Could RME biodiesel be potentially harmful to modern engine? solidification process in RME

• Solidification process in the biodiesel sample has been observed.
• Physical and chemical properties of rapeseed methyl ester was measured up to 350 MPa.
• Intense of transmitted and scattered light versus pressure have been examined.
• Biodiesel was pressurized, with compression rate similar to occurs in CR diesel engine.
• Compression of biodiesel was similar to occurring in common rail diesel engine.

A sample of Fatty Acid Methyl Ester (FAME) has been examined in high pressure conditions. Solidification process in the FAME sample has been observed. The aim of the measurements was to pressurize the sample with different rates of compression. During the pressurization the changes of the transmitted and scattered light intense induced by pressure were recorded. The measurements done at various speed of compression as well as decompression have shown creation of scattering centers, what is typical for high pressure solidification of fats and fatty acids. The character of those changes was expected for the pressure induced phase transitions, observed by authors for various lipids. The experiments were conducted at room temperature. Phase transition was appearing at the pressure above 230 MPa. The phase transition pressure was changing from 230 MPa to 300 MPa, depending on the compression rate. The presented experimental methods have wide applicability to determine rheological properties of those kind of liquids.