Statistical Investigation on the Carbon-Flower Formation in A Pre-combustion Type Diesel Engine
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Fifty kinds of marine diesel fuel oils are prepared by blending atomospheric bottoms with distillates in various proportions, and their rates of carbon-flower formation are compared with each other after 24 hous' running in a pre-combustion type diesel engine. A cylindrical spacer is inserted into the pre-combustion chamber to accelerate the carbon formation around its injection nozzle by reducing the effective volume of the chamber.<BR>The rates of carbon formation in these fuel oils are numerized by counting the frequencies of remarkable changes in exhaust gas temperature, which are regarded to be correspondent to the rise and fall of carbon flowers. The longer is the interval (Y), the less the carbon formation.<BR>Seven variables representing the characters of these fuel oils are selected as follows: carbon residue, specific gravity, viscosity, sulfur content, aniline point, diesel index, and spot test grade (sedimental matter) .<BR>Among the coefficients of correlation between y-value and each variable, only that for the combination between y-value and carbon residue is significant. The dispersions of y-values observed in this simple correlation is also suggested to be attributed to the influences of other variables than carbon residue, and then multiple regression analyses are followed over the 64 linear equations constituted with all combinations of the seven variables.<BR>The coefficients of multiple correlation in all regression equations become larger in accordance with the numbers of variables composing each equation, but some of variables are found to be insignificant as for their factors after t-value testing for each variable.<BR>Finally five linear regression equations are left to be reasonable as the representations for the carbon formation tendency in these fuel oils tested, and the y-values calculated by means of these equations agree well with those observed.<BR>The limiting y-value that would be appropriate to judge the safety in actual performance of such fuel oils as used in this work is proposed to be about 85 minutes in referring to the published data in ship tests, and the safety grade for any one of these fuel oils is predicted by comparing the y-value calculated through one of these equations with the limiting y-value.
- 公益社団法人 日本マリンエンジニアリング学会の論文
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関連論文
- Statistical Investigation on the Carbon-Flower Formation in A Pre-combustion Type Diesel Engine
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