This paper describes NOx and COx emissions from the diesel engine on mini-vessel such as 500GT class vessel under transient operating condition and entering and departing conditions, because the reduction of the marine exhaust emissions has been important subject. And the International Maritime Organization (IMO) advances the prevention of air pollution from ships in 1989. The regulated level of NOx emissions will be decided by the Bulk Chemicals (BCH), in recent years. So the emissions of carbon monoxide (CO), carbon dioxide (CO2), total hydrocarbons (THC), sulfur dioxide (SO2), and nitrogen oxide (NOx), occupy an important part. The transient operating conditions have been formed by change of engine speed and PPA whose region are within the range of 500-673rpm, and 11-20deg. NOx concentration in summer voyage changes within the limits of 600- 1000ppm, and CO2concentration changes within the limits of 4-7%.
Because a marine steam turbine propulsion shafting contains some gear trains which run idling at the transient condition such as astern operation, it is well known that the peculiar torsional vibraton phenomena with gear teeth chattering at the crash astern operation, etc. The author has considered that this phenomena is caused by not only the existing of the gear backlash but also the effect of the bearing oil film which results in self-exciting vibration. And he made a mathematical model of the propulsive shafting system including the gear backlash combined with the bearing oil film of the pinion gear in order to clarify this phenomena. By computer simulation using this mathematical model, it is concluded that the self-exciting vibration occurs at a certain shaft RPM due to the bearing oil film which gives an effect to such a peculiar torsional vibration as has a certain frequency unrelated to the number of the propeller blade and it can be explained well by this model.
The more vigorous bubbling was observed on a silicon-coated copper surface compared to that on a clean mirror-finished surface at a same heat flux. The enhancement of the bubbling was associated with the fact that the non-wetting porous structure in the silicon coating provided the sufficient number of active sites for bubbling nucleation. As the result, the nucleate heat transfer coefficient on the silicon-coated surface was higher than that on the clean mirror-finished surface. On the other hand, the nucleate boiling heat transfer coefficient on the fouling surface was approximately the same as that on the mirror-finished surface. The fouling scale was also the porous material but the wettability was high.