• 한국수소및신에너지학회논문집
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• 제34권5호
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• pp.549-554
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• 2023

In this paper, three kinds of studies have been completed to obtain highly purified carbon dioxide having more than 7N purity as an electronic grade quality. PRO/II with PROVISION release January 2023 from AVEVA company was used, and Peng-Robinson equation of the state model with Twu's alpha function was selected for the modeling of the cryogenic distillation process. When using LN2 cold heat, we can obtain highest recovery of carbon dioxide as a bottom product for a cryogenic distillation column.

• 한국수소및신에너지학회논문집
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• 제31권5호
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• pp.429-435
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• 2020

This paper describes the experimental study of reverse-Brayton refrigeration system for application to high temperature superconductivity electric devices and LNG re-liquefaction. The reverse-Brayton refrigeration cycle is designed with operating pressure of 0.5 and 1.0 MPa, cooling capacity of 2 kW at 77 K, and neon as a working fluid. The refrigeration system is developed with multi scroll compressor, turbo expander and plate heat exchanger. From experiments, the performance characteristics of used components is measured and discussed for 77-120 K of operating temperature. The developed refrigeration system shows the cooling capacity of 1.23 kW at 77 K and 1.64 kW at 110 K.

• Tribology and Lubricants
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• 제38권2호
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• pp.33-40
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• 2022

In this study, we present rotor dynamic analysis and operation test of a turbo expander for a hydrogen liquefaction plant. The turbo expander consists of a turbine and compressor wheel connected to a shaft supported by two hydrostatic radial and thrust bearings. In rotor dynamic analysis, the shaft is modeled as a rigid body, and the equations of motion for the shaft are solved using the unsteady Reynolds equation. Additionally, the operating test of the turbo expander has been performed in the test rig. Pressurized helium is supplied to the bearings at 8.5 bar. Furthermore, we monitor the shaft vibration and flow rate of the helium supplied to the bearings. The rotor dynamic analysis result shows that there are two critical speeds related with the rigid body mode under 40,000 rpm. At the first critical speed of 36,000 rpm, the vibration at the compressor side is maximum, whereas that of the turbine is maximum at the second critical speed of 40,000 rpm. The predicted maximum shaft vibration is 3 ㎛, whereas sub-synchronous vibration is not presented. The operation test results show that there are two critical speeds under the rated speed, and the measured vibration value agrees well with predicted value. The measured flow rate of the helium supplied to the bearing is 2.0 g/s, which also agrees well with the predicted data.

• 청정기술
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• 제23권1호
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• pp.104-112
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• 2017

해조류로부터 수열 액화 반응을 통해 생성된 원료를 이용하여 수소가스를 생산하기 위해 개질 반응용 상용화 촉매와 $K_2Ti_xO_y$가 첨가된 니켈(Ni) 제조 촉매를 사용하여 반응온도에 따른 수증기 개질 반응을 수행하였다. 반응원료는 해조류 바이오매스를 503 K의 반응온도에서 2시간 동안 수열 액화를 통해 생성된 액화 원료를 사용하였으며, 상용화 촉매(FCR-4-02)와 제조 촉매($Ni/K_2Ti_xO_y-Al_2O_3$, $Ni/K_2Ti_xO_y-SiO_2$, $Ni/K_2Ti_xO_y-ZrO_2/CeO_2$, Ni/$K_2Ti_xO_y$-MgO) 및 반응온도에 따른 수증기 개질 반응의 활성을 비교 연구하였다. 실험결과 제조 촉매 4종 모두 상용화 촉매와 비교하여 반응활성이 높게 나타나는 것이 확인되었으며, 제조 촉매의 지지체에 따라 생성되는 가스의 조성이 달라지는 것이 확인되었다. 특히, 산성이나 염기성을 띄는 $Al_2O_3$와 MgO의 지지체와 중성을 띄는 $SiO_2$의 지지체에서는 CO가 선택적으로 높게 생성이 되었으며 환원성을 띄는 $CeO_2$를 포함하는 지지체에서는 수성가스 전환 반응이 일어나 $CO_2$가 높게 생성됨을 보였다.

