Gasoline heating value

In the expression for heating value, it is useful to define the physical state of the motor fuel for conventional motor fuels such as gasoline, diesei fuel, and jet fuels, the liquid state is chosen most often as the reference. Nevertheless, if the material is already in its vapor state before entering the combustion system because of mechanical action like atomization or thermal effects such as preheating by exhaust gases, an increase of usefui energy resufts that is not previously taken into consideration. 

We shonld also utilize liquid hydrocarbons, which frequently accompany natural gas. These so-called natural gas liquids currently have little use besides their caloric heat value. They consist mainly of saturated straight hydrocarbons chains containing 3-6 carbon atoms, as well as some aromatics. As we found (Chapter 8), it is possible by superacidic catalytic treatment to upgrade these liquids to high-octane, commercially usable gasoline. Their use will not per se solve our long-... 

The lower heating value (LHV) of gasoline is assumed to be about 32 MJ/1, and that of diesel about 36 MJ/1. 

The oxygen content of ethanol lowers its stoichiometric air-fuel ratio relative to gasoline in proportion to the difference in heating value. 

Methyl esters have a much greater water solubility than diesel fuel, no doubt due to the polar nature of the methyl groups they contain. The soybean methyl ester of Table 2-8 has a heating value similar to gasoline while the rapeseed methyl ester has a heating value similar to diesel fuel. The difference is most likely due to the larger oxygen content of the soybean methyl ester compared to the rape-seed methyl ester. 

In Section 18.5 one gallon of gasoline is stated to be equivalent to 130.8MJ (HHV). Is this consistent with Table 18.1 If it is, more or less, is this value for the higher heating value in terms of work or heat ... 

Each product and by-product is marketable. The gas has a heat value from 170 to 2,375 Btu/ft3 (natural gas averages 1000 Btu/ft3). The light oils can be sold for gasoline additives to enhance octane, and the heavy oils can be used as a replacement for number six fuel oil. The char can substitute for some carbon black applications, although quality and consistency is a significant impediment. 

Partial substitution for gasoline utilizing up to 15% methanol, compression ratios of the engines in Brazil could be increased. The fuel consumption does not follow the proportion based on the heat values. Practically the 0 value is around 1.4, similar to ethanol. 

Applications of IR analyzers include the measurement of ammonia, CO, C02, ethylene, hexane, methane, moisture, nitrous oxide, propane, and sulfur dioxide. NIR analyzers can detect the concentrations of benzene, caustic, cetane, gasoline boiling point, heating value, molecular weight, octanes, protein, and p-xylene. The measurement errors of these analyzers are IR—2% FS, NIR—1% FS. 

A blend of 15% methanol with gasoline (M15 blend) is the most practical initial approach because it requires only minor adjustments to engine fuel systems and is interchangeable with gasoline. It also provides a 3% improvement in energy efficiency, which largely offsets the lower heating value of methanol. 

NOTE HHV = higher heating value LH V = lower heating value AH = enthalpy J = joule Btu = British thermal unit M = million k = thousand mol = mole N-m3 = normal cubic meter kWh = kilowatt hour. SOURCE NIST (2003), except DOE (2003f) for gasoline data. 

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