• Title/Summary/Keyword: temperature separation

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Numerical Study on the Suppression of Shock Induced Separation on a Strongly Heated Wall (강하게 가열된 벽면 위에서 충격파에 의한 경계층 박리의 제거에 관한 수치 연구)

  • LEE Doug-Bong;SHIN Joon-Cheol
    • Journal of computational fluids engineering
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    • v.2 no.2
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    • pp.59-72
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    • 1997
  • A numerical model is constructed to simulate the interactions of oblique shock wave / turbulent boundary layer on a strongly heated wall. The heated wall temperature is two times higher than the adiabatic wall temperature and the shock wave is strong enough to induce boundary layer separation. The numerical diffusion in the finite volume method is reduced by the use of a higher order convection scheme(UMIST scheme) which is a TVD version of QUICK scheme. The turbulence model is Chen-Kim two time scale model. The comparison of the wall pressure distribution with the experimental data ensures the validity of this numerical model. The effect of strong wall heating enlarges the separation region upstream and downstream. In order to eliminate the separation, wall suction is applied at the shock foot position. The bleeding slot width is about same as the upstream boundary layer thickness and suction mass flow is 10% of the flow rate in the upstream boundary layer. The final configuration of the shock reflection pattern and the wall pressure distribution approach to the non-viscous value when wall suction is applied.

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Phase Separation Characteristics of Low Temperature Bunsen Reactions In Sulfur-Iodine Hydrogen Production Process (황-요오드 수소 제조 공정에서 저온 분젠 반응의 상 분리 특성)

  • Han, Sang-Jin;Lee, Kwang-Jin;Kim, Hyo-Sub;Kim, Young-Ho;Park, Chu-Sik;Bae, Ki-Kwang;Lee, Jong-Gyu
    • Journal of Hydrogen and New Energy
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    • v.22 no.4
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    • pp.424-431
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    • 2011
  • The Sulfur-Iodine(SI) thermochemical hydrogen production process consists of three sections, which are so called the Bunsen reaction section, the $H_2SO_4$ decomposition section and the HI decomposition section. In order to identify the phase separation characteristics in the reaction conditions with the high solubility of $SO_2$, we conducted the Bunsen reaction at the low temperatures, ranging from 283 to 298K, with the $I_2/H_2O$ molar ratios of 2.5/16.0 and 3.5/16.0. The molar ratios of HI/$H_2SO_4$ products obtained from low temperature Bunsen reactions were ca. 2, indicating that there were no side reactions. The amount of reacted $SO_2$ was increased with decreasing the temperature, while the amounts of unreacted $I_2$ and $H_2O$ were decreased. In the phase separation of the products, the amount of a $H_2SO_4$ impurity in $HI_x$ phase was increased with decreasing the temperature, though the temperature has little affected on HI and $I_2$ impurities in $H_2SO_4$ phase.

A Study on Thermodynamics for Compositional Separation in Co-Cr magnetic Alloy Films (Co-Cr 자성합금 박막의 조성적 상분리 현상의 열역학적 고찰)

  • Song, O-Seong;Jeon, Jeon-An
    • Korean Journal of Materials Research
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    • v.9 no.4
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    • pp.341-344
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    • 1999
  • We reported compositional separation(CS) into Co-enriched and Cri-enriched components inside the grains of Co-Cr based thin films prepared by rf sputtering. CS strongly depends on the sputtering conditions of substrate temperature and target composition. Tuning the microstructure of the Co-Cr films is important in order to employ the CS for high-density magnetic recording. We investigated the origin of CS from thermodynamic viewpoint. We employ a spinodal decomposition-like model to describe the origin of the CS in Co-Cr films. We consider the total free energy of the Co-Cr films as the sum of several free energies of; 1) thermodynamic mixing entropy of a binary solid solution, 2) magnetic ordering interaction(MOI) energy below the Curie temperature, and 3) excess interaction energy(XS) caused by the sputtering process as a function of temperature and composition. Those energies distorted the total free energy like the spinodal decomposition and caused the compositionally separated fine microstructure inside the grains. If the second derivative of the total free energy with respect to Cr composition becomes negative at a given substrate temperature, we may observe a metastable compositional separation inside the Co-Cr alloy films. We expect to exploit the microstructure of CS for ultra-high density magnetic recording.

