This study proposes a strategy for evaluating effi cient design of the Gas Management System (GMS) on LNG carriers by

decomposing its performance to subsystems: the reliquefaction system (RS) and the fuel gas supply system (FS). With

increasingly stringent maritime regulations on greenhouse gas emissions, the need for effi cient LNG carrier operations has

become critical. A major factor in reducing fuel consumptions and carbon emissions is optimizing the design of the RS,

given its signifi cant power demand for processing NBOG. However, eff ective GMS design must account for variations in

RS operation performance, as well as the contributions of the FS in treating NBOG with changes in ship speed. This study

compares GSM confi gurations with reliquefaction systems based on two representative refrigeration cycles: the nitrogen

reverse Brayton cycle (NRBC) and the single mixed refrigerant cycle (SMRC), both analyzing eff ects of cold BOG utilization.

Results indicate that the RS of GMS4A-aSMRC [the aSMRC is the refrigeration cycle which utilizes cold BOG within

the Single Mixed Refrigerant Cycle (SMRC)] demonstrates superior RS design performance. However, the most effi cient

GMS confi guration varies with the Boil-off Rate (BOR): GMS2-aNRBC [the aNRBC is the refrigeration cycle which utilizes

cold BOG within the Nitrogen Reverse Brayton Cycle (NRBC)] is optimal aligning with its RS performance for a 0.11%/

day BOR, while GMS3-SMRC without cold BOG in RS is the most effi cient for a 0.075%/day BOR, owing to increased

contributions from the FS. In this study, a performance index with a consistently comparable baseline is derived to accommodate

compositional deviations from fl ash gas recirculation at NBOG disposal streams, enabling the GMS performance to

be correlated with compatible values of its decomposed subsystem.