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Diesel Vehicle Cold Operability: Design of Fuel System Essential Besides Fuel Properties
ISSN: 1946-3952, e-ISSN: 1946-3960
Published September 10, 2012 by SAE International in United States
Citation: Mikkonen, S., Kiiski, U., Saikkonen, P., and Sorvari, J., "Diesel Vehicle Cold Operability: Design of Fuel System Essential Besides Fuel Properties," SAE Int. J. Fuels Lubr. 5(3):977-989, 2012, https://doi.org/10.4271/2012-01-1592.
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.