• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.780-786
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• 2011

Mg hydride had high hydrogen capacity (7.6%), lightweight and low cost materials and it was promising hydrogen storage material at high temperature. However, commercial applications of the Mg hydride are currently hindered by its high absorption/desorption temperature, and very slow reaction kinetics. one of the approaches to improve the kinetic is $MgH_x$ intermixed with carbon. And it shows that carbon and carbon allotropes have a beneficial effect on hydrogen sorption in Mg. The graphene is a kind of carbon allotropes which is easily desorbed reaction at low temperatures because its reaction is exothermic. In this work, the effect of graphene concentration on the kinetics of Mg hydrogen absorption reaction was investigated. The $MgH_x$-Graphene composites has been prepared by hydrogen induced mechanical alloy (HIMA). The synthesized powder was characterized by XRD and simultaneous TG, DSC analysis. The hydrogenation behaviors were evaluated by using a sievert's type automatic PCT apparatus. In this research, results of kinetic profiles exhibit hydrogen absorption rate of $MgH_x$-5wt.% and 10wt.% graphene composite, as 1.25wt.%/ms, 10.33wt.%/ms against 0.88wt.%/ms for $MgH_x$ alone at 473K.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.274-284
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• 2012

Recently, gasification technology for coal blended with biomass has been an issue. Especially, An advantages of coal blended with biomass are 1) obtaining high cold gas efficiency, 2) obtaining syn-gas of high-high heating value (HHV), and 3) controlling occurrence of $CO_2$. In this study, the efficiency and characteristic of 300 MW Shell type gasifier were predicted using CFD simulation. The CFD simulation was performed for biomass coal blending ratios of 0~0.2, 0.5, 1 and $O_2$/fuel ratios of 0.5~0.84. Kinetic parameters (A, $E_a$) obtained by $CO_2$ gasification experiment were used as inputs for the simulation. In results of CFD simulation, residence times of particle in 300MW Shell type gasifer presented as 7.39 sec ~ 13.65 sec. Temperature of exit increased with $O_2$/fuel ratio as 1400 K ~ 2800 K, while there is not an effects of biomass coal blending ratios. Considering both aspects of temperature for causing wall slagging and high cold gas efficiency, the optimal $O_2$/fuel ratio and blending ratio were found to be 0.585 and 0.05, respectively.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.706-713
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• 2011

The effects of silica-alumina type catalysts addition on the thermal decomposition of ethylene vinyl acetate (EVA) resin have been studied in a thermal analyzer (TGA, DSC) and a small batch reactor. The silica-alumina type compounds tested were kaolinite, bentonite, perlite, activated clay and clay. As the results of TGA experiments, pyrolysis starting temperature for EVA resin had the 1st pyrolysis temperature range of 300~$400^{\circ}C$ and the 2nd pyrolysis temperature range of 425~$525^{\circ}C$. The silica-alumina type catalysts did not affect the pyrolysis rate in EVA pyrolysis reaction. In the DSC experiments, addition of kaolinite and bentonite catalysts reduced the heat of fusion and heat of 2nd pyrolysis reaction. In the batch system experiments, the mixing of silica-alumina type catalysts enhanced the yield of fuel oil, and affected to the distribution of carbon numbers. In the silica-alumina type inorganic material used in this experiments, bentonite was the most effective from the pyrolysis heat, yields, and the characteristics of fuel oil.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.599-608
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• 2011

The Ni-Al anodes of the molten carbonate fuel cell (MCFC) with three different structures were successfully fabricated in order to reduce the thickness of the anode down to 0.3 mm; one was the non-supported anode made by a conventional tape casting method, and others were the supported anodes made by lamination or direct casting on the nickel screen. It was seen from the physical analyses and cell operation that the supported thin anodes made by direct casting showed good mechanical strength and cell performance because of a good contact between the anode materials and the support. The single cell using the above anode showed the cell voltage of 0.858 V at the current density of 150$mA/cm^2$ with the nitrogen cross-over of only 0.6% at the operation time of 1,000 h, which was similar to the performance of the conventional thick (0.7 mm) anode. The ability to utilize a thin configuration of anode should cut down the amount of nickel alloy and consequently reduce its manufacturing cost.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.412-419
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• 2012

Increasing demand for natural gas and higher natural gas prices in the recent decades have led many people to pursue unconventional methods of natural gas production. POSCO-Gwangyang synthetic natural gas (SNG) project was launched in 2010. As the market price of natural gas goes up, the increase of its price gets more sensitive due to the high cost of transportation and liquefaction. This project can make the SNG economically viable. In parallel with this project, KEPCO (Korea Electric Power Corporation) joined in launching the SNG Quality Standard Bureau along with KOGAS (Korea Gas Corporation), POSCO and so on. KEPCO Research Institute is in charge of SNG fueled gas turbine combustion test. In this research, several combustion tests were conducted to find out the effect of hydrogen contents in SNG on gas turbine combustion. The hydrogen in synthetic natural gas did not affect on gas turbine combustion characteristics which are turbine inlet temperature including pattern factor and emission performance. However, flame stable region in ${\Phi}$-Air flow rate map was shifted to the lean condition due to autocatalytic effect of hydrogen.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.579-584
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• 2011

