• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.12
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• pp.1245-1251
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• 2009

This paper describes the research on the non-eroding throat insert materials under condition of high-temperature, high-pressure, and long-burn time. C/SiC, CIT and W/$Y_2O_3$ were chosen and tested in thermal protection evaluation motor of burning time 20 seconds. From the test results, a heat resistance of W/$Y_2O_3$ was the most excellent among them, but was happened crack on material surface. Thermal reaction characteristics and heat resistance of these materials and feasibility of W/$Y_2O_3$ as throat material were ascertained.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.75-78
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• 2006

Disposal of highly toxic wastes like polychlorinated biphenyls (PCBs) is very difficult. These substances create a growing mountain of problematic waste that has to be disposed properly. Conventional technologies that are based on common burning(rotary kiln, ${\sim}1100^{\circ}C$) and plasma technology(${\sim}10000^{\circ}C$) do not satisfy important conditions. for example, complete combustion of the toxic waste and the price of waste disposal. The combustor like a rocket engine is operated at relatively high pressure(${\sim}15$ bar) and relatively high temperature(>$3000^{\circ}C$) that are ideal for the complete destruction of extremely toxic substances. In this study, test compound($_o-DCB$) was dissolved in kerosine with a concentration of 10%. Pure gas oxygen was used as an oxidant. Analysis showed that the destruction efficiency achieved for ${o}-DCB$ was 99.9999% or better. The results show that a combustor based on liquid propllant rocket technology is a validated tool for the disposal of highly toxic waste, and a good alternative technology when applied to the destruction of extremely toxic wastes.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.527-527
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• 2009

1세대 바이오디젤인 fatty acid methyl ester(FAME)의 문제점을 극복하기 위하여 많은 연구가 진행 중 이다. 소위 차세대 바이오디젤은 triglyceride의 산소 화합물을 제거하여 정유 공정을 통해 생산된 디젤과 동일한 특성을 지닌 탄화수소로 전환시킨 오일이다. 이를 위하여 수소를 첨가하여 산소를 제거 시키는 Hydrodeoxygenation(HDO) 반응이 필요하다. 고온($300-400^{\circ}C$), 고압(50-100 bar)의 혹독한 조건에서 높은 수율과 안정성을 보이는 촉매 개발이 필요하다. 이를 위하여 반응물중의 산소를 효과적으로 제거하기 위하여 산소 전달능이 뛰어난 $CeO_2$ 담체에 열안정성을 높이는 $ZrO_2$를 조합한 $Ce-ZrO_2$ 담체를 선정하였으며 수소첨가 탈산소 반응에 활성을 나타낼 것으로 예상되는 니켈을 활성성분으로 선정하였다. 본 연구에서는 15%Ni-$Ce_{(1-x)}Zr_{(x)}O_2$ ($0{\leq}x{\leq}1$)촉매를 공침법(co-precipitation)으로 제조하였으며 $500^{\circ}C$에서 소성하였다. 촉매 특성분석은 XRD, BET, H2-TPR을 이용하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.627-633
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• 2001

Characteristics of a diesel spray impingement with the variation of ambient temperature, wall temperature and ambient pressure were investigated through shadowgraphy method by using high speed camera. The radial penetration of spray was increased with ambient temperature and wall temperature. It is resulted from the decrease of ambient gas density caused by the increase of temperature. The height of spray was also increased with ambient temperature and wall temperature, because the height of stagnate region is noticeably increased, although height of wall jet vortex is decreased. At the same ambient pressure, the area ratio of impinging spray of room temperature environment to high temperature environment was increased, as the temperature difference between room temperature and high temperature increases. And the increment of area ratio was higher at low ambient pressure than high ambient pressure.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.75.2-75.2
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• 2011

고온고압에서 운전되는 IGCC용 분류층 석탄가스화기는 석탄에 포함된 회 성분을 대부분 용융 슬래그 형태로 가스화기 벽을 타고 흘러내리게 하여 가스화기 하부로 배출시킨다. 이러한 용융 슬래그를 원활하게 배출시키는 것은 가스화기의 안정적인 운전에 있어서 매우 중요하다. 본 연구에서는 슬래그 층 내의 물질수지, 운동량 및 에너지 보존을 고려하여 석탄가스화기내의 슬래그 거동을 해석할 수 있는 모델 식을 유도하였다. 유도된 슬래그 거동 모델 식들을 적용하고 가스화기의 형상을 고려하여 가스화기 내부에서의 슬래그 거동을 해석하였다. 또한 슬래그 물성치들인 슬래그 점도, 슬래그 비열, 슬래그 밀도, 슬래그 열전달 계수 등을 슬래그의 조성 변화에 따라 별도로 산정하여 슬래그 해석의 입력 데이터로 사용하였다. 슬래그에 첨가되는 석회석의 비율을 해석의 주요 변수로 사용하여 가스화기 하부에서 용융 슬래그 및 고체 슬래그 두께, 용융 슬래그 층 내부에서의 슬래그 점도분포 및 슬래그 속도분포 등 슬래그 거동의 주요 특성들을 예측하였다. 해석결과로 석탄에 석회석의 첨가량을 증가시키면 슬래그의 임계점도온도(temperature of critical viscosity)와 점도가 낮아지므로 가스화기 벽면에서의 용융 슬래그의 유동속도는 빨라지며, 고체 슬래그와 용융 슬래그의 두께가 감소하는 것을 정량적으로 확인할 수 있었다.

