• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.125.1-125.1
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• 2010

A high efficiency polymer electrolyte membrane (PEM) fuel cell stack was developed for pressurized pure hydrogen and oxygen supplying conditions. The design objective for the cell stack was to maximize the electric efficiency and to minimize exhaust-gas emissions from it simultaneously. To achieve this objective, the cell stack was designed to use pure hydrogen and oxygen as fuel and oxidant, respectively, and to be operated under high gas inlet pressures and in a stage-wise dead-end operation mode. Major components constituting the cell stack, such as membrane electrode assembly, bipolar-plate, and gasket, have been developed to meet a target durability even in severe operating conditions: high gas inlet pressures and usage of pure oxygen. A high-power fuel cell stack was assembled using these components to verify the performance. The cell stack showed a good performance in terms of the efficiency and maximum power output.

• Environmental Engineering Research
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• 제25권4호
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• pp.498-505
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• 2020

This study analyzes the velocity and pressure incurred by protruding shapes installed within the inlet part of a pressurized membrane module during operation to determine the fluid flow distribution. In this paper, to find the flow distribution within a module, it investigates the velocity and pressure values at cross-sectional and outlet planes, and 9 sections classified on outlet plane using computational fluid dynamics. From the Reynolds number (Re), the fluid flow was estimated to be turbulent when the Re exceeded 4,000. In the vertical cross-sectional plane, shape 4 and 6 (round-type protrusion) showed the relatively high velocity of 0.535 m/s and 0.558 m/s, respectively, indicating a uniform flow distribution. From the velocity and pressure at the outlet, shape 4 also displayed a relatively uniform fluid velocity and pressure, indicating that fluid from the inlet rapidly and uniformly reached the outlet, however, from detailed data of velocity, pressure and flowrate obtained from 9 sections at the outlet, shape 6 revealed the low standard deviations for each section. Therefore, shape 6 was deemed to induce the ideal flow, since it maintained a uniform pressure, velocity and flowrate distribution.

• 대한기계학회논문집B
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• 제37권5호
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• pp.503-511
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• 2013

연료전지 시스템에서 공급기체 가습은 연료전지 성능효율과 전해질막 수명 향상 측면에서 중요하다. 판형 막 가습기는 일반적으로 유동 방향에 따라 직교류와 대향류로 구분되고 판과 막 사이에서 고온 다습한 공기와 저온 건조한 공기의 열 및 물질전달이 이루어진다. 본 연구에서는 현열 및 잠열 ${\varepsilon}$-NTU 법을 이용하여 입구 온도와 유량 변화에 따른 열 및 물질전달 성능 변화를 유동 방향에 따라 비교하였다. 이를 통하여 저유량 일 때 대향류는 직교류 보다 열 및 물질전달 성능이 높은 것을 알 수 있었고 유량이 증가함에 따라 성능 차이가 감소되는 것을 확인할 수 있었다. 그리고 입구온도가 증가함에 따라 열전달 성능 변화는 작은 반면 물질전달 성능 변화는 비선형으로 크게 감소되는 결과를 얻었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.229-232
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• 2005

This paper presents the design and fabrication of backflow prevented Micropump using the metal membrane. The Micropump is consisted of the lower plate, metal membrane, upper plate and the piezoelectric-element. The lower plate includes the micro channel and the inlet, outlet of the Micropump. The upper plate includes the micro channel and connects the piezoelectric-element. These plate are fabricated on the Pyrex glass wafer by sandblasting process. The metal membrane does roll of check valve that is prevented backflow of the Micropump. The metal membrane is fabricated on the stainless steel by laser machining. Piezoelectric-element is actuated the Micropump and controlled flowing of fluid. The Micropump is fabricated by bonding process of these multi-layer.

• 한국해양학회지:바다
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• 제12권3호
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• pp.244-250
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• 2007

MIMS 시스템은 액체 시료의 용존 가스 농도를 정확하게 측정하는데 이용되어 왔는데, 본 연구에서는 해수와 퇴적물 공극수에 존재하는 용존 메탄 농도를 정량화하는데 사용되었다. 측정의 정밀성을 파악하기 위하여, 여러 분압의 메탄 농도에 대해서 포화된 액체 시료를 준비하였으며 이를 MIMS 시스템으로 측정하였다. 측정된 값은 용존 기체의 포화 상수로부터 계산된 값과 잘 일치하였다. 측정의 표준 오차는 평균값의 $0.13{\sim}0.9%$ 정도였다. 이 시스템을 이용하여 한반도 남해안 인근 해수의 용존 메탄 농도를 측정한 결과, 용존 메탄의 깊이별 분포는 물리적인 요소가 좌우하고 있음을 알 수 있었다. MIMS system을 이용하여, 각 수괴 간의 미세한 용존 메탄 농도의 차이를 구분하여 살펴볼 수 있었다. 또 다른 실험에서는 MIMS 시스템의 inlet 부분을 탐침 형태로 제작하여 퇴적물 깊이에 따른 용존 메탄을 측정할 수 있었다.

