• Korean Chemical Engineering Research
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• 제43권2호
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• pp.249-258
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• 2005

활성탄을 흡착제로 하여 2탑 6단계의 PSA(압력 순환식 흡착) 공정을 통하여 수소/메탄(부피비로 60%/40%)의 이성분 혼합기체에서 수소를 분리하는 연구를 수행하였다. PSA 공정에서 순도 및 회수율에 영향을 미치는 흡착압력, 공급 가스 유량, P/F 비를 변수로 하여 실험과 전산모사를 수행하였다. 본 공정에서 정상 상태는 15 cycle 이후에 도달하는 것을 알 수 있었다. P/F 비와 압력이 증가하고 공급 유량이 감소할 때 수소의 순도가 증가하였고, 반면에 회수율이 감소하는 것을 알 수 있었다. PSA 공정 전산 모사와 실험을 토대로 순도와 회수율이 최대일 때 최적의 PSA 운전 조건을 정하였다. 최적의 운전 조건은 공급가스의 유량이 22 LPM이고, 흡착 압력이 11 atm이며, P/F 비는 0.10으로 나타났고, 그 결과 수소의 회수율은 75% 이상 얻어졌으며, 순도는 99% 이상의 수소를 얻을 수 있었다. 본 연구에서는 비등온 비단열 상태를 고려하였으며, LDF(linear driving force) 모델과 LRC(loading ratio correlation) 등온식을 고려하여 실험과 예상치를 비교하였다.

• 대한환경공학회지
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• 제32권10호
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• pp.936-941
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• 2010

본 연구에서는 나노 사이즈의 은입자가 첨착된 입상활성탄을 적용하여 기체상 포름알데히드의 흡착특성을 확인하고 실험결과를 수치해석 결과와 비교 평가하였다. 나노 은입자 첨착활성탄에 대해 BET분석 결과, 나노 은입자가 활성탄 표면의 미세기공을 막아 활성탄의 비표면적이 다소 감소하였으며, 특히 $20{\AA}$ 이하 micropore의 총 부피가 크게 감소한 것을 확인하였다. 포름알데히드에 대한 등온흡착실험 결과, 최대 겉보기 흡착능은 나노 은입자 첨착활성탄의 값이 일반활성탄에 비해 높았다. BET 표면적이나 미세기공의 감소에도 불구하고 나노 은입자 첨착활성탄이 향상된 포름알데히드 제거능을 나타낸 것은 은입자 첨착활성탄에서 흡착 외에 추가적인 포름알데히드의 촉매산화가 이루어지고 있기 때문으로 판단된다. 흡착강도를 의미하는 1/n은 두 가지 활성탄에 대해 모두 비슷한 기울기를 보여 활성탄의 표면 개질에 의해 활성탄 고유의 물리 화학적 흡착 성능은 영향을 받지 않은 것으로 판단된다. 연속유입 실험 결과에서도 나노 은입자 첨착활성탄이 일반활성탄보다 높은 포름알데히드 제거능을 나타내어 포름알데히드 산화효과를 확인하였다. 활성탄의 연속유입 실험결과를 수치해석 결과와 비교했을 때 나노 은입자 첨착활성탄에 대해서는 나노 은입자에 의한 산화효과를 반영하지 않고 있지 않아 실험결과와 거의 일치하지 않았다. 따라서 금속물질로 표면 개질된 활성탄 컬럼 설계에 수치해석 모델을 활용하고자 한다면 흡착뿐만이 아니라 촉매산화 효과가 반영된 새로운 수치모델의 개발이 필요할 것으로 판단된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권4호
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• pp.323-325
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• 2004

To model the behavior of expanded beds with aqueous feed streams containing different amounts of glycerol, we previously developed a modified Stokes expression that correlates the terminal settling velocity of a particle of a solution with the properties of the particle (particle diameter and density) and the solution (density and viscosity). Two empirical parameters, the effective diameter of the poly-disperse resins for protein adsorption and an exponent of non-unity for $(\rho_{P}-\rho)/\mu$ term, are introduced in the modified Stokes expression. We applied the same type of the modified Stokes expression in combination with the Richardson-Zaki correlation to the published results [1], and found that the expansions of the beds with feed streams containing different amounts of E. coli homogenates can also be successfully described.

