442 
443 
444 
445 
446 
447 
448 
449 
450 
451 
The analysis for the concentration time-series of CO. for different heights above the sea 
level is needed due to the tidal-caused variability of the sea level height relative to the MS level, 
varyıng between 7-11 m. The three time-series that are depicted in Figure 8 correspond to different 
possible VMS for minimum, average and maximum heights, of 7, 9 and 11 meters above water 
level, respectively for Ship 1. The concentration values are larger at higher elevation above the sea 
level, a finding that has already been discussed with Figure 5. The DR at 9 m above the water level 
ranges from 10*:1 to 10°:1 resulting in a maximum concentration of 16 ppm. The MOP values 
correspond to 103 ppm, 107 ppm and 111 ppm for heights of 7 m, 9 m, and 11 m, respectively. 
exhibiting minor differences. Therefore, data exportation in 9 m is considered as the reference for 
the analysis since it corresponds an average possible height. 
20 
X 16 - 
CFD - CO, Time-series 
above water level 
7m 
12 - 
-am 
— 11m 
8 - 
7 A 
I 
) 
. 
0 
0 20 40 60 80 100 120 
Time (s) 
452 
453 
454 
455 
456 
457 
458 
459 
460 
461 
462 
163 
464 
465 
466 
467 
Figure 8: CO, concentration time-series for the three heights of VMS above the water level in the example of Ship 1. 
The comparison between CFD results and measured values, provides data that can be used 
for modelling evaluation. However, the example of Ship 1 in Figure 9 shows that there is a 
discrepancy in the measurement time-series data between CO2 and SO», necessitating an 
investigation into how to compare the measurements with the CFD results. The SO time-series is 
a flattened curve that has a 30-second response time delay when compared to the CO> time-series. 
The factor that causes the SO2 signal deformation is the t90 response time of the SO2 measuring 
instrument which is 30 s, while the corresponding for the CO2 measuring instrument is <5 s. The 
small t90 response time of CO2 measuring instrument indicates its capability to provide direct data. 
Therefore, the CO2 comparison of the simulation versus the measured time-series is the most 
effective method since the compatibility between them is ensured. The simulated time-series of 
CO>z2 have been time-shifted so that the initial concentration rise coincides with the initial rise of 
the measured signal (Figure 10). The orange lines depict modelling results, which correspond to 
the CO» concentration time-series at 9 m above the water level and the yellow line constitutes the 
measured concentration time-series. 
20