• Title/Summary/Keyword: 초임계과정

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초임계 난류연소 모델링

  • Park, Tae-Seon
    • Journal of the KSME
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    • v.56 no.9
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    • pp.32-37
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    • 2016
  • 초임계 유체의 고유한 물리적 특성변화와 난류유동을 결합하여 성능을 높이는 데 활용하고 있는 가장 대표적인 시스템 중의 하나는 연소기이다. 이때 연료와 산화제의 연소반응은 저압조건과 다른 고유한 특성을 가지고 있어 기존의 연소모델에 의해서는 정확한 분석이 어렵게 된다. 따라서 초임계 압력조건에 대한 연소과정을 분석할 수 있는 연소모델이 필요하고 이러한 연소과정이 난류유동조건에서 발생하기 때문에 최근 많은 연구가 초임계 난류연소모델 개발에 집중되어 왔다. 이 글에서는 특히 액체로켓엔진 관련 초임계 연소모델 개발 분야의 연구동향을 살펴보고자 한다.

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Behavior of Cobalt Extraction from Cobalt Sulphate solution using Supercritical 2 (황산코발트용액(溶液)으로부터 초임계(超臨界CO2에 의한 코발트 추출거동(抽出擧動))

  • Shin, Shun-Myung;Joo, Sung-Ho;Sohn, Jeong-Soo;Kang, Jin-Gu
    • Resources Recycling
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    • v.20 no.6
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    • pp.78-82
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    • 2011
  • Supercritical $CO_2$($scCO_2$) extraction has a great possibility to be a new process to recover metal and to replace the existing leaching/solvent extraction processes. The cobalt extraction was carried out using $scCO_2$ from cobalt sulphate solution. The bis (2,4,4-trimethylpentyl) phosphinic acid and diethylamine ligands were used to extract cobalt ion in $scCO_2$. The recommended method consists of $scCO_2$/extractants complexation process and metal extraction process at 60, 200bar. Experimental results showed that the extraction efficiency of Co was increased by 16-99% with increasing the ligand amount.

Enrichment of Coffee Flavors with Supercritical Carbon Dioxide (초임계 이산화탄소를 이용한 커피의 향기 성분 증진)

  • Lee, Joo-Hee;Byun, Sang-Yo
    • KSBB Journal
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    • v.23 no.3
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    • pp.193-198
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    • 2008
  • In this study, the supercritical $CO_2$ extraction was applied for the enrichment of coffee flavors. The extraction efficiency of coffee flavors was dependent on the pressure and temperature and optimized as 350 bar and 80$^\circ$C. Five flavors of high aroma values were analyzed. The flavors extracted by the supercritical $CO_2$ extraction were 76.6 times higher than those by the traditional method, espresso extraction. The modified headspace system proved the enhanced efficiency of supercritical $CO_2$ extraction. The coffee beverage containing the extract of supercritical $CO_2$ resulted 2.3 times of flavor enrichment when it was compared to that without the supercritical extract.

Saccharification of lignocellulosics by Supercritical Water (초임계수를 이용한 목질바이오매스의 당화 가능성)

  • Choi, Joon-Weon;Lim, Hyun-Jin;Han, Gye-Sung;Choi, Don-Ha
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.11a
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    • pp.525-528
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    • 2006
  • 아임계 및 초임계수에 의한 목질바이오매스의 당화특성을 분석하기 위하여 분해공정 동안 압력을 23MPa(물의 임계압력)로 고정하고 물의 아임계 온도$(325^{\circ}C,\;350^{\circ}C)$와 초임계 온도$(380^{\circ}C,\;400^{\circ}C,\;425^{\circ}C)$에서 현사시나무 목분을 각각 60초 동안 처리하였다. 생성된 현사시나무의 분해산물에는 액상과 고형분의 분해산물이 섞여 있었다. 각 처리조건에 따른 목질바이오매스의 분해율은 온도가 상승함에 따라 증가하였으며 초임계 온도인 $425^{\circ}C$에서 최고 83.1%의 분해율을 나타냈다. 아임계 및 초임계수에 의해서 생성된 단당류는 고성능 음이온 교환 크로바토그래프(HPAEC)를 이용하여 분석하였다. 목질바이오매스의 초임계수 분해과정에서 처리 온도가 높아지면서 단당류 수율은 증가하는 경향을 보였으며, $425^{\circ}C$에서 가장 높은 7.3%의 단당류 수율을 나타내었다. 아임계 온도 범위에서는 현사시나무의 섬유소 성분 중에서 자일란이 우선적으로 분해되어 자일로스의 생성비율이 비교적 높았으며, 처리온도가 높아지면서 셀롤로오스의 분해에 의한 글루코오스 생성율이 급격히 상승하였다. 이렇게 생성된 단당류 성분들은 고온의 반응조건하에서 열분해 반응에 의해서 더욱 분해되어 퓨란계 화합물로 변형되었다.

