• 제목/요약/키워드: energy degradation

검색결과 1,725건 처리시간 0.04초

저전류/저가습 조건에서 고분자전해질 막 열화 (Degradation of Polymer Electrolyte Membrane under Low Current/Low Humidity Conditions)

  • 김태희;이정훈;이호;임태원;박권필
    • 한국수소및신에너지학회논문집
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    • 제18권2호
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    • pp.157-163
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    • 2007
  • During PEMFC operation, low current and low humidity conditions accelerate the degradation of perfluorosulfonic acid membrane. But, there have been no studies that clearly explain why these conditions accelerate the membrane degradation. In this study, the hydrogen permeability through the membrane, I-V polarization of MEA, fluoride emission rate(FER) in effluent water were measured during cell operation under low current densities and low relative humidity(RH). The experimental results were evaluated with oxygen radical mechanism the most commonly known for membrane degradation. It seems that low RH of anode is a good condition for $H{\cdot}$ radical formation on the Pt catalyst and the low current condition accelerates the $H{\cdot}$ to form $HO_2{\cdot}$ radical attacking the polymer membrane.

박막 실리콘 태양전지의 광열화현상 연구: 비정질 실리콘 태양전지 및 나노양자점 실리콘 박막 태양전지 (Study of Light-induced Degradation in Thin Film Silicon Solar Cells: Hydrogenated Amorphous Silicon Solar Cell and Nano-quantum Dot Silicon Thin Film Solar Cell)

  • 김가현
    • 한국태양에너지학회 논문집
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    • 제39권1호
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    • pp.1-9
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    • 2019
  • Light induced degradation is one of the major research challenges of hydrogenated amorphous silicon related thin film silicon solar cells. Amorphous silicon shows creation of metastable defect states, originating from elevated concentration of dangling bonds during light exposure. The metastable defect states work as recombination centers, and mostly affects quality of intrinsic layer in solar cells. In this paper we present results of light induced degradation in thin film silicon solar cells and discussion on physical origin, mechanism and practical solutions of light induced degradation in thin film silicon solar cells. In-situ light-soaking IV measurement techniques are presented. We also present thin film silicon material with silicon nano-quantum dots embedded within amorphous matrix, which shows superior stability during light-soaking. Our results suggest that solar cell using silicon nano-quantum dots in abosrber layer shows superior stability under light soaking, compared to the conventional amorphous silicon solar cell.

아세톤 용매분해법에 의한 헤미셀룰로오스의 분해특성 및 연료물질의 생성 (Degradation Properties and Production of Fuels from Hemicellulose by Acetone-Solvolysis)

  • 이종집
    • 한국수소및신에너지학회논문집
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    • 제19권1호
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    • pp.56-63
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    • 2008
  • In this study, thermochemical degradation of hemicellulose by Acetone-Solvolysis, the effects of reaction temperature, conversion yield, degradation properties and degradation products were investigated. Experiments were performed in a tube reactor by varying reaction temperature from $200{\circ}C$ to $400{\circ}C$ at 40 min of reaction time. The liquid products from pyrolysis-liquefaction of hemicellulose contained various kinds of ketones. ketones, as 4-methyl-3-penten-2-one, 3-methylene-2-pentanone, 22,6-dimethyl-2, 5-heptadien-4-one, 4-methyl-2-pentanone, 5-methyl-2-hexanone, 3,5,5-trimethyl-2-cyclohexen-1-one, and bezenes. as 1,4-dimethylbenzene, 1-methyl-2-(1-methylethyl)-benzene, 1,4-dimethyl-2-(2-methylpropyl)benzene, 4-secbutyl-ethyl benzene, could be used as high-octane-value fuels and fuel additives. Combustion heating value of liquid products from thermochemical conversion processes of hemicellulose was in the range of $6,680{\sim}7,170cal/g$. After 40min of reaction at $400{\circ}C$ in Acetone-Solvolysis of hemicellulose, the energy yield and mass yield was as high as 72.2% and 41.2g oil/100g raw material, respectively.

