• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.31-32
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• 2006

• 공업화학
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• 제27권2호
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• pp.128-134
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• 2016

최근 셰일가스의 개발로 프로판, 부탄과 같은 경질알칸으로부터 프로필렌, 부텐, 부타디엔과 같은 올레핀을 제조하는 탈수소 공정에 대한 연구와 상용화가 많이 진행되었다. 특히 직접 탈수소화 반응의 열역학적 한계를 극복하고자 산화적 탈수소 또는 선택적 수소 산화 반응과 같이 산소를 활용한 기술의 연구개발이 진행되거나, 실제 공정에 적용된 사례들도 보고되고 있다. 이에 본 연구에서는 경질알칸의 탈수소 반응을 위한 산소활용기술의 최근 연구동향을 가스상의 산소를 활용하는 방법과 고체산화물의 격자산소를 활용한 기술로 나누어 정리하고, 산소활용기술의 현황과 연구 개발 방향 및 향후 전망에 대해 고찰하였다. 반응물의 반응성에 따라 기체상 산소의 적용이 용이한 경우와 반응성의 조절을 위해 격자산소를 이용하는 기술로 분류할 수 있었고, 전환율을 높이면서 선택도를 낮추지 않는 기술의 개발이 주요한 목표가 되었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.109-114
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• 2009

As one of the promising model on the multiphase fluid mixtures, the Lattice-Boltzmann Method(LBM) is being developed to simulate flows containing two immisible components which are different mass values. The equilibrium function in the LBM can have a nonideal gas model for the equation of state and use the interfacial energy for the phase separation effect. An example on the phase separation has been carried out through the time evolution. The LBM based on the statistic mechanics is appropriate to solve very complicated flow problems and this model gives comparative merits rather than the continuum mechanics model.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.269-270
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• 2006

A finite difference lattice Boltzmann model which allows us to simulate gas-liquid two-phase flows with large density difference, for instance, 800 times for air and water is considered. Two-particle model is used and the density difference is introduced by changing the acceleration according to the fluid density. Numerical measurement of surface tension agrees well with theoretical predictions. Simulations of two-phase phenomenon for phase-transition is carried out, showing applicability of the model for two-phase flows. The two-dimensional cavitating flow around a board set up in the fluid way is also simulated. As a result, it was confirmed that the FDLB method with two-particle model was effective in numerical simulation of cavitating flow and the bubble periodically grew up at the low pressure area behind the board, in which the fluid condition was influenced by the cavitation number.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.519-523
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• 2007

Gas(or methane) hydrates are solid solutions when water molecules are linked through hydrogen bonding and create host lattice cavities that can enclose a large variety of guest gas molecules. The natural gas hydrate crystal may exist at low temperature above the normal freezing point of water and high pressure greater than about 30 bars. A lot of quantities of natural gas hydrates exists in the earth and many production schemes are being studied. In the present investigation, depressurization method was considered to predict the production of gas and the simulation of the two phase flow - gas and water - in porous media is being carried out. The simulation show about the fluid flow in porous media have a variety of applications in industry. Results provide the appearance of gas and water production, the pressure profile, the saturation of gas/ water/ hydrates profiles and the location of the pressure front.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.241-246
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• 2000

Gas hydrates are solid solutions when water molecules are linked through hydrogen bondin create host lattice cavities that can enclose a large variety of guest gas molecules. The natural hydrate crystal may exist at low temperature above the normal freezing point of water and pressure greater than about 30 bars. A lot of quantities of natural gas hydrates exists in the ear many production schemes are being studied. In the present investigation, depressurization method considered to predict the production of gas and the simulation of the two phase flow - gas and - in porous media is being carried out. The simulation show about the fluid flow in porous have a variety of applications in industry. Results provide the appearance of gas and water prod the pressure profile, the saturation of gas/ water/ hydrates profiles and the location of the pl front.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.585-589
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• 2007