Sulfonated poly (ether sulfone)s containing BFBN were prepared from 2,3-bis(4-fluorophenyl)-2-butenedinitrile , 4,4-sulfonyldiphenol and sulfonated 4,4'-difluorodiphenylsulfone sodium salt using potassium carbonate, and followed acidification reaction with 1M $H_2SO_4$. BFBN was prepared from 4-fluorobenzylcyanide, $CCl_4$, NaOH using trimethylbenzylammoniumchloride . Sulfonated poly(ether sulfone)s containing BFBN were studied by FT-IR, $^1H$-NMR spectroscopy, and thermo gravimetric analysis (TGA). The water uptake of synthesized S-PBFBN membranes exhibit 31~62% compared with 28% of Nafion 211. The S-PBFBN membranes exhibit proton conductivities ($80^{\circ}C$, RH 100) of 53.8~117.4 mS/cm compared with 137.4 mS/cm of Nafion 211.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.765-771
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• 2011

This study was conducted to investigate the effect of heat treatment on the start-up performance for anaerobic hydrogen fermentation of food waste. The result showed that hydrogen production was $0.61{\pm}0.31$ mol $H_2$/mol hexose with heat-treatment of food waste at $70^{\circ}C$ for 60 min whereas it was $0.36{\pm}0.31$ mol $H_2$/mol hexose without heat-treatment of one. The heat treatment of food waste enhanced hydrogen yield due probably to the increase of hydrolysis as well as the decrease of non-hydrogen fermentation microorganisms. The removal efficiency of carbohydrate in reactors regardless of heat treatment of food waste maintained over 90%. The hydrogen conversion efficiency from food waste was 1.7-6.3% with heat-treatment whereas it was 0.7-4.5% without heat-treatment. At the time of switchover from batch to continuous operation, lactate concentration was high compared to the n-butyrate concentration in anaerobic hydrogen fermentation reactor without heat-treatment. Anaerobic hydrogen fermentation of food waste with heat treatment was stable in start-up periods because lactate concentration could be maintained at a relatively low compared to n-butyrate concentration due to the decrease of non-hydrogen fermentation microorganisms.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.686-698
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• 2011

Mathematical models for char-slag interaction and near-wall particle segregation developed by Montagnaro et. al. were applied to predict various aspects of coal gasification in an up-flow entrained gasifier of commercial scale. For this purpose, some computer simulations were performed using gPROMS as the numerical solver. Typical design parameters and operating conditions of the commercial gasifiers were used as input values for the simulation. Development of a densely dispersed phase of solid carbon was found to have a critical effect on both carbon conversion and ash flow behavior. In general, such a slow-moving phase was turned out to enhance carbon conversion by lengthening the residence time of char or soot particles. Furthermore, it was also found that guiding the transfer of char or soot into the closer part of the wall to coal burner is favorable in terms of gasification efficiency and vitrified ash collection. Finally, to a certain degree densely dispersed phase of carbon showed an yield-enhancing effect of syngas.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.925-933
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• 2011

The traditional feedstock for dimethyl ether (DME) has been natural gas obtained by pipeline from a nearby natural gas or oil field. This report focuses on other feedstock: Coal bed methane (CBM). The resource availability and suitability of CBM for DME manufacturing have been investigated. CBM in a short time has become an important industry, providing an abundant clean-burning fuel and also suggesting as a feedstock for gas industry. The use of CBM will have very little impact on the KOGAS' DME process design and economics up to 50 vol% of $CO_2$ in the CBM source. Many of the CBM sources in Asia are high in $CO_2$, but pose no difficulties for the KOGAS' DME plant. Since tri-reformer requires substantial $CO_2$ in its feed, no $CO_2$ removal from the CBM feed is needed. The $CO_2$ in the CBM means that less $CO_2$ needs to be recycled from the downstream in the process.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.250-255
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• 2012

In this paper, the development and performance analysis of a fuel cell-powered unmanned aerial vehicle is described. A fuel cell system featuring 1 kW proton exchange membrane fuel cell combined with a highly pressurized fuel supply system is proposed. For the higher fuel consumption efficiency and simplification of overall system, dead-end type operation is chosen and each individual system such as purge system, fuel supply system, cooling system is developed. Considering that fluctuation of exterior load makes it hard to stabilize fuel cell performance, the power management system is designed using a fuel cell and lithium-ion battery hybrid system. After integration of individual system, the performance of unmanned aerial vehicle is analyzed using data from flight and laboratory test. In the result, overall system was properly operated but for more duration of flight, research on weight lighting and improvement of fuel efficiency is needed to be progressed.