• 한국수소및신에너지학회논문집
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• 제31권4호
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• pp.363-371
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• 2020

Recently, the technologies to utilize the cold energy of liquefied natural gas (LNG) have attracted significant attention. In this paper, thermodynamic performance analysis of combined cycles consisting of ammonia Rankine cycle (AWR) and organic Rankine cycle (ORC) with LNG Rankine cycle to recover low-grade heat source and the cold energy of LNG. The mathematical models are developed and the effects of the important system parameters such as turbine inlet pressure, ammonia mass fraction, working fluid on the system performance are systematically investigated. The results show that the thermal efficiency of AWR-LNG cycle is higher but the total power production of ORC-LNG cycle is higher.

• 한국해양공학회지
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• 제31권3호
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• pp.241-247
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• 2017

Plywood, which is created by bonding an odd number of thin veneers perpendicular to the grain orientation of an adjacent layer, was developed to supplement the weak points such as contraction and expansion of conventional wood materials. With structural merits such as strength, durability, and good absorption against impact loads, plywood has been adopted as a structural material in the insulation system of a membrane type liquefied natural gas (LNG) carrier. In the present study, as an attempt to resolve recent failure problems with plywood in an LNG insulation system, conventional PF (phenolic-formaldehyde) resin plywood and its alternative MUF (melamine-urea-formaldehyde) resin bonded plywood were investigated by performing material bending tests at ambient ($20^{\circ}C$) and cryogenic ($-163^{\circ}C$) temperatures to understand the resin and grain effects on the mechanical behavior of the plywood. In addition, the failure characteristics of the plywood were investigated with regard to the grain orientation and testing temperature.

• 한국해양공학회지
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• 제30권5호
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• pp.349-355
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• 2016

Divinycell, which functions as both insulation and a supporting structure, is generally applied in the NO96-type liquefied natural gas (LNG) insulation system. Polymer-material-based Divinycell, which has a high strength and low weight, has been widely used in the offshore, transportation, wind power generation, and civil engineering fields. In particular, this type of material receives attention as an insulation material because its thermal conductivity can be lowered depending on the ambient temperature. However, it is difficult to obtain research results for Divinycell, even though the component materials of the NO96-type LNG cargo containment system, such as 36% nickel steel (invar steel), plywood, perlite, and glass wool, have been extensively studied and reported. In the present study, temperature and strain-rate dependent compressive tests on Divinycell were performed. Both the quantitative experimental data and elastic recovery are discussed. Finally, the mechanical characteristics of Divinycell were compared to the results of polyurethane foam insulation material.

• 해양환경안전학회지
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• 제28권5호
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• pp.809-818
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• 2022

국제해사기구(IMO)의 대기오염물질 배출 규제에 대응하기 위해 액화천연가스(LNG)를 연료로 사용하는 선박이 증가하고 있다. 이와 함께 선박의 안정적인 연료 수급을 위한 LNG 벙커링 인프라 확대의 필요성이 대두되고 있다. LNG 벙커링은 TTS(Truck to ship), PTS(Pipe to ship), STS(Ship to ship) 3가지 방식으로 진행된다. 외국에서는 3가지 방식 모두 진행하고 있지만, 국내의 경우 인프라 부족으로 TTS 방식으로만 LNG 벙커링이 진행되고 있다. LNG 벙커링은 위험 요소가 많은 작업으로 안전한 벙커링 작업을 위해 작업 종사자의 역량이 아주 중요하며 역량 강화를 위한 전문교육과정이 필요하다. 본 연구는 LNG 벙커링 전문인력 육성과 안전하고 체계적인 벙커링 작업수행을 목적으로 LNG 벙커링 종사자 교육 콘텐츠를 설계하기 위해 진행되었다. 이를 위해 LNG 연료추진선박 및 벙커링 현황을 파악하고 국내외 관련 교육내용을 분석하였다. 더불어 전문가 설문을 통해 교육내용의 중요성에 대한 의견을 수렴하였다. 연구의 결과로서 다양한 교육 대상에 적합한 교육 콘텐츠 설계를 하고, 이를 총 4일이 소요되는 기초교육과 상급교육 과정으로 구분하여 제안하였다. 설계된 교육 콘텐츠를 바탕으로 우리나라 벙커링 환경을 충분히 반영하여 추가 연구가 진행된다면 LNG 벙커링 종사자 역량 증진을 도모하고 인적 자원 육성에 큰 도움이 될 것으로 사료 된다.

• 한국안전학회지
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• 제28권2호
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• pp.1-5
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• 2013

Liquefied Natural Gas is liquefied at the condition of atmosphere pressure and cryogenic temperature. LNG is exposed very long time under the cryogenic temperature and high pressure, and it is very important to retain the structural safety in this envelopment. Until now, the material which are composing the storage tank of LNG ship has experimented at room temperature, so it is not enough to apply for the design at the cryogenic temperature. The purposes of this study are investigated mechanical properties for aluminum alloy. To evaluate tensile and fatigue test for aluminum alloy, it was considering static and fatigue conditions at room and cryogenic temperature. S-N curves were designed at both temperature respectively. Also, P-S-N curve was performed statistical method by JSME-S002.

