To reduce harmful exhaust emission from marine diesel engine, a electronic controlled hydraulic system was mounted on a medium speed 4-stroke diesel engin and applied to fuel injection and inlet/exhaust valve actuation. Monitor units were also completed to check the timings of fuel injection and inlet/exhaust valve open/close. The units showed the timing variation which was caused by electromagnetic valve motion. Improvement and adustment of the system were performed for the variation and permitted the engine operation under our directions. The progress of the engine remodeling is described in this report.
The circumstances of medium speed diesel engine have been severe to keep up with the environmental problem such as global warming or IMO regulation. To adapt the market trend, the authors developed a series of“Neo”medium speed diesel engines, model 22HLX, 28HLX and 34HLX. This paper describes design features, development processes and principal inspection results of these engines. On the development, extensive cost analysis of existing engines was made to realize extremely low cost/output rate. Performance simulation, FEM analysis, 3D module planning and component tests were also carried out. As the result, the engines having high reliability and friendly handling with advantageous performance were developed. These engines achieved high output with increasing power rate (24.5MPa⋅m/s) as the product of high brake mean effective pressure (2.45MPa) and increased mean piston speed (10m/s) . High thermal efficiency was achieved by prolonged piston stroke, soft-Miller-cycle and high performance radial turbocharger. Lightweight mono-block piston and compound oil-groove big-end bearing, for example, were the key components to realize such high output engines. Concurrent engineering and virtual factory production were applied by means of unity administration of allied factories. First productions were successfully launched from 1998 to 1999, and the longest running hours reached over 18000 hours in October of 2001. The FOC, LOC and exhaust gas temperature was at low level as expected. At the first principal inspection, the piston top land and piston ring grooves were far clean rather than previous engines. Piston and cylinder liner condition was perfect.
Medium and large-sized diesel engines have two economic advantages: high thermal efficiency and the ability to use cheap fuels, the latter being made possible by the use of bunker fuel oil (BFO) . To burn such low grade fuels well is the most important theme for the marine and stationary engines. Though the fuel-water emulsion was developed as a measure to reduce NOx emission, its effect to improve the combustion is also noteworthy. Recently an European engine builder has announced the possibility to develop the invisible smoke engine using the fuel-water emulsion. In this study, to examine the effect of fuel-water emulsion on combustion, experiments are carried out using a visual engine and a visual combustion chamber. According to the data, it has been confirmed that both combustion temperature and soot formation in the flame of bunker fuel oil can be at the same time restrained applying 25% water emulsion.
The fundamental characteristics of particulate matter and NOx formations by the oxygenated components fuel oil are studied experimentally. This work uses a high quality biomass (Edible Oil) for the oxygen containing fuel oil. Profile of particulate matter and NOx concentrations together with gas species concentration, temperature and spray behaviors are measured in the spray flames of two different fuels: pure Kerosene added Edible oil in the ratio of 70/30 v/v. % . The nozzle type for atomization is used an ultrasonic generator without precedent. When the biomass (Edible oil) fuel oil is used, the gas temperature on the flame axis increases by 100-150°C, is raised as OH radical and O2 concentration increases. Both of the particulate matter formation and decomposition rates increases, the final exhaust of PM is reduced. NOx concentrations in the both flames is no significant difference in the downstream region.