• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.71-79
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• 2010

As hypersonic flight speeds and engines efficiencies increase, heat loads on an aircraft and it's engine increase. Because the temperature of the air flow is too high to cool the aircraft structure at hypersonic flight speeds, it is essential to use the aircraft fuel as the primary coolant. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. The endothermic reactions are improved by catalysts which change the extent of reaction and product distribution. At high temperature, liquid hydrocarbons would lead to coke formation that can reduce the effectiveness of heat exchanger and cause rapid degradation of the catalyst, thus endothermic capacity of endothermic fuels is limited to the temperature at which coke doesn't form. In this study, the essential cooling technologies by applying endothermic fuels and the properties of the endothermic fuels are described.

• Resources Recycling
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• v.17 no.3
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• pp.35-41
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• 2008

The study of coking technology to upgrade oil sand bitumen which is considered as alternative fuel was performed by using thermogravity analyzer and delayed coking reactor(600ml). To analyzed and compared coking characteristics of oil sand bitumen, the reactivities of oil sand bitumen were measured in the TGA. At the temperature conditions of $400{\sim}550^{\circ}C$ and the temperature rising velocity of $50^{\circ}C/min$. the termination time of coking reaction and conversion efficiencies increased with an increase of bed temperature. However the increase rate decreased over $450^{\circ}C$. So the coking reaction with oil sand bitumen might be over $450^{\circ}C$. Also the termination time decreased with increasing the temperature rising velocity. But the content of coke increased with increasing temperature rising velocity. At the experiments in the delayed coker, the temperature condition at maximum oil yield was $475^{\circ}C$ and the fuel properties of oil from coking reaction was almost equal with conventional diesel. It was verified that the coking process might be useful process to upgrade the oil sand bitumem by using API and SIMDAS.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.453-456
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• 2007

감압 증류 후 생성되는 중질유의 고도화를 위하여 코킹 공정을 거친 후 정유 부산물로 생성되는 열적으로 매우 안정하고, 높은 발열량을 갖는 반면 황, 바나듐 함량이 높은 석유코크스의 효과적인 이용을 위하여 본 연구에서는 가스화 공정을 적용하였다. 1T/D 용량의 분류층 가스화기를 이용하여 유연탄(drayton coal), 석유코크스, 또는 혼합한 경우의 가스화 성능을 알아보았으며, 각각의 경우에 대하여 비교하여 보았다. 높은 열 안정성을 갖는 석유코크스의 효과적인 가스화를 위하여 반응기 내 체류시간 및 버너 노즐 변경에 따른 가스화 성능 개선을 시도하였으며, 이때의 온도, 산소/원료 공급량 조건에 따른 생성가스 성분 및 탄소전환율, 냉가스효율 변화 특성을 알아보았다. 버너 노즐 구경 변경으로 인한 슬러리의 미립화를 통하여 향상된 탄소전환율 및 냉가스효율을 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.32-34
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• 2008

Latin Hypercube sampling strategy(LHS)는 출력변수에 의한 목적함수들의 기댓값의 추정을 위한 입력변수를 생성하는데 사용할 수 있는 샘플링 포인트 추출 방법으로, 샘플링 포인트의 "quality"를 향상시켜준다. multi-objective Pare optimization 에 근거한 LHS와 ($1+\lambda$) 진화기법으로 이루어진 최적화 algorithm을 제안 하였고, 이를 이용하여 6MW BLDC 전동기의 코깅토크를 최소화 하였다, 총 2단계의 최적 설계를 통해 초기형상의 코킹토크에 비해 19%로 감소하였다.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.176-185
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• 2018

As global warming accelerates, greenhouse gas reduction becomes more important. Carbon dioxide dry reforming is a promising green-house gas reduction technology that can obtain CO and $H_2$ which are high value-added materials by utilizing $CO_2$ and $CH_4$ which are greenhouse gases. However, there is a significant coking problem during operation of the dry reforming reactor. Because the carbon dioxide dry reforming is a strong endothermic reaction, the temperature of the reactor drops near the reactor inlet and causes coke formation. To solve this problem, it is important to ensure that the reaction takes place in a temperature range where coke production is minimized. In this study, we proposed a design method that can maintain reaction temperature in the region where the coke is rarely generated by using the new catalyst configuration method. The design method also optimizes the reactor by solving the optimization problem which minimizes the reactor length for a given reaction conversion by using the fuel flow rate, catalyst density, and output temperature by section as optimization variables.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.62-66
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• 2009

Utilization and interest of unconventional fuel and process residue such as oil sand and its residue, oil sand coke, have been increased because of the continuous rise of fuel price and conventional fuel availability. In this study, the gasification of oil sand coke produced from coking process of oil sand was performed to utilize as an energy resource using lab-scale fixed bed gasification system. The combustion characteristics of oil sand bitumen and oil sand coke were investigated by using TGA and lab-scale gasification system was applied to reveal the characteristics of produced syngas composition with oxygen/fuel ratio, temperature and steam injection rate. Oil sand coke shows a high carbon content, heating value and sulfur content and low ash content and reactivity. In case of oil sand coke gasification, generally with increasing temperature, the amount of steam introduced and decreasing oxygen injection rate, $H_2$ content in product gas increased while the $CO_2$ content decreased. The calorific value of syngas shows about $2100kcal/Nm^3$ and this result indicates that the oil sand coke can be used as a resource of hydrogen and fuel.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.135-144
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• 2021

In this study, we investigated the characteristics of the process of hydrogen production using boil-of gas (BOG) generated from an LNG-fueled ship and the application of hydrogen fuel cell systems as auxiliary engines. In this study, the BOG steam reformer process was designed using the UniSim R410 program, and the reformer outlet temperature, pressure, and the fraction and consumption of the product according to the steam/carbon ratio (SCR) were calculated. According to the study, the conversion rate of methane was 100 % when the temperature of the reformer was 890 ℃, and maximum hydrogen production was observed. In addition, the lower the pressure, the higher is the reaction activity. However, higher temperatures have led to a decrease in hydrogen production owing to the preponderance of adverse reactions and increased amounts of water and carbon dioxide. As SCR increased, hydrogen production increased, but the required energy consumption also increased proportionally. Although the hydrogen fraction was the highest when the SCR was 1.8, it was confirmed that the optimal operation range was for SCR to operate at 3 to prevent cocking. In addition, the lower the pressure, the higher is the amount of carbon dioxide generated. Furthermore, 42.5 % of the LNG cold energy based on carbon dioxide generation was required for cooling and liquefaction.