Diesel Vehicle Cold Operability: Design of Fuel System Essential Besides Fuel Properties 2012-01-1592
Cold operability is estimated by fuel's cold filter plugging
point (CFPP). However, correlation of CFPP with diesel vehicle
performance originates from a period when simple in-line or
distributor fuel injection systems were applied and fuels did not
contain biocomponents. Today, common rail fuel injection systems
are used and there seem to be remarkable differences in their
design between vehicle models.
Seven cars were tested in a climate chamber. The best cars
operated down to 8°C below fuel's CFPP but the worst get into
problems 5°C above CFPP with the same fuel. It is challenging to
define what CFPP is needed in order to guarantee trouble-free
winter performance because there are big differences between car
models. It is fundamental to get the fuel temperature of a
vehicle's fuel filter above the fuel's cloud point during
driving, and this depends on fuel system design factors, such as
location and size of fuel filter and fuel heater if it is used.
Oil companies prefer diesel fuels which do not have unnecessary
good cold properties because better cold properties reduce the
diesel fuel yield at refineries at a time when there is shortage of
diesel fuels in Europe. Light middle distillate fractions suitable
for winter grades are needed also for aviation kerosene production.
Cold operability problems related to biocomponents can be avoided
by using isomerized HVO.
Trouble-free operation in cold conditions is important for all
stakeholders: oil companies, automotive companies and vehicle
owners. Further exchange of information and cooperation between
oil, automotive and fuel additive companies would be valuable as
well as more vehicle testing.