• Title, Summary, Keyword: Fuel reforming

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Numerical Study on operating conditions of Autothermal Reformer using natural gas (천연가스를 이용한 자열개질기의 운영조건에 대한 수치해석 연구)

  • Kim, Jinwook;Kim, Sangwoo;Park, Dalyung;Jeon, Sanghee;Lee, Dohyung
    • 한국신재생에너지학회:학술대회논문집
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    • pp.91.1-91.1
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    • 2010
  • The Reforming system is an effective method to generate hydrogen which uses for fuel cell system. The purpose of this study is to present characteristics of an autothermal reformer at various operating conditions and to investigate ideal conditions for reforming efficiency. Dominant chemical reactions are Full Combustion, Steam Reforming reaction, Water-Gas Shift reaction and Direct Steam Reforming reaction. Operating parameters of the autothermal reformer are inlet temperature, Oxygen to Carbon Ratio, Steam to Carbon Ratio and Gas Hourly Space Velocity. Autothermal reformer is filled with catalysis of a packbed-bed type. Using numerical approach, we have investigated on various reaction conditions.

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Steam Reforming of Biogas on Nickel Fiber Mat Catalysts (니켈 섬유 매트 촉매를 사용한 바이오가스 수증기개질 반응)

  • Bui, Quynh Thi Phuong;Kim, Yong-Min;Yoon, Chang-Won;Nam, Suk-Woo
    • Journal of Energy Engineering
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    • v.20 no.3
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    • pp.252-258
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    • 2011
  • Nickel fiber mat was investigated as a potential structured catalyst for steam reforming of biogas in the temperature range of $600-700^{\circ}C$. The activity of as-received catalyst was very low owing to the smooth surface of fibers. Pretreatment of the catalyst by oxidation followed by reduction under methane partial oxidation condition significantly improved the catalytic activity, although degradation of the activity was found during the reaction due to oxidation and sintering. This deactivation was retarded by supplying additional hydrogen in the inlet gases or by coating $CeO_2$ over the catalyst surfaces.

Effect of Carbon dioxide in Fuel on the Performance of PEM Fuel Cell (연료중의 이산화탄소 불순물에 의한 연료전지 성능변화 연구)

  • Seo, Jung-Geun;Kwon, Jung-Taek;Kim, Jun-Bom
    • 한국신재생에너지학회:학술대회논문집
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    • pp.184-187
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    • 2007
  • Hydrogen could be produced from any substance containing hydrogen atoms, such as water, hydrocarbon (HC) fuels, acids or bases. Hydrocarbon fuels couold be converted to hydrogen-rich gas through reforming process for hydrogen production. Even though fuel cell have high efficiency with pure hydrogen from gas tank, it is more beneficial to generate hydrogen from city gas (mainly methane) in residential application such as domestic or office environments. Thus hydrogen is generated by reforming process using hydrocarbon. Unfortunately, the reforming process for hydrogen production is accompanied with unavoidable impurities. Impurities such as CO, $CO_2$, $H_2S$, $NH_3$, and $CH_4$ in hydrogen could cause negative effects on fuel cell performance. Those effects are kinetic losses due to poisoning of electrode catalysts, ohmic losses due to proton conductivity reduction including membrane and catalyst ionomer layers, and mass transport losses due to degrading catalyst layer structure and hydrophobic property. Hydrogen produced from reformer eventually contains around 73% of $H_2$, 20% or less of $CO_2$, 5.8% of less of $N_2$, or 2% less of $CH_4$, and 10ppm or less of CO. Most impurities are removed using pressure swing adsorption (PSA) process to get high purity hydrogen. However, high purity hydrogen production requires high operation cost of reforming process. The effect of carbon dioxide on fuel cell performance was investigated in this experiment. The performance of PEM fuel cell was investigated using current vs. potential experiment, long run (10 hr) test, and electrochemical impedance measurement when the concentrations of carbon dioxide were 10%, 20% and 30%. Also, the concentration of impurity supplied to the fuel cell was verified by gas chromatography (GC).

