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.