Similarly, vehicles that run on diesel do not perform any better by using fuel with a cetane number higher than the recommended amount for that specific engine. Cetane number is the measure of the delay of the ignition of a fuel. Technical background on india bs vi fuel specifications. Astm d7668 17 standard test method for determination of. The cetane number see page 4 of the fuel defines its ignition quality. In its simplest terms, cetane number measures the delay between the start of fuel injection into the combustion chamber and the beginning of compression ignition autoignition. A kind of cetane number improver has been proposed and tested to be used with diesel fuel as ameans of reducing exhaust emissions. Cetane number cn a prime indicator of diesel fuel quality, is a quantity indicating the combustion behaviour of diesel fuel and compression required for ignition in diesel engines. Fuel having high octane number is considered as ideal fuel for the gasoline engine. Dependence of cetane index on aromatic content in diesel fuels. Cetane number affects a number of engine performance parameters like combustion, stability, drivability, white smoke, noise and emissions of co and hc.
Technical background on india bs vi fuel specifications 2 international council on clean transportation working paper 20169 octane number the octane number of gasoline provides a measure of the fuel s ability to resist autoignition, which can cause. Suggestions for reporting the fuel properties of biodiesel that correlate to cetane number are also provided. During the winter, we never have to worry about the fuel freezing up. Resascoa, aschool of chemical, biological and materials engineering, the university of oklahoma, norman, ok 73019, usa bconocophillips bartlesville technology center. The cetane number refers to the eace with which desel fuel ignites easily at a relatively low temperature. Standard test method for cetane number of diesel fuel oil. The objective of this paper is to discuss the possible reasons for the wide range in reported values of the cetane number of biodiesel. Octane number is a measure of the performance of a fuel. Cetane number effect on engine performance and gas emission. Characterization of the effects of cetane number improvers. Low volatile fuels tend to give better fuel economy where their characteristics are needed for complete combustion, and will produce less smoke, odor. The energy information administration estimates that worldwide production of diesel fuel in 2002 was nearly 197 billion gallons. If the cn of a fuel is too low, chemical compounds known as cn improvers may be added to increase both the cn and performance of the fuel.
Most of these hcs score in the middle, including many of the paraffins. The higher the cetane number, the more volatile the fuel. Cetane number of a diesel engine fuel is indicative of its ignition characteristics. Research article recent trends on ethanoldiesel fuel. Cetane number is a measure of the ease with which the atomised diesel fuel will ignite and burn, as the air in the engine cylinder is heated during the compression stroke. Standard diesel fuel sometimes called diesel oil comes in two grades. Cetane number measures the ignition delay of the fuel in the diesel engine.
The cetane number is similar to the octane rating in that it is a rating assigned to a fuel to rate the quality of its combustion. Under the texas low emission diesel txled program there are 110 counties where diesel fuel must have a cetane number of 48 or greater, or else must use an approved alternative formulation or comply with the designated alternative limits. Variations of cetane number of jatropha biodiesel blends. Cetane number is a measure of the ignition quality of diesel fuel. The physiochemical properties of fuel are important. Both are measured in a cooperative fuel research cfr engine. The employees are great people and are always there to find. Other diesel types are given their cetane number with comparison to the ignition of cetane liquid. This quote underscores the importance of matching engine cetane requirements with fuel cetane number. Both new and old engines benefit from diesel fuel with high cetane levels. Similar to the octane number seen on a retail gasoline dispenser, a cetane number rates a diesel fuels quality of ignition. Just as the octane number is meaningful for automobile fuels, the cetane number is a means of determining the ignition quality of diesel fuels and is equivalent to the percentage by volume of cetane in the blend with heptamethylnonane, which matches the ignition quality of the test fuel astm d6. Cetane number cetane rating is an indicator of the combustion speed of diesel fuel and compression needed for ignition. A rating on a scale used to indicate how quickly a fuel will ignite in a diesel engine, a figure of merit for diesel fuel as the octane number is a figure of merit for gasoline burned in spark ignition engines.
Despite this, there is sometimes a misconception that any higher cetane number will result in better engine performance and power. It denotes the percentage by volume of cetane chemical name hexadecane in a combustible mixture containing cetane and 1methylnapthalene whose ignition characteristics match those of. Qualified diesel fuel in comparison with federal diesel fuels overview dr. Cetane number is the rating assigned to diesel fuel to rate its combustion quality, like the octane. The engine is optimized for euro premium diesel, 51 cetane or above, and that fuel is very hard, if not impossible, to find in the u. Pdf biodiesel, an alternative fuel can be used in diesel engine as neat or blended with diesel. The more volatile fuels are best for engines where rapidly changing loads and speeds are encountered. Us66094b1 method and apparatus for measuring cetane. A higher cetane number is normally achieved by using commercial nitrate based cetane additives andor by more intensive refining of petroleum in the production of diesel fuel. Diesel fuel can be made up of several thousand different hc molecules and each scores differently on the cetane index.