셀룰로오스의 분해특성 및 연료물질 생성 (I) -열분해·액화반응- (Degradation Properties and Production of Fuels of Cellulose - Pyrolysis-Liquefaction -)

  • 이종집;이병학
    • 한국수소및신에너지학회논문집
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    • 제15권4호
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    • pp.333-340
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    • 2004
  • In this study, thermochemical degradation by pyrolysis-liquefaction of cellulose, the effects of reaction time, reaction temperature, conversion yield, degradation properties and degradation products were investigated . Experiments were performed in a tube reactor by varying reaction time from 20 to 80 min at $200{\sim}500^\circ{C}$. Combustion heating value of liquid products from thermochemical conversion processes of cellulose was in the range of 6,920~6,960cal/g. After 40min of reaction at $400^\circ{C}$ in pyrolysis-liquefaction of cellulose, the energy yield and mass yield was as high as 54.3% and 34.0g oil/100g raw material, respectively. The liquid products from pyrolysis-liquefaction of cellulose contained various kinds of ketones, phenols and furans. ketones and furans could be used as high-octane-value fuels and fuel additives. However, phenols are not valuable as fuels.

5 kW 고온 고분자연료전지 스택 수명 극대화를 위한 운전 방법론 (Operating Method to Maximize Life Time of 5 kW High Temperature Polymer Exchange Membrane Fuel Cell Stack)

  • 김지훈;김민진;손영준;유상석
    • 한국수소및신에너지학회논문집
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    • 제27권2호
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    • pp.144-154
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    • 2016
  • HT-PEMFC (high temperature polymer electrolyte membrane fuel cell) using PA (phosphoric acid) doped PBI (polybenzimidazole) membrane has been researched for extending the lifetime. However, the existing work on durability of HT-PEMFC focuses on identifying degradation causes of lab scale. The short life time of HT-PEMFC is still the problem for its commercialization. In this paper, an operating method to maximize life time of 5kW HT-PEMFC stack are proposed. The proposed method includes major steps such as minimization of OCV (Open Circuit Voltage) exposure, control of the proper stack temperature, and N2 purging for the stack. This long life operating method was based on the fragmentary results of degradation from previous research works. Experimentally, the 5 kW homemade HT-PEMFC stack was operated for a long time based on the proposed method and the stack successfully can operate within the desired degradation rate for the target life time.

Degradation of synthetic dye in water by solution plasma process

  • Panomsuwan, Gasidit;Morishita, Tetsunori;Kang, Jun;Rujiravanit, Ratana;Ueno, Tomonaga;Saito, Nagahiro
    • Journal of Advanced Marine Engineering and Technology
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    • 제40권10호
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    • pp.888-893
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    • 2016
  • In this study, the solution plasma process was utilized with the aim of degrading synthetic dyes in water at atmospheric pressure. The experiments were conducted in a batch-type reactor consisting of a symmetric wire-wire electrode configuration with rhodamine B (RhB) as the target synthetic dye. The effects of the plasma treatment time and initial dye concentration on the RhB degradation were investigated by monitoring the change in absorbance of RhB solutions. The RhB solutions turned lighter in color and finally colorless with prolonged plasma treatment time, indicating the destruction of dye molecules. The RhB solutions were found to have degraded, following the first-order kinetic process. However, for high initial RhB concentrations, another kinetic process or factor seems to play a dominant role at the initial degradation stage. The fitted first-order rate constant decreased as the initial concentration increased. This result suggests that the degradation behavior and kinetic process of the RhB solution strongly depends on its initial concentration. The RhB degradation is considered to be due to a combination of factors, including the formation of chemically oxidative species, as well as the emission of intense UV radiation and high-energy electrons from the plasma. We believe that the solution plasma process may prove to be an effective and environment-friendly method for the degradation or remediation of synthetic dye in wastewater.

저궤도 우주환경에서 에폭시-실리카 나노 복합소재의 열화거동 분석 (Analyses of Nano Epoxy-Silica Degradation in LEO Space Environment)

