• Title/Summary/Keyword: 초임계영역

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Cubic Equation of State Analysis for the Prediction of Supercritical Thermodynamic Properties of Hydrocarbon Fuels with High Critical Compressibility Factor (고 임계 압축인자를 갖는 탄화수소 연료의 초임계 열역학적 물성 예측을 위한 상태방정식 분석)

  • Jae Seung Kim;Jiwan, Seo;Kyu Hong Kim
    • Journal of the Korean Society of Propulsion Engineers
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    • v.26 no.5
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    • pp.24-34
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    • 2022
  • In order to predict the cooling performance of a regenerative cooling channel using hydrocarbon fuel operating in the supercritical region, it is essential to predict the thermodynamic properties. In this study, a comparative analysis was performed on two-parameter equations of state (SRK(Soave-Redlich-Kwong), PR(Peng-Robinson) equations of state) and three-parameter equations of state (RK-PR equations of state) to appropriately predict density and specific heat according to the critical compressibility factor of polymer hydrocarbons. Representatively, n-dodecane fuel with low critical compressibility factor and JP-10 fuel with high critical compressibility factor were selected, and an appropriate equation of state was presented when predicting the thermodynamic properties of the two fuels. Finally, the prediction results of density and specific heat were compared and verified with NIST REFPROP data.

Separation of Volatile Compounds from Tuna Fish Oil With Supercritical Carbon Dioxide (초임계 이산화탄소를 이용한 참치유로부터 휘발성 성분의 분리)

  • Roh Hyung Seob;Youn Hyun Seok;Jung Sun Mi;Hong Yeon Ryun;Kang Kil Yoon;Chun Byung Soo
    • KSBB Journal
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    • v.20 no.1 s.90
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    • pp.12-17
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    • 2005
  • Despite a wide range of fatty acids in fish oil, its the usage are very limited owing to off-flavors and volatile compounds in the oil. A way to extract and remove volatile compounds was performed at a semi-flow extractor by using supercritical carbon dioxide $(SC-CO_2)$. Samples of the oil were treated at the conditions which ranged from $30\;to\;80^{\circ}C$ and from 80 to 200 bar with 10 mL/min flow rate of carbon dioxide. In the oil the volatile compounds were analyzed by gas chromatography. Before extraction with $SC-CO_2$ the oil sample was detected over 129 peaks but 99 compounds were identified. The results demonstrated that at $40^{\circ}C$ and 200 bar extraction condition the volatile compounds in the tuna fish oil were removed, except for 14 compounds identified after extraction and other $SC-CO_2$ extraction conditions reached to high reduction of the volatile compounds.

The heat transfer and pressure drop characteristics of $CO_2$ during supercritical region in a horizontal tube (초임계 영역에서 수평관내 $CO_2$ 열전달과 압력강하)

  • 이동건;오후규;김영률;손창효
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.3
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    • pp.500-508
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    • 2004
  • The heat transfer coefficients during gas cooling process of carbon dioxide in a horizontal tube were investigated. The experiments are conducted without oil in the refrigerant loop. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater, and a gas cooler(test section). The water loop consists of a variable-speed pump, an isothermal tank, and a flow meter. The gas cooler is a counterflow heat exchanger by cooled water flowing in the annulus. The $CO_2$ flows in the horizontal stainless steel tube. which is 9.53mm in O.D. and 7.75mm in I.D. The gas cooler is 6 [m] in length. which is divided into 12 subsections, respectively. The experimental conditions considered in the study are following range of variables : refrigerant temperature is between 20 and $100^{\circ}C$. mass fluxes ranged from 200 to 400kg/($m^2$.s), average pressure varied from 7.5 to 10.0MPa. The main results were summarized as follows : The friction factors of $CO_2$ in the gas cooler show a relatively good agreement with those predicted by Blasius' correlation. The local heat transfer coefficient in the gas cooler has compared with most of correlations, which are the famous ones for forced convection heat transfer of turbulent flow. The results show that the local heat transfer coefficient of gas cooler agrees well with the correlation by Bringer-Smith except that at the region near pseudo critical temperature. while that at the near pseudo critical temperature is higher than the correlation.

