To meet stringent nitrogen oxides (NOx) regulations, a miller cycle with high-pressure turbo-charging is applied to all Niigata-manufactured four stroke diesel engines. At the same time, injection rate and compression ratio are optimized. In this paper, a practical study of NOx emission reduction for low-speed diesel engines is introduced. NOx reduction was attained through thermodynamic simulation as well as engine tests. Such technical countermeasures which are described in this paper are applied to all Niigata marine diesel engines and comply with IMO tier II.

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In order to meet environmental regulations and to satisfy customer needs, YANMAR has developed the EUP (Electronic Unit Pump) system for medium speed four-stroke diesel engines, with service tools to facilitate maintenance. This system improves fuel consumption at partial load and lowers smoke at low load by controlling fuel injection timing and fuel injection quantity depending on the engine speed and load. With regards to safety, this system assures sufficient reliability through the duplication of the main electronic parts. In October 2009, this system has been released to market as a marine propulsion engine for a cement carrier. At present, this EUP system has been operating without any trouble for more than half a year. This paper presents the outline of our new system.

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Improvement of ship energy system has been required for better fuel oil economy and environmental sustainability. The authors proposed a concept of heat recovery system from exhaust gas, connected to diesel engine. Core device of the system is circulating fluidized bed (CFB) heat exchanger which has function of desulfurization. In this report, adjustment of the system was evaluated, speculating factors to familiarize the system: initial building cost, demand quantity of heat or electrical energy, and cooperation of auxiliary devices like air conditioner or SCR, and so on. And the authors proposed group of "One-through Type" system and "Circulation Type" system. The "One-through Type" system is to cooperate auxiliary heat devices, whose heat source is steam once used for electric generation. The "Circulation Type" system is built to focus on electric generation, to add condenser.In analysis of the "One-through Type" connected to 1400kW 4-stroke marine engine, maximum electrical output of "One-through Type A" system, consisting of the CFB and one of steam-turbine generator, was 2.81%of main engine power in 75% load. And "One-through Type B" system, consisting of the CFB, superheater and two of the generators, was up to 8.23%.

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The quality of marine fuel oil has decreased due to high costs brought about by the exhaustion of fossil fuels and the inflow of investment. On the other hand, the IMO (International Maritime Organization) will introduce strict measures on air pollutants from ships. The emission reduction of PM (Particulate Matter) in particular, is absolutely essential. Therefore, this study focused on coal oil as a next-generation fuel. In our previous study, DS (Dry Soot) and SOF (Soluble Organic Fraction) behavior in the PM was reported. However, the formation characteristics of Cenosphere have not been clarified yet. In the present study, the combustion state and exhaust gas properties of Coal Oil and Coal Oil water-emulsified fuel were investigated. The following results were confirmed (1) Coal Oil has a low reaction rate since it contains aromatics, (2) SOx and NOx concentrations in Coal Oil emissions can be reduced by water-emulsification, (3) Cenosphere in Coal Oil PM is approximately 70-80 % by weight, and (4) exhaust gases from Coal Oil contain carcinogenic substances, e.g., pyrene or benzene series compounds, but these emissions can be reduced by water-emulsification.

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Thermogravimetric analyses of fuel oil, lubricant and soluble organic fraction (SOF) extracted from particulate matters (PM) of a medium speed 4-stroke marine diesel engine were carried out. The engine was operated with low sulfur heavy fuel oil of about 0.06% by mass sulfur which conforms to JIS K 2205 A-category (LSA). Derivatives of mass fraction with respect to temperatures (DTG curve) of the LSA evaporated to about 10% of its mass at 180 degrees C and that of the SOF sample have peaks at almost the same temperature (about 210 degrees C). With the pre-evaporation process at 180 degrees C, the DTG curve of LSA and lubricant mixture of which the mass ratio of the former to the latter is 2:3 also fits well for that of the SOF sample. Results of the analyses show that the SOF sample originates from the constituent parts of fuel oil of higher boiling point and the lubricant.

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Thermogravimetric analyses of fuel oil, lubricant and soluble organic fraction (SOF) extracted from particulate matters (PM) of a medium speed 4-stroke marine diesel engine were carried out. The engine was operated with low sulfur heavy fuel oil of about 0.06% by mass sulfur which conforms to JIS K 2205 A-category (LSA). Derivatives of mass fraction with respect to temperatures (DTG curve) of the LSA evaporated to about 10% of its mass at 180 degrees C and that of the SOF sample have peaks at almost the same temperature (about 210 degrees C). With the pre-evaporation process at 180 degrees C, the DTG curve of LSA and lubricant mixture of which the mass ratio of the former to the latter is 2:3 also fits well for that of the SOF sample. Results of the analyses show that the SOF sample originates from the constituent parts of fuel oil of higher boiling point and the lubricant.

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