Methanol, has a greater latent heat of vaporization than ethanol – kooolEthanol (C2H5OH) and Carbinol (CH3OH) are very similar. Both alcohols are homogeneous liquids, each with a simple chemical structure. Both can be used as motor fuels. Okay, okay, but which is best? Wellll, it seems that CH3OH is leading the charge even with its disadvantages. Because of one important advantage - the greater latent heat of vaporization number. Yes, it's corrosive. Its influence over certain gasket and seal materials may cause them to deteriorate so that they could leak. And it’s true, it is highly toxic! Even exposure to small amounts through inhalation, ingestion or direct skin contact with the liquid can raise health issues. Although exposure through vapor inhalation is less than for gasoline, but the latent heat of vaporization number, more than makes up for any disadvantage. Beyond that, one must be careful not to mistake one for the other! Ethanol is a renewable fuel. It can be made from crops, such as sugar cane and corn. While methanol, is made from fossil fuels such as coal natural gas and wood. Its even been made from carbon dioxide. Ethanol fuel value per gallon is 76,500 BTU’s, while methanol is 64,500. This seems almost as though alcohol fuels would be less efficient - powerful. But wait, the expression isn’t complete. Another factor needs to be considered: the fuel’s latent heat of the vaporization (Lv) index. This number refers to the heat lost by the air when a liquid changes to a vapor. For example, gasoline’s Lv is about 900 btu/gal. When in a stoichiometric mixture; without a heating influence, liquid gasoline vaporizes with an air temperature reduction of close to 22°C(40°F). The ethanol and methanol index’s are approximately 2,378 and 3,340 btu/gal. Notice the great difference over gasoline’s. The result of the difference in evaporation is a much larger temperature drop. Yet, with the addition of the same unit mass of charge, less evaporation will occur in the manifold. Hence, with greater evaporative cooling of the charge temperature, the engines volumetric efficiency increases. With this increase and because alcohols have lower molecular weight than gasoline, their vapor fills proportionately more of the cylinders volume than an equivalent mass of gasoline vapor. The result is increased horse power and reduced MPG. For a comparison with Ethanol: Consequently, (CH3OH) has an edge over ethanol for two reasons because of a higher latent heat of vaporization number and it's lighter composition weight, even though ethanol has more power per gallon. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Notes Hey, ocean storms have huge latent heat of vaporization numbers. Could this be why hurricanes form over warm ocean water – the energy of latent heat vapors condensing into clouds. Anyway, as for which is best, my money’s on methanol! Links:  Custom Search
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