• 에너지공학
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• 제5권1호
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• pp.80-86
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• 1996

석탄액화반응의 모델반응으로 나프탈렌의 수소화반응을 소형반응기내에서 수행하였다. 생성물인 테트랄린 및 데칼린의 몰분율은 반응온도와 수소압력에 민감하였다. 38$0^{\circ}C$에서 입자촉매를 사용한 반응은 재현성이 낮았으며 이의 규명을 위한 다양한 방법이 시도되었다. H$_2$S에 의한 효과가 가장 관련이 깊은 것으로 추론되었으며 25$0^{\circ}C$에서 H$_2$S의 효과를 체계적으로 규명하였다. H$_2$S의 분압을 조절하여 중간유도체인 테트랄린의 분율을 최대화할 수 있었으며 반응온도 및 반응시간과 함께 H$_2$S의 분압이 황화촉매를 사용하는 석탄액화반응에서 중요한 실험인자임을 확인하였다.

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.1-7
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• 1997

Kraft oak lignin and ricestraw lignin from acetosolve pulping were dissolved in 50/50 mixture of tetralin/m-cresol solvent. The dissolved lignin was reacted in the pressurized autoclave which was operating at $350{\sim}500^{\circ}C$ of reaction temperature and 10~20 atms of reaction pressure respectively_Hydrogen pressure of 60~80kg/$cm^2$ was exercising into the pressurized autoclave reactor to create thermochemical hydrogenolysis reaction. It was identified by GLC, GC-MS and HPLC that the alkyl-aryl-${\beta}$-O-4 ether bond of lignin was cleaved and degraded into various smaller molecules of aromatic compound such as phenols and cresols under the reaction conditions around $300^{\circ}C$ and 10 atms of reaction temoerature and pressure. Hydrogenolysis reaction of lignin compound which was done above $500^{\circ}C$ of reaction temperature and 20 atms of reaction pressure showed that the amount of aromatic compound such as phenols and cresols degraded from reactant lignin was decreasing with newly present and increasing water out of product mixtures. It was supposed that new aliphatic compound of high molecular weight hydrocarbon is composed due to higher reaction temperature and pressure of hydrogenolysis reaction such as $500^{\circ}C$ and 20 atms, even though it was almost impossible, to identify what kind of degraded products it was by HPLC.

• 에너지공학
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• 제5권2호
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• pp.176-182
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• 1996

소형의 고온 고압 반응장치에서의 석탄액화시 흑액, 리그닌, NaOH, 물, 나무 등을 첨가제로 사용하여 375$^{\circ}C$ 근처에서의 액체생성물의 수율과 비점분포를 분석하였다. 흑액을 석탄액화 과정 중에 첨가하게 되면 석탄액화율이 38.6% 정도 증가하나, 액화율 상승효과의 대부분은 NaOH 때문인 것으로 판단되며, 흑액 중에 포함된 황화합물은 액화과정에서 수소와 결합함으로서 휘발성의 자극성 악취를 발생시키기 때문에 불리한 요인이 될 수 있다. 액화공정에 물이 존재하면 액화 수율에는 변화가 없었으나 액화생성물 중에는 저비점 성분이 증가되며, 가스 중에는 CO가 줄고, $CO_2$성분이 증가되었다. 나무를 석탄액화시 첨가하면 생성물 중 가스의 비율이 증가하고 액체생성물도 다소 증가하게 되는데, 석탄전환율로 보면 나무의 첨가효과는 거의 무시할 수 있는 값이며, 액체 생성물 수율만으로 보면 375$^{\circ}C$에서는 3%, 40$0^{\circ}C$에서는 약 8%정토의 액체생성물의 수율 증가를 보여주었으며, 4$25^{\circ}C$에서는 가스생성물의 증가로 액체생성물의 오히려 감소하였다.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.412-419
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• 2012