A Numerical Study on Improving the Thermal Hydraulic Performance of Printed Circuit Heat Exchanger Using the Supercritical Carbon Dioxide (초임계 이산화탄소를 작동유체로 한 PCHE의 열수력 성능 향상을 위한 수치해석적 연구)

  • Park, Bo Guen;Kim, Dae Hyun;Chung, Jin Taek
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.10
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    • pp.779-786
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    • 2015
  • The objective of this study is to propose a new channel shape that improves thermal-hydraulic performance. The existing Zigzag channel has high pressure loss due to flow separation and reverse flow. To improve this disadvantage, partial straight channel is inserted into bended points. Also, the effects of straight channel's length change on heat transfer and pressure loss are analyzed. Thermal-hydraulic performance of the new shape and existing Zigzag channel are quantitatively compared in terms of Goodness Factor. Mass flow rate was changed from $1.41{\times}10^{-4}$ to $2.48{\times}10^{-4}kg/s$. The average volume goodness factor of 1mm straight channel shape was increased by 25% compared to the Zigzag channel.

Analysis of Heat Transfer and Pressure Drop During Gas Cooling Process of Carbon Dioxide in Transcritical Region (초임계 영역내 $CO_2$ 냉각 열전달과 압력강하 분석)

  • 손창효;이동건;정시영;김영률;오후규
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.1
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    • pp.65-74
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    • 2004
  • The heat transfer coefficient and pressure drop of $CO_2$(R-744) during gas cooling Process of carbon dioxide in a horizontal tube were investigated experimentally and theoretically. The experiments were conducted without oil in the refrigerant loop. The main components of the refrigerant loop consist of a receiver. a variable-speed pump. a mass flowmeter, an evaporator. and a gas cooler(test section). The main components of the water loop consist of a variable-speed Pump. an constant temperature bath. and a flowmeter. The gas cooler is a counterflow heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus The test section consists of smooth, horizontal stainless steel tube of 9.53 mm outer diameter and 7.75 mm inner diameter. The length of test section is 6 m. The refrigerant mass fluxes were 200 ~ 300 kg/($m^2{\cdot}s$) and the inlet pressure of the gas cooler varied from 7.5 MPa to 8.5 MPa. The main results were summarized as follows : The predicted correlation can evaluated the R-744 exit temperature from the gas cooler within ${\pm}10%$ for most of the experimental data, given only the inlet conditions. The predicted gas cooley capacity using log mean temperature difference showed relatively food agreement with gas cooler capacity within ${\pm}5%$. The pressure drop predicted by Blasius estimated the pressure drop on the $CO_2$ side within ${\pm}4.3%$. The predicted heat transfer coefficients using Gnielinski's correlation evaluated the heat transfer coefficients on the $CO_2$ side well within the range of experimental error. The predicted heat transfer coefficients using Gao and Honda's correlation estimated the heat transfer coefficients on the coolant side well within ${\pm}10\;%$. Therefore. The predicted equation's usefulness is demonstrated by analyzing data obtained in experiments.

Permeability and Strength of Cements Exposed to Supercritical CO2 for Varying Periods (초임계 CO2 - 시멘트 반응 전후의 투수율 및 강도 변화)

  • Lee, Hikweon;Kim, Kideok;Kim, Taehee;Kim, Gyo-Won
    • The Journal of Engineering Geology
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    • v.26 no.1
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    • pp.117-128
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    • 2016
  • Chemical reaction tests were performed to assess the properties of hardened specimens of cement pastes (KS-1 Portland and Class G) exposed to supercritical CO2 for 1, 10, and 100 days. After exposure, the samples' measured permeability and strength were compared with values measured for pristine samples. The pristine cements had permeabilities of 0.009~0.025 mD, which increased by one order of magnitude after 100 days of exposure (to 0.11~0.29 mD). The enhancement of permeability is attributed to the stress release experienced by the samples after removal from the pressure vessel after exposure. Despite its enhancement, the measured permeability mostly remained lower than the API (American Petroleum Institute) recommended maximum value of 0.2 mD. The degradation of the cement samples due to exposure to supercritical CO2 led to a layer of altered material advancing inwards from the sample edges. The Vickers hardness in the altered zone was much higher than that in the unaltered zone, possibly owing to the increase in density and the decrease in porosity due to the carbonation that occurred in the altered zone. Hardness close to the edge within the altered zone was found to have decreased significantly, which is attributed to the conversion of C-S-H into less-strong amorphous silica.

