• 한국가스학회지
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• 제17권6호
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• pp.8-14
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• 2013

본 연구에서는 LPG자동차용으로 적용키 위한 플라즈마 개질에서 개질기 형상변화가 개질 특성에 미치는 영향에 대해 실험을 하였다. 수소 수율을 향상시키기 위해, 2차 개질기는 1차 개질기에 비해서 개질기 후단부의 부피를 증가시켜 플라즈마를 통과하는 개질가스의 반응시간을 증가시켰다. 각 개질기의 비교를 위하여 $O_2/C$ 비를 부분산화 조건에서부터 완전산화 조건까지, 총 유량은 20, 30, 40, 50 lpm으로 증가시키며 실험을 하였다. 각 개질기의 특성을 비교해본 결과, $O_2/C$ 비가 부분산화 조건에서 완전산화 조건으로 갈수록 LPG 전환율은 증가하였고, 수소 선택도는 감소하였으며, 수소 수율은 증가하다 감소하는 최적조건이 존재하였다. 개질기는 4.5배 부피가 큰 2차 개질기가 1차 개질기에 비해 동일 유량에서 수소 수율이 4~14% 증가한 결과를 얻을 수 있었다.

• 한국응용과학기술학회지
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• 제21권1호
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• pp.45-50
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• 2004

The effects of reaction temperature and flow rate of reactants on the methane conversion, product selectivity, product ratio, and carbon deposition were investigated with 13wt% Ni/MgO catalyst. Reaction temperatures were changed from 600 to $850^{\circ}C$, and reactants flow rates were changed from 100 to 200 mL/mim. There were no significant changes in the methane conversion observed in the range of temperatures used. It is possibly stemmed from the nearly total exhaustion of oxygen introduced. The selectiveties of hydrogen and carbon monoxide did not largely depend on the reaction temperature. The selectivities of hydrogen and carbon monoxide were 96 and 90%, respectively. Carbon deposition observed was the smallest at $750^{\circ}C$ and the largest at $850^{\circ}C$. It is found that the proper reaction temperature is $750^{\circ}C$. The best reactant flow rate was 150 ml/min.

• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.636-641
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• 2021

Using numerical analysis, various factors influencing the performance development of high-pressure pumps for Dimethyl Ether (DME) engines were identified and the impact of each factor was evaluated using Taguchi method. DME fuels are more compressive than diesel fuels and have the lower heat generation, so it is necessary to increase the size of the plunger and speed (RPM) of the pump as well. In addition, it is necessary to change the shape and design of control valve to control the discharge flow and pressure. In this study, various variables affecting the performance and flow rate increase of high-pressure pumps for DME engines are planned using Taguchi method, and the best design method is proposed using correlation of the most important variables. As a result, we were able to provide the design value needed for a six-liter engine and provide optimal conditions. The best combination factors to optimize the flow rate at RPM 2,000 and diameter plunger with 20 mm. The regression equation can also be used to optimize the flow rate; -8, 13+0, 2552 RPM +54, 17 diam. Plunger.

• 한국결정성장학회지
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• 제14권1호
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• pp.27-32
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• 2004

RF-PECVD 방법을 이용하여 DLC(diamond-like carbon)박막을 메탄-수소 가스 혼합비 및 바이어스 전압에 따라 실리콘 웨이퍼 위에 증착하였다. DLC 박막의 결합구조적 특성 및 기계적 성질은 FT-IR, Raman, 그리고 nano-indenter를 이용하여 평가하였다. 혼합가스내 메탄의 유량과 바이어스 전압이 증가함에 따라 증착속도가 증가하였다. 박막내 탄소의 $sp^3/sp^2$ 결합비와 경도는 반응가스내 수소의 유량 및 바이어스 전압이 증가함에 따라 증가하였다.

• 한국수소및신에너지학회논문집
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• 제33권5호
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• pp.550-556
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• 2022

In this study, the flow uniformity was analyzed by performing numerical analysis on the 1 kWe internal manifold type solid oxide fuel cell stack according to the channel height of the separator. Also, it was examined by varying the fuel utilization rate and oxygen utilization rate. From the calculation results, we found that as the channel height of the separator decreased, the pressure drop increased exponentially. In addition, it was found that as the channel height of the separator decreased, the gas flow resistance inside the unit cell increased, and the flow resistance increased the pressure drop, thereby improving the flow uniformity inside the stack. Finally, the calculation results showed that as the fuel and oxygen utilization increased, the flow uniformity also improved.

