The Properties and Injector Nozzle Fouling Performance of GTL and EN590 Diesel with RME and SME Biodiesel 2013-01-1136

There is a worldwide drive to reduce the dependence on fossil fuels, mainly driven by volatility in the crude oil price, political instability in oil-producing countries and environmental concerns. In several European countries, diesel passenger cars outsell gasoline-powered cars by a significant margin. Common rail diesel injection technology has played a significant role in making diesel engines more acceptable in light-duty applications, given the significantly improved emissions (due to better atomization) and engine noise offered by this technology. These developments have contributed to a renewed interest in alternative diesels like biodiesel and Gas to Liquid (GTL) diesel. Recently, CEN TS 15940:2012 was approved for publication. This specification will enable paraffinic diesel (including GTL diesel) to be sold commercially as a neat fuel or as a blend, containing up to 7% fatty acid methyl ester biodiesel (FAME). Although the injector fouling and emissions properties of neat GTL diesel and GTL diesel/petroleum-derived diesel blends are well described in literature, only limited information exists on the chemical properties and injector fouling performance of FAME/GTL diesel blends.

In the current study, the chemical properties and injector fouling performance of several blends of GTL diesel with rapeseed methyl ester (RME) and soya methyl ester (SME) were evaluated and compared with similar FAME/EN590 diesel blends. The injector fouling behavior of these blends was determined using the CEC XUD9 test and the Sasol common rail injector fouling test.

Blends of GTL diesel and FAME (up to 7% FAME addition) were shown to meet the CEN TS 15940:2012 specifications. Some of the properties of these blends were shown to be superior to those of the corresponding EN590 diesel blends. It was also shown that the addition of less than 1% FAME can improve the lubricity of GTL diesel to meet the specified HFRR lubricity requirement (≺460 micron wear scar). In line with this observation, SL BOCLE data showed that the addition of small quantities of FAME also improved the seizure protection properties of these fuels. The injector fouling evaluations showed that the injector fouling performance of FAME/GTL diesel blends was generally better compared to the FAME/EN590 diesel blends.