• Title/Summary/Keyword: Sweep gas

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Permeate Flux Analysis of Direct Contact Membrane Distillation (DCMD) and Sweep Gas Membrane Distillation (SGMD) (직접접촉식과 동반기체식 막증류 공정의 투과수 변화에 따른 비교해석)

  • Eum, Su-Hwan;Kim, Albert S.;Lee, Yong-Taek
    • Membrane Journal
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    • v.21 no.3
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    • pp.236-246
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    • 2011
  • In this study, we used prepared a cylindrical module consisting 100 hollow fibers of commercialized (hydrophobic) polyethylene membrane of $0.4{\mu}m$ pore size and systematically studied performance of direct contact membrane distillation (DCMD) and sweep gas membrane distillation (SGMD) in terms of variation of permeate flux and salt rejection with respect to temperature drop across the membrane, salt concentrations in feed, and flow rates of cooling water and sweep gas. SGMD was regarded as DCMD with a sweep gas layer between permeate-side membrane surface and cooling water. Sweep gas flow decreases the permeate flux from that of DCMD by providing an additional gas-layer resistance. We compared DCMD and SGMD performance by using mass balance with a fitting parameter (${\omega}$), indicating fraction of permeate flow rate.

Hydrogen separation of $V_{99.8}B_{0.2}$ Alloy Membrane in Water-gas shift Reaction (수성 가스 전이반응에서 $V_{99.8}B_{0.2}$ 합금 분리막의 수소분리)

  • Jeon, Sung-Il;Jung, Yeong-Min;Park, Jung-Hoon;Lee, Yong-Taek
    • Membrane Journal
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    • v.22 no.1
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    • pp.16-22
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    • 2012
  • The influence of co-existing gases on the hydrogen permeation without sweep gas was studied through a Pd-coated $V_{99.8}B_{0.2}$ alloy membrane. Membranes have been investigated in the pressure range 1.5-8.0 bar under pure hydrogen, hydrogen-carbon dioxide and hydrogen-carbon monoxide gas mixture without sweep gas at $400^{\circ}C$. Preliminary hydrogen permeation experiments without sweep gas have been confirmed that hydrogen flux was $40.7mL/min/cm^2$ for a Pd-coated $V_{99.8}B_{0.2}$ alloy membrane (thick : 0.5 mm) using pure hydrogen as the feed gas. In addition, hydrogen flux was $21.4mL/min/cm^2$ for $V_{99.8}B_{0.2}$ alloy membrane using $H_2/CO_2$ as the feed gas. The hydrogen permeation flux decreased with decrease of hydrogen partial pressure irrespective of pressure when $H_2/CO_2$and $H_2/CO$mixture applied as feed gas respectively and permeation fluxes were satisfied with Sievert's law in different feed conditions. It was found from XRD, SEM/EDX results after permeation test that the Pd-coated $V_{99.8}B_{0.2}$ alloy membrane had good stability and durability for various mixtures feeding condition.

Membrane Degassing Process of Sweep Gas-vacuum Combination Type for Ammonia Removal (스윕 가스-진공 혼합식 탈기막 시스템을 활용한 암모니아 제거)

  • Yoon, Hongsik;Min, Taijin;Lee, Gunhee;Kim, Hyoung-Tak;Shin, Wanho
    • Journal of the Korean Society of Industry Convergence
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    • v.25 no.5
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    • pp.835-842
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    • 2022
  • In this study, the membrane degassing process of the sweep gas - vacuum combination type was proposed for ammonia wastewater treatment. The effect of pH, initial ammonia concentration and scale-up on ammonia degassing performance was investigated. As a result, as the pH and the initial ammonia concentration increased, the degassing permeate flux was improved. On the other hand, the ammonia mass transfer coefficient increased as the initial ammonia reduced, which seems to be due to the driving force of the sweep gas-vacuum combination type membrane degassing system proposed in this study. In addition, 80 mg NH3/min of the ammonia degassing rate was achieved using a 6×28 inch size module. Better degassing performance is expected if consideration for maintaining vacuum pressure is involved in the scale-up design.