Increasing demand for natural gas and higher natural gas prices in the recent decades have led many people to pursue unconventional methods of natural gas production. POSCO-Gwangyang synthetic natural gas (SNG) project was launched in 2010. As the market price of natural gas goes up, the increase of its price gets more sensitive due to the high cost of transportation and liquefaction. This project can make the SNG economically viable. In parallel with this project, KEPCO (Korea Electric Power Corporation) joined in launching the SNG Quality Standard Bureau along with KOGAS (Korea Gas Corporation), POSCO and so on. KEPCO Research Institute is in charge of SNG fueled gas turbine combustion test. In this research, several combustion tests were conducted to find out the effect of hydrogen contents in SNG on gas turbine combustion. The hydrogen in synthetic natural gas did not affect on gas turbine combustion characteristics which are turbine inlet temperature including pattern factor and emission performance. However, flame stable region in ${\Phi}$-Air flow rate map was shifted to the lean condition due to autocatalytic effect of hydrogen.

• 공업화학
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• 제9권5호
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• pp.742-748
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• 1998

본 연구에서는 Alaska산 아역청탄과 PP에 의한 공동액화실험을 통하여 상승효과 및 반응기구를 규명하고자 하였다. 반응온도 $430^{\circ}C$에서 30분간 액화시, tetralin 4ml 첨가한 석탄과 PP 또는 LDPE의 공동액화는 석탄 또는 플라스틱의 단독액화에 비해 각각 17%, 15%의 상승효과를 나타냈으며 석탄과 PP의 공동액화가 석탄과 LDPE의 공동액화에 비해 액화율이나 상승효과 측면에서 더 높은 결과를 나타냈다. 또한 공동액화시 석탄의 경우 석탄과 tetralin에 의한 2차식, PP의 경우 0차식의 반응속도모델을 개발하여 실험결과를 모사하였으며 상관계수 0.99 이상으로 부합도가 매우 높았다. 반응온도가 $410^{\circ}C$에서 $470^{\circ}C$로 상승함에 따라 석탄 단위질량 변환에 필요한 tetralin 소요량이 0.4에서 1.0으로 증가하며 이는 tetralin이 액화유의 저분자화에 기여하는 것으로 GPC 분석결과 확인되었다. Tetralin은 PP 단독액화시 PP의 액화를 저해하지만, 석탄과 PP의 공동액화시 석탄에 우선적으로 수소공여용매 역할을 하므로 PP의 액화를 저해하지 못한다. 따라서 PP의 액화율은 증가하며 공동액화시 액화상승효과는 PP가 주도하는 것으로 나타났다.

• 한국수소및신에너지학회논문집
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• 제19권1호
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• pp.56-63
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• 2008

In this study, thermochemical degradation of hemicellulose by Acetone-Solvolysis, the effects of reaction temperature, conversion yield, degradation properties and degradation products were investigated. Experiments were performed in a tube reactor by varying reaction temperature from $200{\circ}C$ to $400{\circ}C$ at 40 min of reaction time. The liquid products from pyrolysis-liquefaction of hemicellulose contained various kinds of ketones. ketones, as 4-methyl-3-penten-2-one, 3-methylene-2-pentanone, 22,6-dimethyl-2, 5-heptadien-4-one, 4-methyl-2-pentanone, 5-methyl-2-hexanone, 3,5,5-trimethyl-2-cyclohexen-1-one, and bezenes. as 1,4-dimethylbenzene, 1-methyl-2-(1-methylethyl)-benzene, 1,4-dimethyl-2-(2-methylpropyl)benzene, 4-secbutyl-ethyl benzene, could be used as high-octane-value fuels and fuel additives. Combustion heating value of liquid products from thermochemical conversion processes of hemicellulose was in the range of $6,680{\sim}7,170cal/g$. After 40min of reaction at $400{\circ}C$ in Acetone-Solvolysis of hemicellulose, the energy yield and mass yield was as high as 72.2% and 41.2g oil/100g raw material, respectively.