• 한국수소및신에너지학회논문집
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• 제28권3호
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• pp.295-299
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• 2017

In this study, computer simulation and optimization works have been performed for an open-loop Rankine cycle to generate power using five cases of liquefied natural gas compositions. PRO/II with PROVISION V9.4 from Schneider electric company was used, and the Soave-Redlich-Kwong equation of the state model was utilized for the design of the power generation cycle. It was concluded that more power was obtained from less molecular weight liquefied natural gas since there was more volumetric flow rate with less molecular weight.

• 한국항공우주학회지
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• 제32권3호
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• pp.66-73
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• 2004

탄화수소 계열의 액체로켓엔진용 연료로서의 액화천연가스의 특성을 성분 및 함량 분석, 냉각제로서의 특성과 엔진 성능 인자로서 특성속도와 비추력 관점에서 평가하였다. 액화천연가스내의 메탄의 함량이 연료로서의 특성을 결정짓는 주요한 인자이었으며, 재생냉각형 액체로켓엔진의 연료로 사용되기 위해서는 최소 90% 이상의 메탄 함량이 요구되는 것으로 판단된다. 한편, 예비 냉각에 의한 액화천연가스의 일부 성분의 응결이 예상되어 정상적인 엔진 작동을 방해하는 요소가 될 수 있다. 약 90%의 메탄 체적 함량을 가지는 액화천연가스의 액체로켓엔진의 작동 조건은 화학 당량비적 혼합비로 표준화한 추진제 혼합비로 0.75가 최적이었다.

• 한국수소및신에너지학회논문집
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• 제35권3호
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• pp.318-323
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• 2024

In this paper, computer modeling works have been performed for the power generation Rankine cycle using new working fluids and liquefied natural gas (LNG) cold heat. PRO/II with PROVISION released January 2023 from AVEVA company was used, and Peng-Robinson equation of the state model with Twu's alpha function was selected for the modeling of the power generation cycle. Optimal working fluid composition was determined to maximize LNG cold heat to increase power generation efficiency and net power production.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2211-2216
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• 2007

Liquefied gas vaporizer means machine to vaporize the liquefied gas as liquid nitrogen($LN_2$), liquefied natural gas(LNG), liquid oxygen($LO_2$) etc. In the air type vaporizer, the frozen dew is also created by temperature drop (below 273 K) on vaporizer surface. This problem increases as the time progresses and humidity increases. In addition, the frozen dew gradually becomes frost deposit consequently, heat transfer through vaporizer decreases because frost deposit form adiabatic sheet. Because of this reason, recent vaporizer system is installed as parallel type, this vaporizer system needs more expensive installation costs and more space. This paper was investigated on the heat transfer characteristics of liquefied gas vaporizer with super low temperature and this paper was carried out the numerical about air heating vaporizer with super low temperature. The numerical analysis on the heat transfer was studied on the effect of geometric parameters of the vaporizer, which are length 1000 mm of 4fin75le type vaporizer. 4fin75le means number of fin is 4 and height of fin is 75 mm.

• 한국가스학회지
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• 제20권1호
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• pp.62-67
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• 2016

가장 깨끗한 화석연료 가운데 하나인 천연가스는 장거리 수송 시 부피를 줄이기 위해 액화된다. 그 중 소형 해양 천연가스 액화 플랜트는 면적이 작기 때문에 안전문제가 크게 대두된다. 하지만, 기존에 쓰이는 DMR (Dual Mixed Refrigerants) 공정은 가연성 냉매를 사용함으로써 화재의 위험이 있으며, N2 Expander 공정은 안전하지만 압축 에너지 효율이 낮다는 문제점이 있다. 따라서 안전하면서도 압축 에너지 효율 또한 높은 공정의 개발이 지속적으로 요구되는 상황이다. 본 연구에서는 DMR 공정에 비가연성 냉매인 Hydrofluorocarbon을 사용하여 안전성을 높임으로써 기존 공정들에 대한 대안을 제시하였다. 그 결과, 화재위험이 있는 DMR 공정보다 34.8% 낮은 압축에너지 효율을 보였으나, Single N2 Expander 공정보다 42.6% 향상된 압축 에너지 효율을 나타내었다. 결론적으로 이 연구에서는 안전하면서도 높은 에너지 효율을 내는 소형 해양 천연가스 액화 플랜트 공정을 설계하였다.

