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Temperature-Dependent Structural Transitions in Methane–Ethane Mixed Gas Hydrates
Kwon, Minchul,Lee, Jong-Won,Lee, Huen American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.49
<P>A thermodynamic interpretation of the interconversion between structures I and II occurring in methane (CH<SUB>4</SUB>) + ethane (C<SUB>2</SUB>H<SUB>6</SUB>) mixed gas hydrates is of great importance from both fundamental and applied perspectives. The present study experimentally confirms the predicted temperature dependence of structural changes in the lower transition region (72–74 mol % of CH<SUB>4</SUB> balanced with C<SUB>2</SUB>H<SUB>6</SUB>) of the CH<SUB>4</SUB> + C<SUB>2</SUB>H<SUB>6</SUB> + H<SUB>2</SUB>O system. The measurements of phase equilibria and Raman spectra, at the macroscopic and microscopic levels, respectively, reveal the phase transition point at which the structural rearrangements occur. The isothermal data reported here clearly demonstrate significant changes of transition behavior from sII inhibition to sII promotion in accordance with increased equilibrium temperatures. This solid–solid transition trend may be dictated by the peculiar structural feature of the CH<SUB>4</SUB> + C<SUB>2</SUB>H<SUB>6</SUB> mixed gas hydrates on the basis of the comprehensive experimental and theoretical data published previously. The predominance of CH<SUB>4</SUB> over C<SUB>2</SUB>H<SUB>6</SUB> in cage occupancy may lead to a change in guest molecules playing a dominant role in determining the preferential hydrate structure.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-49/jp5102219/production/images/medium/jp-2014-102219_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5102219'>ACS Electronic Supporting Info</A></P>
Kwon, Minchul,Youn, Yeobum,Seo, Yongwon,Lee, Jong-Won,Lee, Jaehyoung,Lee, Joo Yong,Kim, Se-Joon,Lee, Huen American Chemical Society 2013 Energy & fuels Vol.27 No.9
<P>Investigations on the intrinsic properties of gas hydrates with multiple guests are essential to scientific and technological fields. In particular, even though evaluating and designing a hydrate phase process require isothermal phase equilibria, it is difficult to obtain extensive data with various components and compositions in a short period of time due to the static-analytic method. The present study introduces a new experimental determination on hydrate phase equilibria using continuous dissociation induced by extremely slow vapor volume expansion at a constant temperature. When a syringe pump is automatically operated at the microliter level during the dissociation process, the endothermic dissociation can be traced from the temperature readings. The validity and stability of the proposed technique were evaluated using pure CH<SUB>4</SUB> hydrates, and repeated measurements of three-phase (L<SUB>W</SUB>–H–V) equilibrium conditions are used to optimize the volumetric expansion rates. Then, an experimental approach is applied to incipient CH<SUB>4</SUB> + C<SUB>2</SUB>H<SUB>6</SUB> hydrates and identifies the structural transition behavior. This method is thought to provide extensive data and further improvements in terms of hydrate phase equilibria with multiple gas components.</P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ef401072s'>ACS Electronic Supporting Info</A></P>
Lattice Contraction Behavior Occurring in Ionic Clathrate Hydrate
권민철(Kwon, Minchul),차민준(Cha, Minjun),신규철(Shin, Kyuchul),이흔(Lee, Huen) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
Unlike non-ionic clathrate hydrates stably formed by van der Waals interaction between a guest molecule and a surrounding host framework, ionic clathrate hydrates are stabilized by ionic interaction between an ionic guest molecule and the host water-framework. Here, we firstly described the stable entrapment of the superoxide ions in {gamma}-irradiated Me₄NOH+O₂ hydrate. Owing to peculiar direct guest-guest ionic interaction, the lattice structure of {gamma}-irradiated Me₄NOH+O₂ hydrate shows significant change of lattice contraction behavior even at relatively high temperature(120K). Particularly, we note that ionic-induced dimensional change is much greater than thermal-induced change. Such findings are expected to provide useful information for a better understanding of unrevealed nature of clathrate hydrate fields.
Introduction of DPLR DFCO(Deceleration Fuel Cut Off) Pumping Loss Reduction
Minchul Park,Ohcheol Kwon,Seungheon Yoo,Youngsoo Jeong 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Hybrid technology increased fuel economy in many ways. Motor produced torque enables engine stop at vehicle stop or runs engine in the optimized modes and Regenerated power by motor in a vehicle deceleration save energy to the RESS. Those are typical way to save fuel in a Hybrid vehicle. GM developed another way to save energy in a Hybrid vehicle by reducing engine pumping loss while in deceleration fuel cut off. On conventional powertrain systems, the pumping losses cannot be substantially reduced because it would add to response delays when the driver tips in due to the need to pump down the manifold pressure before the fuel can be turned on. However, on hybrid powertrain systems, the electric motor can be used to provide the propulsion that the driver needs until the manifold pressure is pumped down. It is called DFCO Pumping Loss Reduction. We will introduce this new method in this paper and show how much engine pumping loss reduced and how much fuel economy increased with it.
