Among the lubricating oils used onboard, the cylinder oil for two stroke diesel engines is used under the most severe conditions. Cylinder oil performance greatly affects a vessel’s safe operation because it is used for engine propulsion. Meanwhile, from an economical viewpoint ship owners always consider the reduction of cylinder oil consumption. It is, therefore, important to understand the properties of cylinder oil to ensure the safe operation of a vessel, and to reduce costs. Various laboratory tests/analyses on over 20 brands of oil from different companies were performed in order to evaluate the performance of these oils. There were evaluated comprehensively, based on the ranking of each test/analysis result. It is considered that oil performance is influenced by the type of base oil and additive used.
Verification test of the semi-permanent use of engines and no waste oil was conducted over a period of 8 years 33,000h, the results of which were presented in SAE 2011-01-2113 at SAE 2011 held at Kyoto, Japan. The test has reached 10 years 45,000h as of August 2013 and is still on-going. This technology which almost completely removes sludge and maintains lubricating oil cleanliness has been in practical use in many marine and power diesel engines for a long time. It is theoretically and technologically simple to integrate various oils only if the oil is clean without sludge. Clean lubricating oil even with a low alkalinity value can prevent engine corrosion due to acids. In this paper, EBAS (Efficient BASicity) is used instead of TBN as proposed by C. Amblard and S. Esson at CIMAC 2013 held at Shanghai, China.
Fuel economy is one of the most important issues facing marine industries from the standpoint of both reducing greenhouse gas emissions and saving costs. Although engine manufacturers, ship builders, and ship owners have evaluated various means to improve the fuel efficiency of ships, there are only a few studies that deal with the contribution of marine engine lubricants to fuel efficiency. The authors investigated the influence of viscosity characteristics and additives (e.g. friction modifiers) in lubricants on the fuel efficiency of medium-speed trunk piston engines. Through laboratory tests, bench-and full-scale engine tests, it was found that optimized formulations with unprecedented low-viscosity improved fuel efficiency. The best formulation improved fuel efficiency by over 3% in full scale engine.
Particulate matter (PM) emitted from medium and large marine diesel engines contains a high quantity of soluble organic fraction (SOF) and sulfate compared with PM emitted from small high-speed diesel engines used in cars. For this reason the diesel particulate filter (DPF) used in cars are unsuitable for use in ships, because sulfate deteriorates the catalyst used in DPFs. In this study, the following experiments and analysis were carried out for the purpose of decreasing PM emissions from marine diesel engines that use heavy fuel oil and marine diesel oil. (1) The difference in the quantity (g/kWh) and composition (soot, SOF, sulfate) of PM emissions between small high-speed diesel engines and large low-speed marine diesel engines was examined. Using these results, the formation mechanism of PM for each engine was clarified. (2) To clarify the effect of DPF on PM reduction, the filter material used in DPF was installed between PM sampling probes set in the exhaust lines of test engines and dilution tunnels. The components of the PM with and without the filter material were compared. (3) Finally, guidelines for PM reduction were discussed based on this analysis, and their effectiveness was verified in actual engines and ships.
As an application of superconducting technology to the field of maritime sciences, the authors have studied a seawater magnetohydrodynamics (MHD) power generator/hydrogen generator using a high-field superconducting magnet, focusing on natural marine energy. The seawater MHD power generator is a unique system that not only transforms the kinetic energy of ocean and tidal currents directly into electric energy but also generates hydrogen gas in accordance with the law of electromagnetic induction. Recently, a new helical-type seawater MHD generator with partitioned electrodes having a helical insulation wall with an outer diameter of 97 mm and a length of 155 mm and a 7 T solenoid superconducting magnet has been designed, fabricated and examined to elucidate the relationship between the characteristics of the generator and helical flow. It was found that the electromotive force obtained was in agreement with the calculated value in stable helical flow and was independent of the direction of the induced electric field.
Generally, a compact diesel engine equipped with a turbocharger can obtain higher mean effective pressure and higher power. For such engines, the power and rotational speed of the turbocharger cannot match sudden increases in engine load. In this case, engine stall occurs resulting in poor combustion and increased smoke. A jet assist system installed on the compressor casing can effectively reduce turbocharger lag. This jet assist system is useful to improve the acceleration performance of the turbocharger. Therefore, the application of a jet assist system in turbocharged engines prevents engine stalls and reduces smoke. This paper describes the design approach and test results of a turbocharger equipped with a jet assist system.