What is the difference between hydrous and anhydrous ethanol

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Fuel , , We are the plurality in the form of energy. Our nine agroindustrial units have the capacity to grind 36 million tons of sugarcane. From cane and biomass, we produce sustainable, renewable and responsible energy. Hydrous ethanol, popularly called alcohol , is a biofuel sold at gas stations and used in vehicles, fueling thousands of cars every day.

By Brian J. April 22, Ethanol C 2 H 5 OH , otherwise known as ethyl alcohol, alcohol, or grain spirit, is a clear, colorless, flammable oxygenated hydrocarbon with a boiling point of In transportation, ethanol is used as a vehicle fuel by itself E , blended with gasoline E85 , or as a gasoline octane enhancer and oxygenate 10 percent concentration.

Anhydrous ethanol means an ethyl alcohol that has a purity of at least ninety-nine percent, exclusive of added denaturants, that meets all the requirements of the American Society of Testing and Materials ASTM D, the standard specification for ethanol used as motor fuel. Hydrous or wet ethanol is the most concentrated grade of ethanol that can be produced by simple distillation, without the further dehydration step necessary to produce anhydrous or dry ethanol.

Initial tests conducted in Europe have confirmed that hydrous ethanol can be blended effectively with gasoline without phase separation or other problems. In addition to confirming the effectiveness of hydrous ethanol for gasoline blending in actual vehicle trials, these initial tests have shown measurable increases in volumetric fuel economy, indicating higher thermodynamic efficiencies resulting from hydrous ethanol.

This recently discovered phenomena for mid-level ethanol blends appears to be due to the benefits of oxygenation and heat of vaporization in conjunction with capitalizing on the change in chemical and physical properties which occur as a result of combining water, ethanol, and gasoline. When appropriately combined in mid-level ethanol blends, the chemical reactions of these compounds optimize the efficiency at which internal combustion engines operate.

For hydrous ethanol blends, this is accomplished primarily through the total heat of vaporization resulting from combining ethanol and water.

Essentially, the lower energy content of hydrous ethanol is counteracted by increasing engine performance due to higher heat of vaporization of ethanol and water in comparison with gasoline and anhydrous blends. The result is more efficient combustion, cooler running engines, lower exhaust temperatures, and increased longevity of engine life.

The water contained in hydrous ethanol blends also reduces NOx emissions. In addition to the effects of higher water content in hydrous ethanol, ethanol increases compression ratios and decreases engine knocking detonation. Essentially, both water and ethanol increase the octane level of the fuel mixture. The octane number is a measure of the resistance of a fuel to auto-ignition.

It is also defined as a measure of anti-knock performance of a gasoline or gasoline component such as hydrous ethanol. Higher octane levels contribute to enhancing the thermodynamic efficiency of combustion engines, which subsequently increases fuel efficiency. The increase in total engine efficiency results in optimizing fuel efficiency for both ethanol and gasoline. In addition to the strong hydrogen bonds contained in water molecules, the polarity of the OH groups contained in ethanol molecules can form hydrogen bridges causing relatively strong attractive forces between molecules in liquid phases.

Upon vaporization of hydrous ethanol as a fuel, the distance between the water and ethanol molecules increase such that molecular interactions including physical properties are disrupted.

This process accumulates a certain amount of latent stored energy. During combustion of these vapors, this explains why the heat of vaporization of hydrous ethanol blends is so much higher than that of regular gasoline components and non-alcohol oxygenates like methyl tertiary butyl ether MTBE which do not contain OH groups non-alcohols. High heat of vaporization values are typical for water and alcohols including hydrous ethanol and hydrous ethanol blends oxygenated hydrocarbons.