• Journal of Navigation and Port Research
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• v.44 no.4
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• pp.283-290
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• 2020

BOG (Boil Off Gas) generation is unavoidable in the liquefied hydrogen carrier, and proper measures are necessary to prevent pressure problems inside the cargo tank. The BOG can be used as propulsion fuel for ships, and the remaining parts used for propulsion must be effectively managed, such as in the form of reliquefying or burning. This study proposes an BOG reliquefaction system optimized for a 160,000 m3 liquefied hydrogen carrier with a hydrogen propulsion system. The system comprises a hydrogen compression and helium refrigerant section, and increases the efficiency by effectively using the cold energy of the BOG discharged from the cargo tank. In this study, the system was evaluated through the exergy efficiency and SEC (Specific Energy Consumption) analysis according to the rate of the reliquefaction of the BOG while the hydrogen BOG with a supply temperature of -220℃ entered the reliquefaction system. As a result, it showed SEC of 4.11 kWh/kgLH2 and exergy efficiency of 60.1% at the rate of reliquefaction of 20%. And the parametric study of the effects of varying the hydrogen compression pressure, inlet temperature of the hydrogen expander, and the feed hydrogen temperature was conducted.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.269-274
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• 2009

Recently, the construction of Liquefied Natural Gas Carriers(LNGC) is being promoted larger and larger depending on long voyage. In 1950 years, $5,000m^3$ class of LNGC had been changed to $71,500m^3$ class in 1973. and to $210,000-266,000m^3$ class in 2007. Especially, the system of main engines and cargo control, Re-liquefaction of natural gases have become possible in LNGC. This research deals with the LNG projects, world markets of energy and developing tendency of liquefied natural gas carriers.

• Tribology and Lubricants
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• v.26 no.3
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• pp.190-198
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• 2010

GTL(gas-to-liquid) fuel produced by the Fischer-Tropsch process using carbon monoxide(CO) and hydrogen(H2) is expected to be one of the environmental friendly fuel for alternative and blended to petrodiesel. But GTL have poor lubricity due to paraffin as main component of GTL which is not involve polar materials. In this paper, we had investigated the lubricity improvement of GTL fuels with various lubricants using HFRR(high frequency reciprocating rig).

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.4
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• pp.809-816
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• 2001

This is a fundamental study to improve the performance of the LPG engine. The result were summarized as followed. 1. The measured torque and power on the fuel of LPG were indicated about 8% lower than those on gasoline with the same compression ratio. 2. In the case of LPG, BSFD at compression ratio of 9.7 was about 5% lower than that of 8.3 at 3,000ppm 3. HC and CO concentrations of the LPG were lower about 53%, 35% than those of gasoline

• Environmental and Resource Economics Review
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• v.18 no.4
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• pp.787-813
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• 2009

Because of global warming, the thawing of the Arctic ice cap is slowly accelerating. That is the hot issue nowadays. According to the each country's climate change policy, it is boom in the world to lessen the consuming of the fossil fuel those are oil, coal and natural gas. But on the contrary the thawing of the Arctic ice cap is the chance to make the natural gas producing unit cost lower. The purpose of this paper is to search the Arctic policy of each country under the contradictory relationship between promoting the climate change policy and exploiting the natural gas on the Arctic. Specially, there are huge natural gas reserves in Russia on the Arctic region, Russia's exploiting the natural gas on the Arctic will affect on the natural gas supply-demand balance of world natural gas market strongly in the future. Therefore it needs to prepare the future energy alternative policy for Korea's energy security. Russia has Yamal Peninsular where is abundant on natural gas reserver, and she can supply natural gas by LNG ship all over the world via the Arctic route. This means that the structure of world natural gas market be changed gradually. It will be possible in 2030~2040. And such a change is very important because new natural gas trading type can do it through not only overcoming the geological restriction but also shifting the main trading type from PNG(Pipeline Natural Gas) to LNG(Liquified Natural Gas). Therefore it is necessary that we should let this be a good lesson to ourselves through the government action of other countries (China, Japan) those also have no sovereignty over the Arctic as Korea.

