• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.67-75
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• 2019

The laminar burning velocity of endothermic fuel surrogates is measured in this study, in order to investigate combustion characteristics of aviation fuel after being used as coolant in an active cooling system of a hypersonic flight vehicle. A Bunsen burner was manufactured such that the laminar burning velocity can be taken for two types of surrogate fuels, SF-1 and 2. The results showed that the burning velocity of surrogate fuels was faster at high equivalence ratio conditions than that of the reference fuel (RF), and specifically, the velocity of SF-1 had the maximum value at the highest equivalence ratio compared with those of SF-2 and RF.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.3
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• pp.27-39
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• 2009

The main objective of this study is to investigate the characteristics of combustion by analyzing fuel gases from a combustion equipment with various combustion conditions for refuse-derived fuels (RDFs). CO gas is a parameter for indicating of incomplete combustion during a combustion process. The lowest CO gas was produced when the experiment conditions were m=2 under air-fuel condition and $800^{\circ}C$. $CO_2$ gas is a final product after complete combustions. The highest amount of $CO_2$ gas was produced when the experiment conditions were m=2 under air-fuel condition and $800^{\circ}C$. The highest level of $SO_2$ gas was produced in S.1 sample containing the highest sulfur. The highest level of NOx gas was produced in S.1 sample with the highest nitrogen content and air-fuel condition of m=2 under temperature of $800^{\circ}C$. HCl gas that is generated by reacting with metals catalyst through oxygen catalyst reaction during combustion process is a precursor of dioxin formation. The higher level of HCl gas was produced in the sample with higher chlorine content. The lowest level of HCl gas was produced when the experiment conditions were air-fuel condition of m=2 and $800^{\circ}C$. The lowest level of $NH_3$ gas was generated when the experiment condition was m=2 under air-fuel condition and after 3 minutes. Air-fuel condition is more important to create $NH_3$ gas than operating temperatures. Higher level of $H_2S$ gas was generated in S.1 sample with the higher sulfur content and was created in RDFs that contain higher mixture ratios of sewage sludge and food wastes. A result of combustion, gases and gases levels from the combustion of S.1 and S.2 were very similar to the combustion of a stone coal. As results of this research, when evaluating the feasibility of the RDFs, the RDFs could be used as auxiliary and main fuels.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.8
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• pp.503-510
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• 2016

Incinerators generally emit pollutants such as NOx and CO during the combustion process. In this paper, pollutant emissions and temperature distributions were studied in a simulated incinerator with a reversed (relative to the flue gas flow) secondary air injection system. The experiments were performed by using a lab-scale furnace in order to evaluate the effects of the injection location, direction and flow rate of secondary air jets. The emission of NOx was lower in the case of reversed secondary air injection than in the case of cross injection, due to the recirculation and mixing of the exhaust gas. In the reversed air injection cases, thermal NOx emissions decreased as secondary air ratio increased from 30 to 60 and slightly increased at secondary air ratios higher than 60. In most cases, CO emissions were not detected except for a few reversed secondary air injection cases, in which cases CO concentrations below 2ppm were observed.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.98-104
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• 2010

The moisture in the atmosphere exerts a lot of influence upon Gas turbine engine performances. There is a noticeable influence of wet air at the summer sea level, high flight mach number and low engine rpm increasingly. An altitude Engine Test Facility is used to accomplish the engine performance tests at dry air condition and wet air condition, through which engine performance results is revealed. Also, Gas turbine Simulation Program is used to predict the variation of engine performance due to inlet humidity. In the result, net thrust and specific fuel consumption measured -2.826% and 1.325%, respectively at wet air condition compared to dry air condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.335-338
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• 2010

The moisture in the atmosphere exerts a lot of influence upon Gas turbine engine performances. There is a noticeable influence of wet air at the summer sea level, high flight mach number and low engine rpm increasingly. An altitude Engine Test Facility is used to accomplish the engine performance tests at dry air condition and wet air condition, through which engine performance results is revealed. In the result, net thrust and specific fuel consumption measured -2.826% and 1.325%, respectively at wet air condition compared to dry air condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.285-288
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• 2008

The Present Study describes the numerical investigations concerning a fuel(Hydrogen), inert gas (Nitrogen) or supersonic air stream issued between each other. The basic flow configuration consists of a plane, double shear/mixing layer flow. For the numerical solution, a fully conservative unsteady $2^{nd}$ order time accurate sub-iteration method and a $2^{nd}$ order Total Variation Diminishing(TVD) scheme are used with the finite volume method(FVM). The results are consist of three categories ; single shear layer consist of fuel and supersonic air stream, inert gas stream issued between supersonic air and fuel stream, fuel gas stream issued between supersonic air and fuel stream. The numerical calculations has been carried out in case of 1,2, and 4mm thickness of center stream. The width of total gas stream is 4cm.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.93.2-93.2
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• 2012

