• 제목/요약/키워드: Concentration Efficiency

검색결과 4,544건 처리시간 0.036초

온도와 이온농도의 변화에 대한 바나듐 레독스 플로우 배터리의 방전 효율에 관한 수치해석 (Numerical Investigation of the Discharge Efficiency of a Vanadium Redox Flow Battery with Varying Temperature and Ion Concentration)

  • 이종현;박희성
    • 대한기계학회논문집B
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    • 제40권12호
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    • pp.769-776
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    • 2016
  • 본 연구는 화학종을 포함한 반응을 위해 종합적인 보존법칙과 운동학적 모델을 사용하여 수치해석을 진행하였다. 삼차원 형상으로 전극 전위, 바나듐 이온농도, 과전압 그리고 저항손실을 계산하였다. 셀의 온도, 초기 바나듐 이온농도를 변수로 설정하고 각 변수에 따른 전압과 손실을 계산하였다. 계산된 양극, 음극에서의 과전압과 전해액 상의 저항 손실을 통해 각각의 변수가 바나듐 레독스 플로우 배터리의 전기화학적 성능에 미치는 영향을 수치해석적으로 예측하고 분석하였다. 셀의 온도가 $20^{\circ}C$에서 $80^{\circ}C$로 증가되면 전압효율은 89.34%에서 87.29%로 2.05% 감소한다. 바나듐 농도가 $1500mol/m^3$에서 $3000mol/m^3$으로 증가되면 전압효율은 88.65%에서 89.25%로 0.6% 상승하였다.

라이다 관측자료를 이용한 미세먼지 농도 산정 (Estimation of Particle Mass Concentration from Lidar Measurement)

  • 김만해;여희동;;임한철;이철규;허복행;유영석;손병주;윤순창;김상우
    • 대기
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    • 제25권1호
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    • pp.169-177
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    • 2015
  • Vertical distribution of particle mass concentrations was estimated from 8-year elastic-backscatter lidar and sky radiometer data, and from ground-level PM10 concentrations measured in Seoul. Lidar ratio and mass extinction efficiency were determined from aerosol optical depth (AOD) and ground-level PM10 concentrations, which were used as constraints to estimate particle mass concentration. The mean lidar ratio (with standard deviation) and mass extinction efficiency for the entire 8-year study period were $60.44{\pm}23.17$ sr and $3.69{\pm}3.00m^2g^{-1}$, respectively. The lidar ratio did not vary significantly with the ${\AA}ngstr{\ddot{o}}m$ exponent (less than ${\pm}10%$); however, the mass extinction efficiency decreases to $1.82{\pm}1.67m^2g^{-1}$ (51% less than the mean value) when the ${\AA}ngstr{\ddot{o}}m$ exponent is less than 0.5. This result implies that the particle mass concentration from lidar measurements can be underestimated for dust events. Seasonal variation of the particle mass concentration estimated from lidar measurements for the boundary layer, was quite different from ground-level PM10 measurements. This can be attributable to an inhomogeneous vertical distribution of aerosol in the boundary layer.

Plasma반응에 의한 NOx와 Ozone의 특성에 관한 연구 (A Study on Characteristics of NOx and Ozone by Plasma Reaction)

  • 최재욱;산외서수;최재진
    • 한국가스학회지
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    • 제4권2호
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    • pp.1-6
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    • 2000
  • 가스중에 포함되어 있는 NOx를 안전하게 처리하기 위하여 침상전극을 취부한 플라즈마 반응기를 제작하여 장치의 특성을 실험적으로 조사하여 유효성을 검정하였다. 반응가스는 $NO/N_2$ 혼합가스와 $N_2/O_2$ 혼합가스를 이용하여 초기 NO농도를 설정하고, 유속을 2${\iota}$/min으로 공급하였다. NOx의 반응특성은 방전주입전력이 높을때는 NO의 농도가 감소하였으며, 산소의 농도 증가시에 NO의 분해가 용이하고 NO의 분해에너지 효율이 높았다. 또한 NO의 농도가 증가할 수록 NO의 분해에너지 효율은 높으나 분해율은 낮았다. 오존의 특성은 방전주입전력이 높을수록 오존의 생성이 증가하고, $NO/N_2$의 농도가 증가할 수록 오존의 생성량이 감소하였다.

