Cetane is the shortdelay reference fuel and is mixed. It determines how fast the fuel will enter combustion stage. Better antiknock quality allows us to compress the airfuel mixture to a larger extent befo. As another important difference between gasoline and diesel, gasoline can be rated according to the octane number, whereas diesel is rated according to the cetane number. Octane and cetane ratings are two important parameters that describe a fuels ignition qualities. Motor octane number an overview sciencedirect topics.
What is the difference between novelty and newness in scientific research field. Dec 15, 2017 octane number and cetane number are exactly opposite to each other. Cetane number, a measure of the ingition quality of a fuel, is of importance in the satisfactory operation of a diesel engine. As you know, octane number is a quantity which pertains to gasoline rating in combustion. Apart from that, diesel is cheaper than gasoline, but gasoline is cleaner and more environmentally friendly. Thus a fuel with an octane number of 80 has an antiknock rating equal to that of a test mixture containing 80 per cent of isooctane. In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower cetane fuels. Both these are colorless liquids at room temperature with a gasolinelike odor. Octane and cetane number of fuel fuel research octane number rom motor.
Octane goes in your cars fuel, but cetane goes in a diesels. Griffiths b a department of chemistry, y ork university, t oronto, ontario, canada m3j 1p3. Cetane number is an important parameter in evaluating the quality of biodiesel fuel. Difference between gasoline and diesel compare the. The octane number posted octane number pon, commercially used for gasoline referred to as the road octane number, is the average of its research octane number ron and motor octane number mon.
An octane rating, or octane number, is a standard measure of the performance of an engine or aviation fuel. If your fuel has a high cetane number, it will have a low octane number, and vice versa. The ignition delay of the fuel can then be calculated as the time difference. Distinguish between octane number and cetane number ques10. It plays a similar role for diesel as octane rating does for gasoline. How we can relate the octane number and cetane number of the. Jun 24, 2015 the guys from the psc online store break it down and explain the difference between cetane and octane in gasoline and diesel fuel systems. As you know, octane number is a quantity which pertains to gasoline rating in. In broad terms, fuels with a higher octane rating are used in highperformance gasoline engines that require higher compression ratios. It is loosely linked to the octane number of gasoline, since both give a measure of each substances efficacy and are inversely related.
The octane number of a sample of fuel is determined by burning the gasoline in an engine under controlled. Hence, use of methyl esters of vegetable oils may be an alternative for the diesel fuel in future. Differences between octane number and cetane number. Measure of the ignition quality of gas gasoline or petrol. Furthermore, octane is highly volatile while cetane is not volatile. 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. The resulting cetane number is then calculated by determining which mixture of cetane and isocetane 2,2,4,4,6,8,8heptamethylnonane will result in the same ignition delay. Octane number is the ability of resistance of a fuel to knocking in comparison to iso octane, which has octane number 100 and has high antiknock quality. Cetane number definition is a measure of the ignition value of a diesel fuel that represents the percentage by volume of cetane in a mixture of liquid methylnaphthalene that gives the same ignition lag as the oil being tested called also cetane rating.
The cetane number refers to the eace with which desel fuel ignites easily at a relatively low temperature. 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. Investigation of cetane number and octane number correlation. Octane and cetane are readily flammable hydrocarbon compounds. Differences between octane number and cetane number scribd. Ignition quality tester iqt another reliable method of measuring the derived cetane number dcn of diesel fuel is the ignition quality tester iqt. Octane number is the ability of resistance of a fuel to knocking in comparison to.
An equation was developed relating the cetane number and. Jun 23, 2017 cetane number 16 carbon atoms its for diesel engine due to composition of diesel has mostly 16 carbon atoms. The higher the octane number, the more compression the fuel can withstand before detonating igniting. This is the time period between the start of injection and start of combustion ignition of the fuel. The main difference between octane number and cetane number is that octane number gives an idea about the performance of a fuel whereas. The cetane index is a figure which denotes the quality of a diesel fuel, based upon its density and volatility, and which is roughly approximate to its cetane number. What differences are they when putting some 87, 89 or 91 octane gas in a car. Octane number, cetane number octane number indicates the tendency of fuels to knock. Octane number is related to petrol and cetane number gives quality of diesel. Oct 07, 2015 it is the fuels eagerness to ignite from the heat created in the bore from the compression of the air. Octane number and cetane number are exactly opposite to each other. This means it has to be mixed with regular gasoline or diesel at some level. Difference between octane number and cetane number mech4study. The importance of cetane number in diesel fuel aong website.
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 and cetane numbers gives the rating of fuel for petrol and diesel engines respectively. It is the fuels eagerness to ignite from the heat created in the bore from the compression of the air. Difference between octane number and cetane number. Both these are hydrocarbon compounds that are used as references for the ranking of different engine fuels according to their performance octane rating and cetane rating. The difference between cetane and octane petroleum. The time delay is used with aformula to calculate the derived cetane number dcn which correlates to the cn from that of the d6 cetane engine apparatus. What is difference between octane number and cetane number. Feb 08, 2017 octane and cetane number are standard measure of performance of a fuel. Does operating a car that calls for high octane gasoline on regular gasoline. If the cetane measured of the two fuels is the cetane index and not the number, then a 5050 mix of 60 index and 40 index will give you a 50 cetane index. Cetane number is a measure of the ignition quality of a diesel fuel. Feb 23, 2011 octane number and cetane number cetane number diesel fuel and octane number gasoline both measure the tendency of the fuel to ignite spontaneously.
