What is fractional analysis?
Fractional composition is the main indicator of fuel volatility.
The combustion rate of diesel fuel directly depends on the content of light fractions in it - the lower the start temperature of boiling and distillation at 10% vol., the faster the fuel burns. However, there is a downside - with a high content of light fractions, the viscosity of diesel fuel is reduced, which entails more severe engine operation. Low boiling points at 50% vol. distillation of diesel fuel characterize easier starting of the engine.
If the values obtained during the distillation of diesel fuel are outside the limits at the boil-off control point at 95% vol., this indicates the content of heavy fractions in the fuel, which have a negative effect on mixture formation and, as consequently, on the completeness of fuel combustion.
The volatility of gasoline is associated with such engine characteristics as starting at low temperatures, the probability of formation of vapor locks, vehicle acceleration, engine warm-up rate, as well as wear of the cylinder-piston group and fuel consumption.
The characteristic of gasoline for cold start is usually associated with the volume fraction (%) of gasoline distilled at 70 ° C. The rate of engine warm-up and the throttle response of the car when driving are affected by the volatility of medium fractions, denoted by the distillation control point at 100°C.
Heavy fractions in gasoline, as a rule, are limited due to the possibility of their incomplete evaporation and getting into the engine in liquid state. In this case, the fuel that has entered the cylinders washes away the oil film, which leads to increased engine wear, thinning and increased oil consumption, increased fuel consumption.
In the course of determining the fractional composition, petroleum products are separated into fractions in accordance with their boiling range. Thus, based on the values obtained during distillation, both the chemical composition and its influence on some characteristics that affect the operation of the engine can be predicted.
The fractional composition is determined in the laboratory and is an important tool for the oil industry, as how it allows you to determine the optimal conditions for the production of various petroleum products in accordance with their chemical and physical properties.
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