Ammonia Wastewater Treatment and Selective Recovery Using a Sweep Gas-Vacuum Hybrid Type Membrane Degassing Process (스윕 가스-진공 하이브리드식 탈기막 공정을 활용한 암모니아 폐수처리 및 선택적 회수)

  • Hongsik Yoon;Taijin Min;Minkyu Jeon;Sungil Lim;Sechul Oh;Kyungha Ryu;Chungsung Lee;Bosik Kang
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.6_2
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    • pp.1171-1181
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    • 2023
  • In this study, a sweep gas - vacuum hybrid type membrane degassing process was proposed for ammonia wastewater treatment. In addition, the ammonia selective recovery of the hybrid type membrane degassing process was also investigated. As a result, the hybrid type membrane degassing process showed better degassing performance (54.9 mg NH3/m2min for 360 min) than the sweep gas type (32.3 mg NH3/m2min) or vacuum type (22 mg NH3/m2min). Additionally, the hybrid type membrane degassing process showed an excellent ammonia selectivity (103 times compared to Na+ Na+, 133 times compared to Ca2+). The ammonia selectivity was appeared to be due to the conversion characteristics of ammonium ion / dissolved ammonia depending on pH. The results in this study are expected to be used in the development of ammonia wastewater treatment and ammonia recovery in the future.

Feasibility Study of Employing a Catalytic Membrane Reactor for a Pressurized CO2 and Purified H2 Production in a Water Gas Shift Reaction

  • Lim, Hankwon
    • Clean Technology
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    • v.20 no.4
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    • pp.425-432
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    • 2014
  • The effect of two important parameters of a catalytic membrane reactor (CMR), hydrogen selectivity and hydrogen permeance, coupled with an Ar sweep flow and an operating pressure on the performance of a water gas shift reaction in a CMR has been extensively studied using a one-dimensional reactor model and reaction kinetics. As an alternative pre-combustion $CO_2$ capture method, the feasibility of capturing a pressurized and concentrated $CO_2$ in a retentate (a shell side of a CMR) and separating a purified $H_2$ in a permeate (a tube side of a CMR) simultaneously in a CMR was examined and a guideline for a hydrogen permeance, a hydrogen selectivity, an Ar sweep flow rate, and an operating pressure to achieve a simultaneous capture of a concentrate $CO_2$ in a retentate and production of a purified $H_2$ in a permeate is presented. For example, with an operating pressure of 8 atm and Ar sweep gas for rate of $6.7{\times}10^{-4}mols^{-1}$, a concentrated $CO_2$ in a retentate (~90%) and a purified $H_2$ in a permeate (~100%) was simultaneously obtained in a CMR fitted with a membrane with hydrogen permeance of $1{\times}10^{-8}molm^{-2}s^{-1}Pa^{-1}$ and a hydrogen selectivity of 10000.

Prediction of Soot Emissions and Particle Size distribution by KIVA3V and SWEEP in a diesel engine (KIVA3V와 SWEEP을 이용한 디젤 엔진에서의 soot 총량 및 입자 크기 분포 예측)

  • Lee, Jaeseo;Huh, Kang Y.
    • 한국연소학회:학술대회논문집
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    • 2012.11a
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    • pp.129-132
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    • 2012
  • Computation is performed to predict number density, volume fraction and size distribution of soot particles in typical operating conditions of a diesel engine. KIVA has been integrated with the CMC routine to consider turbulence/chemistry coupling and gas phase kinetics for heat release and soot precursors. The compositions of soot precursors are estimated by tracking Lagrangian particles to consider spatial inhomogeneity and differential diffusion in KIVA. The soot simulator SWEEP is employed as a postprocessing step to calculate conditional and integral quantities of soot particles.

