As awareness on air pollution in marine environment increases, transition of ship fuel to natural gas has been recognized as a practical solution for emission minimization. It is realized with LNG-fueled ship, whose implementation in practice demands cost-effective and energy-efficient re-liquefaction of BOG. The purpose of this study is to introduce precooling cycle to BOG re-liquefaction process to enhance energy efficiency and explore the most appropriate usage of pre-cooling refrigerants between CO₂ and NH₃. Three different configurations for precooling are compared, and operating conditions are optimized with an objective function to minimize energy consumption. Pre-screening based on sensitivity analysis, before optimization, is carried out to exclude any potential infeasible solution space. It allows robust optimization, leading to high quality optimal solution. Up to 7.9% reduction in overall energy consumption is achieved with the integration of precooling cycles, illustrated by high dependence on physical properties of saturated refrigerants. The modeling and optimization framework proposed in this study can serve as an effective application to the wide range of refrigeration systems subject to various refrigerants.

随着人们对海洋环境中空气污染的认识的提高，船舶燃料向天然气的过渡已被视为减少排放的实用解决方案。这是通过液化天然气船实现的，在实践中实施该技术需要对BOG进行具有成本效益和能效的液化。这项研究的目的是在BOG再液化过程中引入预冷循环，以提高能源效率，并探索最合适地使用CO ₂和NH ₃之间的预冷制冷剂。。比较了三种不同的预冷配置，并通过目标函数优化了运行条件，以最大程度地降低了能耗。在优化之前，将基于灵敏度分析进行预筛选，以排除任何潜在的不可行解决方案空间。它可以进行可靠的优化，从而提供高质量的最佳解决方案。通过集成预冷循环，可将总能耗降低7.9％，这在很大程度上取决于饱和制冷剂的物理特性。本研究中提出的建模和优化框架可以有效地应用于各种制冷剂所致的各种制冷系统。