Innovative refrigeration concept for passenger ships - combining CO2 refrigerant, cold recovery and cold storage

More stringent international regulations on ship's emissions require a shift towards more climate friendly fuels, such as liquefied natural gas (LNG). On LNG-driven ships, the fuel is stored onboard at cryogenic temperature. The fuel must be vaporised before injected into the engine, implying a potential for cold recovery. Today, concepts are commercially available for utilising this surplus cold in conventional AC chiller system. This paper proposes an innovative concept where the LNG cold recovery system is integrated with a provision refrigeration system based on a CO2 booster unit and a cold thermal storage (CTES) due to the dynamic nature of loads and cold-recovery availability. The CTES is based on phase change materials (PCM) which, together with the choice of CO2 as refrigerant, ensures a compact system. The results show a potential for significant reduction in power consumption of the refrigeration systems and thereby contributing to reduced GHG emissions.