
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• 2017

A premixed combustion has many advantages including low NOx and CO emission, high thermal efficiency and a small volume of combustor. This study focused on combustion characteristics in a premixed combustion burner using the nickel based metal foam. The results show that the blue flame is found to be very stable at heating load 6,300-25,200 kcal/h by implementing the proper nickel based metal foam and baffle plate. The premixed flame mode is changed into green flame, red flame, blue flame and lift off flame with decreasing equivalence ratio. NOx emission was measured 80 ppm(0% oxygen base) from 0.710 to 0.810 of equivalence ratio and CO emission is 90 ppm(0% oxygen base) under the same equivalence ratio. It is also found that the stable blue flame region in flame stability curve becomes wider with increasing the heat load.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.182-189
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• 2005

In order to investigate the effect of premixed gasoline, diesel fuel, and n-heptane charges on the combustion and exhaust emission characteristics in a direct injection (DI) diesel engine, the experimental studies are performed. The premixed fuels are injected into the premixing chamber that installed upstream of the intake port in order to minimize the inhomogeneity effect of premixed charge. The injection nozzle for directly injected fuel is equipped in the center of the combustion chamber. The air temperature control system is equipped in the intake manifold to examine the effect of air temperature. The experimental results of this study show premixing fuel is effective method to reduce the NOx and soot emissions of diesel engine. NOx emissions are linearly decreased with increasing premixed ratio for the three kinds of premixed fuels. The heating of intake air $(80^{\circ}C)$ reduced the deterioration of BSFC in high premixed ratio, because it promotes evaporation of premixed diesel droplet in the premixing chamber.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.100-107
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• 2016

In this study confirmed the reduction effect of pollutant by applying Fi-EGR and FPI-EGR to hybrid combustion system realizing premixed flame and non-premxied flame at once. The results showed that NOx emission index decreased significantly in case of adopting EGR. Additionally, the hybrid combustion system with EGR resulted in a better performance compared to usual non-premixed combustion system such that it can reduce $NO_x$ emission at equivalent EGR ratios. Especially, in the case of 25% of FI-EGR ratio at hybrid combustion system that the ratio of non-premixed and premixed is 50 : 50, NOx emission index reduction rate was about 59% compared to $NO_x$ emission of non-premixed combustion system without EGR and in the case of 15% of FPI-EGR ratio at hybrid combustion system that the ratio of non-premixed and premixed is 70 : 30, $NO_x$ emission index reduction rate was about 48% compared to $NO_x$ emission of hybrid combustion system without EGR.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.119-126
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• 2004

In order to elucidate the modes of double-droplet combustion speed in premixed spray flame, the difference between flame propagation speed and droplet cluster disappearance speed are experimentally investigated using a premixed spray burner system, It was confirmed that flame speed concerned with premixed-mode combustion in the spray flame was approximately 2.0 m/s in average while mean disappearance speed of droplet clusters, which were dominated by diffusion-mode combustion in downstream of the flame, was evaluated as much as 0.45 m/s. It was clarified that both characteristics of premixed-mode and diffusion-mode combustion in spray flames are of much difference in nature, even though both speed, which are supposed to depend on local properties of the spray itself and flow conditions surrounding droplet clusters, are scattered in experiments.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.48-54
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• 2004

The purpose of this work is to investigate the effect of premixing condition on the combustion and exhaust emission characteristics in a HCCI diesel engine. To from homogeneous charge before intake manifold, the premixed gasoline fuel is injected into a premixed tank by fuel injection system and the premixed gasoline fuel is ignited by direct injected diesel fuel. Experimental result shows the NOx and soot emissions are decreased linearly with the increase of premixed ratio. In the case of intake air temperature $20^{\circ}C$ with light load, the specific fuel consumptions are increased with the rise of premixed ratio and HC and CO emissions are also increased. But the intake air heating can improve the specific fuel consumption at light load condition because increased air temperature promotes the combustion of premixed mixture. In the case of high intake air temperature with high load condition, premixed fuel is auto-ignited before diesel combustion and soot emission is increased.

