umber 20 В°
C, g/cm3 25 Й
C, kJ/kg 25 Й
C, Btu/gal Naphthalene Aromatic 10 1.175 38,854 163,800 Tetralin Aromatic 10 0.9695 40,524 140,960 1,3-Diethylbenzene Aromatic 10 0.8639 41,384 128,270 n-Butylcyclohexane Naphthene 10 0.7992 43,717 124,500 n-Pentylcyclopentane Naphthene 10 0.7912 43,585 123,720 Decane n-Paraffin 10 0.7301 44,236 115,880 2,2-Dimethyloctane Isoparaffin 10 0.7245 44,145 114,750 Anthracene Aromatic 14 1.251 38,412 172,410 n-Nonylbenzene Aromatic 15 0.8558 42,147 129,410 n-Nonylcyclohexane Naphthene 15 0.816 43,431 127,150 n-Decylcyclopentane Naphthene 15 0.811 43,545 126,710 n-Pentadecane n-Paraffin 15 0.7684 43,980 121,250 n-Tetradecylbenzene Aromatic 20 0.8549 42,482 130,310 n-Tetradecylcyclohexane Naphthene 20 0.825 43,445 128,590 n-Pentadecylcyclopentane Naphthene 20 0.8213 43,524 128,260 Eicosane n-Paraffin 20 0.7843 43,852 123,400
Cetane Number
Cetane number also varies systematically with hydrocarbon structure. Normal paraffins have high cetane numbers that increase with molecular weight. Isoparaffins have a wide range of cetane numbers, from about 10 to 80. Molecules with many short side chains have low cetane numbers; whereas those with one side chain of four or more carbons have high cetane numbers. Naphthenes generally have cetane numbers from 40 to 70. Higher molecular weight molecules with one long side chain have high cetane numbers; lower molecular weight molecules with short side chains have low cetane numbers. Aromatics have cetane numbers ranging from zero to 60. A molecule with a single aromatic ring with a long side chain will be in the upper part of this range; a molecule with a single ring with several short side chains will be in the lower part. Molecules with two or three aromatic rings fused together have cetane numbers below 20. br/>
Reduction of sulfur emissions
In the past, diesel fuel contained higher quantities of sulfur. European emission standards and preferential taxation have forced oil refineries to dramatically reduce the level of sulfur in diesel fuels. In the United States, more stringent emission standards have been adopted with the transition to ULSD starting in 2006 and becoming mandatory on June 1, 2010 (see also diesel exhaust). U. S. diesel fuel typically also has a lower cetane number (a measure of ignition quality) than European diesel, resulting in worse cold weather performance and some increase in emissions.
Refining
Petroleum diesel, also called petrodiesel, or fossil diesel is produced from the fractional distillation of crude oil between 200 В° C (392 В...