• Korean Journal of Materials Research
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• v.5 no.3
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• pp.379-386
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• 1995

LiOH-$H_{3}$BO_{3}$ 용액중에서의 Zircaloy-4 핵연료 피복관의 부식가속과 억제현상을 조사하고 이러한 부식특성에 미치는 Li 및 B의 영향을 해석하기 위하여, 여러 조건의 LiOH-$H_{3}$BO_{3}$ 용액을 사용하여 35$0^{\circ}C$, 165bar의 고온, 고압 조건에서 Zircaloy-4 피복관의 노외 부식시험을 수행하였다. 원전 수화학 모의조건에 대응되는 용액 중에서의 부식속도의 천이는 물 분위기에서 보다 빨리 발생되고 천이후 물 분위기와 거의 유사한 부식속도를 나타내는 천이적 후의 부식거동을 보였다. 한편 pH의 변화는 부식특성에 큰 영향을 미치지 않았다. 부식가속과 억제 모의실험으로부터, 산화막내로 침투하는 Li의 양이 용액중 Li 농도에 크게 의존하며, Li 농도가 일정하게 정해진 용액의 경우 B 첨가에 관계없이 산화막내에 일정량의 Li이 농축될수 있다는 가정을 제시하였다. 또한 B 첨가에 의한 부식억제가 B 또는 B-(OH) 화합물의 산화막내 Li 침투 억제에 의한 것이 아니라 일들에 의해 산화막내로 산화성 성분의 이동이 억제되는데 기인할 수 있음을 제시하였다. 부식가속 개시점에 대응되는 산화막 두께측정 결과와 용액내 Li 농도간의 관계로부터, 용액중 Li 농도가 높을수록 부식가속이 얇은 산화막 두께에서 시작됨을 알았다. 특히 노내조건에서의 핵연료 피복관의 부식가속이 산화막내 Li 농축에 의해 일어나는 부식특성으로 해석될 수 있음을 보였다.

• Journal of the Korean Chemical Society
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• v.24 no.6
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• pp.405-412
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• 1980

The effect of pressures and temperatures on the stabilities of the mesitylene-iodine charge transfer complex have been investigated through ultraviolet spectrophotometric measurements in n-hexane. The stabilities of complexes were measured at 25, 40 and $60^{\circ}C$ under 1∼1600 bars. The equilibrium constant of the complex was increased with pressure and decreased with temperature raising. The absorption coefficient was increased with both pressure and temperature. Changes of volume, enthalpy, free energy and entropy for the formation of complexes were obtained from the equilibrium constants. The red-shift observed a higher pressure, the blue-shift at a higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions.

• Journal of ILASS-Korea
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• v.15 no.1
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• pp.17-24
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• 2010

The objective of this work is to analyze the macroscopic behavior of spray and injection characteristics on the DME blended biodiesel at different mixing ratios by using spray visualization and injection rate measurement system. The spray images were analyzed to a spray tip penetration, a spray cone angle and a spray area distribution at various mixing ratio of DME by weight. The influence of different injection pressure and ambient pressure on the fuel spray characteristics are investigated for the various injection parameters. In order to analyze the injection characteristics of test fuels, the fuel injection rate is measured at various blending ratio. The variation of viscosity of the blended fuel by the mixing of DME fuel shows the improved effect of spray developments. Also, it was found that the injection quantities of high blended ratio were larger than that of lower blended fuel. Also, higher blending fuel showed a faster evaporation than that of mixing ratio of test fuel because kinetic viscosity was changed by blending ratio.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.65-71
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• 2018

There is no significant difference in the initial viscosity of a propellant applied with yellow iron oxide and red iron oxide. In addition, the thermal decomposition rate of the material with added yellow iron oxide is faster than that with the addition of red iron oxide. Specifically, it was confirmed that the pressure exponent was 18% lower at high temperature and high pressure with yellow iron oxide than with red iron oxide. The initial viscosity was lowest at 71% of the large particle to small particle ratio.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.2
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• pp.87-93
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• 2015

Recently, the heat exchangers are requiring higher performance and reliability since they are being used under the operating condition of high temperature and pressure. To satisfy these requirements, we need special materials and bonding technology. This study presents a manufacturing technology for high temperature and high pressure micro channel heat exchanger using Inconel 617. The bonding performance for diffusion bonded heat exchanger was examined and analyzed. The analysis were conducted by measuring thermal and mechanical properties such as thermal diffusivity and tensile strength, and parametric studies about bonding temperature and pressing force were also carried out. The results provided insight for bonding evaluation and the bonding condition of $1200^{\circ}C$, and 50 tons was found to be suitable for this heat exchanger. From the results, we were able to establish the base technology for the manufacturing of Inconel 617 heat exchanger through the application of the diffusion bonding.