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Study on Possibility of Diesel Reforming with Hydrogen Peroxide in Low-Oxygen Environments (산소희박환경에서 과산화수소를 이용한 디젤개질 가능성 탐구)

  • Han, Gwangwoo;Bae, Minseok;Bae, Joongmyeon
    • Korean Chemical Engineering Research
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    • v.53 no.5
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    • pp.584-589
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    • 2015
  • For effective power generation with fuel cells in low-oxygen environments such as submarines and unmanned underwater vehicles, a hydrogen source which has a high hydrogen storage density is required. Diesel fuel is easy to storage and supply due to its liquid phase and it has a high density per unit volume and unit mass of hydrogen that required for driving the fuel cells. In this paper, diesel fuel was selected as a hydrogen source for driving the fuel cell in oxygen lean environments. In addition, the aqueous hydrogen peroxide solution was suggested as an alternative oxidant for hydrogen production through the diesel reforming reaction because of its high oxygen density and liquid phase which makes it easy to storage. In order to determine the characteristics of hydrogen peroxide as an oxidant of diesel reforming, comparative experiments were conducted and it was found that hydrogen peroxide solution has the same characteristics when reformed with oxidants of both steam and oxygen. Moreover, the commercial diesel reforming performances were analyzed according to the reaction temperature and concentration of aqueous hydrogen peroxide solution. Then, through the 49 hours accelerated degradation tests, the possibility of hydrogen production via diesel and aqueous hydrogen peroxide solution was confirmed.

Characteristics of Heat Transfer and Chemical Reaction in Reformer Tube for Fuel Reynolds Number and Burner Gas Temperature (개질관 내부 레이놀즈 수와 버너 온도에 따른 열유동 및 반응 특성)

  • Han, Jun Hee;Yoon, Kee Bong;Kim, Ji Yoon;Lee, Seong Hyuk
    • Journal of the Korean Institute of Gas
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    • v.19 no.5
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    • pp.69-74
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    • 2015
  • The study investigated numerically the heat transfer and chemical reaction characteristics of a methane-steam reforming by using a 3-dimensional computational fluid dynamics (CFD) code (Fluent ver. 16.1). The fuel temperature and its species mole fractions were estimated for various Reynolds number in the reformer tube at different burner temperatures. The catalysts were modeled as the porous medium of nicrome in the reformer tube. We considered radiation effect as well as conduction and convective heat transfer because the methane-steam was reformed at very high temperature condition above 1000 K. For two different Reynolds numbers of 49,000 and 88,000 and the burner temperatures were in the range from 1,100 K to 1,300 K. At a low Reynolds number, the fuel temperature increased, leading to increase in hydrogen reforming. However, fuel temperature and hydrogen reforming decreased because of higher convective heat transfer from relatively low fuel temperature. Moreover, the hydrogen reforming also increased with burner temperature.

Characteristics of Partial Oxidation Reforming with Various Sorts of Hydrocarbon Fuel (연료의 종류에 따른 부분산화 반응 특성에 관한 연구)

  • Park, Cheol-Woong;Choi, Young;Oh, Seung-Mook
    • Journal of the Korean Institute of Gas
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    • v.13 no.4
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    • pp.46-52
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    • 2009
  • Hydrogen can extend the lean misfire limit to a large extent when it is mixed with conventional fuels for an internal combustion engine. This study is about fuel reforming to produce hydrogen enriched gas as a fuel for engine. Especially gasoline, which consists of numerous hydrocarbon fuels, considered as source of reformed gas. Various hydrocarbons, including commercial fuel were reformed and potentialities of reformed gas on vehicles were accessed. The reforming efficiency and hydrogen yield were observed. Maximum hydrogen yield were found with different gas hourly space velocity(GHSV) and O2/C ratio of reforming conditions.

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NUMERICAL STUDY OF STREAM REFORMING IN PRECONVERTER FOR MCFC (MCFC용 프리컨버터 수증기 개질반응의 수치연구)

  • Byun, Do-Hyun;Sohn, Chang-Hyun
    • 한국전산유체공학회:학술대회논문집
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    • pp.228-232
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    • 2010
  • In this paper, various operating parameters of stream reforming process from methane in preconverter for MCFC is studied by numerical method. Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). The hydrogen production is tested with different wall temperature, Gas Hourly Space Velocity(GHSV), and different reactor shapes.

