The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
Jaemyung Lee - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of nanoparticle-enhanced polyurethane foams and evaluation of mechanical characteristics
Composites Part B: Engineering, 2018Co-Authors: Jong-min Kim, Jeong-hyeon Kim, Jae-hyeok Ahn, Jeong-dae Kim, Sungkyun Park, Kang Hyun Park, Jaemyung LeeAbstract:Abstract Owing to their many advantageous properties, polyurethane-based insulating materials are suitable for liquefied Natural Gas Carrier (LNGC) cargo containment systems (CCSs). Because an LNGC CCS, which has a 110 K operating temperature, is exposed to continuous sloshing impact loads from ocean waves, the insulating and mechanical capabilities should be simultaneously secured. However, cracking and failure problems have been consistently reported in shipyards owing to the performance limitations of current insulating materials. Therefore, for the present study, nanoparticle-enhanced polyurethane foams (PUFs) with various contents of graphene oxide (GO) and graphite were synthesized to resolve such industrial problems. A wt%-dependent SEM analysis was then carried out to understand the effects of nanoparticles on the cell morphologies of the developed materials. The mechanical properties were investigated at both ambient and boiling temperatures of LNG (110 K). In addition, the thermal conductivity of nanoparticle-enhanced PUF was evaluated. Finally, the macroscopic failure characteristics were also determined. The results indicate that the microstructure and mechanical strength are enhanced compared with neat PUFs, with a significant dependence on the weight percent of the nanoparticles.
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failure analysis of reinforced polyurethane foam based lng insulation structure using damage coupled finite element analysis
Composite Structures, 2014Co-Authors: Chiseung Lee, Jaemyung LeeAbstract:Abstract The primary aim of this study was to develop a unified anisotropic elasto-viscoplastic-damage model that describes the material nonlinear behavior and damage/crack growth of a reinforced polyurethane foam-based liquefied Natural Gas Carrier insulation system. A Bodner–Partom unified elasto-viscoplastic model independent of the yield surface and loading history was expanded to an anisotropic unified model. To predict the damage growth and the crack initiation/growth of reinforced polyurethane foam, a Bodner–Chan damage model was applied to the proposed unified elasto-viscoplastic-damage model. The developed mechanical model was implicitly formulated and implemented into an ABAQUS user-defined material subroutine. To validate the proposed numerical method, the simulation results were compared with the results of a series of static uniaxial tests and dynamic cyclic tests conducted on the reinforced polyurethane foam and the liquefied Natural Gas Carrier insulation system, respectively.
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A Comparative Evaluation of Fatigue and Fracture Characteristics of Structural Components of Liquefied Natural Gas Carrier Insulation System
Journal of Pressure Vessel Technology, 2013Co-Authors: Hyeon Su Kim, Jaemyung Lee, Min Sung Chun, Myunghyun KimAbstract:density R-PUF (130kg/m 3 ) and high density R-PUF (210kg/m 3 ). The fracture toughness of R-PUF and STS 304L was investigated in terms of the density effect of R-PUF and the difference in the nickel composition of STS 304L, STS 304L (10.2%Ni) versus STS 304L (9.4%Ni) at both ambient and cryogenic temperatures. In this study, the high density R-PUF (210kg/m 3 ) and STS 304L (9.4%Ni) were proposed to improve the structural strength of the LNGC insulation system and reduce the cost. The fracture toughness was characterized in terms of the critical strain energy release rate (GIC) in the context of linear elastic fracture mechanics (LEFM). The geometries of the fracture toughness test used were the center-cracked tension (CCT) and double-edge-cracked tension (DECT) specimens according to ASTM STP381 standard. [DOI: 10.1115/1.4007473]
Jong-min Kim - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of nanoparticle-enhanced polyurethane foams and evaluation of mechanical characteristics
Composites Part B: Engineering, 2018Co-Authors: Jong-min Kim, Jeong-hyeon Kim, Jae-hyeok Ahn, Jeong-dae Kim, Sungkyun Park, Kang Hyun Park, Jaemyung LeeAbstract:Abstract Owing to their many advantageous properties, polyurethane-based insulating materials are suitable for liquefied Natural Gas Carrier (LNGC) cargo containment systems (CCSs). Because an LNGC CCS, which has a 110 K operating temperature, is exposed to continuous sloshing impact loads from ocean waves, the insulating and mechanical capabilities should be simultaneously secured. However, cracking and failure problems have been consistently reported in shipyards owing to the performance limitations of current insulating materials. Therefore, for the present study, nanoparticle-enhanced polyurethane foams (PUFs) with various contents of graphene oxide (GO) and graphite were synthesized to resolve such industrial problems. A wt%-dependent SEM analysis was then carried out to understand the effects of nanoparticles on the cell morphologies of the developed materials. The mechanical properties were investigated at both ambient and boiling temperatures of LNG (110 K). In addition, the thermal conductivity of nanoparticle-enhanced PUF was evaluated. Finally, the macroscopic failure characteristics were also determined. The results indicate that the microstructure and mechanical strength are enhanced compared with neat PUFs, with a significant dependence on the weight percent of the nanoparticles.