What is the influence of octane number and cetane number on. Its determination is usually arduous and expensive. Octane number and cetane number are very important in determining the best fuel that can be used for engines of automobiles. The octane rating of gasoline is measured in a test engine and is defined by. While gasolines octane number signifies its ability to resist autoignition also referred to as preignition, knocking, pinging, or detonation, diesels cetane number is a measure of the fuels 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. Diesel fuel is more efficient than gasoline because it contains 10% more energy per gallon than gasoline. How we can relate the octane number and cetane number of. The cetane number is typically measured either in a singlecylinder engine or a constantvolume combustion chamber. Methods for determining cetane number of diesel fuels there are basically four different methods in use.
Cetane number 16 carbon atoms its for diesel engine due to composition of diesel has mostly 16 carbon atoms. 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 cetane specification per astm d975 is the cetane number. Oct 26, 2011 moreover, diesel is oily like and smells differently than gasoline. However, there is a significant difference in what exactly these two ratings measure. Cetane rating is done considering the ignition of cetane. The key difference between octane and cetane is that octane has 8 carbon atoms whereas cetane has sixteen carbon atoms per molecule. Higher the octane number, better the quality of petrol, and hence the vehicle gives higher efficiency. Just as gasoline is rated by its octane, diesel fuel is rated by its cetane, which indicates how easy it is to ignite and how fast it burns. The higher the cetane number, the shorter the ignition delay and the better the ignition quality. The guys from the psc online store break it down and explain the difference between cetane and octane in gasoline and diesel fuel systems. It signifies the time gap between time of injection and time of ignition of a diesel. Cetane number or cn is an inverse function of a fuels ignition delay, and the time period between the start of injection and the first identifiable pressure increase during combustion of the fuel.
In the newer vehicles, the same result is achieved by the engine design that increases turbulence in the combustion chamber, andor by adding aromatic hydrocarbons such as xylenes and oxygenates oxygencontaining compounds such as alcohols to the gas the unleaded gas. Differences between octane number and cetane number free download as word doc. The octane number is related to the fuels resistance to autoignition and is an important indicator of engine knock, which ultimately limits a spark. Octane and cetane number are standard measure of performance of a fuel. Cetane number is actually a measure of a fuels ignition delay. A cetane number is a measure of the ignitiondelay period in a diesel engine provided by the fuelthe higher the cetane number the shorter the delay period. Standard gasoline uses a rating system of octane numbers to measure its efficiency. In the octane number scale, high values represent fuels that resist spontaneous ignition and.
Astm d6 portable octane meterdiesel oil cetane number apparatus technical parameters technical parameters test method determines the pump octane number aki, research octane number ron, and motor octane number mon of unleaded gasolines, and optional cetane index and cetane number for. This only works for cetane index, not the cetane number of the fuel. Octane number and cetane number are used to characterize the combustion phenomena in. The percentage by volume of cetane in a mixture of cetane and. The octane number is related to the fuels resistance to autoignition and is an important indicator of engine knock, which ultimately limits a sparkignition engines compression ratio and, thus, efficiency. The main difference between cetane and octane ratings is that the octane rating represents how well a fuel can resist preignition due to compressionensuring the fuel ignites only from a spark from the spark plug. Octane number and cetane number cetane number diesel fuel and octane number gasoline both measure the tendency of the fuel to ignite spontaneously. Cetane number is a measure of the ignition quality of diesel engine fuels as it indicates the comparative ease with. Cetane number cetane rating is an indicator of the combustion speed of diesel fuel and compression needed for ignition. In the cetane number scale, high values represent fuels that ignite readily and, therefore, perform better in a diesel engine. Values in the 2004 compendium derived from octane numbers have been removed and replaced with a brief analysis of the correlation between cetane numbers and octane numbers. Apr 09, 2017 watch this video to learn about octane and cetane number.
A high cetane rating represents a fuel that can readily ignite and perform better in a diesel. Watch this video to learn about octane and cetane number. The present study is aimed at developing the mathematical relationship between viscosity, density, calorific value, flash point and cetane number cn. Octane numbers are based on a scale on which isooctane is 100 minimal knock and heptane is 0 bad knock. The cn is an important factor in determining the quality of diesel fuel, but not the only one. The difference between ron and mon is known as fuel sensitivity s. Suggestions for reporting the fuel properties of biodiesel that correlate to cetane number are also provided. Octane number shows the ability of a fuel to resist knock preignition of the fuel in the engine. Cetane number effect on engine performance and gas. They can be differentiated based on few considerations. Moreover, diesel is oily like and smells differently than gasoline. The cetane number is a very important property of diesel oils indicating the quality of ignition of the diesel fuel the higher, the better, somewhat analogous to octanes for gasoline. The difference between octane and cetane is that octane has 8 carbon atoms whereas cetane has sixteen carbon atoms per molecule. Octane number apparatus, octane number apparatus suppliers.
Following are provided some basic difference between octane number and cetane number based on the general basic points of difference. Cetane number definition of cetane number by merriamwebster. Octane number measures the performance of gasoline while cetane number measure the performance of the diesel. Difference between octane and cetane compare the difference. Its a fact that more is better, but only when high cetane is combined with more power. In a similar manner, diesel uses cetane numbers as a measurement of how well it combusts. However, the cetane number measures the delay in the ignition time of the fuel. Cetane numbers are only used for the relatively light distillate diesel oils.