• 설비공학논문집
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• 제9권2호
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• pp.189-197
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• 1997

The vaporizing characteristics of LNG(liquefied natural gas) via heat exchanger with sea water are analytically studied for an open rack vaporizer(ORV). This study is intended to supply the design data for the domestic fabrication of the corrosion-resistant vaporizer tube. A computational program is developed to predict the exit temperature of LNG for various conditions. In the program, thesimple and justifiable heat transfer models are selected for fully-developed internal flow of LNG, the star-shaped finned-tube, and the external falling films of sea water, as well as the possible ice formation and the fouling on the tube walls. It is found that the enongh corrugation inside of the tube wall is the most significant in the vaporizer performance for the current operating conditions. the effects of other design parameters on the heat exchanger between LNG and sea water are quantitatively presented.

• International Journal of Ocean System Engineering
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• 제1권4호
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• pp.230-235
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• 2011

Reinforced polyurethane foam (RPUF) is one of the important materials of Mark III type insulation systems used in liquefied natural gas (LNG) cargo containment systems. However, RPUF is the most difficult material to use with regard to its safety assessment, because there is little public and reliable data on its mechanical properties, and even some public data show relatively large differences. In this study, to investigate the structural response of the system under compressive loads such as sloshing action, time-dependent characteristics of RPUF were examined. A series of compressive load tests of the insulation system including RPUF under various temperature conditions was carried out using specimens with rectangular section. As a result, the relationship between deformation of RPUF and time is linear and dependent on the loading rate, so the concept of strain rate could be applied to the analysis of the insulation system. Also, we found that the spring constant tends to converge to a value as the loading rate increases and that the convergence level is dependent on temperature.

• Korean Chemical Engineering Research
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• 제62권1호
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• pp.70-79
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• 2024

라만분석기는 분자가 가지는 고유 진동에 빛을 조사하여 발생하는 빛의 산란이 생기는 "라만효과"를 이용하여 분자 구분과 성분 분석을 할 수 있는 분석기로, 천연가스 산업에서도 LNG(액화천연가스) 수출 및 수입 기지 외에 벙커링 및 탱크로리 분야에서도 폭 넓게 사용 중이다. 본 연구에서는 실제 현장 조건하에서, LNG 성분 분석 및 주요 물성(발열량, 기준밀도 등)을 산출하기 위해 LNG 수입기지에 라만분석기를 설치, 운영하였으며, 측정된 LNG 성분 및 발열량을 기존 검증되어 운영 중인 가스분석기에 의해 분석된 성분 및 발열량과 비교하였다. 시험 결과 라만분석기는 매우 빠르고 안정되게 LNG 성분 및 발열량을 측정하였으며, LNG 거래의 기준이 되는 발열량을 기존 가스분석기 결과값과 비교시에도 적정 오차 기준 내에 있는 것을 확인하였다. 추가적으로 본 연구를 통해 얻은 측정 결과는 관련 표준(ASTM D7940-14)의 정확도 기준을 만족하였고, 국외 대규모 실증 사례와의 비교 시에도 유사한 결과를 산출하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제37권1호
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• pp.22-28
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• 2013

본 논문은 액화 천연 가스(LNG)를 주 연료로 사용하는 선박용의 LNG기화기의 특성을 조사하기 위하여 기화기 내부에서의 열전달 특성을 연구하였다. LNG를 기화하기 위한 가열열원으로서는 주 엔진에서 발생하는 워터 쟈켓의 가온수를 직접 이용하지 않고 열교환기를 통하여 간접 가열된 글리콜 워터(Glycol Water)를 사용하는 시스템을 채택하였다. LNG의 기화 과정은 상변화를 동반하기 때문에 이를 검증하기 위하여 액화질소(LN2)의 기화과정을 통하여 신뢰성을 확보하였고, LNG 기화기 내부의 최적 열적특성을 도출하기 위하여 LNG의 유입량과 가열열원인 글리콜 워터 유량변화에 대한 LNG 기화특성을 연구하였다. 해석 결과 LNG 질량유량이 0.111 kg/s과 가열원수인 부동액 질량유량이 1.805 kg/s일 경우 가스 출구 온도는 약 $6^{\circ}C$로서 LNG 선박의 최적 운전 조건임을 알 수 있었다.

• 한국해양공학회지
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• 제33권5호
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• pp.394-399
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• 2019

Plywood is a laminated wood material where alternating layers are perpendicular to each other. It is used in a liquefied natural gas (LNG) carrier for an insulation system because it has excellent durability, a light weight, and high stiffness. An LNG cargo containment system (LNG CCS) is subjected to loads from gravity, sloshing impact, hydrostatic pressure, and thermal expansion. Shear forces are applied to an LNG CCS locally by these loads. For these reasons, the materials in an LNG CCS must have good mechanical performance. This study evaluated the shear behavior of plywood. This evaluation was conducted from room temperature ($25^{\circ}C$) to cryogenic temperature ($-163^{\circ}C$), which is the actual operating environment of an LNG storage tank. Based on the plywood used in an LNG storage tank, a shear test was conducted on specimens with thicknesses of 9 mm and 12 mm. Analyses were performed on how the temperature and thickness of the plywood affected the shear strength. Regardless of the thickness, the strength increased as the temperature decreased. The 9 mm thick plywood had greater strength than the 12 mm thick specimen, and this tendency became clearer as the temperature decreased.