• 멤브레인
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• 제28권2호
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• pp.83-89
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• 2018

열유도상분리법(TIPS) 및 연신의 복합공정으로 막증류(Membrane distillation, MD)용의 소수성 및 다공성 PVDF 중공사 분리막을 제조하였다. 제조된 분리막을 막증류 공정에 적용하여 처리수량을 극대화하기 위한 방안으로 모듈의 형태와 운전조건 및 병렬 연결 시 배관의 크기 영향을 확인하고자 하였다. 진공 막증류 모듈의 최적화 실험에서는 모듈 내 분리막의 충진율과 길이가 증가할수록 플럭스는 감소하며, 진공포트의 위치는 모듈을 수직으로 연결하였을 때 원수의 inlet 방향에 위치할수록 플럭스 측면에서 가장 유리한 것으로 확인되었다. 모듈의 헤더배관의 크기선정에서는 중공사막의 내경면적과 헤더배관의 내경면적이 동일할 경우 최대 플럭스를 나타냄을 확인할 수 있었으며, 모듈 내 선속도가 높을수록 높은 플럭스를 나타내지만 모듈에 작용하는 압력 역시 비례하여 증가하기 때문에 최적 선속도를 찾는 것이 필요하다.

• 상하수도학회지
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• 제34권6호
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• pp.393-402
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• 2020

In the membrane process, it is important to improve water treatment efficiency to ensure water quality and minimize membrane fouling. In this study, a pilot study of membrane process using reservoir water was conducted for a long time to secure high flux operation technology capable of responding to influent turbidity changes. The raw water and DAF(Dissolved Air Flotation) treated water were used for influent water of membrane to analyze the effect of water quality on the TMP (Trans Membrane Pressure) and to optimize the membrane operation. When the membrane flux were operated at 70 LMH and 80 LMH under stable water quality conditions with an inlet turbidity of 10 NTU or less, the TMP increase rates were 0.28 and 0.24 kPa/d, respectively, with minor difference. When the membrane with high flux of 80 LMH was operated for a long time under inlet turbidity of 10 NTU or more, the TMP increase rate showed the maximum of 43.5 kPa/d. However, when the CEB(Chemically Enhanced Backwash) cycle was changed from 7 to 1 day, it was confirmed that the TMP increase rate was stable to 0.23 kPa/d. As a result of applying pre-treatment process(DAF) on unstability water quality conditions, it was confirmed that the TMP rise rates differed by 0.17 and 0.64 kPa/d according to the optimization of the coagulant injection. When combined with coagulation pretreatment, it was thought that the balance with the membrane process was more important than the emphasis on efficiency of the pretreatment process. It was considered that stable TMP can be maintained by optimizing the cleaning conditions when the stable or unstable water quality even in the high flux operation on membrane process.

• Journal of Korean Society for Atmospheric Environment
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• 제12권E호
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• pp.19-28
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• 1996

A pore concensation-based separation technique was studied experimentally using toluene and xylene in a nitrogen stream. The removal rate of toluene and xylene on a microporous ceramic membrane was enhanced by increasing the partial pressure difference across the membrane, but the selectivity was reduced with increasing flux of nitrogen. This was found both in vacuum and pressure modes of operation. The experimental results from this study suggest that the pores mear the inlet portion of the module were filled with the organic solvent while the pores near the exit section of the module were slightly opened as the solvent concentration was depleted along the module. In the case of xylene, the rate of N$_{2}$ permeation was reduced considerably relative to toluene, resulting in a much higher separation gactor. Condensibility of xylene appeared to be higher than that of toluene, the potential for pore condensation-based separation of xylene was also found to be higher than that for toluene.

• 상하수도학회지
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• 제7권2호
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• pp.1-8
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• 1993

Constant rate permeat experiments using polyethylene hollow fiber membranes were conducted in order to treat dam water for potable purposes. The experiments consisted of two series. One series consisted of six bench scale apparatuses, each having a $0.4m^2$ nominal permeat area, which were applied in determining the optimum operating conditions. The other series was comprised of two pilot scale plant, each having a $40m^2$ nominal permeat area. Both series were operated for six months. Coagulant was not used in any of the experiments. To suppress an increase in differential pressure between the inlet and outlet of the membrane, a hydrophilic membrane was found to be better than a hydrophobic membrane. Also, permeat flux should not be more than 0.03m/h, and air bubbling-washing for 1 minute should be conducted at 180 minutes intervals or less.

• 대한환경공학회지
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• 제37권11호
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• pp.607-618
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• 2015

본 연구에서는 CFD 모사와 PIV 기법을 이용하여 실규모의 사이드 스트림 방식의 막 모듈을 대상으로 유입부의 수리구조를 개선하여 모듈로 유입되는 유입 유량을 수직으로 균등하게 분포시킬 수 있는 방안을 제시하고 이를 실험적으로 검증하고자 하였다. 사이드 스트림 방식의 막 모듈을 대상으로 유입 유량을 수직으로 균등하게 분포시킬 수 있는 방안을 CFD로 설계한 결과, 내부 유입 수리구조에 유공 격벽을 설치함으로써 모듈내로의 유입유량은 표준편차 기준으로 약 40% 정도 감소됨을 확인하였다. 또한 CFD 결과를 검증하고 사이드 스트림 막 모듈의 편중된 오염의 원인을 조사하기 위해 수행된 입자영상유속 측정 결과로부터 유입구 반대편 유공에서 막 모듈 내부로 들어오는 수체의 유속이 상대적으로 커 수체의 모멘텀이 유입구 측벽에 강한 전단력을 발생하지만 유입구 반대 측벽에서는 사류가 형성됨을 확인하였다.