Methanol thermodynamic properties

Our recent research efforts have been directed to developing an improved and extended set of parameters for the various groups used in the PFGC equation of state (16). We have dubbed our version of this equation the PFGC-MES. A thorough evaluation of the ability of this equation to predict the thermodynamic properties of hydrocarbon systems has been a part of this development process. A companion project has been the extension of the equation to describe the behavior of hydrocarbon-water-alcohol-nonhydrocarbon systems. This paper gives some of the results of our work on hydrocarbon-water-methanol systems. We also report some of our work on extending the SRK equation of state to hydrocarbon water systems. 

We have made a quantitative investigation of the spectra of methanol, ethanol and 6-butanol over rather wide temperature and concentration ranges ( —15° to + 60°C, and 0 005 to 1 M) in order to obtain more precise information as to the spectral and thermodynamic properties of the alcohol systems. We are particularly interested in establishing such properties for a single specific species, the dimer. 

The (liquid 4- liquid) equilibria diagram for (cyclohexane + methanol) was taken from D. C. Jones and S. Amstell, The Critical Solution Temperature of the System Methyl Alcohol-Cyclohexane as a Means of Detecting and Estimating Water in Methyl Alcohol , J. Chem. Soc., 1930, 1316-1323 (1930). The G results were calculated from the (vapor 4- liquid) results of K. Strubl, V. Svoboda, R. Holub, and J. Pick, Liquid-Vapour Equilibrium. XIV. Isothermal Equilibrium and Calculation of Excess Functions in the Systems Methanol -Cyclohexane and Cyclohexane-Propanol , Collect. Czech. Chem. Commun., 35, 3004-3019 (1970). The results are from M. Dai and J.-P.Chao, Studies on Thermodynamic Properties of Binary Systems Containing Alcohols. II. Excess Enthalpies of C to C5 Normal Alcohols + 1,4-Dioxane , Fluid Phase Equilib., 23, 321-326 (1985). 

Thermodynamic properties of the flow streams at various locations as well as the thermal and mechanical energy flows for the cycle are shown in Figure 2 using 1 g-mole of liquid methanol as the basis. Also shown in the figure are the magnitudes of entropy production and exergy destruction in each of the process steps. 

The values in these tables were generated from the NIST REFPROP software (Lemmon, E. W., McLinden, M. O., and Huber, M. L., NIST Standard Reference Database 23 Reference Fluid Thermodynamic and Transport Properties—fePPROP, National Institute of Standards and Technology, Standard Reference Data Program, Gaithersburg, Md., 2002, Version 7.1). The primary source for the thermodynamic properties is de Reuck, K. M., and Craven, R. J. B., Methanol, International Thermodynamic Tables of the Fluid State—12, lUPAC, Blackwell Scientific Publications, London, 1993. Validated equations for the viscosity and thermal conductivity are not currently available for this fluid. 

In Section 13.5.1 we presented the data of Vogelpohl for the distillation of two ternary systems acetone-methanol-water and methanol-2-propanol-water in a bubble cap column. Krishnamurthy and Taylor (1985b) simulated these experiments using a nonequilibrium stage model similar to the one described above. The AIChE correlations were used to calculate the mass transfer coefficients. Thermodynamic properties were calculated with the models described by Prausnitz et al. (1980). 

Butcher, K. L., and Medani, M. S., 1968. Thermodynamic properties of methanol -t- benzene mixtures at elevated temperatures. J. Appl. Chem., 18 100-107. 

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