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난류형 클린룸내의 Layout 변화에 따른 분진제거 특성에 관한 연구 (A Study on the Phenomena of Dust Removal by the Layout Changes in the Turbulent Type Clean Room)

  • 김연희;김홍
    • 한국안전학회지
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    • 제21권5호
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    • pp.46-52
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    • 2006
  • The purpose of this paper is to investigate the removal efficiency of fine dusts as the configuration condition of machinery and equipments in Clean Room and to analyze the flowing behaviors of fine dusts as the layout of Clean Room. The layout of the Clean Room was classified into side layout type, 2 center line type and center concentration type layout, and the flow rates used in this research were 0.22m/s, 0.44m/s and 0.80m/s. Dust removal efficiency as layout change was decreased 37% for side layout type, 31% for 2 center line type and 20% for center concentration type layout at the flow rate of 0.22m/s, compared with the state without machinery and equipments in Clean Room. The efficiency was decreased 42% for side layout type, 22% for 2 center line type and 8% for center concentration type layout at the flow rate of 0.44m/s, and decreased 20% for side layout type, 18% for 2 center line type and 10% for center concentration type layout at the flow rate of 0.80m/s. According to the result of dust removal behavior, $0.3{\mu}m,\;1{\mu}m\;and\;3{\mu}m$ dust except for $5{\mu}m$ showed the higher change of the behavior in side layout type than in center concentration type layout due to the change of air flow. It was confirmed that removal behavior depends on the layout of machinery and equipments as the dust size decreases.

Investigation of Nickel Removal from Heavy Metal Containing Industrial Wastewater by Electrocoagulation Method

  • Baybars Ali, Fil;Cansu, Elgun;Sevim Alya, Cihan;Sermin, Gunaslan;Alper Erdem, Yilmaz
    • Journal of Electrochemical Science and Technology
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    • 제13권4호
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    • pp.424-430
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    • 2022
  • In the study, Ni2+ (nickel) removal from synthetically prepared wastewater by electrocoagulation method, which is one of the electrochemical treatment processes, was investigated and parameters such as current density, pH, mixing speed, initial Ni2+ concentration, supporting electrolyte type and concentration were determined to determine Ni2+ removal efficiencies effects were studied. Experiment conditions during 30 minutes of electrolysis; the current density was determined as 0.95 mA/cm2, the initial pH of the wastewater was 6, the mixing speed was 150 rpm, and the initial nickel concentration was 250 mg/L. The Ni2+ removal efficiency was obtained as 75.99% under the determined experimental conditions, while the energy consumption was calculated as 3.15 kW-h/m3. In the experiments, it was observed that the type and concentration of the supporting electrolyte did not have a significant effect on the Ni2+ removal efficiency. In the trials where the effect of the support electrolyte concentration was examined, the Ni2+ removal efficiency was 75.99% in the wastewater environment without the supporting electrolyte, while the Ni2+ removal efficiency was 81.55% when 7.5 mmol/L NaCl was used after the 30-minute reaction, and the energy consumption was 2.15 kW-h/m3 obtained as. As a result of the studies, it was concluded that the electrocoagulation process can be applied in the treatment of wastewater containing Ni2+.

