(577g) Enthalpy of Vaporization of Ethanol-Gasoline Fuel

Nations today often face divergent challenges in the form of climate change, air pollution, energy production, consumption security, and shrinking oil supplies. In response to these challenges, countries around the world have developed programs to support the use of clean fuels, including ethanol. The properties of gasoline have been altered in recent years to reduce motor vehicle emissions of carbon monoxide, photochemical smog precursors, and toxic organic air pollutants such as benzene. Changes have been made to sulphur, olefin, and aromatic contents, and to distillation properties of gasoline. Presently, there is an increasing interest in adding oxygenated compounds to gasoline, because of their octane-enhancing and pollution-reducing capabilities. In the last several years, many interesting works have been published on ternary, quaternary, or quinary systems that contain a synthetic reformate (hydrocarbon mixtures), an oxygenated compound (ethers or alcohols), and water, at approximately ambient temperature. However, studies of systems that contain gasoline, an oxygenated compound, and water are found in the literature not often. Within the oxygenated compounds, ethers and alcohols are the most important. Among ethers and alcohols, ethanol has been receiving much current attention. Vapour pressure measurements were used to evaluate the enthalpy of vaporization of ethanol-gasoline mixtures. Enthalpy of vaporization is calculated by means of Clausius-Clapeyron equation; partial molar values were derived. These values can help to normalize alcohol-gasoline blended fuel volatility and to make this fuel more competitive to ordinary gasoline. Dispersed structure of ethanol-gasoline fuel is studied for the first time by the method of correlation spectroscopy of light scattered (DLS). A large range of dispersed particle sizes in different alcohol-gasoline systems was found. The dependence of drop mean radius on ethanol (C2H5OH) content is determined. It was found, that coalescence phenomenon occurs in the systems when extra alcohol is added. These data can help to prevent phase-separation in ethanol-gasoline fuel caused mainly by alcohol-water drops coalescence and precipitation. Change of colloid structure of ethanol-gasoline systems can be effective way change/modify quality coefficients of the fuel.