NYK will install a variable compression ratio system (VCR system) on two large LNG-fueled coal carriers to be built at Oshima Shipbuilding. The vessels are scheduled to be delivered by the end of 2025, and NYK reports this will be the first time for VCR systems to be installed on vessels, including existing vessels that use heavy fuel oil as their main fuel.
The VCR system can adjust the air compression ratio in the engine combustion chamber to an optimal balance according to engine power and LNG fuel properties. This optimal adjustment will improve fuel efficiency during operation by about 3% in LNG gas mode and about 6% in diesel oil mode.
The system is also expected to play an important role in reducing GHG emissions from existing ships and improving engine efficiency when decarbonized fuels are introduced.
Based on its technology and experience with large low-speed marine engines, Mitsui E&S DU Co., Ltd. developed the VCR system together with Winterthur Gas & Diesel Ltd.