연료전지는 전기화학반응을 이용한 발전 장치로서 기존 장치에 비하여 발전 효율이 높아 화석연료를 사용하면서 현재 당면 과제인 $CO_2$ 배출량 절감이 가능하고, 환경 보전성이 우수하여 미래의 전원으로 많은 연구개발이 진행되고 있다. 특히 제3세대 연료전지라 불리는 고체산화물 연료전지(Solid Oxide Fuel Cell이하 SOFC)는 고가의 외부 개질 장치 없이도 연료가 갖는 화학에너지를 연소과정 없이, 공기와 $H_2$, CO, $CH_4$와 같은 환원성 가스를 공급받아 $600{\sim}1000^{\circ}C$에서 전기화학적 반응을 통하여 직접 전기를 얻는 방식이며, 낮은 소음과 진동으로 인하여 온 사이트(On-site) 발전이 가능한 장점이 있는 연료전지이다. Decalcomanie는 전사용지에 Screen printing하여 건조 후 coating하는 방법으로 기존의 여러 coating 방법보다 다전지셀 제작이나 Buffer layer의 적용이 용이하고, 소재의 크기나 두께조절이 간편하며, 구성층의 표면조도나 굴곡에 대응이 용이한 방법이다. 새로운 Decalcomanie를 사용하여 평관형 다전지식 SOFC Cell 제작 및 각 Buffer layer에 적용, Screen printing법과 동일한 Cell 제조 후 MPD와 Impedance 분석을 통하여 Support 위에 전사지를 이용, 적층한 Cell의 전기화학적 특성에 관하여 분석하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.81-87
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• 2018

In hypersonic aircraft, increase of aerodynamic and engine heat lead thermal load in airframe. It could lead structural change of aircraft's component and malfunctioning. Endothermic fuels are liquid hydrocarbon fuels which absorb the heat load by undergoing endothermic reactions. In this study, we investigated the relationship between product, coke formation and catalytic properites of endothermic catalysts by using exo-tetrahydrodicyclopentadiene as a fuel in a fixed bed flow reactor similar to the actual reaction conditions.

• Journal of Energy Engineering
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• v.19 no.2
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• pp.73-80
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• 2010

A solid oxide fuel cells(SOFC) is a clean energy technology which directly converts chemical energy to electric energy. When the SOFC is used in cogeneration then the efficiency can reach higher than 80%. Also, it has flexibility in using various fuels like natural gases and bio gases, so it has an advantage over polymer electrolyte membrane fuel cells in terms of fuel selection. A typical cathode material of the SOFC in conjunction with yttria stabilized zirconia(YSZ) electrolyte is still Sr-doped $LaMnO_3$(LSM). Recently, application of mixed electronic and ionic conducting perovskites such as Sr-doped $LaCoO_3$(LSCo), $LaFeO_3$(LSF), and $LaFe_{0.8}Co_{0.2}O_3$(LSCF) has drawn much attention because these materials exhibit lower electrode impedance than LSM. However, chemical reaction occurs at the manufacturing temperature of the cathode when these materials directly contact with YSZ. In addition, thermal expansion coefficient(TEC) mismatch with YSZ is also a significant issue. It is important, therefore, to develop cathode materials with good chemical stability and matched TEC with the SOFC electrolyte, as well as with high electrochemical activity.

• Korean Journal of Materials Research
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• v.11 no.4
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• pp.283-289
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• 2001

Composite cathodes of 50/50 vol% LSM- YSZ (La$_{1-x}$Sr$_{x}$MnO$_3$-yttria stabilized zirconia) were deposited onto surface- Polished YSZ electrolytes by colloidal deposition technique. The cathode characteristics were then examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) and studied by ac impedance spectroscopy (IS). The typical impedance spectra measured for an air/LSM- YSZ/YSZ/Pt/air cell at $700^{\circ}C$ were composed of two depressed arcs. Addition of YSZ to the LSM electrode significantly enlarged the triple-phase boundaries (TPB) length inside the electrode, which led to a pronounced decrease in cathodic resistivity of LSM-YSZ composite electrodes. Polishing the electrolyte surface to eliminate the influences of surface impurities and to enlarge the TPB length can further reduce cathode resistivity. The cathodic resistivity of the LSM- YSZ electrodes was a strong function of operation temperature, composition and particle size of cathode materials, applied current, and electrolyte surface roughness.