• 상하수도학회지
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• 제20권5호
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• pp.709-717
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• 2006

This research was conducted to figure out the feasibility of several sorption materials to treat various pollutants in road runoff. In advance of the major feasibility test with various sorption materials, the separation process with $1.2{\mu}m$ filter was conducted and showed that slight portion of pollutants was removed(Orgamic pollutant - 20%, Nutrient salt - 50%, Heavy metals - 0~30%). To remove dissolved pollutants in runoff, various materials were tested through an isotherm sorption experiment. As a result, GAC showed most effective material among them to lessen most contaminants such as organic compounds and nutrients. On the other hand, ion-exchange resin and Zeolite showed limited usefulness on the some heavy metals. Freundlich model was most suitable for the current experiment data, and the amount of adsorbent (GAC) could calculated based on this model.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.281-285
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• 2000

The effect of the presence of dissolved organic matters(DOM) on the binding of phenanthrene to cetylpyridinium chloride(CPC) coated sand was investigated. The distribution coefficient of phenanthrene increased with increase of sufactant coverage, and decreased with the presence of dissolved organic matters except for the 1.600mg/g coverage case. Both Aldrich humic acid and extracted dissolved organic matter showed the similar tendency. For the quantification of the overall distribution coefficient, this study presented mass distribution model and estimated the sorption equilibrium coefficients of hydrophobic organic compounds(HOCs) in multi system. The suggested model combined a series of sorption equilibrium relationships including the adsorption of DOMs on sorbents, the binding between HOCs and DOMs, and the sorption of HOCs on sorbents with or without DOMs.

• Applied Science and Convergence Technology
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• 제23권4호
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• pp.169-178
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• 2014

Fluid model based numerical analysis is done to simulate a low damage etch back system for 20 nm scale semiconductor fabrication. Etch back should be done conformally with very high material selectivity. One possible mechanism is three steps: reactive radical generation, adsorption and thermal desorption. In this study, plasma generation and transport steps are analyzed by a commercial plasma modeling software package, CFD-ACE+. Ar + $CF_4$ ICP was used as a model and the effect of reactive gas inlet position was investigated in 2D and 3D. At 200~300 mTorr of gas pressure, separated gas inlet scheme is analyzed to work well and generated higher density of F and $F_2$ radicals in the lower chamber region while suppressing ions reach to the wafer by a double layer conducting barrier.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.79-84
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• 2004

We evaluated the reduction performance of NOx storage catalyst and TWC for lean-burn natural gas engine by the model gas. The method of unsteady state reaction was used to compare with reduction performances of NOx storage catalyst and TWC. It was found that the effective parameter was rich spike duration, temperature of the model gas. In the presence of $CO_2$ and $H_2O$ in the reaction mixture was decreased the NOx reduction performance.

• 청정기술
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• 제8권2호
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• pp.93-99
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• 2002

Adsorption dynamics for toluene and trichloroethylene with an isothermal fixed bed of activated carbon fiber were investigated. Equilibrium isotherms were measured by a static method for toluene and trichloroethylene onto activated carbon fiber at temperatures of 298, 323, and 348 K and pressure up to 3 kPa for toluene and 6 kPa for trichloroethylene, respectively. These results were correlated by the Toth equation. And dynamic experiments in an isothermal condition of 298 K were examined. Breakthrough curves reflected the effects of the experimental variables such as partial pressures for adsorbate and interstitial bulk velocities of gas flow. To present the column dynamics, a dynamic model based on the linear driving force (LDF) mass transfer model was applied.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.149-154
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• 1997

In order to predict the onset of the corrosion of steel bars in the concrete, a mathematical model including the diffusion of chloride ion in aqueous phase of pores, the adsorption and desorption of chloride ions to and from the surface of solid phase of concrete, and the chemical reaction of chloride ions with solid phase was established. Finite element method was employed to carry out numerical analysis. The chlorides penetrating through the wall of concrete structure from the external environment and the chlorides contained in the concrete admixture were confirmed to be two important factors to determine the onset of corrosion of steel bars.

• 한국전산유체공학회지
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• 제14권2호
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• pp.46-51
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• 2009

The slip effect from the molecular interaction between fluid particles and solid surface atoms plays a key role in microscale fluid transport and heat transfer since the relative importance of surface forces increases as the size of the system decreases to the microscale. There exist two models to describe the slip effect: the Maxwell slip model in which the slip correction is made on the basis of the degree of shear stress near the wall surface and the Langmuir slip model based on a theory of adsorption of gases on solids. In this study, as the first step towards developing a general purpose numerical code of the compressible Navier-Stokes equations for computational simulations of microscale fluid flow and heat transfer, two slip models are implemented into a finite element numerical code of a simplified equation. In addition, a pressure-driven gas flow in a microchannel is investigated by the numerical code in order to validate numerical results.