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Measurement of Hydrogen Crossover by Gas Chromatograph in PEMFC (고분자전해질 연료전지에서 기체 크로마토그래프에 의한 수소투과도 측정)

  • Jeong, Jaejin;Jeong, Jaehyeun;Kim, Saehoon;Ahn, Byungki;Ko, Jaijoon;Park, Kwonpil
    • Korean Chemical Engineering Research
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    • v.52 no.4
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    • pp.425-429
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    • 2014
  • Until a recent day, degradation of PEMFC MEA(membrane and electrode assembly) has been studied, separated with membrane degradation and electrode degradation, respectively. But membrane and electrode were degraded coincidentally at real PEMFC operation condition. During simultaneous degradation, there was interaction between membrane degradation and electrode degradation. Hydrogen permeability was used often to measure degradation of electrolyte membrane in PEMFC. In case of hydrogen permeability measured by LSV(Linear Sweep Voltammetry) method, the degradation of electrode decrease the value of hydrogen crossover current due to LSV methode's dependence on electrode active area. In this study hydrogen permeability was measured by gas chromatograph(GC) when membrane and electrode degraded at the same time. It was showed that degradation of electrode did not affect the hydrogen permeability measured by GC because of GC methode's independence on electrode active area.

Comparison of Measurement Method of Hydrogen Permeability in Proton Exchange Membrane Fuel Cell (고분자전해질연료전지에서 수소투과도 측정법의 비교)

  • Oh, So-Hydong;Yun, Jeawon;Lee, Daewoong;Park, Kwonpil
    • Korean Chemical Engineering Research
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    • v.57 no.4
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    • pp.507-511
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    • 2019
  • Hydrogen permeability is widely used to evaluate the polymer membrane durability of polymer electrolyte fuel cells (PEMFC). Linear sweep voltammetry (LSV) is mainly used to measure hydrogen permeability easily. There are many differences in LSV measurement method among researchers, and it is often difficult to compare the results. Therefore, in this study, we tried to confirm the accuracy by comparing the hydrogen permeability of LSV method and gas chromatograph which is difficult to measure but accurate value. The LSV method used the DOE and NEDO methods. When the hydrogen permeability was measured by varying the temperature and the relative humidity, the DOE LSV method showed an accuracy of less than 5% in the error range compared with the GC method. In the NEDO LSV method, the error was reduced when the hydrogen permeation current density was determined at the current value of 0.3 V as the DOE method.

Acoustical Dynamic Response Analysis of a Gas Turbine Combustor Using a Sine-Sweep Forcing Model (사인-스윕 가진 모델을 통한 가스터빈 연소기의 음향 동적 반응 해석)

  • Son, Juchan;Kim, Daesik
    • Journal of the Korean Society of Propulsion Engineers
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    • v.26 no.4
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    • pp.1-9
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    • 2022
  • In the current study, in order to understand the dynamic response characteristics of the system according to the external acoustic forcing, a numerical approach was developed by adding an sign-sweep forcing function to the existing network model. Through this model, the sensitivity of frequency and pressure amplitude changes according to system parameters such as the physical dimensions and boundary conditions of the target combustor was analyzed in a wide frequency range. Analysis results of dynamic response characteristics of the target combustor are shown that the frequency regime with high dynamic pressure response was similar to the instability frequency range measured in the same combustor, and in particular, the response of the system depends greatly on the location of the acoustic forcing source term.

Performance Analysis of Water Gas Shift Reaction in a Membrane Reactor (막반응기에서의 수성가스전이반응의 성능 분석)

  • Lim, Hankwon
    • Applied Chemistry for Engineering
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    • v.25 no.2
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    • pp.204-208
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    • 2014
  • This study investigated the effect of hydrogen permeance and selectivity, catalyst amount, $H_2O/CO$ ratio in a feed stream, and Ar sweep gas on the performance of a water gas shift reaction in a membrane reactor. It was observed that a minimum hydrogen selectivity of 100 was needed in a membrane reactor to obtain a hydrogen yield higher than the one at equilibrium and the hydrogen yield enhancement gradually decreased as the hydrogen permeance increased. The CO conversion in a membrane reactor initially increased with the catalyst amount and reached a plateau later for a membrane reactor with a low hydrogen permeance while the high CO conversion independent of a catalyst amount was observed for a membrane reactor with a high hydrogen permeance. For the $H_2O/CO$ ratio in a feed stream higher than 1.5, a hydrogen permeance had little effect on the CO conversion in a membrane reactor and it was found that a minimum Ar molar flow rate of $6.7{\times}10^{-6}mol\;s^{-1}$ was needed to achieve the CO conversion higher than the one at equilibrium in a membrane reactor.