• 한국가스학회지
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• 제15권1호
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• pp.60-67
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• 2011

화석연료의 고갈과 대기오염 문제의 부담을 덜어줄 수 있는 신에너지 및 재생에너지에 대한 관심이 증가하면서 현재 사용 중인 LPG 및 LNG 가스의 대체 (혼합)연료로, DME (dimethyl ether)와 수소를 혼합 (HCNG)하여 사용하는 방안이 추진되고 있다. 이와 같은 에너지원은 인화성 가스 폭발의 위험을 가지고 있기 때문에, 본 연구에서는 기존의 시설에서 이 혼합연료를 사용할 경우에 대비한 안전관리의 일환으로, 3가지 폭발피해 예측방법 (TNT 당량모델, PHAST 및 CFD기반의 FLACS)을 이용하여 정량적 위험성 평가를 실시하였다. 그리고 각 폭발모델에 의해 산출된 사고결과인 과압의 차이를 비교하였고, 폭발모델의 사용방안을 제시하였다. 그 결과, 기존의 2가지 충전소에서 신에너지 혼합연료를 사용할 경우에는 폭발에 의한 추가 피해는 없을 것으로 예상되었다.

• 대한기계학회논문집B
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• 제34권5호
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• pp.449-456
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• 2010

HCCI 엔진은 고효율, 저공해를 실현할 수 있는 차세대 내연기관이다. 그러나 HCCI 엔진이 상용화되기 위해서는 몇 가지 문제점들이 해결되어야 한다. 그 중에서 가장 큰 문제점은 과도한 압력 상승률이 노킹을 발생시키기 때문에 운전영역이 제한되는 것이다. 이번 연구의 목적은 HCCI 엔진에서 압력상승률 저감을 위하여 온도 성층화와 농도 성층화 효과를 조사하는 것이다. 그리고 Multi-zone 모델을 이용한 화학반응 수치해석을 통하여 연소 및 배기가스 특성에 미치는 영향을 알아보았다. 수치해석에서 2 단계 열발생을 가지는 DME와 1단계 열발생을 가지는 메탄을 사용하였다.

• 대한기계학회논문집B
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• 제31권11호
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• pp.926-935
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• 2007

The NOx emission characteristics of DME in laminar coaxial jet and counterflow nonpremixed flames were investigated using experimental and numerical approaches, respectively. The flame structure and NOx emission of DME were compared with those of $C_2H_6$ and $C_3H_8$. The DME flame was calculated using the Kaiser's mechanism, while the $C_2H_6$ and $C_3H_8$ flames were calculated using the $C_3$ mechanism. These mechanisms were combined with the modified Miller-Bowman mechanism for the analysis of NOx. Experimental results show in coaxial jet flame that DME flame has the characteristics of partial premixed flame and the flame length decreases up to 1/3 than that of $C_3H_8$ in the same condition of fuel mass flowrate. Then, the NOx emission of DME decreases to 40% approximately, comparing with that of $C_3H_8$. In the calculated results of counterflow nonpremixed flame, DME flame shows the $EI_{NO}$ decreases up to 50% approximately than those of$ C_2H_6$ and $C_3H_8$ flames when the equivalent fuels are consumed per unit mass and time. Although the overall NOx reaction path of DME is similar with other hydrocarbon fuels, it can be identified that DME flame has a distinct NO reduction mechanism due to the reburning NO chemistry in fuel rich region. From these results, we can conclude that the different NOx emission characteristics of DME flame with other hydrocarbon fuels are attributed to not the temperature increase and the activation of NO reactions due to O atom in DME fuel but the rapid processes of pyrolysis/oxidation.

• 에너지공학
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• 제24권4호
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• pp.33-41
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• 2015

DME는 높은 세탄가와 낮은 배출가스로 인하여 청정 디젤엔진 대체연료로 사용될 수 있고, LPG와 물리적 특성이 유사하기 때문에 혼합사용이 가능하다. 본 연구에서는 DME-LPG 혼합연료를 LPG 차량 연료에 적용한 실증평가를 수행하였다. 평가 차량으로는 LPG 연료 공급방식별로 액상연료공급방식(LPLi), 기상연료공급방식(LPGi), 분배식펌프 방식(Mixer type)의 LPG 자동차를 선택하였다. 배출가스(CO, THC, $NO_X$)와 연료소비효율에 대한 영향을 비교하기 위하여 LPG와 DME-LPG 혼합연료에 대한 성능평가를 수행하였다. 차량의 주행거리가 증가함에 따라 DME-LPG 혼합연료를 사용한 차량의 배출가스와 연료소비효율은 LPG 연료를 사용한 경우와 비교해서 동등한 수준으로 평가되었다.

• 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.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.149-162
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• 2003

Moisturizing the skin is one of the most important functions of skincare cosmetics, because water plays a significant role in keeping the skin healthy. There are various humectants including polyol (glycerin and 1,3-butylene glycol), water-soluble polymers, and botanical extracts. It is well known that the increased amount of polyol in lotion for obtaining high moisturizing effect gives a sticky feeling to the skin. Therefore, a few humectants that can give high moisturizing effect without a sticky feeling for lotion formula is available. On the other hand, oil-based lipstick is well known to have a difficulty to contain a large amount of hydrophilic humectants, because the humectants is unable to be mixed well into oil-based lipsticks and give the lips a peculiar taste. There are newly developed humectants, polyoxyethylene/polyoxypropylene dimethyl ether (EPDME) that can solve these problems describable above. EPDME is a random copolymer of ethylene oxide and propylene oxide. EPDME gives a low sticky feeling with a high moisturizing effect when it is used in lotion. As a remarkable character, EPDME can show not only a preventing effect on rough and dry skin, but also a improving effect upon the use for 1-4 weeks. EPDME can show a synergistic effect with glycerin on preventing to rough and dry skin. Since EPDME can be dissolved in oil-based formulation and used as an ingredient of lipsticks, EPDME can give a moisturizing effect that allows lip to be healthy condition. EPDME can also give no peculiar taste even upon the use of a large amount. EPDME is a useful cosmetic ingredient that can show a good skin care effect in both water-based formula and oil-based formula. EPDME of which polarity can be controllable is expected to be used for various cosmetic applications in near future.

