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Fifth Edition Worldwide Fuel Charter

ACEA, Auto Alliance, EMA, JAMA | September 2013

Review of fuel quality recommendations for worldwide legislators, fuel users and produces, which introduces Category 5 fuel specifications, which establishes a high quality hydrocarbon-only specification that takes advantage of the characteristics of certain advanced biofuels, allows up to 5% biodiesel by volume in Category 4, has new diesel fuel oxidation stability limits.

  • Charter created in 1998 to increase understanding of fuel quality needs of motor vehicle and engine technologies & promote fuel quality harmonization worldwide in accordance with those needs
  • Fifth Edition introduces Category 5 for markets with highly advanced requirements for emission control and fuel efficiency, for example those that require US 2017 light duty fuel economy, US heavy duty fuel economy, CA LEV III or equivalent emission control and fuel efficiency standards in addition to Category 4 level emission control standards
  • Highlights:
    • Raises minimum research octane number (RON) to 95 for gasoline
    • Diesel: establishes high quality hydrocarbon-only specification that takes advantage of the characteristics of certain advanced biofuels, including hydrotreated vegetable oil (HVO) and Biomass-to-Liquid (TTL)
    • Charter now allows 5% biodiesel by volume in Category 4 diesel, has new diesel fuel oxidation stability limits and includes an alternative oxidation stability test method
    • Charter now references B100 guidelines published by the WWFC Committee in 2009
  • Diesel Fuel
    • Cetane = measure of the compression ignition behavior of the fuel; higher cetane enables quicker ignition, influences cold startability, exhaust emissions and combustion noise; artificial (through additives) cetane performs differently than natural cetane
    • Density and Viscosity = affects fuel injection rate/timing, resulting in variations in engine power and therefore emissions and fuel consumption
    • Sulphur = occurs naturally, can cause engine corrosion and wear if not removed and contributes to particulate matter (PM) and reduces efficiency of exhaust after-treatment systems; however, removal can cause thermal instability which can result in fuel filter plugging by oxidized products (sludge)
    • Ash = ash forming metals can be present in additives or as byproduct of refining process; contributes to coking on injector nozzles and has significant effect on life of particulate filters
    • Aromatics = molecules containing at least one benzene ring; aromatics content affects combustion and formation of particulate and polycyclic aromatic hydrocarbons (PAH) emissions as well as flame temperature and therefore NOx emissions during combustion
    • Distillation Characteristics = distillation curve indicates amount of fuel that will boil off at a given temperature; 3 parts: 1) light end – affects startability; 2) 50% evaporation point – related to viscosity and density; 3) heavy end – affects tailpipe emissions
    • Cold flow performance = paraffinic hydrocarbons present in diesel have limited solubility and if cooled sufficiently will come out of solution as a wax
    • Foam = diesel has tendency to generate foam during tank filling which slows process and risks over-flow; additives can control it
    • Biofuels = Fatty acid methyl esters (FAME); made by reacting oil with alcohol to form ester compounds (unprocessed oils/animal fats unacceptable as transportation fuels due to low cetane levels, inappropriate cold flow properties, high injector fouling tendency and high kinematics viscosity level); biodiesel made with ethanol called fatty acid ethyl ester (FAEE)
    • Injector cleanliness = tip of injector subject to very harsh environment as result of being in direct contact with combustion process – solid matter products of combustion are deposited on the tip and can result in partial or complete hole blockage, which will significantly alter operation of the injector by reducing fuel flow and affecting power and emissions
      • New type of injector deposit: Internal Diesel Injector Deposits (IDID) – differ from normal coking deposits in location and effects – cause increased engine noise, rough running, power loss and inability to start – which all causes oil dilution, EGR line fouling, increased emissions and reductions in efficiency and durability of emission control systems
        • Incidents have increased with growth of common rail engines and their increasingly high fuel injection pressures (thought to be contributing factor)
    • Lubricity= critical for protecting engines and fuel handling systems; believed to come from heavier hydrocarbons and polar fuel compounds; process to remove Sulphur tends to reduce fuel components that provide natural lubricity
    • Particulate Contamination = injection pressures have been increasing due to attempts to reduce emissions and fuel consumption; higher pressures demand reduced orifice sizes and component clearances (2-5); small hard particles which may be carried into these engine parts are potential sources of engine failure
    • Contaminants = calcium, copper, sodium, manganese, potassium, phosphorus, zinc, chlorine

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