(4) This analysis proved that the impact of the cetane index is great on NOx concentration increase in the low- engine load range. However, in the case of high-engine load range, adding fuel oil properties as correction factors does not make any difference in the results of the correction on NOx concentration.

　

ACKNOWLEDGEMENT

　

This study was accomplished in collaboration with Japanese Marine Equipment Association under the subsidy of The Nippon Foundation, for which we express our appreciation.

　

REFERENCES

　

[1] IMO, "The Text of the Technical Code on Control of Emission of Nitrogen Oxides from Marine Diesel Engines" (October 1997)

[2] H. KONDOH et al., "Study of Some Correction Factors for Application to Stationary Diesel Engine NOx Data" (1990) ,ISME KOBE

[3] H. KONDOH et al., "Influences of Fluctuation Factors on NOx Emission from Medium Speed Diesel Engine" (1998) ,CIMAC COPENHAGEN

　

APPENDIX

　

(1) Maximum allowable NOx emission limits for marine diesel engines

　

(2) CCI - Calculated Cetane Index - (JIS K2280)

　

CCI = 45.2 + (0.0892) (T_10N)

+ [0.131+(0.901) (B) ] [T_50N]

+ [0.0523-(0.420) (B)] [T_90N]

+ [0.00049] [(T_10N)²: (T_90N)²]

+ (107) (B) + (60) (B)²

　

B = [exp (-0.0035D_N) ] -1

D_N = D - 850

D = D₁ × 1000(kg/m³)

　

D₁: Fuel density (g/cm³) at 15 ℃

　

T_10N = T_10N - 215

T_50N =T_50N - 260

T_90N = T_90N - 310

　

T_10N: Distillation 10% vol (℃)

T_50N: Distillation 50% vol (℃)

T_90N: Distillation 90% vol (℃)

　

(3) CCAI - Calculated Carbon Aromaticity Index.

　

CCAI = D - 140.7 log₁₀ log₁₀ (V + C) - A

D: Fuel density (kg/m³) at 15℃

V: Kinematic viscosity (mm²/s) at 50℃

C: 0.3 (MDF)

A: 80.6

　

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