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Research of High Efficiency Integrated Reforming System Using Separated Reforming System (분리형 개질기를 이용한 고효율 일체형 개질기 개발에 관한 연구)

  • PARK, SANG-HYOUN;KIM, CHUL-MIN;SON, SUNG-HYO;JANG, SE-JIN;KIM, JAE-DONG;BANG, WAN-KEUN;LEE, SANG-YONG
    • Transactions of the Korean hydrogen and new energy society
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    • v.29 no.1
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    • pp.11-18
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    • 2018
  • A high efficiency integrated reforming system for improving the efficiency of the 5 kW PEMFC system used as the back up power of building was studied. The separated reforming system consisted of three parts - A steam reformer with two stage concentric circular shape, a heat exchanger type steam generator and a CO shift reactor. Temperature and steam carbon ratio (SCR) were control variables during operation. The operating conditions were optimized based on the thermal efficiency of the steam reformer as reformate gas composition changes at different temperature. In experiments, water was fully vaporized in the steam generator up to SCR 3.5 and the maximum thermal efficiency was achieved at the operating temperature around $700^{\circ}C$ in the steam reforming reactor. With the results of the separated reforming system research, we improved the shape of high efficiency integrated reformer. The performance evaluation of the integrated reformer was based on optimized operating conditions in SCR 3.5. As a result, the developed integrated reforming system maintained an efficiency of 76% and constant performance over 3,000 hours.

Study on Pressurized Diesel Reforming System for Polymer Electrolyte Membrane Fuel Cell in Underwater Environment (수중 환경에서 고분자 전해질 연료전지(PEMFC) 공급용 수소 생산을 위한 가압 디젤 개질시스템에 관한 연구)

  • Lee, Kwangho;Han, Gwangwoo;Bae, Joongmyeon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.20 no.4
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    • pp.528-535
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    • 2017
  • Fuel cells have been spotlighted in the world for being highly efficient and environmentally friendly. A hydrogen which is the fuel of fuel cell can be obtained from a number of sources. Hydrogen source for operating the polymer electrolyte membrane fuel cell(PEMFC) in the current underwater environment, such as a submarine and unmanned underwater vehicles are currently from the metal hydride cylinder. However, metal hydride has many limitations for using hydrogen carrier, such as large volume, long charging time, limited storage capacity. To solve these problems, we suggest diesel reformer for hydrogen supply source. Diesel fuel has many advantages, such as high hydrogen storage density, easy to transport and also well-infra structure. However, conventional diesel reforming system for PEMFC requires a large volume and complex CO removal system for lowering the CO level to less than 10 ppm. In addition, because the preferential oxidation(PROX) reaction is the strong exothermic reaction, cooling load is required. By changing this PROX reactor to hydrogen separation membrane, the problem from PROX reactor can be solved. This is because hydrogen separation membranes are small and permeable to pure hydrogen. In this study, we conducted the pressurized diesel reforming and water-gas shift reaction experiment for the hydrogen separation membrane application. Then, the hydrogen permeation experiments were performed using a Pd alloy membrane for the reformate gas.

A Study on Combustion Characteristics with Ethanol and Hydrogen Enriched Gas Addition in Gasoline Engine (가솔린 엔진에서 에탄올 및 수소농후가스 첨가에 의한 희박연소특성 연구)

  • Park, Cheol-Woong;Choi, Young;Oh, Seung-Mook;Kim, Chang-Gi;Lim, Ki-Hoon
    • Proceedings of the KSME Conference
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    • pp.2928-2933
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    • 2008
  • Trends of the automotive market require the application of new engine technologies, which allows for the use of different types of fuel. Since ethanol is a renewable source of energy and it contributes to lower $CO_2$ emissions, ethanol produced from biomass is expected to increase in use as an alternative fuel. It is recognized that for spark ignition (SI) engines ethanol has advantages of high octane number and high combustion speed. In spite of the advantages of ethanol, fuel supply system might be affected by fuel blends with ethanol like a wear and corrosion of electric fuel pumps. So the on-board hydrogen production out of ethanol reforming can be considered as an alternative plan. This paper investigates the influence of ethanol fuel on SI engine performance, thermal efficiency and emissions. The combustion characteristics with hydrogen-enriched gaseous fuel from ethanol reforming are also examined.

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