The Role of Isopropyl Alcohol in the Properties of Sudanese Reformat Gasoline
The role of isopropyl alcohol in the properties of Sudanese reformat gasoline (produced by the refinery located at Algily, Khartoum North city, in Sudan) was studied. The properties of the reformat gasoline which were investigated include , distillation, sulfur content, density, vapor pressure, oxidation stability, copper strip corrosion, gum existence, lead content, and the octane number . The addition of isopropyl alcohol (5 and 10% (v/v)) improved the properties of the Sudanese reformat gasoline to the limits assigned by American Society For Testing And Materials (ASTM) and Khartoum refinery. The motor octane number (MON) of the reformat gasoline was determined initially by the Cooperative Fuels Research engine (CFR engine), MON was found to be 88.5. Results revealed that the addition of isopropyl alcohol 5 and 10 % (v/v) to the Sudanese reformat gasoline shift the value of the (MON) to 94.1 and 96 respectively. keywords: Isopropyl alcohol, Sudanese gasoline properties, Motor octane number, Cooperative fuels research engine.
Determination of quantitative structure–octane rating relationships of hydrocarbons by genetic algorithms
Abstract The influence of the molecular structure of organic compounds on their knocking behavior was determined using a non-binary genetic algorithm (GA). The molecular structures of 240 potential gasoline components were described by use of 16 different structural groups. Partial octane numbers were calculated for these structural groups dependent on the substance classes paraffins, naphthenes, olefins, aromatics and oxygenates. The sum of the calculated partial octane numbers supplies the octane number of the compound. A multiple linear regression (MLR), a neural network and a GA were used for the computations of the connections between the structural groups and the knock ratings. Results obtained by GA were significantly better than these obtained by MLR. The correlation coefficients between the calculated and the test engine determined blended research octane numbers were for paraffins R GA =0.988 ( R MLR =0.954), naphthenes R =0.975 (0.877), olefins R =0.984 (0.959), aromatics R =0.945 (0.877) and for the oxygenates R =0.964 (0.919). The calculated partial octane numbers allows the quantitative determination of influences of structure modifications on the knocking characteristics of gasoline components.
Asphalt Study by Neuronal Networks. Correlation between Chemical and Rheological Properties
In this paper we investigate the prediction of rheological properties of bitumens using some structural parameters calculated from 13 C NMR data. This study was carried out using methods of quantitative structure properties relationships (QSPR) and more particularly neural networks (NN). Such a mathematical tool can find out non linear relations between descriptors and properties. Two asphalt rheological properties, m (creep slope at low temperature) and G * /sin δ (stiffness at high temperature) were selected, whereas the descriptors are the average molecular parameters which characterize the hydrocarbon skeleton of bitumens. This work permitted to prove that the skeleton information contained in the average molecular parameters could be correlated to the m value but not to the G * /sin δ. Thus, the low-temperature rheological behavior appears to be highly dependent on the aliphatic part of the bitumens.