ABSTRACT
Crude oils and most of their commercial derivatives such as diesel fuels and fuel oils are complex fluids containing normal and branched alkane molecules, aromatic compounds, and other polar and nonpolar compounds. Of these, the long-chain normal alkane molecules, CnH2n+2, (also known as normal paraffins or simply as waxes) play an important role in controlling the rheological properties of these mixtures, particularly at low temperatures. As the temperature of such a solution is lowered, the larger n-alkanes (those with nz 20) precipitate from solution, forming a weakly linked, gellike network of crystals, drastically increasing its viscosity. This causes difficulties in the production, transport, and storage of crude oils and fuels, particularly in cold climates. An important case where such concerns arise is the use of diesel fuels in winter.
