• Title/Summary/Keyword: $H_2O$ emission hydrogen

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THE CENTRAL REGION OF THE BARRED SPIRAL GALAXY NGC 1097 PROBED BY AKARI NEAR-INFRARED SPECTROSCOPY

  • Kondo, T.;Kaneda, H.;Oyabu, S.;Ishihara, D.;Mori, T.;Yamagishi, M.;Onaka, T.;Sakon, I.;Suzuki, T.
    • Publications of The Korean Astronomical Society
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    • v.27 no.4
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    • pp.257-258
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    • 2012
  • With AKARI, we carried out near-infrared spectroscopy of the nearby barred spiral galaxy, NGC 1097, categorized as Seyfert 1 with a circumnuclear starburst ring. Our observations mapped the galactic center region. As a result, we obtain the spatial distributions of the polycyclic aromatic hydrocarbon $3.3{\mu}m$ and the aliphatic hydrocarbon $3.4-3.6{\mu}m$ emission. The former is detected from all the observed regions and the latter is enhanced near the bar connecting the ring with the nucleus. In addition, we detect absorption features due to $H_2O$ ice and CO/SiO at the ring and the galactic center, while we detect the hydrogen recombination line $Br{\alpha}$ only from the ring. Hence the observed spectra change dramatically within the central 1 kpc region.

Conversion of Cellulose into Polyols over Noble Metal Catalysts Supported on Activated Carbon (활성탄에 담지된 귀금속 촉매를 이용한 셀룰로우스의 폴리올로의 전환)

  • You, Su-Jin;Kim, Saet-Byul;Kim, Yong-Tae;Park, Eun-Duck
    • Clean Technology
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    • v.16 no.1
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    • pp.19-25
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    • 2010
  • In this work, the conversion of crystalline cellulose into polyols in the presence of hydrogen was examined over noble metal (Pt, Ru, Ir, Rh, and Pd) catalysts supported on activated carbon. For comparison, Pt/${\gamma}-Al_2O_3$ and Pt/H-mordenite were also investigated. Several techniques: $N_2$ physisorption, X-ray diffraction(XRD), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), temperature-programmed reduction with $H_2$ ($H_2$-TPR) and CO chemisorption were employed to characterize the catalysts. The cellulose conversion was not strongly dependent on the types of the catalyst used. Pt/AC showed the highest yields to polyols among activated carbon-supported noble metal catalysts, viz. Pt/AC, Ru/AC, Ir/AC, Rh/AC and Pd/AC.

Studies on Reforming Gas Assisted Regeneration of Multi-channel Catalyzed DPF (합성가스(Reforming gas)를 이용한 멀티채널 CDPF의 재생 특성 연구)

  • Choi, Kwang-Chun;Chung, Jin-Hwa;Song, Soon-Ho;Chun, Kwang-Min
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.3
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    • pp.138-145
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    • 2011
  • Diesel particulate filter (DPF) systems are being used to reduce the particulate matter emission of diesel vehicles. The DPF should be regenerated after certain driving hours or distance to eliminate soot in the filter. The most widely used method is active regeneration with oxygen at $550{\sim}650^{\circ}C$. Syngas (synthetic gas) can be used to lower the regeneration temperature of Catalyzed DPF (CDPF). The syngas is formed by fuel reforming process of CPOx (Catalytic Partial Oxidation) at specific engine condition (1500rpm, 2bar) using 1wt.% $Rh/CeO_2-ZrO_2$ catalyst. The oxidation characteristics of PM with syngas supplied to filter were studied using partial flow system that can control temperature and flow rate independently. The filter is coated with washcoat loading of $25g/ft^3$ $Pt/Al_2O_3-CeO_2$, and multi-channel CDPF (MC-CDPF) was used. The filter regeneration experiments were performed to investigate the effect of syngas exothermic reaction on soot oxidation in the filter. For this purpose, before oxidation experiment, PM was collected about 8g/L to the filter at engine condition of 1500rpm, bmep 8bar and flow temperature of $200^{\circ}C$ Various conditions of temperature and concentration of syngas were used for the tests. Regeneration of filter started at 2% $H_2$ and CO concentration respectively and inlet temperature of $260^{\circ}C$. Filter Regeneration occurs more actively as the syngas concentration becomes higher.

