To comply with IMO NOx Tier III regulations, Mitsubishi Heavy Industries Marine Machinery & Engine Co., Ltd. has developed a new and unique technology called “Low Pressure Exhaust Gas Recirculation (LP-EGR) system”. The Mitsubishi LP-EGR system is a system which recirculates a part of the low pressure exhaust gas emitted from an engine turbocharger outlet into a turbocharger intake after scrubbed by an EGR scrubber. Now, we have applied integrated on-engine LP-EGR system into a commercial engine 6UEC45LSE-Eco-B2 aiming for onboard durability confirmation. We confirmed its NOx emission level was complied with IMO Tier III regulations and the increase of fuel oil consumption was less than approximately 1%. Adaptation of the LP- EGR system into IMO NOx Tier III regulations is the world’s first effort for marine low speed two-stroke diesel engine.

Furthermore, we installed the system into a 34,000DWT Bulk Carrier and now are conducting long-term durability confirmation during the sea trial and commercial voyages. The installation of the LP-EGR system complied with IMO NOx Tier III regulations into an actual vessel is also the world’s first effort for marine low speed two-stroke diesel engine.

The use of alternative marine fuels such as methane, ethane, methanol, ethanol, LPG and DME has been highlighted as a means to comply with the exhaust gas emission regulation (MARPOL Annex VI). Recently, two kinds of 2-stroke dual-fuel marine diesel engines that use such alternative marine fuels, namely, the Mitsui-MAN B&W ME-GI engine and the Mitsui-MAN B&W ME-LGI engine, came into market. This paper explains the design features and measurement results of both Mitsui-MAN B&W ME-GI and ME-LGI engines. Lower NOx emissions have been obtained when using such alternative fuels, and with further performance optimization a reduction in fuel consumption was achieved.

  The application of underwater injection of dispersants against discharged oil and gas has been carried out during the ‘Deep Water Horizon’ incident that occurred in the Gulf of Mexico in 2010. Research on the effect of underwater injection of dispersants has been done both experimentally and theoretically after the incident.

  The authors have investigated the dispersive performance of dispersants using a pre-mixed sample of oil and dispersant on the diffusion and rise velocity of oil droplets in a previous study. The oil droplet distribution was measured using the laser diffraction method, and experiments on the rise velocity were conducted. The rise velocity was estimated using a modified Weber number derived from the Weber number, viscosity number, and experimental constants.

  Experiments on dispersant injection against an upright rising oil flow using a duct installed at some distance above the exit were also conducted. The effect of reduced rise velocity on improving the mixing efficiency of oil and dispersants is shown.

This research focused on friction-based techniques for modifying the wear properties of a titanium alloy, particularly under seawater conditions. The surface modification processes employed were powder intrusion and friction stirring. Three different kinds of powder materials were used for the surface modification: Cr₂N,TiN and Al₂O₃. Wear tests were conducted on the specimens under both dry and artificial seawater conditions. The results revealed that the Cr₂N modified material presents excellent wear resistance under dry conditions, whereas modification using Al₂O₃ and Zn-coated Cr₂N led to excellent wear properties under artificial seawater conditions.

We aim to provide basic technology for the marine transportation of liquid hydrogen (LH₂). As one of the basic technologies, we are currently developing an external-heating-type superconducting magnesium diboride (MgB₂) level sensor for large liquid hydrogen tanks. The optimization of sensor performance and the effect of sensor length on thermal response were previously reported. Sloshing inside a liquid hydrogen tank, which is predicted to be more complex than that of liquefied natural gas (LNG), has not yet been clarified. In this study, we examined sloshing in a small liquid hydrogen tank using multiple external-heating-type MgB₂ sensors since these sensors exhibit good level-detection characteristics. As a result, the liquid level detection error from these sensors was up to about 4 mm, thereby showing good characteristics of dynamic level detection. Moreover, sloshing measurements with five level sensors were carried out successfully.