Fig. 6 Analyzed results of the changes of Tmax in layout diagram
It is seen from the figure (e) that Tmax/Tmax0 increase considerably along with the decrease of pmax/pme0 under the constant pmax and the constant ps/pme condition, but Tmax/Tmax0 is kept almost constant even under the constant pmax condition if the slope of ps/pme against pme/pme0 is set as -0.11 and then ps/pme is made to increase gradually along with the decrease of pmax/pme0.
4. Analyzed results of the measured NOx values
4.1 Measured NOx data and the cause of the dispersion
Fig. 7 shows the measured NOx values at 100%L of the engines shown in Table 1 with the different symbols for each group against engine speed n. These NOx data have been modified already by the compensations regarding the humidity, temperature, and etc. according to the IMO Technical Code. For reference, the IMO NOx regulation curve is shown in this figure extrapolatedly in the area bellow 130 rpm. The tendency of the measured data coincides well with this regulation curve, but the dispersion of the data is very large.
The main cause of these dispersion of the measured NOx data is considered the scattering of the four performance parameters of pmax/pme, ps/pme, V1/VH, V2/VH at shop trials which control fundamentally the engine performance, in addition to the measurement errors for the gas density, and etc. That is to say, at the shop trials, pmax/pme is set by arranging the fuel injection timing, ps/pme is set by altering the turbocharger matching, V1/VH is set by changing the exhaust valve open and close timing and V2/VH is set by modifying the shim thickness at the bottom part of the piston rod, however these performance parameters are not always same on the same rating engines.
Fig. 7 Measured data of NOx at 100%