정민철,정혜성,김성민,이정훈,박권필,안호근 한국공업화학회 2005 응용화학 Vol.9 No.1
We have been used for the Pt catalyst of cathode electrode in fuel cell. Weak point of Pt electrode are easily deactivated by the CO poisoning which are producing in reaction at electrode. Recent, researchers have developed cathode electrode to avoid the CO poisoning in electrode using the Pt-alloy or another novel metal. We now report Au-carbene complexes as an Au-electrode precursor derived from the reaction of the carbene with the ClAu(PPh₃) complex in THF/MeOH.
박민철(Park, Minchul),권혁찬(Kwon, Hyukchan),신효희(Shin, Hyohee),장기수(Jang, Gisoo),이송(Lee, Song) 한국지반환경공학회 2011 한국지반환경공학회논문집 Vol.12 No.12
연직배수공법은 효과적인 연약지반 압밀촉진 방법으로 적용빈도가 증가하고 있다. 연직배수 공법 중에서 PBD공법은 현재 가장 많이 사용되고 있는 압밀촉진공법으로 경제성 및 시공성 면에서 우수하나, 환경오염 및 대심도의 경우 배수재의 굴곡으로 인한 통수능 저하 문제점을 지니고 있다. SCP공법은 과거에 통수능력이 우수하여 많이 사용되었으나, 재료의 수급불균형으로 인한 가격급등으로 현재는 과거보다 사용이 많이 줄고 있는 실정이다. 이에 따른 대책 재료로 쇄석말뚝을 이용한 GCP공법이 대두되고 있다. 따라서 GCP공법의 통수능 효과를 분석하기 위하여 ?38×70cm의 원형토조를 이용하여 쇄석말뚝과 비교대상인 모래말뚝, PBD공법의 3종류의 연직배수재를 이용하여 복합통수능 실험을 실시하였다. 또한, 쇄석말뚝의 클로깅(Clogging) 범위를 파악하기 위하여 1.0m×0.5m×1.1m 대형토조를 정면에 투명 아크릴로 제작하여 하중단계별 클로깅(Clogging) 범위를 분석하였다. 복합통수능 시험결과 하중증가에 따른 간극비 감소 및 클로깅(Clogging) 현상이 많이 발생한 GCP공법에서 가장 적게 발생하였으며, 또한 GCP 공법의 클로깅(Clogging)의 범위는 거의 10% 내에서 발생하는 것으로 분석되었다. An application frequency of vertical drainage method is increasing as an effective consolidation acceleration method. PBD method is most frequently used as a consolidation acceleration method in vertical drainage methods. PBD is economical and easy to operate but has some problems those are an environmental pollution and a decrease of a discharge capacity caused by bending of drainage materials when it is used in great depth. SCP method was frequently used because it"s discharge capacity was good but now it is rarely used because of an increase of the material price because of an order imbalance. As the way to solve these problems, GCP method has been to the fore. For analyzing the effect of GCP method on the discharge capacity, three types of composite discharge capacity tests are done by using GCP, SCP and PBD respectively with the circle case, Φ38×h70cm. On the contrary to this, GCP shows the worst discharge capacity for a decrease of the void ratio and the clogging phenomenon caused by increasing load. Also to figure out the clogging range of GCP, the clogging of GCP is checked in each load stage with a large case(1.0m×0.5m×1.1m) which has clear acrylic front face. The diameter of GCP was 35cm and a clogging phenomenon occurred in 10% approximately. The result shows that the discharge capacity of GCP was given the lowest value for a decrease of the void ratio and the clogging phenomenon causing by increasing load. And the clogging phenomenon mostly occurred within 10% of GCP’s diameter range.
Cha, Minjun,Kwon, Minchul,Youn, Yeobum,Shin, Kyuchul,Lee, Huen American Chemical Society 2012 Journal of chemical and engineering data Vol.57 No.4
<P>In this study, we introduce a new structure-II hydrate former, 2-methylpropane-2-peroxol (tert-butyl hydroperoxide, TBHP), and identify the structure and guest distributions through spectroscopic tools including high-resolution powder diffraction (HRPD), C-13 solid-state NMR, and Raman spectroscopy. Here, the (H + L + V) phase equilibrium data of (TBHP + X) hydrates (X = CH4, N-2, and O-2) were measured at (3.3 to 7.56) MPa and (282.2 to 288.5) K for CH4, (4.0 to 8.5) MPa and (271.6 to 277.5) K for N-2, and (4.0 to 8.6) MPa and (273.8 to 279.6) K for O-2. The (TBHP + X) hydrate phase equilibria showed that the addition of TBHP increased the structural stability with lower hydrate dissociation pressures when compared with those of pure CH4, N-2, and O-2 hydrates. However, we noticed that the TBHP did not promote hydrate formation conditions as effectively as tetrahydrofuran.</P>