5.1.3 Enlarged photos of internal surface of nozzle
Fig.8-a is the photo of the surface at the tip part of the fuel injection valve which has never been used, Fig.8-b is the photo of that of the fuel injection valve used in the A-oil mono-fuel mode, and Fig.8-c is the photo of that of the fuel injection valve used in the emulsified fuel mode. The machining traces are found on the surface inside the new nozzle substantially orthogonal to the running direction. Damages generated by the running operation of the needle valve were found inside the nozzle in addition to the machining traces in the fuel injection valve in the A-oil mono-fuel mode. Damages in the running direction similar to those in the A-oil mono-fuel mode were found in the fuel injection valve in the emulsified fuel mode. In comparison with the A-oil mono-fuel mode, the machining traces are still left behind though its degree is worse, and the degree of the running damages is small. In the A-oil mono-fuel mode, the A-oil itself achieves the lubrication effect to the running part. On the other hand, the emulsified fuel is more viscous than the A-oil, and the sufficient lubrication effect to the running part can not be demonstrated. It is thus estimated that the wear of the running part was suppressed since the additive was poured in the emulsified fuel to maintain the lubrication effect.
5.2 Fuel injection pump
As illustrated by the photo of the surface of the plunger in Fig.9, the gloss of the running part around the notch in the plunger was dull compared with that in the A-oil mono-combustion mode.
5.3 Fuel oil system
Generation of rusts caused by water in the fuel oil piping was feared, but no changes were found through the internal observation by cutting the additionally fitted pipe.
5.4 Turbine blade of turbocharger
Fouling of the exhaust gas system was feared; however, fouling was less different from that in the normal overhaul inspection, and the degree of deposition of the soot was felt to be rather small. Further, no abnormality was felt in the wetness of the soot.
5.5 Products of combustion
Table 2 shows the result of the analytical inspection of the sampled combustion product of each part when the engine was overhauled. Since the sampling amount was different by the sampling part, the names of the detected elements are listed, and the quantity of the elements is omitted. What is characteristic of each part in comparison with the components identified in the A-oil mono-combustion mode is that sodium (Na) and silicon (Si) were contained only in the emulsified fuel mode. Further, vanadium leading to the high-temperature corrosion was contained in the piston head part.
