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. 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. Diesel fuel s cetane number or rating is calculated based on laboratory tests. The energy information administration estimates that worldwide production of diesel fuel in 2002 was nearly 197 billion gallons. The benchmark standard we traditionally refer to was created by. Difference between octane number and cetane number. Cetane number is a relative ranking of a fuels autoignition characteristics for use in compression ignition engines. The objective of this paper is to discuss the possible reasons for the wide range in reported values of the cetane number of biodiesel. Pdf effect of fuel cetane number on a premixed diesel combustion.
The more volatile fuels are best for engines where rapidly changing loads and speeds are encountered. 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. Variations of cetane number of jatropha biodiesel blends. 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. Hydrogen partial pressure and lhsvarekeyoperatingconditions. 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. Heavyduty diesel fuel analysis moves and other mobile. A kind of cetane number improver has been proposed and tested to be used with diesel fuel as ameans of reducing exhaust emissions. 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. In other words, it determines the ignition quality of diesel fuel when injected in the combustion chamber of a diesel engine. 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. Other diesel types are given their cetane number with comparison to the ignition of cetane liquid. Astm d7668 17 standard test method for determination of. Pdf biodiesel, an alternative fuel can be used in diesel engine as neat or blended with diesel.
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. The employees are great people and are always there to find. During the winter, we never have to worry about the fuel freezing up. Cetane rating, also known as cetane number is a measurement of the quality or performance of diesel fuel. Doesnt cal air resource board mandate a min 45 cetane rating. Pdf determination of cetane number of biodiesel and its influence. In the astm d6 test, the cetane number of a diesel fuel is determined by comparing its. Most of these hcs score in the middle, including many of the paraffins. Diesel fuel can be made up of several thousand different hc molecules and each scores differently on the cetane index. 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 importance of cetane number in diesel fuel aong website. The cetane number cn is a measure of the ignition quality of a fuel for compressionignition engines according to the selfignition delay. Technical background on india bs vi fuel specifications. Dependence of cetane index on aromatic content in diesel fuels. Diesel fuels with cetane number lower than minimum engine requirements can cause rough engine operation. Octane number and cetane number cetane number diesel fuel and octane number gasoline both measure the tendency of the fuel to ignite spontaneously. This study examines the determination of cn of jatropha biodiesel blends with mineral diesel using their physical properties, and their variations of cn with. Cetane number measures the ignition delay of the fuel in the diesel engine. Characterization of the effects of cetane number improvers.
Carb ulsd test fuel cetane number 10 12 volume % higher than the. Ive written quite a bit about cetane, cetane number, cetane index, and cetane additives used in diesel fuel. Cetane number of a diesel engine fuel is indicative of its ignition characteristics. The cetane number is typically measured either in a singlecylinder engine or a constantvolume combustion chamber. Diesel fuel fuel volatility requirements depend on the same factors as cetane number. It is based on the amount of time between fuel injection and ignition, also known as ignition delay. 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.
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. 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. Qualified diesel fuel in comparison with federal diesel fuels overview dr. Difference between octane number and cetane number definition. For example, the cetane numbers of neat methanol and ethanol are about 3 and 8, respectively. 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. 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. First introduced in 1938, the cfr f5 today continues to provide a stable, accurate testing platform for defining the ignition quality of diesel fuels. Both new and old engines benefit from diesel fuel with high cetane levels. Higher the cetane number better it is in its ignition properties. This is 5 points higher than the fed req but 5 points under current euro spec. Cetane number cetane rating is an indicator of the combustion speed of diesel fuel and compression needed for ignition.
A method of continually measuring the cetane number of a diesel fuel, the method comprising the steps of. Pdf effect of fuel cetane number on a premixed diesel. Cetane number is the rating assigned to diesel fuel to rate its combustion quality, like the octane. Diesel fuel comparison study workshop january 8, 2009. Evaluation of different reaction strategies for the. A comparative assessment of biodiesel cetane number. The physiochemical properties of fuel are important. Despite this, there is sometimes a misconception that any higher cetane number will result in better engine performance and power. Octane number is a measure of the performance of a fuel. Us66094b1 method and apparatus for measuring cetane. 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. Initial burn rates are higher causing more heat release at constant. Evaluation of different reaction strategies for the improvement of cetane number in diesel fuels roberto c. Both are measured in a cooperative fuel research cfr engine.
Cetane number affects a number of engine performance parameters like combustion, stability, drivability, white smoke, noise and emissions of co and hc. The higher the number, the better the fuel burns within the engine of a vehicle. Research article recent trends on ethanoldiesel fuel. 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. The cetane number refers to the eace with which desel fuel ignites easily at a relatively low temperature. 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. 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. Gaseous emissions are a function of combustion phasing and exhaust gas recirculation egr quantity, but are not directly tied to fuel cetane number. Following epefe, two important remaining diesel fuel quality questions were the difference if any between natural and additivederived cetane. Cetane index is a calculated number used as a substitute for cetane number. Most diesel vehicles use fuel with a rating of 40 to 55.
Effect of fuel cetane number on multicylinders direct injection. 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. The higher the cetane number, the more volatile the fuel. 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. Effect of fuel cetane number on a premixed diesel combustion mode. Lower cetane numbers mean longer ignition delays allowing more time for fuel to vaporize before combustion starts. This quote underscores the importance of matching engine cetane requirements with fuel cetane number. Similar to the octane number seen on a retail gasoline dispenser, a cetane number rates a diesel fuels quality of ignition. Cetane number, exhaust gas emission, biodiesel property, fatty acid.
Fuel having high octane number is considered as ideal fuel for the gasoline engine. 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. Suggestions for reporting the fuel properties of biodiesel that correlate to cetane number are also provided. Cetane number is the measure of the delay of the ignition of a fuel. Cetane number effect on engine performance and gas emission. Standard diesel fuel sometimes called diesel oil comes in two grades. Figure 1 cetane engine for determining cetane number. Low volatile fuels tend to give better fuel economy where their characteristics are needed for complete combustion, and will produce less smoke, odor. Octane number measures the ability of a fuel to resist preignition of the fuel in the gasoline engine. The cetane number see page 4 of the fuel defines its ignition quality. We have been buying 50 cetane diesel fuel from the southern states at the fredericksburg, virginia plant for 21 years. This paper demonstrates how variations in fuel cetane number affect the detailed combustion behaviour of a directinjection, dieselfuelled, premixed combustion. Cetane number is a measure of the ignition quality of diesel fuel.