The study on feasibility of HFO refrigerants in BOG re-liquefaction process

As regulation of ship emission established, using liquefied natural gas (LNG) as ship fuel is one of the method to reduce ship emission. For LNG carrier, boil-off gas (BOG) generated from the storage tank can be used as fuel and it is economical to adopt BOG re-liquefaction system on the vessel. In this study, we investigate the feasibility of hydro- fluoroolefins (HFO) refrigerants in the BOG re-liquefaction system. We simulate BOG re-liquefaction system and optimize it to minimize energy consumption. Then, the global warming potential(GWP) generation during lifecycle of the ship is estimated. As the results, HFO refrigerants has similar performance in BOG re-liquefaction system in terms of energy consumption compared to hydrocarbon refrigerants. In case using HFO refrigerants, the specific power consumption (SPC) of re-liquefaction process is 0.479 kWh/kg and in case using hydrocarbon refrigerants it is 0.471 kWh/kg. However, although HFO refrigerants has lower GWP than hydrocarbons, the total GWP generation is larger than when using hydrocarbons due to GWP generation caused by CO2 emission. © 2022 Elsevier B.V.