Octane energy density

A comparison of the volumetric energy densities of compressed hydrogen gas, liquid hydrogen and other fuels is presented in Figure 1.11 methane represents natural gas and octane represents petrol. The data show that highly compressed methane and liquid fuels are much superior to hydrogen. 

One reason why the energy density of a fuel is important is that to move a vehicle one must ako move its unburned ftieL Octane is a major component of gasoline. It bums according to the reaction,... 

Starting from this thermochemical equation, describe how you would determine the energy density, in kj/g, for octane. Be sure to indicate what you would need to calculate or look up to complete this problem. 

The interest in w-butanol as a biofuel has increased in recent years owing to its superior fuel qualities compared to ethanol. These include a higher octane number, lower heat of vaporization, higher energy density (energy/volume), and lower vapor pressure. However, in the traditional ABE (acetone-butanol-ethanol) fermentation process, the concentration of n-butanol coming from the fermenter is lower than that achieved in ethanol fermentation. In addition, acetone and ethanol are also produced. Recent studies to improve yield and increase w-butanol concentration have explored fed-batch systems with stripping, adsorption, liquid-liquid extraction, distillation, and/or pervaporation to recover products. 

In contrast as shown in Figure 6.11, for vehicle powertrains that employ a PEM fuel cell and a liquid fuel reformer to produce the required hydrogen, liquid fuels will be required to have zero sulfur (this means less than 10 ppm in the fuel, possibly coupled with an on-board sulfur trap resulting in less than 0.5 ppm delivered to the reformer or stack), as well as the highest H/C ratio possible and an acceptable energy density. There will be no octane requirement, and vapor pressure limits will be needed only to control evaporative emissions from the fuel tank. Some oxygenated components in the fuel blend might be used for a variety of performance attributes, but there cannot be any contaminants that would interfere with or poison the fuel cell stack. 

Alternative energy sources that are renewable and that can reduce greenhouse gas emissions are actively being developed. In this example, you wish to explore the feasibiUty of two alternative energy sources to petroleum. The U.S. petroleum consumption is approximately 3 million m per day. You may assume that the fuel value of petroleum can be represented by octane. The density of octane is 0.70 g/cm. Take the average power density for solar radiation over a 24-hour period to be 200 W/m. ... 

How many liters of octane, QHig, the primary component of gasoline, must be burned to C02(g) and H20(g) to produce as much energy as the fission of one gram of U-235 fuel Octane has a density of 0.703 g/mL its heat of formation is —249.9 kj/mol. 

At T = 1.3 K, the sir rate is exclusively determined by the direct process, as will be shown explicitlybelow. By use of Eq. (15) and with the values of (1.3 K) = 1.39 X 10 s and AEn j = 7 cm and under assumption of reasonable values for the mass density (p = 0.9 g/cm , as determined from the crystal structure of n-octane [85]) and the velocity of sound (v = 1.3 km/s for a similar compound [109,158]) one can estimate the size of the matrix element (II V I) to 1.1 cm [65]. This interaction energy expresses the size of coupling of the triplet substates II and I induced by the phonon perturbation. Interestingly, application of a magnetic field of B = 10 T reduces this matrix element to about 0.7 cm k In Ref. [24], it has been proposed that this reduction could be related to a field-induced reorientation of the spin system from the molecular frame towards the external magnetic field axis. 

The quality of the product is of primary importance in developing a recycling technology converting plastics into fuels by pyrolysis. Today the characterization of a liquid fuel from any sources is obviously based on the qualification methods and standards of fuels from mineral oil. The properties of the pyrolysis-derived fuels from plastics are expected to be similar to conventional fuels (energy content, viscosity, density, octane and cetane number, flash-point, etc.). However, in addition to the familiar ranking values it is necessary to know more about the chemical composition of the plastic pyrolysis oil, because of the peculiarities as follows ... 

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