The cetane number in distillate diesel fuel is a combination of the crude oil used at the refinery and the process units available at the refinery. It is based on the amount of time between fuel injection and ignition, also known as ignition delay. Get more cetane with premium dieselex4 countrymark. Epas heavyduty diesel fuel analysis program sought to quantify the hydrocarbon, nox, and pm emission effects of diesel fuel parameters such as cetane number, aromatics content, and fuel density on various nonroad and highway heavyduty diesel engines. The importance of cetane in diesel fuels fuel magics. A comparative assessment of biodiesel cetane number. The importance of cetane number in diesel fuel aong website. The cetane number is typically measured either in a singlecylinder engine or a constantvolume combustion chamber. Effect of fuel cetane number on a premixed diesel combustion mode. Herzog by pac pioneered the cetane ignition delay 510 instrument, a unique technology that is proven to provide the best precision in the market for determining the derived cetane number of all types of diesel fuel, biodiesel, fame, hvo, btl, and gtl.
Effect of fuel cetane number on a premixed diesel combustion mode article pdf available in international journal of engine research 104 august 2009 with 1,669 reads how we measure reads. Octane number and cetane number cetane number diesel fuel and octane number gasoline both measure the tendency of the fuel to ignite spontaneously. Cetane plays an important role during the fuel combustion process and helps users get the most value from every gallon of fuel used. Diesel fuel s cetane number or rating is calculated based on laboratory tests.
This study examines the determination of cn of jatropha biodiesel blends with mineral diesel using their physical properties, and their variations of cn with. On fuel quality, the epefe test programme had evaluated in detail the influences of cetane number, polyaromatics, density and backend distillation t95 on emissions. The cetane number cn is a measure of the ignition quality of a fuel for compressionignition engines according to the selfignition delay. Doesnt cal air resource board mandate a min 45 cetane rating. Cetane rating, also known as cetane number is a measurement of the quality or performance of diesel fuel. The key combustion parameter for gasoline is measured by determination of the octane number of the fuel while the combustion parameter for diesel is measured by the determination of cetane number. Accordingly, the cetane number specified should be as low as possible to insure maximum fuel availability.
In the astm d6 test, the cetane number of a diesel fuel is determined by comparing its. Pdf effect of fuel cetane number on a premixed diesel combustion. Ive written quite a bit about cetane, cetane number, cetane index, and cetane additives used in diesel fuel. Diesel fuels with cetane number lower than minimum engine requirements can cause rough engine operation. Difference between octane number and cetane number definition. Evaluation of different reaction strategies for the improvement of cetane number in diesel fuels roberto c. Hydrogen partial pressure and lhsvarekeyoperatingconditions. Following epefe, two important remaining diesel fuel quality questions were the difference if any between natural and additivederived cetane. Figure 1 cetane engine for determining cetane number. Higher the cetane number better it is in its ignition properties. Carb ulsd test fuel cetane number 10 12 volume % higher than the. Lower cetane numbers mean longer ignition delays allowing more time for fuel to vaporize before combustion starts. Cetane index is a calculated number used as a substitute for cetane number. Cetane number is a relative ranking of a fuels autoignition characteristics for use in compression ignition engines.
Evaluation of different reaction strategies for the. In other words, it determines the ignition quality of diesel fuel when injected in the combustion chamber of a diesel engine. A diesel engine run on a fuel with a lower cetane number than it was designed for will be harder to start, noisier, operate roughly and have higher emissions. The benchmark standard we traditionally refer to was created by. Diesel fuel comparison study workshop january 8, 2009. Pdf determination of cetane number of biodiesel and its influence. Diesel fuel fuel volatility requirements depend on the same factors as cetane number. Cetane number, exhaust gas emission, biodiesel property, fatty acid.
Effect of fuel cetane number on multicylinders direct injection. While gasolines octane number signifies its ability to resist autoignition also referred to as preignition, knocking, pinging, or detonation, diesel s cetane number is a measure of the fuel s delay of ignition time the amount of time between the injection of fuel into the combustion chamber and the actual start of combustion of the fuel. Pdf effect of fuel cetane number on a premixed diesel. Gaseous emissions are a function of combustion phasing and exhaust gas recirculation egr quantity, but are not directly tied to fuel cetane number. This is 5 points higher than the fed req but 5 points under current euro spec. Difference between octane number and cetane number. For example, the cetane numbers of neat methanol and ethanol are about 3 and 8, respectively. Octane number measures the ability of a fuel to resist preignition of the fuel in the gasoline engine. Heavyduty diesel fuel analysis moves and other mobile. Most diesel vehicles use fuel with a rating of 40 to 55. A method of continually measuring the cetane number of a diesel fuel, the method comprising the steps of. First introduced in 1938, the cfr f5 today continues to provide a stable, accurate testing platform for defining the ignition quality of diesel fuels. Initial burn rates are higher causing more heat release at constant.