Experimental Study on Corrosion Characteristics of 1.25Cr-0.5Mo in the 1st-mathanator reactor for Synthetic Natural Gas according to Gas Compositions (1.25Cr-0.5Mo강을 이용한 합성가스 조성 변화에 따른 SNG 1차반응기의 부식특성에 관한 실험적 연구)

  • Kim, Jin-Hyun;Cho, Honghyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.5
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    • pp.709-716
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    • 2016
  • Recently, the operating conditions of the various mechanical structures have become more severe and the running time has become longer as the development of plant equipment increases with the introduction of high technology. Thus, the reliability of the system and its accessories is becoming a problem. Normally, synthetic natural gas (SNG) plants use 1.25Cr-0.5Mo or 2.25Cr-1Mo heat resistant steel according to the operating conditions. In this study, a lab-scale reactor was set up using 1.25Cr-0.5Mo steel, in order to carry out corrosion tests for producing synthetic natural gas. The corrosive characteristics were investigated under 1st-methanator operating conditions and fundamental data about the durability and reliability were obtained by using the experimental test. The analysis of results obtained on the durability of the reactor under emission and injection compositions showed that the hydrogen embrittlement caused by hydrogen and the oxidation corrosion caused by H2O had the most effect on the durability of 1.25Cr-0.5Mo steel in the SNG reactor. However, the hydrogen embrittlement and oxidation corrosion occurred simultaneously under emission conditions, so that the corrosion of the material increased suddenly after a long operating time. Besides, the corrosion of the 1.25Cr-0.5Mo steel under the injection composition was faster than that under the emission composition.

Direct Growth of CNT on Cu Foils for Conductivity Enhancement and Their Field Emission Property Characterization (전도성 향상을 위한 구리호일 위 CNT의 직접성장 및 전계방출 특성 평가)

  • Kim, J.J.;Lim, S.T.;Kim, G.H.;Jeong, G.H.
    • Journal of the Korean Vacuum Society
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    • v.20 no.2
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    • pp.155-163
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    • 2011
  • Carbon nanotubes (CNT) have been attracted much attention since they have been expected to be used in various areas by virtue of their outstanding physical, electrical, and chemical properties. In order to make full use of their prominent electric conductivity in some areas such as electron emission sources, device interconnects, and electrodes in energy storage devices, direct growth of CNT with vertical alignment is definitely beneficial issue because they can maintain mechanical stability and high conductivity at the interface between substrates. Here, we report direct growth of vertically aligned CNT (VCNT) on Cu foils using thermal chemical vapor deposition and characterize the field emission property of the VCNT. The VCNT's height was controlled by changing the growth temperature, growth time, and catalytic layer thickness. Optimum growth condition was found to be $800^{\circ}C$ for 20 min with acetylene and hydrogen mixtures on Fe catalytic layer of 1 nm thick. The diameter of VCNT grown was smaller than that of usual multi walled CNT. Based on the result of field emission characterization, we concluded that the VCNT on Cu foils can be useful in various potential applications where high conductivity through the interface between CNT and substrate is required.

A Study on the Emission Characteristics of Greenhouse Gas from Diesel Medium Duty Trucks According to Driving Modes (주행모드별 경유 중형화물자동차의 온실가스 배출 특성 연구)

  • HONG, HEEKYOUNG;CHUNG, TAEKHO;JUNG, SUNGWOON;KIM, SUNMOON;SEO, SEOKJUN;KIM, INGU;LEE, SANGEUN;LEE, SEOUNGHWAN;KIM, JOUNGHWA;HONG, YOUDEOG;MUN, SUNHEE
    • Journal of Hydrogen and New Energy
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    • v.30 no.1
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    • pp.76-82
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    • 2019
  • This study was investigate the characteristics of GHGs ($CO_2$, $CH_4$, and $N_2O$) emissions of diesel medium duty trucks according to their various driving modes. GHGs emissions decreased as vehicle speed increased, and emissions increased after 64.7 km/h. The 4.5 ton trucks show higher values of $CO_2$, $CH_4$, $N_2O$, 35%, 25%, and 57%, respectively, comparing of the 2.5 ton trucks. Also, $CO_2$ emissions under WHVC mode were 20% lower than those under the NEDC mode. In the case of cold start condition, $CO_2$ emissions were 12-13% higher than those for hot start condition. In the future, the result of present study will provide basic data to set up GHGs emission standards for medium and heavy duty vehicles.

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

  • Kim, Taehee;Lee, Junghun;Lee, Ho;Lim, Tae Won;Park, Kwonpil
    • Korean Chemical Engineering Research
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    • v.45 no.4
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    • pp.345-350
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    • 2007
  • During PEMFC operation, OCV(open circuit voltage) and low humidity conditions accelerate the degradation of perfluorosulfonic acid membrane. 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) and $H_2O_2$ concentration in condensed water were measured during cell operation under OCV 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 OCV condition accelerate the $H{\cdot}$ to form $HO_2{\cdot}$ radical attacking the polymer membrane.

