ECIL

Journal

전체 22건

2025
Hierarchical Bayesian Intelligence Framework for Uncertainty Quantification and Reliability Assessment of Solid Oxide Fuel Cells Solid oxide fuel cell (SOFC) stacks face reliability challenges because multiple degradation mechanisms interact with operational and environmental variability. We develop a hierarchical Bayesian framework that couples a monotone area-specific resistance (ASR) growth law with a Weibull time-to-failure model and employs a Student-t observation layer to down-weight outliers. Using multi-cell data, the approach narrows to 95 % predictive-interval widths for ASR and lifetime by up to 33 % relative to ..
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Design and modeling of liquid hydrogen cargo transfer system with make-up boil-off gas compression This study proposes and evaluates a compressor-assisted liquid hydrogen (LH2) unloading system that utilizes boil-off gas (BOG) to enable LH2 transfer without a submerged pump. An integrated dynamic simulation of the carrier tank, pipeline, and terminal tank was developed to compare the performance of this proposed system with that of conventional pump-assisted unloading. The analysis was extended to several operational scenarios,including increased make-up BOG injection, the presence of thermal s..
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Design and Thermodynamic Analysis of CO2 Liquefaction Processes for Onboard Carbon Capture and Storage This study evaluates the thermodynamic performance of the following two CO2 liquefaction processes for onboard carbon capture and storage (OCCS) on a 174,000 m3 LNG carrier: the Linde–Hampson and vapor compression refrigeration cycles. The cycles were designed based on realistic vessel operating conditions and compared using the specific energy consumption (SEC) as the primary performance indicator, alongside the coefficient of performance (COP). To enable a fair comparison of the two distinct c..
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Comparative study of vapor pressure requirements for rule-based design of IMO Type C tanks for LCO2: Guidelines for optimizing pressure conditions The safe and efficient design of liquefied carbon dioxide (LCO2) storage tanks is essential for carbon capture, utilization, and storage (CCUS), particularly in maritime transport. IMO Type C pressure vessels are widely used, with minimum design vapor pressure determined by rule-based criteria. These regulations, based on fracture mechanics principles, prevent crack propagation-induced leaks. However, discrepancies between regulatory and operational pressures increase design complexity and iterati..
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Techno-economic analysis of liquefied hydrogen and liquefied natural gas power systems for coastal vessels: Economic feasibility and critical parameters This study evaluates the economic feasibility of liquefied hydrogen (LH2) and liquefied natural gas (LNG) power generation systems for coastal vessels in the 1.3 and 2.2MW classes. A comprehensive life-cycle cost (LCC) analysis was conducted to determine the conditions under which the LH2 system can become economically competitive relative to the LNG system. Under our initial assumptions, the LNG system exhibited a lower LCC for both vessel classes. Three critical parameters were identified as key..
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Predictive durability modeling of solid oxide fuel cells under maritime environmental conditions This study proposes a predictive durability modeling framework for solid oxide fuel cells (SOFCs) operating under realistic maritime environmental conditions. A mechanistic reaction–diffusion degradation model was first calibrated via Bayesian inference against accelerated coastal and open‐sea experimental durability data. Subsequently, the calibrated model was employed to simulate long-term performance under high humidity, salt‐spray, and vibration stresses characteristic of marine service...
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Analysis of Bunkering Procedures for Establishing Safety Regulations for Ammonia-Fueled Ships As environmental concerns increase globally, the International Maritime Organization has been strengthening regulations to limit pollution from ships, attracting increasing interest in ammonia as a zero-carbon marine fuel. This study aimed to establish safe bunkering procedures for ammonia-fueled ships through thermodynamic analysis. The research analyzed two bunkering scenarios, ship-to-ship and truck-to-ship, calculating the boil-off rate and return boil-off gas for each scenario. A thermal anal..
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Thermodynamic Analysis of LH2 Boil-off Gas Re-condensation Process This study proposes a re-condensation system aimed at efficiently managing boil-off gas generated in cargo tanks of liquefied hydrogen import terminals. The system’s performance was assessed and validated through thermodynamic analysis, deriving condensation ratios and specific energy consumption (SEC). The sensitivity analysis revealed that as pressure increased from 4.0 to 12.8 bar, the condensation ratio decreased from 24.6 to 7.63, while SEC increased from 0.175 kWh/kg to 0.399 kWh/kg. These..
