• Journal of Advanced Marine Engineering and Technology
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• 제38권7호
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• pp.799-805
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• 2014

Recently, the regulations of the Local and Global for a variety of air pollution prevention has been enhanced by the steep rise in fuel oil prices. So, the appearance of Gas Fuelled Ships became necessary. In this study, we configured a regasification system which uses Eglycol water as a heating medium to evaporate before being supply fuel to the DF engine, then we analysed the system properties according to the Eglycol water mixing ratio. The results were as follows. When pressure, temperature, and flux of natural gas(NG) which are supplied to DF engines are uniformly kept, the higher mixing ratio of Eglycol is, the lower mixing specific heat of Eglycol water. And the cycle flux and electric power were 1.65 and 1.54 times more required. respectively, than water was used as the heating medium. Basic variables including mass flux according to the mixing ratio of Eglycol water, required electric power of operating fluid pumps, the temperature of natural gas which is supplied to the engine, and the heat exchanger's capacity were drawn from the gotten results.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.425-431
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• 2015

LNG (liquefied natural gas) is considered the best alternative eco-fuel, and many studies on the LNG fuel system have been performed to use LNG as the fuel for ships. For the LNG fuel supply system, natural gas transfers from the vaporizer to the engine in the gaseous state with a temperature of $50^{\circ}C$ and a pressure of 35MPa. Therefore, a structural safety evaluation of the double-walled pipelines considering thermal load is essential. In this article, an uniaxial tensile test for super duplex stainless steel, material for double-walled pipe, according to the annealing time was carried out to analyze the thermal effect. In addition, thermo-structural analysis of the high temperature-high pressure double-walled pipe with fixed supports that are now used widely was carried out to evaluate the structural safety. To minimize stress concentration of the connection point between the support and inner pipe, the shapes of the new type support that can slip through inner pipe were proposed, and the supports which has best structural performance was selected using the results from the thermo-structural analyses of new supports and an analysis of the whole double-walled pipeline was performed to ensure structural safety. These results can be used as a database for the design of double-walled pipelines and sliding support.

• Journal of the korean Society of Automotive Engineers
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• 제8권2호
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• pp.22-30
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• 1986

메탄올 자동차의 도입은 공해책연에서나, 대체연료면에서 중요한 과제라는 인식하에서 일본우수 성은 벌써부터 그의 열현을 목표로 개조차에 의한 성능테스트 실시 등의 여러 가지 준비를 하여 왔는데, 최근에는 자동차 공해대책의 견지에서 디젤엔진을 탑재하여 사용중인 트럭 및 버스에 대 하여 경유대신으로 깨끗한 연료의 사용을 요망하는 소리가 높아지고 있다. 또 운수부문에서도 석유대체에너지의 도입이 요망되고 있어, 메탄올 자동차는 다른 대체에너지를 사용하는 것에 비 해서 기술적, 경제적으로 가장 실용성이 높고, 도입이 준비기간이 짧기 때문에 매우 유망시되고 있다. 자동차연료로서의 메탄올에는 몇가지 문제점이 있다고 지적되기도 하였으나 현재는 모두 기술적 대응이 이루어져 메탄올 자동차의 실용화를 저해하는 문제는 거의 없다고 하겠다. 뿐 만아니라 매탄올의 원료가 되는 천연가스는 세계적으로 대량, 광범하게 존재하고 있어 석유가 격면에서도 대량생산이 궤도에 오르게 되면 경유와 비슷하게 될 가능성이 있다. 따라서 메탄올 자동차는 금후 적극적으로 도입을 추진하여야 할 것이며, 도시버스, 시내집배 트럭 등에 사용되면 자동차공해대책, 에너지 대책의 측면에서 상당히 큰 효과가 기대될 수 있을 것이다. 이러한 메 탄올이 석유대체연료로서 안착될 때까지는 당연히 조성조치가 필요하며 전입을 방해하는 과제는 없어야 할 것이다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제44권7호
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• pp.603-610
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• 2016

This paper describes experimental results about emission and NOx reduction of dilution effect (Nitrogen and carbon dioxide) about various fuel compositions of synthetic natural gas (SNG). Combustion experiment was performed to investigate the combustion characteristics for SNG with various hydrogen ratio in SNG, heat input and equivalence ratio in a partially premixed model gas turbine combustor. NOx emission was similar to each hydrogen ratio and flame characteristics was investigated from OH chemiluminescence images. There was a singularity of CO emission in stoichiometric condition and it can be identified using OH chemiluminescence intensity. In addition, dilution effect was studied in using nitrogen and carbon dioxide as diluent to reduce the NOx emission. Carbon dioxide diluent was more effective to NOx reduction than nitrogen diluent because of its high diluent specific heat and its heat capacity.

• Journal of the Korean Institute of Gas
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• 제17권5호
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• pp.15-21
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• 2013

This study evaluated comparison of the risk according to the type of fuel by three-dimensional simulation tool(FLACS). The consequence analysis of fire explosion and jet-fire was carried out in the layout of a typical high-pressure gas filling stations using CNG, hydrogen and 30%HCNG. Under the same conditions, hydrogen had a 30kPa maximum overpressure, CNG had a 0.4kPa and HCNG had a 3.5kPa. HCNG overpressure was 7.75 times higher than the CNG measurement, but HCNG overpressure was only 11.7% compared to hydrogen. In case of flame propagation, hydrogen had a very fast propagation characteristics. On the other hand, CNG and HCNG flame propagation velocity and distance tended to be relatively safe in comparison to hydrogen. The estimated flame boundary distance by jet-fire of hydrogen was a 5.5m, CNG was a 3.4m and HCNG was a 3.9m.