• 한국수소및신에너지학회논문집
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• 제19권1호
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• pp.26-34
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• 2008

This study presents an aerodynamic design and an experimental performance test of a turbo air compressor consisted of mixed-flow impeller and curved diffuser for the PEM fuel cell vehicle application. Many studies compare the efficiency, cost or noise level of high-pressure and low-pressure operation of PEM fuel cell systems. Pressure ratio 2.2:1 is considered as design target The goal of compressor design is to enlarge the flow margin of compressor from surge to choke mass flow rate to cover the operational envelope of FCV. Large-scale rig test is performed to evaluate the compressor performance and to compare the effects of compressor exit pipe volume to stall or surge characteristics. The results show that the mixed-flow compressor designed has large flow margin, and the flow margin of compressor configuration with small exit volume is larger than that with large exit volume.

• 한국수소및신에너지학회논문집
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• 제19권3호
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• pp.232-238
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• 2008

Research has been proceeded on fuel cell which is fueled by hydrogen. Polymer electrolyte membrane fuel cell (PEMFC) is promising power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, temperature dependent performance. These problems could be solved by experiment which is useful for analysis and optimization of fuel cell performance and heat management. In this paper, when hydrogen flows constantly at the stoichiometry of ${\xi}=1.6$, the performance of the fuel cell stack was increased and the voltage difference between each cells was decreased according to the increase of air stoichiometry by 2.0, 2.5, 3.0. Therefore, the control of air flow rate in the same gas channel is important to get higher performance. Purpose of this research is to expect operation temperature, flow rate, performance and mass transportation through experiment and to help actual manufacture of PEM fuel cell stack.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.477-482
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• 2011

In the present study, the diffusion process of hydrogen leaking from a FCV (Fuel Cell Vehicle) in an underground parking lot was analyzed by numerical simulations in order to assess the risk of a leakage accident. The temporal and spatial changes of the hydrogen concentration as well as the flammable region in the parking lot were predicted numerically. The effects of the leakage flow rate and an additional ventilation fan were investigated to evaluate the ventilation performance in the parking lot to relieve the accumulation of the leaked hydrogen gas. The present numerical analysis can provide useful information such as the distribution of the leaked hydrogen concentration for safety of various hydrogen applications.

• 한국재료학회지
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• 제27권2호
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• pp.119-126
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• 2017

WC-CrC-Ni coatings were prepared by nine processes of the Taguchi program with three levels for the four spray parameters: spray distance, flow rates of hydrogen and oxygen, and powder feed rate. The optimal coating process (OCP) was oxygen flow rate of 38 FMR, hydrogen flow rate of 53 FMR, powder feed rate of 25 g/min, and spray distance of 7 inches. Hardness of 1150 Hv and porosity of 1.2 %, were obtained by OCP; these are better results compared with the highest 1033 Hv and the lowest 1.5 % porosity obtained by nine processes of the Taguchi program. Friction coefficient of the WC-CrC-Ni coating decreased from $0.36{\pm}0.07$ at $25^{\circ}C$ to $0.23{\pm}0.07$ at $450^{\circ}C$. These values were smaller than those of the EHC (electrolytic hard chrome) plating at both temperatures due to lubrication from the oxide debris. The wear trace and wear depth of the coating are smaller than those of the EHC at both temperatures. Pitting was not found in the WC-CrC-Ni coating sample, while it did appear in the EHC sample.

• Journal of Welding and Joining
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• 제25권4호
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• pp.42-48
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• 2007

An inert gas atomized NiTiZrSiSn bulk metallic glass feedstock was sprayed onto the copper plate using vacuum plasma spraying process. In order to change the in-flight particle energy, that is, thermal energy, the hydrogen gas flow rate in plasma gas mixture was increased at the constant flow rate of argon gas. Coating and single pass spraying bead were produced with the least feeding rate. Regardless of the plasma gas composition, fully melted through unmelted particle could be observed on the overlay coating. However, the frequency of the unmelted particle number density was increased with the decrease of the hydrogen gas flow rate. The amorphous phase fraction within coating was also affected by the number density of the unmelted particle.