1. Introduction
by a standard fuel mixture of isooctane and n-heptane composition. Isooctane as excellent antiknock standard octane number is set to 100; n-heptane in the gasoline at elevated temperature and pressure more easily lead to spontaneous combustion, resulting blast phenomenon, reduce engine efficiency, but may lead to overheating of the cylinder wall piston damage and even crack. Thus heptane octane number is set to zero. These two different standard fuel volume ratio mixed, the mixture obtained seismic rating, the octane number in the range 0-100. Other hydrocarbons have different octane, may be less than 0 (e.g., n-octane), there may be greater than 100 (e.g., toluene). Engine operating under the same conditions, compared with the fuel to be tested. Equal to the percentage of isooctane seismic mixture contained in the sample, i.e. the octane number of the sample. Gasoline octane large, shock resistance, better quality.
2. Determination
Measurement
octane is carried out in a specially designed test cylinder variable compression ratio in the machine. Hydrocarbon different chemical structures, having different resistance to knocking. Isooctane (2,2,4-trimethylpentane) antiknock good, given as 100 octane. N-heptane antiknock difference, given as 0. Measurement of Gasoline Octane is based isooctane and n-heptane as the standard fuel, according to standard conditions, for comparison with a standard method on a laboratory single-cylinder gasoline engine. Adjusting the ratio of the standard fuel composition, fuel produced that the standard knock intensity and the same sample, then the volume percentage occupied isooctane standard sample is octane fuel. According to different measurement conditions, there are the following octane:
Motor Octane Number (the MON)
Determination of the harsher conditions, the engine speed is 900r / min, inlet temperature 149 ° C. It reflects antiknock gasoline cars at high speed and heavy load conditions.
Research Octane Number (RON)
Measurement conditions ease, speed of 600r / min, air at room temperature. This reflects the octane number of gasoline antiknock car in the slow-moving urban areas. For the same gasoline research octane number higher than the motor octane number of from about 0 to 15 units, said the difference between the sensitivity or sensitivity.
antiknock index
antiknock degrees (of AKI) is a reference model of gasoline used in the US and Canada, which is about the average of MON and RON.
Road Octane
octane, also known as driving, with a motor vehicle or be found on the highway at full power conditions simulation test bed was measured. Road octane motor method can also be used and the research octane number calculated by empirical formula obtained. Average of Motor Octane Number and the research method octane antiknock index referred to, which can approximately indicate a road octane.
octane permittivity
The measurement of gasoline octane number gasoline dielectric constant, a measurement method using piecewise regression corresponds to calibration using direct reading octane differential method, the method is simple and fast. Changsha Flanders developed an octane analyzer FDR-3601, calibrated with standard samples of oil, and then the sample was detected by the calibrated instrument.
3, action
Gasoline difference
octane gasoline is generally distinguish between different levels of key standards, vehicle grades of gasoline is octane according distinguished. There 66,70,76,80,85 equal sign. For example, number 70 indicates that the gasoline octane number of gasoline that is not less than 70. According to the measured results can be determined to belong octane grades of gasoline; labeling method gasoline brands in various regions are not uniform, such as Taiwan, unleaded petrol 95, showing the octane rating of 95, 97 in mainland China gasoline, it said its octane rating of 97, the value in gasoline sold in some countries it is not equal to a common research method octane obtained (such as the US), while others simply do not indicate a numerical value (such as Germany).
economic performance
octane antiknock is an important indicator of good or bad performance carburetor engine fuel, the first item listed in automotive gasoline specifications. The higher the octane, the better the antiknock, the engine compression ratio can be higher. That is, if the octane refinery production of gasoline continues to improve, the car manufacturer may increase as the compression ratio of the engine, thereby enhancing engine power, increase traffic mileage, but also saveFuel, gasoline to improve the driving force of economic performance is of importance.
antiknock performance
Samples spiked with gasoline octane antiknock, antiknock measurable effect, to find out a suitable amount of anti-knock agent is added.
4, a method for improving
to increase gasoline octane method comprises adding tetraethyl lead and methyl tert-butyl ether, dimethyl carbonate, an MMT (methylcyclopentadienyl manganese tricarbonyl) and the like. Because lead is toxic, so many countries have not provided leaded gasoline, jet fuel only still contain lead.
5, the common fuel octane
octane fuel uprising of a research octane number motor method hexadecane lt; -30 -10 n-heptane, n-octane, diesel, 15-25 iso-octane gasoline 87-93E85 10090-9295-96E10 methane gas 105 107 typical two-stroke engines outside the desired octane 696 567