Gas hydrate is a special kind of inclusion compound that can be formed by capturing gas molecules to water lattice in high pressure and low temperature conditions. When referred to standard conditions, $1m^3$ solid hydrates contain up to $172Nm^3$ of methane gas, depending on the pressure and temperature of production, Such large volumes make natural gas hydrates can be used to store and transport natural gas. In this study, three-phase equilibrium conditions for forming methane hydrate were theoretically obtained in aqueous single electrolyte solution containing 3wt% Nacl. The results show that Nacl acts as a inhibitor, but help gases such as ethan, propane, i-butane, and n-butane reduce the hydrate formation pressure at the same temperature.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.51-58
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• 2007

Gas hydrate is a special kind of inclusion compound that can be formed by capturing gas molecules to water lattice in high pressure and low temperature conditions. When referred to standard conditions, $1m^3$ solid hydrates contain up to $172Nm^3$ of methane gas, depending on the pressure and temperature of production. Such large volumes make natural gas hydrates can be used to store and transport natural gas. In this study, three-phase equilibrium conditions for forming methane hydrate were theoretically obtained in aqueous single electrolyte solution containing 3wt% NaCl. The results show that the predictions match the previous experimental values very well, and it was found that NaCl acts as an inhibitor.

• 세라미스트
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• 제23권2호
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• pp.211-230
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• 2020

Perovskite-type oxides with the nominal composition of ABO₃ can exsolve the B-site transition metal upon the controlled reduction. In this exsolution process, the transition metal emerges from the oxide lattice and migrates to the surface at which it forms catalytically active nanoparticles. The exsolved nanoparticles can recover back to the bulk lattice under oxidation treatment. This unique regeneration character by the redox treatment provides uniformly dispersed noble metal nanoparticles. Therefore, the conventional problem of traditional impregnated metal/support, i.e., sintering during reaction, can be effectively avoided by using the exsolution phenomenon. In this regard, the catalysts using the exsolution strategy have been well studied for a wide range of applications in energy conversion and storage devices such as solid oxide fuel cells and electrolysis cells (SOFCs and SOECs) because of its high thermal and chemical stability. On the other hand, although this exsolution strategy can also be applied to gas phase reaction catalysts, it has seldomly been reviewed. Here, we thus review recent applications of the exsolution catalysts to the gas phase reactions from the aspects of experimental measurements, where various functions of the exsolved particles were utilized. We also review non-perovskite type metal oxides that might have exolution phenomenon to provide more possibilities to develop higher efficient catalysts.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.2032-2039
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• 2005

The lattice Boltzman method (LBM) and the finite difference-based lattice Boltzmann method (FDLBM) are quite recent approaches for simulating fluid flow, which have been proven as valid and efficient tools in a variety of complex flow problems. They are considered attractive alternatives to conventional finite-difference schemes because they recover the Navier-Stokes equations and are computationally more stable, and easily parallelizable. However, most models of the LBM or FDLBM are for incompressible fluids because of the simplicity of the structure of the model. Although some models for compressible thermal fluids have been introduced, these models are for monatomic gases, and suffer from the instability in calculations. A lattice BGK model based on a finite difference scheme with an internal degree of freedom is employed and it is shown that a diatomic gas such as air is successfully simulated. In this research we present a 2-dimensional edge tone to predict the frequency characteristics of discrete oscillations of a jet-edge feedback cycle by the FDLBM in which any specific heat ratio $\gamma$ can be chosen freely. The jet is chosen long enough in order to guarantee the parabolic velocity profile of a jet at the outlet, and the edge is of an angle of $\alpha$=23$^{o}$. At a stand-off distance w, the edge is inserted along the centerline of the jet, and a sinuous instability wave with real frequency is assumed to be created in the vicinity of the nozzle exit and to propagate towards the downstream. We have succeeded in capturing very small pressure fluctuations resulting from periodic oscillation of the jet around the edge.