• Journal of Aerospace System Engineering
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• v.3 no.4
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• pp.41-49
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• 2009

This paper present result of numerical simulation of premixed combustion around a triangle Bluff Body. And a numerical simulation of a premixed flame stabilization by a bluff body was performed using LES Model. The calculated results from the LES showed a good agreement with experiment data than k-model. Premixture combustion has flammability limit, quenching distance, smallest ignition energy has the combustion quality of the back. Bluff body makes a recirculation zone. Therefor velocity of behind bluff body is very slow. It was caused by slowly position speed and the fire occurred after the Bluff Body. Occurrence of fire it made the waste gas of high speed and the thrust made well.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.906-913
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• 2003

Lean premixed combustion has been considered as one of the promising solutions for the reduction of NOx emissions from gas turbines. However, unstable combustion of lean premixed flow becomes a real challenge on the way to design a reliable, highly efficient dry low NOx gas turbine combustor. Contrary to a conventional diffusion type combustion system, characteristics of premixed combustion significantly depend on a premixing degree of combusting flow. Combustion behavior in terms of stability has been studied in a model gas turbine combustor burning natural gas and air. Incompleteness of premixing is identified as significant perturbation source for inducing unstable combustion. Application of a simple convection time lag theory can only predict instability modes but cannot determine whether instability occurs or not. Low frequency perturbations are observed at the onset of instability and believed to initiate the coupling between heat release rate and pressure fluctuations.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.7-12
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• 2003

The purpose of this work is to investigate the effect of premixing condition on the combustion and exhaust emission characteristics in a HCCI diesel engine. To form homogeneous charge before intake manifold, the premixed fuel is injected into premixed tank by GDI injection system and the premixed fuel is ignited by direct injected diesel fuel. But in the case of high intake air temperature, premixed fuel is auto-ignited before diesel combustion and soot emission is increased. In the case of light load condition, the BSFC is improved by intake air heating because increased air temperature promoted the combustion of premixed mixture. NOx and smoke concentration of exhaust emissions are reduced compared to conventional diesel engine. The combustion characteristics of the HCCI diesel engine such as combustion pressure, rate of heat release, and exhaust emission characteristics are discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.349-352
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• 2008

This study has numerically modeled the combustion processes of the turbulent swirling premixed lifted syngas flames in the low-swirl burner (LSB). In these turbulent swirling premixed flames, the four tangentially-injected air jets induce the turbulent swirling flow which plays the crucial role of stabilizing the turbulent lifted flames. In the present approach, the turbulence-chemistry interaction is represented by the level-set based flamelet model. Numerical results indicate clearly that the present level-set based flamelet approach has realistically simulated the structure and stabilization mechanism of the turbulent swirling premixed lifted flames in the low-swirl burner. Computations are made for the wide range of the syngas chemical composition and the dilution level at two pressure conditions (1.0, 5.0 bar). Numerical results indicate that the lifted height in the LSB is increased by decreasing the H2 percentage and increasing the dilution level at the given equivalence ratio. It is also found that the flashback is occurred for the hydrogen composition higher than 80% at the equivalence ratio, 0.8. However, at the syngas composition range in the IGCC system, the stable lean-premixed lifted flames are formed at the low-swirl burner.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.252-257
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• 2010

The availability of the thermal energy has been deeply recognized recently to encourage the cascade usage of thermal energy from combustion. Within the frame work, a 1 kW class Stirling engine based cogeneration system has been proposed for a unit of a distributed energy system. The capacity has been designed to be adequate for the domestic usage, which requires high compactness as well as low emission and noised. To develop a highly efficient system with satisfying these requirements, a premixed slot flame burner has been proposed and a series of numerical simulation has been performed to establish a design tool for the combustion chamber. The thermal radiation model has been found to highly affect the computational results and a proper resolution to analyze the heat transfer characteristics of the high temperature heat exchanger. Finally, the combustion characteristics of the premixed flame with the metal fiber type burner has been studied.