• Elastomers and Composites
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• 제45권1호
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• pp.40-43
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• 2010

본 연구에서는 전기방사 장치의 드럼형태 컬렉터의 회전속도를 조절함으로써 제조된 섬유가 랜덤 또는 배향성 (1축, 2축)을 갖는 폴리이미드(PI) 나노섬유 매트를 제조하였다. 제조된 PI 매트의 구조를 전자현미경(SEM)을 통해 관찰한 결과 전술한 배향성을 확인할 수 있었다. 1 M 리튬트리풀루오로-메탄-설포네이트와 테트라-에틸렌 글리콜디메틸 에테르의 혼합용액에 PI 매트를 침지시킨 후 이온전도기로 이온전도도를 측정하였다. 2축배향 매트가 가장 높은 이온전도도를 나타내었다. 1축 배향의 경우 이온의 이동방향과 수직방향이 평행방향보다 이온전도도가 낮게 나타났고, 아울러 일정한 주기성을 나타내었다. 주기성은 섬유간 거리와 이온 속도를 이용하여 설명할 수 있었다.

• International Journal of Automotive Technology
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• 제7권1호
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• pp.1-7
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• 2006

The ignition delay of a dual fuel system has been numerically investigated by adopting a constant volume chamber as a model problem simulating diesel engine relevant conditions. A detailed chemical kinetic mechanism, consisting of 28 species and 135 elementary reactions, of dimethyl ether (DME) with methane ($CH_{4}$) sub-mechanism has been used in conjunction with the multi-dimensional reactive flow KIVA-3V code to simulate the autoignition process. The start of ignition was defined as the moment when the maximum temperature in the combustion vessel reached to 1900 K with which a best agreement with existing experiment was achieved. Ignition delays of liquid DME injected into air at various high pressures and temperatures compared well with the existing experimental results in a combustion bomb. When a small quantity of liquid DME was injected into premixtures of $CH_{4}$/air, the ignition delay times of the dual fuel system are longer than that observed with DME only, especially at higher initial temperatures. The variation in the ignition delay between DME only and dual fuel case tend to be constant for lower initial temperatures. It was also found that the predicted values of the ignition delay in dual fuel operation are dependent on the concentration of the gaseous $CH_{4}$ in the chamber charge and less dependent on the injected mass of DME. Temperature and equivalence ratio contours of the combustion process showed that the ignition commonly starts in the boundary at which near stoichiometric mixtures could exists. Parametric studies are also conducted to show the effect of additive such as hydrogen peroxide in the ignition delay. Apart from accurate predictions of ignition delay, the coupling between multi-dimensional flow and multi-step chemistry is essential to reveal detailed features of the ignition process.

• 한국수소및신에너지학회논문집
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• 제26권5호
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• pp.477-483
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• 2015

LFG (Land-Fill Gas) includes components of $CH_4$, $CO_2$, $O_2$, $N_2$, and water. The preparation of synthesis gas from LFG as a DME (Dimethyl Ether) feedstock was studied by methane reforming of $CO_2$, $O_2$ and steam over $NiO-MgO-CeO_2/Al_2O_3$ catalyst. Our experiments were performed to investigate the effects of methane conversion and syngas yield on the amount of LFG components over $NiO-MgO-CeO_2/Al_2O_3$ catalyst. Results were obtained through the methan reforming experiments at the temperature of $900^{\circ}C$ and GHSV of 8,800. The results were as following; it has generally shown that syngas yield increase with the increase of oxygen and steam amounts and then decrease. Highly methane conversion of above 98% and syngas yield of approximately 60% were obtained in the feed of gas composition flow-rate of 243ml/min of $CH_4$, 241ml/min of $CO_2$, 195ml/min of $O_2$, 48ml/min of $N_2$, and 450ml/min of steam, respectively, under reactor pressure of 1 bar for 200 hrs of reaction time. Also, it was shown that catalyst deactivation by coke formation was reduced by excessively adding oxygen and steam as an oxidizer of the methane reforming.

• 한국수소및신에너지학회논문집
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• 제23권5호
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• pp.559-571
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• 2012

Dimethyl ether (DME) is a new clean fuel as an environmentally-benign energy resource. DME can be manufactured from various energy sources including natural gas, coal, and biomass. In addition to its environmentally friendly properties, DME has similar characteristics to those of LPG. The aim of this article is to represent the development of new DME process with KOGAS's own technologies. KOGAS has investigated and developed new innovative DME synthesis process from synthesis gas in gaseous phase fixed bed reactor. DME has been traditionally produced by the dehydration of methanol which is produced from syngas, a product of natural gas reforming. This traditional process is thus called the two-step method of preparing DME. However, DME can also be manufactured directly from syngas (single-step). The single-step method needs only one reactor for the synthesis of DME, instead of two for the two-step process. It can also alleviate the thermodynamic limitations associated with the synthesis of methanol, by converting the produced methanol into DME, thereby potentially enhancing the overall conversion of syngas into DME. KOGAS had launched the 10 ton/day DME demonstration plant project in 2004 at Incheon KOGAS LNG terminal. In the mid of 2008, KOGAS had finished the construction of this plant and has successively finished the demonstration plant operation. And since 2008, we have established the basic design of commercial plant which can produce 3,000 ton/day DME.