코코넛 기반 활성탄 필터의 라돈 제거 효율 (Radon Removal Efficiency of Activated Carbon Filter from Coconut)

  • 안윤진;김기섭;김태환;김상록
    • 대한방사선기술학회지:방사선기술과학
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    • 제46권2호
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    • pp.141-149
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    • 2023
  • The Korea Institute of Radiological and Medical Sciences plans to produce 225Ac, a therapeutic radio-pharmaceutical for precision oncology, such as prostate cancer. Radon, a radioactive gas, is generated by radium, the target material for producing 225Ac. The radon concentration is expected to be about 2000 Bq·m-3. High-concentration radon-generating facilities must meet radioactive isotope emission standards by lowering the radon concentration. However, most existing studies concerning radon removal using activated carbon filters measured radon levels at concentrations lower than 1000 Bq·m-3. This study measured 222Rn removal of coconut-based activated carbon filter under a high radon concentration of about 2000 Bq·m-3. The 222Rn removal efficiency of activated carbon impregnated with triethylenediamine was also measured. As a result, the 222Rn removal amount of the activated carbon filter showed sufficient removal efficiency in a 222Rn concentration environment of about 2000 Bq·m-3. In addition, despite an expectation of low radon reduction efficiency of Triethylenediamine-impregnated activated carbon, it was difficult to confirm a significant difference in the results. Therefore, it is considered that activated carbon can be used as a radioisotope exhaust filter regardless of whether or not Triethylenediamine is impregnated. The results of this study are expected to be used as primary data when building an air purification system for radiation safety management in facilities with radon concentrations of about 2000 Bq·m-3.

전류밀도와 전기삼투 현상이 전기투석 공정의 탈염성능에 미치는 영향 (Effect of Current Density and Electroosmotic Phenomena on the Desalination Performance of the Electrodialysis Process)

  • 천은서;최재환
    • 공업화학
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    • 제34권3호
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    • pp.272-278
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    • 2023
  • 이 연구에서는 전류밀도와 전기삼투 현상이 전기투석(electrodialysis, ED)의 탈염성능에 미치는 영향을 분석하였다. 농축액의 농도를 10~200 g/L로 변화시키면서 정전압 조건에서 ED 실험을 진행하였다. ED 운전과정에서 스택에 공급되는 전류밀도와 전하량, 희석액과 농축액의 농도, 그리고 전기삼투에 의한 물 이동량을 측정하여 탈염성능을 분석하였다. 농축액의 농도가 증가함에 따라 이온교환막의 선택성이 감소하여 전류효율이 감소하였다. 또한 전류효율은 스택에 공급되는 전류밀도에 영향을 받는 것으로 나타났다. 전류밀도가 15 mA/cm2 이상에서는 역 확산이 억제되어 전류효율이 증가하였다. ED 운전과정에서 전기삼투에 의한 물 이동량을 분석하였다. 물 이동량은 농축액과 희석액의 농도비에 비례하여 증가하는 것을 알 수 있었다. 농도비가 100 이상에서는 삼투압에 의한 물 이동량이 급격히 증가하여 200 g/L 이상의 농축액을 얻는데 한계가 있는 것으로 나타났다.

Bacillus drentensis sp. 사균과 polysulfone으로 이루어진 미생물담체를 이용한 수용액 내 벤젠 제거 (Removal of Benzene in Solution by using the Bio-carrier with Dead Bacillus drentensis sp. and Polysulfone)

  • 박상희;이민희
    • 한국지하수토양환경학회지:지하수토양환경
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    • 제18권1호
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    • pp.46-56
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    • 2013
  • Laboratory scale experiments to remove benzene in solution by using the bio-carrier composed of dead biomass have been performed. The immobilized bio-carrier with dead Bacillus drentensis sp. and polysulfone was manufactured as the biosorbent. Batch sorption experiments were performed with bio-carriers having various quantities of biomass and then, their removal efficiencies and uptake capacities were calculated. From results of batch experiments, 98.0% of the initial benzene (1 mg/L) in 1 liter of solution was removed by using 40 g of immobilized bio-carrier containing 5% biomass within 1 hour and the biosorption reaction reached in equilibrium within 2 hours. Benzene removal efficiency slightly increased (99.0 to $99.4%{\pm}0.05$) as the temperature increased from 15 to $35^{\circ}C$, suggesting that the temperature rarely affects on the removal efficiency of the bio-carrier. The removal efficiency changed under the different initial benzene concentration in solution and benzene removal efficiency of the bio-carrier increased with the increase of the initial benzene concentration (0.001 to 10 mg/L). More than 99.0% of benzene was removed from solution when the initial benzene concentration ranged from 1 to 10 mg/L. From results of fitting process for batch experimental data to Langmuir and Freundlich isotherms, the removal isotherms of benzene were more well fitted to Freundlich model ($r^2$=0.9242) rather than Langmuir model ($r^2$=0.7453). From the column experiment, the benzene removal efficiency maintained over 99.0% until 420 pore volumes of benzene solution (initial benzene concentration: 1 mg/L) were injected in the column packed with bio-carriers, investigating that the immobilized carrier containing Bacillus drentensis sp. and polysulfone is the outstanding biosorbent to remove benzene in solution.