• Journal of the Korean Institute of Gas
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• v.28 no.2
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• pp.32-37
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• 2024

Recently, transportations using hydrogen energy is being researched for the alternative energy of fossil fuels. To use them, processes of producing, storing and transferring are required. When carrying them in liquid under 90 MPa pressure, it costs less than in a gas status. Thus, a hydrogen pump is necessary and in this research we predicted the flow in the chamber using finite element methods (FEM) program ANSYS. As a result, when the valve was opened by 3 mm, between the 1^st chamber and the 2^nd chamber, the maximum velocity was decreased to 8.111 m/s by 10.6% (without valve, 9.075 m/s). In addition, pressure was also increased to 0.63 MPa by 1.6% (without valve, 0.62 MPa). When using these results, more efficient processes would be possible in designing them in detail.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.23-27
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• 2012

To make synthetic liquid fuel from biomass such as wood pellet, energy crop and so on, a biomass to liquid (BTL) process by using a biomass gasifier with Fisher-Tropsch (FT) reaction was developed. However $H_2S$, COS and $CO_2$ in syngas from biomass gasifiers resulted in a decrease of the conversion efficiency and the deactivation of the catalyst. To remove acid gases in syngas, a lab-scale methanol absorption tower was developed and the removal characteristics of acid gases were investigated. The methanol absorption tower efficiently removed $H_2S$ and COS with a removal of $CO_2$, so it could be useful process for the BTL process.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3323-3328
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• 2007

Conventional LPG pump for Liquified Petroleum injection(LPi) engine has been adopted vane type. But the BLDC type fuel pump for LPi system has complicated structure and its price is high. Therefore, as a alternative, this study has mainly focused on the development of turbine type LPG pump which has lower cost and simple structure than conventional BLDC type. To verify the possibility of substitute the performance tests were performed for each fuel pump. The comparative items were pressure settling time, variation of fuel outlet temperature and engine performance of hot restart ability. As a result, performances of turbine type LPG pump were equivalent or high comparing to the BLDC type all over the tests for different fuel composition.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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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.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.217.2-217.2
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• 2010

자연 상태에서의 가스하이드레이트의 존재는 물의 빙점보다 높은 온도에서 가스 수송관이 막히는 사고가 관내에 생성된 하이드레이트에 의한 것으로 규명된 이후영구동토지역이나 심해저에 부존되어 있는 막대한 매장량으로 인해 매우 활발한 연구가 최근에 진행되고 있다. 가스하이드레이트는 수분의 량에 비해 대량의 가스를 함유하므로 인위적인 가스하이드레이트를 제조하기 위하여 여러 가지 연구 중 하이드레이트 반응을 촉진하는 촉진제(promoter)와 생성을 억제하는 억제제(inhibitor)를 찾는 연구가 활발히 이루어지고 있다. 계면활성제와 고분자물질이 이들의 다양한 첨가제로 현제 사용되고 있다. 이러한 연구에서 메탄가스하이드레이트 형성에 영향을 미치는 대상물질로 선택한 DME(Dimethane Ether)는 산소 함유율이 34.8wt%인 함산소연료로 최근 신에너지로 부상하고 있으며, 해외 가스전 개발과 맞물려서 상용화단계에 들어와 있다. DME의 물리화학적인 특성으로는 상온의 온도에서 약5기압의 압력으로 액화 시킬 수 있다. 마취성이 강한 디에틸에테르와는 달리 마취성이 없을 뿐만 아니라 인체에 무해한 무색기체로 세탄가가 60가까이되어 경유(세탄가 55) 대체연료로 내연기관의 실증사업이 진행되고 있다. 이러한 특성을 갖고 있는 DME가 메탄가스 하이드레이트 생성에는 어떤 영향을 미치는지를 본 연구에서는 실험을 통해서 분석을 수행하였다. 실험과정에는 세 단계로 구분하여 진행하였는데 첫 번째 단계에서는 메탄가스만으로 하이드레이트 생성조건을 실험분석하였고, 두 번째 단계에서는 DME가스를 먼저 주입한후 동일 온도에서 메탄가스를 주입시켜 하이드레이트 생성 압력을 실험측정하였다. 마지막 단계에서는 DME가스를 약 두 배 정도 많이 주입한 후 동일 온도에서 메탄가스를 주입하여 하이드레이트 생성 압력을 측정하였디. 이러한 단계별 과정을 다소 온화한 $-5^{\circ}C{\sim}4^{\circ}C$의 온도 범위에서 반복적으로 수행하였다. 실험결과에서는 메탄만의 하이드레이트 형성보다 빙점($0^{\circ}C$) 이하의 온도 범위에서는 DME가 메탄하이드레이트 형성에 촉진제 역할을 하였고, 빙점 이상의 온도에서는 억제제의 역할을 하는 것으로 측정되었다. 또한 첨가된 DME의 양에 따라 촉진제의 역할과 억제제의 역할에 확연한 차이를 보였다. 추후 실험에서는 좀더 넓은 농도, 온도 및 압력범위에서 재현성 실험을 추가로 수행할 것도 제안한다.