  • 장서현;한유수;황도순;정주원;김영국
    • 한국항공우주학회지
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    • 제48권12호
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    • pp.945-952
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    • 2020
  • 이 연구에서는 저궤도 우주 환경(LEO) 조건에서 나노실리카 에폭시 복합소재의 실리카 농도가 재료의 열화 거동에 미치는 영향에 대해 알아보았다. 실리카 입자를 에폭시 수지에 10%와 18% 두 가지 서로 다른 무게비로 나노복합소재를 제작하여 저궤도 우주 환경 모사장치에서 열화시켰다. 열화된 나노복합소재를 대상으로 열중량분석(Thermogravimetric Analysis, TGA)를 수행하였고 등변환법(Iso-conversional Method)에 기반한 Friedman 방법, Flynn-Wall-Ozawa(FWO) 방법, Kissinger 방법, 그리고 DAEM(Distributed Activation Energy Method)으로 활성화에너지를 계산하였다. 그 결과 나노입자가 섞이지 않은 샘플은 열화가 진행되면서 중가함을 보였다. 그러나 10%와 18%는 열화 싸이클이 15회일 때까지 증가하였으나 그 이후에는 감소하였으며, 따라서 나노 입자가 열화 거동에 부정적인 영향이 있음을 보였다. 또한 활성화에너지 계산에 적용된 방법에 대해 토의하였다.

Enhancement of Pendimethalin Degradation Activity in Bacillus sp. MS202 using Gamma Radiation

  • Lee Young-Keun;Chang Hwa-Hyoung;Lee Ho-Jin;Park Heesoon;Lee Kyung Hee;Joe Min-Ho
    • 환경생물
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    • 제23권4호
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    • pp.405-408
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    • 2005
  • To induce the enhanced mutants of dinitroaniline herbicide pendimethalin degrading bacterium, Bacillus sp. MS202 was irradiated with gamma radiation at the dose of $LD_{99}$ (3.35 kGy). Three enhanced mutants (MS202m7, MS202m14, MS202m18) were isolated from the candidates by the generation - isolation method. Clear zone formation and the GC analysis confirmed that the degrading activity of each enhanced mutant (MS202m7, MS202m14, MS202m18), the formation of pendimethalin metabolite, increased by $11\%,\;45\%,\;and\;32\%$ than a wild type, respectively. It suggested that these mutants induced by gamma radiation could be useful for the application of pesticide degradation.

Removal of Rhodamine Dye from Water Using Erbium Oxide Nanoparticles

  • Luaibi, Hasan M.;Al-Taweel, Saja S.;Gaaz, Tayser Sumer;Kadhum, Abdul Amir H.;Takriff, Mohd S.;Al-Amiery, Ahmed A.
    • 한국재료학회지
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    • 제29권12호
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    • pp.747-752
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    • 2019
  • Environmental pollution remains a considerable health risk source all over the world; however, hazards are usually higher in developing countries. Iraq has long been suffering from the problem of pollution and how to treat pollution. Photocatalytic degradation has turned out to be most productive process for dye degradation. In this investigation, Rhodamine B (RhB), dye has been selected for degradation under visible light illumination. To address this issue, we fabricate erbium trioxide nanoparticles (Er2O3/NPs). Erbium trioxide nanoparticles are prepared and utilized for photo-catalytic degradation. The characterization of Er2O3/NPs is described and confirmed by utilizing of XRD (X-ray diffraction) and SEM (Scanning Electron Microscopy). The average size of Er2O3 nanoparticles is observed to be 16.00 nm. Er2O3/NPs is investigated for its ability of photo-catalytic degradation through certain selected parameters such as concentration and time. The methodological results show that the synthesized Er2O3/NPs is a good photo-catalytic for Rhodamine degradation.

원자력 발전소용 통신케이블 자켓의 가속열화시험 (An Accelerated Degradation Test of Nuclear Power Plants Communication Cable Jacket)

  • 정재한;김용수
    • 품질경영학회지
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    • 제45권4호
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    • pp.969-980
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    • 2017
  • Purpose: The purpose of this study was to estimate the lifetime, and verify the target lifetime at steady state temperature, of communication cable jackets used in nuclear power plants. Method: This study was completed according to test and analysis methods required by international standards. After measuring the residual elongation(%) of specimens at specific points in time with the accelerated degradation test, average failure time of each temperature was computed. Thus, the activation energy could be derived by applying the temperature-Arrhenius law to estimate cable jacket lifetime at steady state temperature. Results: The cable jacket lifetime was estimated as 363.8 years assuming a normal nuclear power plant operating temperature of $90^{\circ}C$. Conclusion: To ascertain stable operating conditions for a nuclear power plant, accelerated degradation tests were performed according to the Arrhenius law for components of the nuclear power plants. The lifetime was estimated from the degradation data collected during the accelerated degradation test.