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Effect of different conditions on pervaporation dehydration in CA/NYL66 blend membrane

  • Kazemzadeh, Akram;Mousavi, Seyed M.;Mehrzad, Jamshid;Motavalizadehkakhky, Alireza;Hosseiny, Malihesadat
    • Membrane and Water Treatment
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    • v.10 no.6
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    • pp.441-449
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    • 2019
  • In this study, cellulose acetate (CA) / nylon66 (NYL66) (95/5) blend membranes with different thicknesses were prepared by a solvent evaporation method. The effects of membrane thickness (almost $7-25{\mu}m$), feed concentration (70-95 wt.% isopropanol), and feed temperature ($30-60^{\circ}C$) were investigated on the performance of membrane in the separation of isopropanol-water mixtures. With regard to the results of sorption experiments, it was found that the increase of feed temperature enhanced the overall sorption while by increasing feed concentration, the overall sorption passed through a maximum value at 70 wt. % isopropanol (IPA). The best separation factor 3080.51 was gained at high isopropanol concentration 95 wt.%, low feed temperature $30^{\circ}C$, and high membrane thickness $24.62{\mu}m$. Regarding the pervaporation separation index, the obtained results showed that proper values for the thickness of membrane, feed temperature, and isopropanol concentration in feed were $24.62{\mu}m$, $40^{\circ}C$, and 70 wt.%, respectively.

Nonlinear optical behavior of binary mixture protein and water near the phase separation temperature (상분리 온도 근방에서 섞임체 단백질-물의 비선형 광학적 특성)

  • 조창호;김태균;서영석
    • Korean Journal of Optics and Photonics
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    • v.8 no.6
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    • pp.461-465
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    • 1997
  • The 3rd order nonlinear optical susceptibility was measured through the self-induced ellipse rotation. The phase separation temperature increases with the increase of salt and it decreases with the increase of glycerol.

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Treatment and Reuse of Acrylic Wastewater using Membrane Separation System

  • Lee, Kwanghyun
    • Proceedings of the Membrane Society of Korea Conference
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    • 2004.05a
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    • pp.117-120
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    • 2004
  • The separation characteristics were investigated with the variations of pressure and temperature using ultrafiltration and reverse osmosis membrane module sets composed of different membrane types and materials. TDS, T-N and COD removal efficiencies were not affected and low with the change of temperature and pressure in case of using UF modules contained in module set 1, 2, 3. TDS, T-N and COD removal efficiencies were very high in RO modules. The final water quality of acrylic wastewater was satisfied within the discharge limit value of plant wastewater. It was known that membrane module sets could be used for the reuse of wastewater.

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The removal of iron oxides from raw materials by superconducting magnetic separator (초전도 자기분리에 의한 원재료에서의 철산화물 제거)

  • Kwon, Jun-Mo;Ha, Dong-Woo;Kim, Tae-Hyung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.193-193
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    • 2010
  • Magnetic separation is expected to be applied for material refinement as an important supporting technology. In the superconducting magnetic separation, the cohesive force between particles is strong compared with that in the other magnetic separation. The use of high magnetic field by the superconducting magnet enhances the magnetic substance capture ability of the magnetic separation. Industrial raw materials was used for the superconducting magnetic separation. Cry-cooled, NB-Ti superconducting magnet with. 100 mm room temperature bore and 600 mm of height was used for magnetic separator.