Phase Behavior on the Binary and Ternary System of Poly(propyl acrylate) and Poly(propyl methacrylate) with Supercritical Solvents (초임계 용매를 포함한 Poly(propyl acrylate)와 Poly(propyl methacrylate)의 이성분 및 삼성분계에 관한 상거동)

  • Byun, Hun-Soo;Lee, Ha-Yeun
    • Korean Chemical Engineering Research
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    • v.40 no.6
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    • pp.703-708
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    • 2002
  • High pressure phase behavior data for poly(propyl acrylate) and poly(propyl methacrylate) with supercritical $CO_2$, ethylene, propane, butane, propylene, 1-butene, dimethyl ether, and $CHClF_2$ were measured in the temperature range from $23^{\circ}C$ to $186^{\circ}C$ and at pressures up to 2,400 bar. The cloud point were obtained at dissolved pressure below 2,070, 1,400, 1,880, 450, 2,200, 250, and 150 bar for poly(propyl acrylate) in supercritical $CO_2$, ethylene, propane, propylene, butane, 1-buthen, and dimethyl ether, respectively. The temperature range is $23-175^{\circ}C$. The poly(propyl methacrylate) does not dissolve in $CO_2$ at temperature of $240^{\circ}C$ and pressure 2,900 bar. The poly(propyl methacrylate)-propane, poly(propyl methacrylate)-butane, poly(propyl methacrylate)-propylene, poly(propyl methacrylate)-1-butene, and poly(propyl methacrylate)-$CHClF_2$ systems were dissolved at the pressures less than 2,390 bar, below 2,100 bar, below 570 bar, below 310 bar, below 300 bar, and below 170 bar, respectively. The temperature range shows from 40 to $186^{\circ}C$. The phase behavior of between binary poly(propyl acrylate)-$CO_2$ and poly(propyl acrylate)-dimethyl ether system were measured from upper critical solution temperature region to lower critical solution temperature region with added dimethyl ether concentrations of 5, 15 and 50 wt%.

Heat Transfer Characteristics of CO2 at Supercritical Pressure in a Vertical Circular Tube (수직원형관에서 초임계압 CO2의 열전달 특성)

  • Yoo, Tae-Ho;Bae, Yoon-Yong;Kim, Hwan-Yeol
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.1
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    • pp.23-31
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    • 2011
  • At supercritical pressure, the physical properties of fluid change substantially and the heat transfer at a temperature similar to the critical or pseudo-critical temperature improves considerably; however, the heat transfer may deteriorate due to a sudden increase in the wall temperature at a certain condition of a mass and heat flux. In this study, the heat transfer rates in $CO_2$ flowing vertically upward and downward in a circular tube with a diameter of 4.57 mm under various conditions were calculated by measuring the temperature of the outer wall of the tube. The published heat transfer correlations were analyzed by comparing their prediction values with 7,250 experimental data. By introducing a buoyancy parameter, a heat transfer correlation, which could be applied only to a normal heat transfer regime, was extended such that it can be applied to regime of heat transfer deterioration. The published criteria for heat transfer deterioration were evaluated against the conditions obtained from the experiment in this study.

A Study on the Removal of Aromatic Compounds from Soil and Zeolite Using Supercritical Carbon Dioxide (초임계 이산화탄소를 이용한 토양과 제올라이트중의 방향족 화합물 제거에 관한 연구)

  • Bae, Won;Shin, Bohyun;Kang, Hoseok;Kim, Hwayong
    • Clean Technology
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    • v.9 no.4
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    • pp.197-206
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    • 2003
  • We performed removal of aromatic compounds, benzene and toluene, from soil and zeolite using supercritical carbon dioxide. Extraction was performed at $50^{\circ}C$ and 27.7 MPa with changing the extent of pollutant concentration and the results were compared and analyzed. Experiments were carried out using flow method and high pressure extractor of 1.27 cm in diameter and 25cm in length was used. The pollutants were sampled every ten minutes and their concentrations were analyzed with GC/FID. As a result, highly contaminated sample followed solubility/elution model and slightly contaminated sample followed desorption/kinetics model. At the same condition benzene was extracted faster than toluene. In the case of zeolite, more time is required to extract pollutants than soil. This phenomena was due to high adsorption capacity of zeolite. In the case of highly contaminated soil, we could correlate experimental data using simple Brady's fixed bed extractor model. But in the case of slightly contaminated soil, that was governed with desorption/kinetics model, there was some errors.

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