• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.123-123
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• 2014

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.121-121
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• 2015

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.37-41
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• 2004

Quenching phenomena is one of major concern in development of millimeter or sub-millimeter scale micro combustor for the size of the combustor is near extinction condition. In this work we focused on the effect of combustor wall condition that was parameterized by Perovskite LSC($La_{0.8}$$Sr_{0.2}$$CoO_3$) redox catalyst. The experiment was done by variable gap-width 2D wall equipment. The flame was produced by premixed methane-air jet issuing from millimeter-scale slot burner and it propagated through the narrow gap of the walls. By comparison of flame behaviour near catalyst-coated wall and simple glass wall, we investigated the effect of possible surface reaction on quenching phenomena. The flame between two plates was observed where the gap of the plates was reduced stepwise from 20mm to a distance of quenching occurrence. The two flames with and without surface modification were almost same by observation. But the gap for the occurrence of quenching was increased between catalyst-coated wall. So we concluded that surface reaction close to combustor wall has a negative effect on micro combustion.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.170-177
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• 2005

The fuel-lean premixed flame has been considered one of the most efficient ways to reduce $NO_X$ emission during a combustion process. However, it is difficult to achieve stable fuel-lean premixed flames over the wide range of equivalence ratios: therefore, the application of fuel-lean flames to a practical combustion system is rather limited. In this study, the stability characteristics of fuel-lean flames stabilized by fuel-rich flames are investigated experimentally using a slot burner as a part of the basic research for practical application such as lean burn engines. Spontaneous emission of radical species were examined to understand the stability mechanisms of rich-lean premixed flames. The presence of fuel-rich flames could significantly lower the lean limit of fuel-lean flames. The stability of a fuel-lean flame is enhanced with the increase of fuel flow rate in a fuel-rich flame; how ever, it is not sensitive to the equivalence ratio of fuel-rich flames in the range of 1.2-2.4. The mechanisms of stable rich-lean premixed flames could be understood based on the characteristics of triple flame.

• Journal of the Korean Society of Combustion
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• v.10 no.4
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• pp.33-40
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• 2005

The propagation rates of advancing and retreating non-premixed edge flames in a slot-jet counterflow were measured as a function of strain rate for varying jet spacing, mixture strength, stoichiometric mixture fractions $(Z_{st})$ and Lewis numbers (Le). Methane and propane fuels were tested and nitrogen and carbon dioxide were used as inerts. As results, we could identify igniting fronts, retreating fronts, two total extinction limits, and short-length edge flames. A burner separation affected to a low extinction limit only. Regimes for advancing and retreating edges together with total extinction were mapped in terms of normalized flame thickness and heat loss factor for $CH_4/O_2/N_2$ mixtures. Edge flames for $Z_{st}$ > 0.5 behaved like a stronger mixture while for $Z_{st}$ < 0.5 showed deteriorated feature, because of relative locations of a non-premixed flame and intermediate species such as CO and $H_2$. Furthermore, due to the relative importance of heat loss, propagating speeds of edge flames were significantly enhanced in $CH_4/O_2/CO_2$ mixtures (Le < 1) demonstrating increasing stability limits. However $C_3H_8/O_2/N_2$ mixtures (Le > 1) showed opposite result.

• 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.

• Journal of computational fluids engineering
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• v.16 no.3
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• pp.88-94
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• 2011

The availability of the thermal energy has been deeply recognized recently to encourage the cascade usage of thermal energy from combustion. Within the framework, 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 noise. To develop a highly efficient system with satisfying these requirements, a premixed slot type short 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.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2192-2197
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• 2008

An experimental study was performed to investigate the effects of configuration of burner and air excess ratio on CO & NOx emission characteristics of the cooktop burners which are used extensively. In this study, the combustion characteristics were investigated with the variation of design factor of cooktop burners. The results showed that as the thermal input increases, flammable region go narrower. With the increase of loading height from the cap to grate, the CO emission decrease owing to the reduction of quenching by flame impingement on the load. Additionally, the CO emission increase with angle of main slot, however the NO emission is almost unaffected.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.211-216
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• 2012

The availability of thermal energy has been widely recognized recently, and the cascade usage of thermal energy from combustion has been encouraged. Within this framework, a 1-kW-class Stirling-engine.based cogeneration system has been proposed as a unit of a distributed energy system. The capacity has been designed to be adequate for domestic usage, which requires high compactness as well as low emissions and noise. To develop a highly efficient system satisfying these requirements, a premixed slot-type short-flame burner has been proposed, and a series of experiments has been performed to understand its combustion characteristics. Flame images have been captured to observe the dependence of the flame mode on the combustion load and air/fuel ratio. The exhaust gas has been sampled and analyzed to study the emission characteristics for each flame mode.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.7-14
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• 2004

The lift-off characteristics of the triple flame have been studied experimentally with various mean velocities and concentration gradients using a multi-slot burner, which can control the concentration gradient and the mean velocity independently, Lift-off height, axial maximum velocity, flame temperature, and some other characteristics were examined for methane and propane flame, It was found that minimum values of the lift-off heights exist at a certain concentration gradient for constant mean velocity, and this result implies that the propagation velocity has a maximum value at this condition, OH radical distribution was measured with LIF method and velocity variation along streamline was measured with PlV system. In addition maximum temperature along streamline was measured with CARS system. The intensity of the diffusion flame affects on the propagation velocity of triple flame in the region of very weak concentration gradient.