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Collagen Extraction Using Supercritical CO2 from Animal-Derived Waste Tissue (동물 유래 폐지방으로부터 초임계 CO2를 이용한 콜라겐 추출)

  • No, Seong-Rae;Shin, Yong-Woo;You, Seong-sik
    • Korean Chemical Engineering Research
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    • v.60 no.3
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    • pp.386-391
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    • 2022
  • This study is about a technique for obtaining collagen by extracting fat by treating collagen-containing liposuction effluent in the presence of supercritical fluid. Using a supercritical solvent, a collagen extract could be obtained from animal-derived fat in a short time (about 6 hours), and about 2-3% of collagen by mass compared to the raw material could be obtained. The presence of collagen in the extract obtained by supercritical extraction was confirmed by SDS-PAGE, and it was confirmed that it was type 1 collagen having a relatively large molecular weight. In addition, the growth factors of IGF-1, bFGF, VEGF and NGF were analyzed to find out which growth factors were present in the collagen obtained by supercritical extraction, and it was found that these growth factors were contained in the extract. There was no significant difference in DNA content per mg of sample before and after supercritical treatment. Further in-depth studies are likely to be needed on decellularization technology using the supercritical process. In conclusion, the extracellular matrix obtained through the solvent extraction process using a supercritical fluid contains growth factors above a certain amount even after decellularization and removal of fat, so that it was found that not only biocompatibility is greatly increased, but also tissue regeneration can be rapidly induced.

Phospholipids Isolation from Squid Viscera Residues After Supercritical Carbon Dioxide Extraction (오징어 내장의 초임계 이산화탄소 추출 잔류물로부터 인지질의 분리)

  • U, Pyoung-Ook;Chun, Byung-Soo
    • Korean Chemical Engineering Research
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    • v.48 no.6
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    • pp.741-746
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    • 2010
  • Phospholipids were recovered from squid viscera residues by ethanol extraction after supercritical carbon dioxide($SCO_2$) extraction and from squid viscera was not processed $SCO_2$ by various organic solvent extraction. $SCO_2$ extraction were performed at $45^{\circ}C$ and 20 MPa for removal of non polar lipid molecules from freeze dried squid viscera sample. Phospholipids were extracted from freeze dried squid viscera sample by chloroform, hexane, methanol, and ethanol and from $SCO_2$extracted squid viscera sample by ethanol. The pH was fixed at 5.7 for all phospholipids extraction conditions. Phospholipid classes were analyzed by HPLC equipped with evaporative light scattering detector (ELSD). Phosphatidyl choline(PC) extracted by ethanol from $SCO_2$ extracted residues was higher than that of extracted by ethanol from squid viscera. But phosphatidyl ethanolamine(PE) and phosphatidic acid(PA) were extracted higher percentage in raw squid viscera. The fatty acid compositions in phospholipids extract by ethanol extract from $SCO_2$ extracted residues were analyzed by gas chromatography(GC). Docosahexanoic acid(DHA) was found in highest percentage in phospholipid extract.

An Experimental Study on Heat Transfer and Pressure Drop Characteristics during Supercritical Process of Carbon Dioxide in a Horizontal Tube (수평관 내에서 이산화탄소 초임계 가스냉각 과정의 열전달 및 압력강하 특성에 관한 실험적 연구)

  • 최이철;강병하;김석현
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.5
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    • pp.414-420
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    • 2004
  • The heat transfer and pressure drop characteristics associated with the gas cooling of the supercritical carbon dioxide in a horizontal tube have been investigated experimentally. This problem is of particular interest in the design of a gas cooler of cooling systems using $CO_2$refrigerant. The test section is consisted of 6 series of 455 mm in length, 4.15 mm ID copper tube, respectively. The effects of the inlet temperature, pressure and mass flow rate on the heat transfer and pressure drop of $CO_2$in a horizontal tube is studied in detail. The heat transfer coefficient of $CO_2$is varied by temperature, inlet pressure, and mass flow rate of $CO_2$. This has maximum value at near the pseudocritical temperature. The pressure drop is changed by inlet pressure and mass flow rate of $CO_2$. The results have been compared with those of previous work. The heat transfer correlation at the supercritical gas cooling process is also suggested.