$PtCl_4$ 농도에 따른 염료감응형 태양전지의 효율 변화 (The Effect of $PtCl_4$ Concentration on Dye-Sensitized Solar Cell Efficiency)

  • 서현승;박미주;최은창;이성욱;김형진;홍병유
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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    • pp.435-436
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    • 2008
  • Dye-sensitized Solar Cells(DSSCs) which convert incident sun light into electricity were expected to overcome global warming and depletion of fossil fuels. And it is one of study that is lately getting into the spotlight because manufacturing method is more simple and inexpensive than existing silicon solar cells. In this respect, DSSCs are in the limelight as the next generation solar cells. DSSCs are generally composed of a dye-modified $TiO_2$ photoelectrode, a Pt counter electrode, and an electrolytes containing a redox couple$(I^-/I_3^-)$. Among these elements, pt electrode were prepared by applying electric potential to FTO substrate in the $H_2PtCl_6$ solution. In this study, we report the solar cell efficiency depending on $PtCl_4$ concentration change. $PtCl_4$ concentration was 1mM, 5mM, 10mM, and 20mM, and adhered on FTO glass substrate by sintering process. When applied each $PtCl_4$ counter electrode on DSSC, the best efficiency was found at 10mM of $PtCl_4$ concentration. The catalyst promotes the movement of electron from the counter electrode to the electrolyte the higher the molarity, the better the efficiency. However, in case of 20mM, it is estimated that over-deposited $PtCl_4$ tends to restrict the movement of electron due to its bundle formation.

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악취 발산감소를 위한 필터의 이용 효과 (Effect of Biofilter on Reducing Malodor Emission)

  • 김원영;정광화;노진식;김원호;전병수;류호현;전영륜
    • 한국축산시설환경학회지
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    • 제4권2호
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    • pp.161-166
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    • 1998
  • Controlling malodor originating from livestock feces has become a major issue, due to its influence on the health of man and livestock, together with its influences on atmospheric pollution. In this study, Five types of biofilters filled with saw-dust, night soil, fermented compost, leaf mold and a mixture(a compound of night soil, fermented compost and leaf mold at the same rates, respectively) were manufactured and tested. To study the effect of the biofilter on reducing malodor in a composting facility and swine building, a pilot scale composting facility enclosed with polyethylene film was constructed. Swine feces was composted in the facility and malodorous gas generated from the decomposition of organic matter in the feces was gathered by vacuum pump. Each biofilter achieved 87∼96% NH3 removal efficiency. This performance was maintained throughout 10 days of operation. The highest NH3 removal efficiency was achieved by leaf mold on the first day of operation period. It reduced the concentration of NH3 by about 96%. Night soil and fermented compost showed nearly equal performance of 93 to 94% for 10 days from the beginning of operation. The mixture achieved the lowest NH3 removal efficiency. It reduced NH3 concentration by about 89∼94% for 10 days from the beginning of operation. However NH3 removal efficiency of each biofilter declined with the passage of operational time. After 30 days from the beginning of operation, NH3 removal efficiency of each biofilter of each biofilter was below 60%, respectively. The concentration of H2S and CH3-SH originating from compost were equal to or less than 5mg/l and 3mg/l, respectively. After passing throughout the biofilter, the concentration of H2S and CH3-SH were not detected.

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