• Journal of Energy Engineering
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• 제19권2호
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• pp.62-72
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• 2010

Solid oxide fuel cells(SOFCs) directly convert the fuel gases to electric energy through electrochemical reactions. The advantage of SOFCs is that they easily operate with diversified fuels such as natural gases owing to their high temperature operation. However, high temperature operation also incurs the challenge in enhancing long term reliability and durability of SOFCs. The most commonly used anode material is Ni/YSZ. This has, however, some drawbacks in terms of long-term reliability at high temperatures, hydrocarbon fuel usages, and so on, therefore the need to develop the new anode materials increases. This article summarizes the trend of the novel anode materials development of SOFCs.

• Journal of the Korean Institute of Gas
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• 제19권6호
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• pp.67-71
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• 2015

Natural frequencies of a cryogenic fuel tank of LNG vehicle were computed to check the safety related to the resonances, and tests were performed to confirm the vibrational durability of a cryogenic fuel tank. There were 3 tests. The first test started at excitation frequency of 31.9Hz, and the test was performed reducing the excitation frequencies. Failure took place at 22.1Hz. The second test was performed with the frequencies to be increased. At 12.7 Hz, failure took place and nitrogen gas was exhausted. In the third test, the excitation frequencies were continuously changed, and the vibration port was failed in the range between 8 Hz and 19.3 Hz. Detailed research on the failed parts of the tank in this study is recommended to enhance the safety of the cryogenic fuel tanks of LNG vehicles.

• Journal of the KSME
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• 제30권6호
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• pp.555-563
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• 1990

연료전지 발전시스템은 발전효율이 높고, 공해물질이 없는 등 많은 장점을 갖는 에너지생산 방 식에 따라 장래의 이용이 크게 기대되고 있다. 현재 연구개발에 많은 성과를 보이고 있는 미국. 일본에서는 인산형 연료전지의 상업화를 위해 수 MW급의 발전시스템의 신뢰성 실험을 진행 중에 있으며 용융탄산염형 연료전지, 고체산화물형 연료전지의 기초연구를 거의 완성한 단계에 있다. 국내에서도 연료전지발전은 화력발전의 한계, 발전연료의 다원화에 따른 천연가스의 수 입이용이 대폭 확대될 전망임에 따라 이용의 필요성이 많이 대두되고 있다. 특히 많은 섬과 산간지방 등 고립분산지역을 갖고 있는 국내 여건으로 볼 때, 송전. 배전시설이 필요 없는 온사이 트형 연료전지 발전설비가 설치될 경우 많은 이점을 가져올 수 있기 때문에 동 분야의 연구개 발이 필요한 상황이다. 전력은 국가의 핵심에너지로서 전력생산기술의 자립은 매우 중요하다. 특히 우리나라도 선진화되면서 새로운 첨단기술의 도입에 의한 에너지생산기술의 확보가 선진 국들의 기술보호정책에 의해 장애를 받고 있다. 연료전지기술의 경우도 일본이 동 분야를 국 책과제로 지정한 뒤 각 기업이 연구개발에 나서고 있는데, 이미 1980년대 초에 미국과 기술제휴 를 하면서 아시아지역 전체에 대한 전매권을 확보한 상태이며, 다른 타국과의 기술제휴 및 기 술이전을 거부한 채 실용화를 위한 경제성 확보의 시기를 기다리고 있다. 이와 같은 이유로 극복하기 위해 집중적인 투자를 확대하여 독자적인 기술을 확보해야한다.

• Journal of the Korean Institute of Gas
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• 제20권1호
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• pp.62-67
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• 2016

Natural gas, one of the cleanest fossil fuel, is liquefied to reduce its volume for the long distance transportation. Small size floating liquefied natural gas plant has small area that safe issue is highly considered. However, Dual Mixed Refrigerants (DMR) process has fire potential by using flammable refrigerants and N2 Expander process has low compressed energy efficiency which has high inherent process safety. Therefore, safe process with high compressed energy efficiency is constantly needed. This study suggested an alternative refrigerants to existing DMR process by using Hydrofluorocarbon which has high safety due to its non-flammable properties. As a result, it showed 34.8% lower compressed energy efficiency than DMR process that contains fire potential whereas 42.6% improved compressed energy efficiency than Single N2 Expander process. In conclusion, this research proposed safe process for small size floating liquefied natural gas plant while having high efficiency.

• Journal of the Korean Institute of Gas
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• 제18권5호
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• pp.72-77
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• 2014

It is known that there is no demand for building the arctic environment in Korea. However, it is important to use the different energy source instead of fuel source due to global warming. It is now demanded of using gas of Alaska and Siberia for long term developing the natural gas. The design of gas pipelines in Korea is very different from the arctic region. The operation of gas in arctic region have to consider of arctic region such as permafrost and active regions. It is needed to understand of gas pipeline design with different arctic soil properties. Nowadays, the pipelines is designed with stress-based and but there is demanded for strain based design with more deformed pipeline. We study of arctic environment with different active region using Finite Element Method of thermal elasto-plastic analysis.