Methane physical constants

We have now laid the foundation for considering the other hydrocarbons which are similar to methane and ethane and for understanding an interesting relationship which makes of them a familyor series. At the present time about fifty hydrocarbons are known which resemble methane and ethane in being saturated stable, inactive compounds, and to which the name paraffin strictly applies. Some of these hydrocarbons with their empirical formulas and a few of their physical constants are given in the following table ... 

The AHJ of a given compound is a physical constant and is independent of the process by which the compound is formed. Therefore, AHJ values are additive and can be calculated precisely for balanced chemical equations if all the necessary data are available. For example, it might be experimentally impossible to measure the A// of methane directly by calorimetry, but it can be calculated as the sum of the enthalpy for an equivalent reaction sequence, e.g ... 

One of the important physical constants is surface tensions at the liquid-vapor border. Temperature dependence of a for freons of the methane series has not been sufficiently studied, and for Freons-20 and -23, for example, only few experimental points are known [0.34]. It is, therefore, useful to adopt the generalized equations [0.33, 1.2, 1.8]. The most universal equation is derived in Ref. [0.33] ... 

A simple model of the chemical processes governing the rate of heat release during methane oxidation will be presented below. There are simple models for the induction period of methane oxidation (1,2.>.3) and the partial equilibrium hypothesis (4) is applicable as the reaction approaches thermodynamic equilibrium. However, there are apparently no previous successful models for the portion of the reaction where fuel is consumed rapidly and heat is released. There are empirical rate constants which, due to experimental limitations, are generally determined in a range of pressures or concentrations which are far removed from those of practical combustion devices. To calculate a practical device these must be recalibrated to experiments at the appropriate conditions, so they have little predictive value and give little insight into the controlling physical and chemical processes. 

In many respects, the acoustic, strength, thermal, and rheological properties of gas hydrates are similar to those of ice. However, there are a few properties, including the dielectric constant and the thermal conductivity, which differ significantly from that of ice. The vast majority of data available on the physical properties of gas hydrates is only for methane hydrates. Davidson presented a comparison of the physical properties of hydrates with those of ice. Table 2 summarizes some of these properties. 

The constants A, B, C, a, b, c, a and P are characteristic for a given fluid. BWR-EOS and its recent modifications permit accurate calculations of physical properties of light gases, non-polar or slightly polar components medium pressure. BWR-EOS can be used for both thermodynamic properties, as enthalpy and entropy, and phase equilibrium. It is also suited for light hydrocarbon processes, including rich methane and hydrogen mixtures, as well as in gas liquefaction. 

At 190°F and 600 psia, a methane/n-butane vapor mixture of 0.6037 mole fraction methane is in equilibrium with a liquid mixture containing 0.1304 mole fraction methane. Using physical property constants and correlation coefficients from Appendix I,... 

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