Jungho Choi - One of the best experts on this subject based on the ideXlab platform.
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development of partial liquefaction system for liquefied Natural Gas Carrier application using exergy analysis
International Journal of Naval Architecture and Ocean Engineering, 2018Co-Authors: Jungho ChoiAbstract:Abstract 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.
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Development of partial liquefaction system for liquefied Natural Gas Carrier application using exergy analysis
Elsevier, 2018Co-Authors: Jungho ChoiAbstract: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. Keywords: Reliquefaction, PRS, Boil-off Gas, Open cycle, Exergy analysis, Specific power consumptio
Chiseung Lee - One of the best experts on this subject based on the ideXlab platform.
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failure analysis of reinforced polyurethane foam based lng insulation structure using damage coupled finite element analysis
Composite Structures, 2014Co-Authors: Chiseung Lee, Jaemyung LeeAbstract:Abstract The primary aim of this study was to develop a unified anisotropic elasto-viscoplastic-damage model that describes the material nonlinear behavior and damage/crack growth of a reinforced polyurethane foam-based liquefied Natural Gas Carrier insulation system. A Bodner–Partom unified elasto-viscoplastic model independent of the yield surface and loading history was expanded to an anisotropic unified model. To predict the damage growth and the crack initiation/growth of reinforced polyurethane foam, a Bodner–Chan damage model was applied to the proposed unified elasto-viscoplastic-damage model. The developed mechanical model was implicitly formulated and implemented into an ABAQUS user-defined material subroutine. To validate the proposed numerical method, the simulation results were compared with the results of a series of static uniaxial tests and dynamic cyclic tests conducted on the reinforced polyurethane foam and the liquefied Natural Gas Carrier insulation system, respectively.
Jean-david Caprace - One of the best experts on this subject based on the ideXlab platform.
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An early-stage approach to optimise a marine energy system for liquefied Natural Gas Carriers: Part B — Application
Ocean Engineering, 2019Co-Authors: C. H. Marques, Carlos Rodrigues Pereira Belchior, Jean-david CapraceAbstract:Abstract The present work aims to provide a comprehensive early-stage approach to optimise the design, synthesis and operation of a marine energy system for liquified Gas Carriers, considering their economic and technical aspects, and also weather along the route. Part A of this work details the approach that we have developed while Part B will summarise the first part, it will then describe the case study, results and discussion, as well as the conclusion. Various propellers, 16 engines and 4 operational profiles are assessed. In this part, we will apply a differential evolution optimisation algorithm, whose objective function will be maximised as the net present value. The case study is designed to use a liquefied Natural Gas Carrier of 175,000 m3 sailing between Lake Charles (USA) and Tokyo Bay (Japan), via the Panama Canal. All of the suitable matchings for 15,023 propellers are found. This approach shows a gain of 22% between the worst individual of the initial population and the worst individual of the final population. The required brake power is approximately 22% higher for rough weather than for still water. A difference of over 120% was found by comparing varied matchings of economic scenarios and fuel profiles. Our approach shows a significant gain and highlights the value of exploring a broad range of energy system configurations in an integrated manner, especially considering the weather conditions.
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Optimising the engine-propeller matching for a liquefied Natural Gas Carrier under rough weather
Applied Energy, 2018Co-Authors: C. H. Marques, Carlos Rodrigues Pereira Belchior, Jean-david CapraceAbstract:Abstract Dual-fuel Diesel engines have become the most interesting alternative for liquefied Natural Gas Carriers (LNGCs) since they are able to use boil-off Gas as fuel. However, there is a lack of studies about the optimisation of propulsion system selection considering weather conditions in an integrated approach. Thus, the present work aims to provide a comprehensive approach to perform the optimisation of engine-propeller matching for an LNGC under rough weather. A weather condition was included in the assessment of total resistance and thereby affected the propeller’s open water efficiency, shaft speed and brake power. Constraints were included to the approach in order to avoid propellers that could present issues concerning strength, cavitation and vibration. A differential evolution optimisation algorithm was applied to minimise the fuel expenditure of propulsion for a round trip. The case study was designed using an LNGC with cargo capacity of 175,000 m3 sailing in laden condition from Lake Charles to Tokyo Bay, via Panama Canal, and returning in ballast. All suitable matchings for 5346 propellers were found in 2.8 h and over 28% of them were constrained. The method has shown gains up to 19% of fuel expenditure reduction. The required brake power was approximately 20% higher for rough weather than for still water. Therefore, the approach used here has shown a significant gain and highlighted the value of exploring a broad range of propellers and engines in an integrated manner, as well as considering the weather condition.