• 한국가스학회지
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• 제19권6호
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• pp.99-104
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• 2015

천연가스의 이송을 위해 현재까지 가장 효율적인 방법은 액화를 통한 운반이다. 천연가스를 액화하기 위해서는 $-160^{\circ}C$이하로 냉각시켜야 하는데, 그 방법에는 여러 가지가 있다. 본 논문에서는 가장 대표적인 액화 공정인 C3MR 공정에 대한 제어 방법에 대해 연구하였다. 천연가스 액화 공정의 제어는 천연가스 품질을 유지할 수 있는 도구이며 안정된 운전을 보장하는 수단이다. C3MR 공정을 분석하고 제어 밸브에 대한 제어 변수를 선택하고 제어 변수의 계단 응답 결과를 통해 혼합냉매의 제어 구조를 도출 하였다. 도출된 제어 결과를 동적 모사를 통해서 임의로 외란을 주어 정상상태를 유지하는 결과를 확인 하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권5호
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• pp.609-616
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• 2018

The cargo handling system, which is composed of a fuel gas supply unit and cargo tank pressure control unit, is the second largest power consumer in a Liquefied Natural Gas (LNG) carrier. Because of recent enhancements in ship efficiency, the surplus boil-off gas that remains after supplying fuel gas for ship propulsion must be reliquefied or burned to regulate the cargo tank pressure. A full or partial liquefaction process can be applied to return the surplus gas to the cargo tank. The purpose of this study is to review the current partial liquefaction process for LNG carriers and develop new processes for reducing power consumption using exergy analysis. The developed partial liquefaction process was also compared with the full liquefaction process applicable to a LNG carrier with a varying boil-off gas composition and varying liquefaction amounts. An exergy analysis showed that the Joule-Thomson valve is the key component needed for improvements to the system, and that the proposed system showed an 8% enhancement relative to the current prevailing system. A comparison of the study results with a partial/full liquefaction process showed that power consumption is strongly affected by the returned liquefied amount.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.181-181
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• 2017

• 동력기계공학회지
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• 제11권3호
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• pp.22-28
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• 2007

Liquefied gas vaporizer is a machine to vaporize liquefied gas such as liquid nitrogen($LN_{2}$), liquefied natural gas(LNG), liquid oxygen($LO_{2}$) etc. For the air type vaporizer, the frozen dew is created by temperature drop (below 273 K) on vaporizer surface. The layer of ice make a contractions on vaporizer. The structure analysis on the heat transfer was studied to see the effect of geometric parameters of the vaporizer, which are length 1000 mm of various type vaporizer. Structure analysis result such as temperature variation, thermal stress and thermal strain have high efficiency of heat emission as increase of thermal conductivity. As the result, Frist, With-fin model shows high temperature distribution better than without-fin on the temperature analysis. Second, Without-fin model shows double contractions better then with-fin model under the super low temperature load on the thermal strain analysis. Third, Vaporizer fin can be apply not only heat exchange but also a stiffener of structure. Finally, we confirm that All model vaporizer can be stand for sudden load change because of compressive yield stress shows within 280 MPa on thermal stress analysis.

• 한국해양공학회지
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• 제38권3호
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• pp.87-102
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• 2024

Given the inadequate regulatory framework for liquefied hydrogen gas storage tanks on ships and the limitations of the IGC Code, designed for liquefied natural gas, this study introduces a critical assessment procedure to ensure the safety and suitability of such tank designs. This study performed a heat transfer analysis for boil-off gas (BOG) calculations and established separate design load cases to evaluate the yielding and buckling strength. In addition, the study assessed methodologies for both high-cycle and low-cycle fatigue assessments, complemented by comprehensive structural integrity evaluations using finite element analysis. A comprehensive approach was developed to assess the structural integrity of Type C tanks by conducting crack propagation analysis and comparing these results with the IGC Code criteria. The practicality and efficacy of these methods were validated through their application on a 23K-class liquefied hydrogen carrier at the concept design stage. These findings may have important implications for enhancing safety standards and regulatory policies.