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Optimization and analysis of reliquefaction system utilizing hydrogen as refrigerant for liquid hydrogen carriers In this study, a reliquefaction system utilizing a reverse Brayton cycle with hydrogen as a refrigerant to handle boil-off hydrogen (BOH) generated within liquid hydrogen carriers operating in oceanic routes from a thermo- dynamic perspective is proposed. Furthermore, optimization targeting specific energy consumption (SEC) as the fitness function was performed using a genetic algorithm. Subsequently, an economic analysis was conducted at the equipment unit level for the reliquefaction system. The..
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Design and thermodynamic evaluation of onboard NH3 BOG re-liquefaction systems for ocean-going NH3 Carriers This study stems from the burgeoning interest in ammonia (NH3) as a green energy source, particularly for maritime applications where conventional refrigeration cycles pose both environmental and economic challenges, specifically focusing on an 88,000 m3 class Very Large Ammonia Carrier (VLAC). Two distinct refrigeration cycle concepts were evaluated for the re-liquefaction system. The optimization technique used in the study was a hybrid method that combined the SQP and BOX algorithms to optimize..
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2024
A novel designation of LNG solid oxide fuel cells combined system for marine application This paper presents a pioneering multigeneration system for marine vessel applications, involving the integration of solid oxide fuel cells (SOFCs) fueled by liquefied natural gas (LNG), coupled with LNG cold energy utilization cycles and exhaust gas heat recovery systems. The system comprises a tandem arrangement of organic Rankine cycle (ORC) and trans-critical carbon di- oxide cycle (TCO2), specifically engineered to harness the cold energy released during LNG regasification process. The elevat..
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Techno-Economic Evaluation of Direct Low-Pressure Selective Catalytic Reduction for Boil-Off Gas Treatment Systems of NH3-Fueled Ships This study proposes a feasible solution for boil-off gas (BOG) treatment to facilitate NH3 fuel use by ocean-going ships, which is currently considered an alternative fuel for ships. Two systems were designed and analyzed for BOG in IMO Type-A NH3 fuel storage tanks for 14,000 TEU container ships. First, BOG lost inside the storage tank minimized economic losses through the onboard re-liquefaction system. The total energy consumed by the system to process NH3 gas generated in the fuel tank at 232...
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Comparative Life Cycle Assessments and Economic Analyses of Alternative Marine Fuels: Insights for Practical Strategies The growth of the global shipping industry has increased the interest in the environmental impact of this sector. The International Maritime Organization adopted the initial Greenhouse Gas strategy for reducing GHG emissions from ships at the 72nd Marine Environment Protection Committee in April 2018. In this study, we carried out a life cycle assessment of nine production pathways of alternative fuels, including LNG, ammonia, methanol, and biofuels, and conducted an economic analysis considering ..
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Technical–Economic Analysis for Ammonia Ocean Transportation Using an Ammonia-Fueled Carrier This study performed a technical–economic analysis for ship-based ammonia transportation to investigate the feasibility of international ammonia transportation. Ammonia is considered to be a vital hydrogen carrier, so the international trade in ammonia by ship will considerably increase in the future. This study proposed three scenarios for transporting ammonia from the USA, Saudi Arabia, and Australia to South Korea and employed an 84,000 m3 class ammonia carrier. Not only traditional very low ..
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2023
Heat Integration of Liquid Hydrogen-Fueled Hybrid Electric Ship Propulsion System This study introduced the methodology for integrating ethylene glycol/water mixture (GW) systems which supply heat energy to the liquid hydrogen (LH2) fuel gas supply system (FGSS), and manage the temperature conditions of the battery system. All systems were designed and simulated based on the power demand of a 2 MW class platform supply vessel assumed as the target ship. The LH2 FGSS model is based on Aspen HYSYS V11 and the cell model that makes up the battery system is implemented based on a T..
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Design and analysis of liquid hydrogen-fueled hybrid ship propulsion system with dynamic simulation In this study, we examine a liquid hydrogen (LH2)-fueled hybrid ship propulsion system (HSPS) consisting of an LH2 fuel gas supply system (FGSS), a polymer electrolyte membrane fuel cell (PEMFC), and battery systems. The LH2-HSPS is analyzed through three dynamic simulations, representing different PEMFC outputs, for a 2-MW-class tugboat. During transient states of LH2 FGSS, hydrogen temperature changes from 11 to 41 °C at the LH2 vaporizer outlet. Dynamic simulations considering hydrogen tempera..
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