Phase equilibria in three component systems alcohol-hydrocarbon-water
- Authors: Siswana, Msimelelo Patrick
- Date: 1992
- Subjects: Chemical equilibrium , Liquid-liquid equilibrium , Alcohol as fuel , Hydrocarbons , Water chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4327 , http://hdl.handle.net/10962/d1004988 , Chemical equilibrium , Liquid-liquid equilibrium , Alcohol as fuel , Hydrocarbons , Water chemistry
- Description: The fuel industry in many parts of the world is blending alcohols with motor fuel either to extend the fuel or to improve its octane rating or both. Unfortunately alcohols are hygroscopic and as a result, water becomes a component of the fuel. This can lead to phase separation and the formation of a water-rich layer which could have serious corrosion consequences. In an attempt to understand the phase-splitting in alcohol-petrol-water blends, phase equilibria in ternary systems (alcohol-hydrocarbon-water) have been determined by experiment. The phase equilibria in these ternary systems are also discussed in terms of modern theories of liquid mixtures and the UNIQUAC theory is applied to the "ethanol + benzene + water" ternary system. The alcohols are all the C₁, C₂, C₃ and C₄ alcohols, and the hydrocarbons include those typically found in petrol, e.g. cyclohexane, benzene and substituted benzenes.
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- Date Issued: 1992
A study of petrol and diesel fuel blends with special reference to their thermodynamic propeties and phase equilibria
- Authors: Hayward, Caroline
- Date: 1986
- Subjects: Gasoline , Diesel fuels , Thermodynamics , Liquid-liquid equilibrium , Alcohol as fuel
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4065 , http://hdl.handle.net/10962/d1004902 , Gasoline , Diesel fuels , Thermodynamics , Liquid-liquid equilibrium , Alcohol as fuel
- Description: The ternary phase behaviour of the n-heptane-l-propanol-water system was studied and compared with the theoretical prediction based on the UNIQUAC model for non-electrolyte solutions. The results showed that this model adequately approximated experimental studies. The excess enthalpies and excess volumes for several binary mixtures were determined. The excess enthalpies were measured using a LKB flow microcalorimeter and the excess -volumes determined using a PAAR densitometer. The study showed that no significant enthalpy or volume changes occurred when petrol/n-heptane were mixed with alcohols . Ternary phase diagrams, including tie lines have been determined for a number of petrol-alcohol-water systems (including the Sasol blend of alcohols). The tie line results show that the concentration of water in the water-rich layer is strongly dependent on the type of alcohol used. The Sasol alcohol blended with petrol resulted in a high water concentration in the water-rich layer which forms on phase separation. This is believed to contribute significantly to the corrosion problems experienced by motorists using the Sasol blended fuel on the Witwatersrand. The effect of temperature on several of these blends was included in the study. Diesel-alcohol blends and the co-solvent properties of ethyl acetate investigated. Ethyl acetate ensures miscibility at low concentrations for diesel-ethanol blends. Octyl nitrate and two cetane improvers from AECI were assessed in terms of their ability to restore cetane rating of blended diesel fuel to that of pure diesel fuel. The results indicated that all three samples were successful in this application. , KMBT_363
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- Date Issued: 1986