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Treatment of Aquacultural Recirculating Water by Foam Separation - I. Characteristics of Protein Separation- (포말 분리법을 이용한 양어장 순환수 처리 - I Protein 분리특성 -)

  • SUH Kuen-Hack;LEE Min-Gyu
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.28 no.5
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    • pp.599-606
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    • 1995
  • The feasibility of foam separation to remove protein produced from fish culture water was investigated, By assuming foam separation column as a single well-mixed pool, a simplified model for foam separator conditions was alse studied under the batch operation. The model indicated that the protein removal could be described as a first-order reaction whose rate increases with both superficial air velocity and protein concentration in the bulk solution. from ,the results of an experimental study on the effects of superficial air velocity, the protein concentration, temperature, and pH on protein removal, the superficial air velocity and initial protein concentration in bulk solution were found to be important operational factors. Other experimental results important that foam separator operated under batch conditions would be considered as a completely mixed reactor. The protein removal rate by foam separation process was increased proportionally with the superficial air velocity, and the adsorptive removal rate of protein was found to obey Langmuir adsorption formula. The preposed simplified model was verified with the experimental data obtained from this study. Under the experimental range used, both temperature and pH did not affect the protein removal.

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Development of Chiral Stationary Phases for the Gas Chromatographic Separation of Amino Acid Enantiomers New diamide chiral stationary phase (아미노산 광학이성질체 분리를 위한 가스크로마토그라피용 키랄 고정상의 개발 -새로운 diamide계 키랄 고정상의 응용-)

  • Park, Man-Ki;Yang, Jeong-Sun;Lee, Mi-Yung
    • YAKHAK HOEJI
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    • v.33 no.2
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    • pp.129-139
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    • 1989
  • New diamide chiral stationary phases of four systematically substituted optically active N-(N-benzoyl-L-amino acid)-anilide synthesized from L-valine, L-leucine, L-isoleucine, and L-phenylalanine were described. The behaviors of these diamides as optically active stationary phases for the separation of N-trifluoroacetyl-D,L-amino acids were examined with respect to separation factors(${\alpha}$) and thermodynamic properties of interaction. The separation of twelve N-trifluoroacetyl-D,L-amino acid isopropyl esters were improved by the order of N-(N-benzoyl-L-leucyl)-anilide>N-(N-benzoyl-L-isoleucyl)-anilide>N-(N-benzoyl-L-valyl)-anilide>N-(N-benzoyl-L-phenylalanyl)-anilide. Eight amino acid derivatives with non-polar R-group and threonine, serine, aspartic acid, and glutamic acid enantiomers were separated on N-(N-benzoyl-L-leucyl)-anilide as chiral stationary phase with good separation factor between 1.07-1.25. The separation factors decreased with respect to increasing column temperature. Possible working temperature of diamide phase was between $130-190^{\circ}C$ for N-(N-benzoyl-L-phenylalanyl)-anilide and $130-180^{\circ}C$ for other three diamide phases. The differential Gibb's free energy (${\Delta}{\Delta}G$) of enantiomers was in the range of -100--180 cal/mol for ten amino acids and -40--60 cal/mol for alanine and aspartic acid.

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The Relationship between Affinity of Membrane and Optimum Operation Conditions in the Pervaporation of Aqueous Ethanol (에탄올 수용액의 투과증발에 있어서 막의 친화성과 최적 조업조건의 관계)

  • 전종기;명완재;임선기
    • Membrane Journal
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    • v.1 no.1
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    • pp.34-43
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    • 1991
  • The relationships between affinity of membranes and optimum operation conditions were investigated in the pervaporation of water(1)/ethanol(2) mixture through cellulose acetate(CA) membranes having more affinity to water and silicone rubber(SR) membranes having more affinity to ethanol. CA and SR membranes were prepared and amount of sorption, sorption selectivity, pervaporation separation factor and pervaporation rate in both of membranes were determined and compared. The effects of downstream pressure were analyzed using Thompson diagram and the sorption and pervaporation characteristics with composition of feed and operation temperature were examined in terms of affinity, activity coefficient, plasticizing effect and activation energy of individual species. In the separation of water through CA membranes, high performance of both pervaporation separation factor (water to ethanol, $[\alpha^2_1]_{PV}$) and pervaporation rate was obtained in the conditions of low downstream pressure, middle range of feed concentration and high temperature. In the separation of ethanol through SR membranes, pervaporation separation factor(ethanol to water, $[\alpha^2_1]_{PV}$) increased with downstream pressure and decreased with concentration of ethanol in feed and operation temperature, while pervaporation rate showed opposite trends to those of ($[\alpha^2_1]_{PV}$).

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