Application of Artificial Neural Network to Flamelet Library for Gaseous Hydrogen/Liquid Oxygen Combustion at Supercritical Pressure (초임계 압력조건에서 기체수소-액체산소 연소해석의 층류화염편 라이브러리에 대한 인공신경망 학습 적용)

  • Jeon, Tae Jun;Park, Tae Seon
    • Journal of the Korean Society of Propulsion Engineers
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    • v.25 no.6
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    • pp.1-11
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    • 2021
  • To develop an efficient procedure related to the flamelet library, the machine learning process based on artificial neural network(ANN) is applied for the gaseous hydrogen/liquid oxygen combustor under a supercritical pressure condition. For hidden layers, 25 combinations based on Rectified Linear Unit(ReLU) and hyperbolic tangent are adopted to find an optimum architecture in terms of the computational efficiency and the training performance. For activation functions, the hyperbolic tangent is proper to get the high learning performance for accurate properties. A transformation learning data is proposed to improve the training performance. When the optimal node is arranged for the 4 hidden layers, it is found to be the most efficient in terms of training performance and computational cost. Compared to the interpolation procedure, the ANN procedure reduces computational time and system memory by 37% and 99.98%, respectively.

Influence of Critical Point of Hydrocarbon Jet Injected into Near-Critical Environment on Injection Behavior (근임계 환경으로 분사되는 탄화수소 제트의 임계점이 분사거동에 미치는 영향)

  • Yoon, Taekyung;Shin, Dongsoo;Lee, Keonwoong;Koo, Jaye
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.5
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    • pp.32-39
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    • 2018
  • Supercritical injection behavior of liquid hydrocarbon compounds, which are used as main components of propellant fuel, was analyzed. Decane and Methylcyclohexane (MCH) with different critical points were selected as experimental fluid and Shadowgraphy technique was used. Decane and MCH behave differently in the initial state under the subcritical condition. However, near the critical point, the enthalpy of evaporation became close to 0, so that phase change into supercritical fluid occurred, not vaporization process, and no breakup of both fluids occurred.

Biological activity of supercritical extraction residue 60% ethanolic extracts from Ulmus davidiana (느릅나무 초임계 추출박 60% 주정추출물의 생리활성)

  • Mun, Myung-Jae;Park, Kwang-Hyun;Choi, Sun Eun
    • Journal of Convergence for Information Technology
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    • v.8 no.5
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    • pp.29-36
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    • 2018
  • Ulmus davidiana supercritical fluid residue EtOH extracts(USCFR) and ethyl acetate solvent fraction (USCFREA) of supercritical extraction foil were investigated in order to examine the recycling of supercritical extraction foil in the process of studying Ulmus davidiana branch supercritical extract. Experiments were performed for the determination of total phenol content. The $IC_{50}$ value(ppm) of DPPH radical scavenging activity and ABTS radical scavenging activity was $7.42{\pm}0.09$, $7.50{\pm}0.05$, $22.94{\pm}0.09$, $6.43{\pm}0.10$, and USCFREA, respectively, as compared with the positive control (vitamin C) with values $17.80{\pm}0.14$ and $5.34{\pm}0.06$, respectively. The antioxidative activities of USCFR and USCFREA were confirmed to be superior to the positive control group. In anti-allergic activity studies, both USCFR and USCFREA showed concentration-dependentanti-allergic activity, and USCFREA showed strong anti-allergic activity even at very low concentrations. Thetotal phenolic contents (ugEG, ugGA; ppm) of USCFR were $134.17{\pm}0.13$, $132.02{\pm}0.24$ and USCFREA were $154.77{\pm}1.05$ and $153.18{\pm}1.10$, respectively. Based on the above results and strong antioxidant activity, USCFR and USCFREA hold the potential to be considered as basic research materials for the development of therapeutic supplements based medicines or functional cosmetics related to chronic inflammatory skin immunity diseases.