Cetane Number The cetane number of a diesel fuel is the numerical result of engine test designed to evaluate fuel ignition delay. It is defined as the whole number nearest to the value determined by calculation from percentage by volume of normal cetane (cetane No. = 100) in a blend with heptamethylnonane (cetane No. = 15) which matches the ignition quality of the test fuel when compared by this method. High cetane number fuels generally cause lower combustion noise, improved control of combustion, resulting in increased engine efficiency and power output. CN = (u40 + 17.8) 1587.9/ ρ40
Where; u40 is the Kinematic viscosity at 40°C, mm2/sec ρ40 is the density of the fuel at 40°C, Kg/ m3
Flash Point
The flash point is the temperature
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The temperature at which wax is first precipitated from the solution can be measured by the cloud point test.
The pour point of oil is an indication of the lowest temperature at which the fuel can be pumped. Pour points often occurs 8F to 10F below the cloud point. Pour point increases with molecular weight, but they are strongly influenced by molecular shape.
Procedure
The sample was brought to a temperature at least 14°C above the expected cloud point. Pour the sample into test jar to the level mark. Close the jar tightly by the cork carrying the test thermometer. The position of the cork and the thermometer was adjusted so that the cork fit tightly, the thermometer and the jar were coaxial, and the thermometer bulb resting on the bottom of the jar. The test jar was places in the ice box containing freezing mixture. In the determination of the cloud point the sample was cooled and inspected at intervals of 2°C until a cloud and haze appeared, than noted the thermometer reading. This was the cloud point. As soon as cloud point was determined the test jar was further cooled and inspected at intervals of 5F. Until it ceases to flow when test jar was tilled & kept horizontal for 5 seconds. Than noted the thermometer reading. This was the pour
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The oil sample was mixed with neutralized alcohol. Heat the mixture of oil and alcohol on hotplate until it almost boiling. Added few drops of phenolphthalein to the mixture and titrate with 0.1M NaOH solution. Swirl the flask to thoroughly mix the contents. The pink color was appeared which is end point of reaction. Noted the volume used to neutralize the FFA. Using below formula to calculate the % of FFA.
FFA Range Sample Size (g) NaOH molarity Volume of neutralized alcohol (ml)
0-0.5 56.4 0.1 50
0.5-2 28.2 0.1 50
2-5 10 0.1 75
5-10 5 0.1 75
10-30 10 0.1 100
% free fatty acid =(T × M ×