Effect of Aeration Rates on Emissions of Oxygen and Sulfur compound gases during Composting of Dairy Manure (우분(牛糞) 퇴비화시(堆肥花時) 공기주입률(空氣注入率)이 산소 및 황화합물 가스 배출(排出)에 미치는 영향(影響))

  • Kang, Hang-Won;Zhang, Ruihong;Rhee, In-Koo
    • Korean Journal of Soil Science and Fertilizer
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    • v.33 no.6
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    • pp.472-481
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    • 2000
  • This experiment used the enclosed bench-scale reactors was conducted to find out optimal aeration rate for reducing the emission of odors and producing the good-quality compost with the mixture of dairy manure and rice straw. The reactors with gas sampler were aerated at four different rates of 0.09, 0.18, 0.90 and $1.79l\;min^{-1}kg^{-1}$dry solids for 574 hours. The oxygen content within composting pile instantly decreased after aeration. Oxygen limitation(below 15%) in the treatments of $0.90l\;min^{-1}kg^{-1}$ and less was exponentially negative relationship with aeration rates and in the range of 35 to 300 hours after aeration. However, the treatment of $1.79l\;min^{-1}kg^{-1}$ didn't show the oxygen limitation. The oxygen consumption rate and the cumulative amount of oxygen consumed by different aeration rates was ranged in $0.80{\sim}1.57O_2g\;h^{-1}\;kg^{-1}VS^{-1}$, $460{\sim}900O_2g\;kg^{-1}VS^{-1}$, respectively, and they were high in the order of 0.90, 1.79, 0.18, $0.09l\;min^{-1}kg^{-1}$. The maximum oxygen consumption rate was estimated in the range of $1.2{\sim}1.3lmin^{-1}kg^{-1}$. The emission concentrations of sulfur compounds such as hydrogen sulfide, sulfur dioxide and methylmercaptan were remarkably high in the initial composting time. Then they were rapidly decreased with the passing of composting time and clearly with increasing aeration rates. Their average concentrations were in the range of 0.03~2.18, 0~0.50, $0.07{\sim}3.38mg\;kg^{-1}$, respectively and high in the order of methylmercaptan, hydrogen sulfide, and sulfur dioxide. Concentrations of sulfur compounds emitted from composting showed exponentially negative relationship at 1% statistically with the oxygen concentration. It was estimated that hydrogen sulfide and methylmercaptan suddenly increased in the level of 5% oxygen concentration and below, that they were little emitted in 15% and over but sulfur dioxide was emitted in the level of 20% oxygen.

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Effect of Electrode Degradation on the Membrane Degradation in PEMFC (PEMFC에서 전극 열화가 전해질 막 열화에 미치는 영향)

  • Song, Jinhoon;Kim, Saehoon;Ahn, Byungki;Ko, Jaijoon;Park, Kwonpil
    • Korean Chemical Engineering Research
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    • v.51 no.1
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    • pp.68-72
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    • 2013
  • 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. The effect of electrode degradation on membrane degradation was studied in this work. We compared membrane degradation after electrode degradation and membrane degradation without electrode degradation. I-V performance, hydrogen crossover current, fluoride emission rate (FER), impedance and TEM were measured after and before degradation of MEA. Electrode degradation reduced active area of Pt catalyst, and then radical/$H_2O_2$ evolution rate decreased on Pt. Decrease of radical/$H_2O_2$ reduced the velocity of membrane degradation.

Formation and Photoluminescence of Silicon Oxide Nanowires by Thermal Treatment of Nickel Nanoparticles Deposited on the Silicon Wafer

  • Jang, Seon-Hui;Lee, Yeong-Il;Kim, Dong-Hun
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.10a
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    • pp.27.1-27.1
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    • 2011
  • The recent extensive research of one-dimensional (1D) nanostructures such as nanowires (NWs) and nanotubes (NTs) has been the driving force to fabricate new kinds of nanoscale devices in electronics, optics and bioengineering. We attempt to produce silicon oxide nanowires (SiOxNWs) in a simple way without complicate deposition process, gaseous Si containing precursors, or starting material of $SiO_2$. Nickel (Ni) nanoparticles (NPs) were applied on Si wafer and thermally treated in a furnace. The temperature in the furnace was kept in the ranges between 900 and $1,100^{\circ}C$ and a mixture of nitrogen ($N_2$) and hydrogen ($H_2$) flowed through the furnace. The SiOxNWs had widths ranging from 100 to 200 nm with length extending up to ~10 ${\mu}m$ and their structure was amorphous. Ni NPs were acted as catalysts. Since there were no other Si materials introduced into the furnace, the Si wafer was the only Si sources for the growth of SiOxNWs. When the Si wafer with deposition of Ni NPs was heated, the liquid Ni-Si alloy droplets were formed. The droplets as the nucleation sites induce an initiation of the growth of SiOxNWs and absorb oxygen easily. As the droplets became supersaturated, the SiOxNWs were grown, by the reaction between Si and O and continuously dissolving Si and O onto NPs. Photoluminescence (PL) showed that blue emission spectrum was centered at the wavelength of 450 nm (2.76 eV). The details of growth mechanism of SiOxNWs and the effect of Ni NPs on the formation of SiOxNWs will be presented.

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