• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.8
• /
• pp.815-823
• /
• 2011

Combustion phenomena in porous media combustors are widely used in industrial fields for the combustion of lowgrade fuels and the regeneration of combustion heat. However, studies of combustion phenomena in porous media have been limited, because these phenomena are difficult to observe, and the configurations of porous media are complex. We propose a simple model combustor: a multi-channel combustor that consists of many layers of combustion channels made of quartz plates. We conducted an experimental observation of the flames in the multi-channel combustor and obtained experimental results for the flame stabilization limits. Flames formulated in the multi-channel combustor showed variation in the spatial distribution depending on the heat transfer between neighboring channels. A simple analytical model was developed and the variation in the flammability limits of the multi-channel combustor was discussed. This study will enhance our understanding of flame behavior in a porous-media combustor.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.1
• /
• pp.321-327
• /
• 1996

Experiments were performed on the laminar premixed flame stabilized in a porous medium to know whether the flame downstream of the combustor exists or not. In previous theoretical studies, a stable flame has been predicted in the downstream region of the combustor, but it has never been observed in experiments. In this study, a stable downstream flame could be obtained for the lower burning velocity through circumferential heating by a blue flame positioned outside the periphery of the specially devised combustor. The existence of the stable downstream flame was confirmed by a direct photography of soot line, and temperature measurements. The effect of combustor diameter to flame stability was also considered. As the diameter of the combustor increases, the lean flammability limit was extended.

• 한국연소학회:학술대회논문집
• /
• 2014.11a
• /
• pp.249-251
• /
• 2014

Synthesis gas such as hydrogen and carbon monoxide was produced from $CH_4//oxygen$ mixture using two-section porous media combustor. Heat recirculation through the inner foam structure could extend the flow velocity of stable region over the laminar burning velocity. $H_2/CO$ ratio and module M from concentration of flue gas measured by Gas Chromatography was similar to those calculated by equilibrium. But it was made sure that the heat loss effect becomes more influential than heat recirculation effect as the mixture gets richer. To generate synthesis gas appropriate for methanol production, insulated pressurized porous media combustor will be designed and built in the future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.6 no.4
• /
• pp.399-405
• /
• 1994

Beacuse of the energy resources exhaustion, the aggravating environmental air pollution and the smoke phenomena etc., the importance of clean gas fuel compared with liquid fuel is highly considered in recent years. The combustion system which consists of porous media is actively studied as a new method for solving above problems. Therefore, excess enthalpy combustion using porous media was interested by many researchers and investigated through numerical and experimental analysis. In this study, the simplified combustor has the unique combustion characteristics of mixture gas preheated effect using radiative and convective heat energy by changing the flow passage of unburned gas with solenoid valves and has the intensive excess enthalpy phenomena As the result of according to reduce equivalence ratio, flame temperature was remarkably higher than adiabatic flame temperature. This show the ability of super-lean combustion.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.168-174
• /
• 2000

This paper illustrates the validity of reciprocating type superadiabatic combustor as a industrial applicable dryer. After the investigations of inner and surface temperature distributions of combustor various with air-fuel(methane) ratio, mixture flow rate and reciprocating time, this combustor can be applied in industrial dryer at certain operating conditions. The results are as follows. 1) Higher equilivalence ratio emits more radiation heat flux at the censer chamber 2) Higher mixture flow rate makes more uniform temperature distribution. however, due to the heat transfer from censer chamber to porous media, the radiation beat flux is worse. 3) Longer reciprocating time emit more radiation heat flux. however, this case also makes temperature distribution wide

• Journal of the Korean Society of Combustion
• /
• v.18 no.2
• /
• pp.1-7
• /
• 2013

Flame stabilization characteristics of premixed flames in narrow annular coaxial tubes (NACT) were investigated experimentally. The NACT burner was proposed as a model of a cylindrical refractory burner, and it was made of quartz tubes. Flame stabilization conditions affected by the characteristic length of the burner was investigated with the variation of the equivalence ratio and the flow rates. Flame behaviors in narrow spaces could be directly observed. Conclusively, more wide flame stabilization conditions could be obtained at the case of the decreased channel scale. A flame instability, such as combustion noise was detected concerned with the flame oscillation observed at the surface of multi channel stage. Some flame propagation characteristics had complicated tendencies that may exist in practical porous-media combustors. Therefore, this NACT burner can be a basic configuration for the development of flame stabilization model in porous media combustor, and it will enhance our understanding about the behavior of flames in meso-scale combustion spaces.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.1
• /
• pp.328-335
• /
• 1996

The one-dimensional flame analysis was carried out to understand the combustion phenomena in porous media. The downstream as well as upstream solution corresponding to upper and lower solutions could be obtained. While upper flame temperature gets higher, lower flame temperature gets lower, as the flame approaches the central part of the combustor. The reason why upstream flame and downstream flame exist at the same flow condition is that the regions where net heat recirculation is identical exist in upstream and downstream of the combustor. In order for the downstream flame to be stabilized, more heats needed to be recirculated towards upstream because of larger radiation loss of downstream flame.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.9
• /
• pp.781-788
• /
• 2012

Flow in the oxidizer manifold of a liquid rocket combustor has been analysed using an open source CFD toolbox, OpenFOAM. The applicability of OpenFOAM to the problems with complex geometries involving porous media zones for simulating the pressure drop induced by the injectors has been evaluated by performing turbulent, incompressible steady-state flow analysis. The usefulness and applicable area of the OpenFOAM as a design evaluation and analysis tool will be confirmed and enlarged by further evaluation with various computational cases representing major physical phenomena in rocket combustion devices.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.10
• /
• pp.3243-3250
• /
• 1996

Emission characteristics of nitric oxides and carbon monoxide from a porous media combustor has been experiment studied. The relationship between the change of flame shape and emission has also been examined. As the equivalence ratio decreases, the flame shape on the ceramic matrix plate changes from a diffusion flame, R(radiant)-type flame, to B(Blue)-type flame. With large fuel flow rate, R-type flame turns to be two dimensional R-II type flame around the equivalence of 0.7. Carbon monoxide emission increases very rapid with decreasing equivalence ratio. It changes a lot from some 10 ppm to 100-10,000 ppm with the change of flame type from R-I to R-II type. Nitric oxide emission from the premixed burner is less than 25 ppm over all range of fuel flow rate, which is less than 20% of NOx emission from conventional gas burners.

• 한국연소학회:학술대회논문집
• /
• 2015.12a
• /
• pp.73-74
• /
• 2015

Synthesis gas such as hydrogen and carbon monoxide was produced from $CH_4/oxygen$ mixture using insulated pressurized porous media combustor. Experimentally, two cylindrical SiC foams with the different pore density were piled up in a quartz tube and fully premixed mixture was supplied in the axial direction. After stabilizing fuel-rich flame at the interface of the two foams at several pressure conditions, mole fractions of synthesis gases were measured by gas chromatography. Heat recirculation through the inner foam structure could extend the flow velocity of stable region over the laminar burning velocity. As the pressure increased, the rich flammability limit, $H_2/CO$ ratio, and module M increased.