Alwarappa Sivaraman

A versatile apparatus to study the vapor pressures and heats of vaporization of carbazole, 9-fluorenone and 9-hydroxyfluorene at elevated temperatures

Abstract A versatile, high-temperature static vapor-pressure apparatus to measure the vapor pressures of both normally liquid and normally solid condensed-ring hydrocarbons of high-molecular-weight is described. This apparatus has been used to study the vapor pressures and heats of vaporization of three polynuclear aromatic compounds (carbazole, 9-fluorenone and 9-hydroxyfluorene) with vapor pressures in the range 1–1000 mm H g over the elevated temperature range 425–645 K. The above-mentioned three compounds are the homomorphic compounds of fluorene, a familiar coal-derived liquid component. The measured vapor pressures have been fitted to Chebyshev polynomials. The Clapeyron equation has been used to evaluate the heats of vaporization of all three compounds from their respective detailed values of d P /d T , the compressibility factors for the saturated vapors and liquids, the acentric factors and the estimated critical constants.

Vapor pressures and enthalpies of vaporization of thianthrene, acridine, and 9-methylanthracene at elevated temperatures

Abstract Vapor pressures (0.13 to 197.99 kPa) were measured of three polynuclear compounds, one containing a sulfur group, the second containing pyridinic nitrogen, and the third a methyl group. The temperature ranges of the measurements were as follows: acridine, 423.80 to 621.16 K; thianthrene, 430.79 to 593.01 K; and 9-methylanthracene, 423.76 to 587.64 K. The measurements were performed in a high-temperature static apparatus. For each compound Chebyshev polynomials have been used to fit the experimental vapor pressures. The results have been further processed to evaluate the enthalpies of vaporization.

Correlation for prediction of interfacial tensions of pure alkane, naphthenic and aromatic compounds between their freezing and critical points

Abstract A simple equation has been developed for predicting the interfacial tensions of pure alkanes, aliphatic and aromatic hydrocarbons between their freezing and critical points. The equation has the form and represents the interfacial tension using a generalized correlation developed by Sivaraman et al. (1984) for predicting the latent heats of vaporization of normal fluids and coal-liquid model compounds. Here σ* is the reduced dimensionless interfacial tension, and L*(0) and L*(1) are the reduced dimensionless latent heats of vaporization; A and N are system-independent constants. Subsequent tests of this correlation in predicting interfacial tension over a broad domain of reduced temperatures for a large number of different types of compounds have confirmed the validity of our approach. The percentage deviations in interfacial tension are in the range− 3.87 to 5.99 in the range of reduced temperatures 0.03

Correlation for prediction of latent heat of pure components incorporating renormalization group formulations with corresponding-states principle

Abstract A corresponding-states correlation has been developed using renormalization group theory, phenomenological scaling theory and Pitzer et al.s (1955) three-parameter corresponding-states principle to predict latent heats of vaporization for simple fluids (aliphatic and atomatic hydrocarbons, including complex coal-liquid model compounds) from the freezing point to the critical point. The resulting correlation consists of an expansion in the acentric factor which is truncated after the second term, in accordance with the linear dependence observed for experimental data. The dimensionless latent heat of vaporization defined as L * = L/RT c is given by L * = L (0) * + ω * L (1) * , where L * is a nonanalytic function (Torquato and Stell, 1982). Subsequent tests of the ability of this correlation to predict latent heats of vaporization over a board domain of reduced temperatures for a large number of different types of compounds have confirmed the validity of the present approach. The results show root-mean-square deviations between reported and predicted latent heats of vaporization in the range 0.46–6.93% for aliphatic and aromatic hydrocarbons including one-, two- and three-ring coal-liquid model compounds in the range of reduced temperatures 0.02 T c T )/ T c

The molar volume and fugacity of liquid dibenzofuran at high temperatures and high pressures

Abstract Molar volumes of liquid dibenzofuran, a potential coal liquid compound, were measured at high temperatures from 391.55 to 563.15 K and at high pressures up to 25.331 MPa. The volumetric measurements were performed in a high-temperature high-pressure v.l.e. apparatus. The vapor pressures of dibenzofuran were measured to 586.46 K and 171.756 kPa in a high-temperature static apparatus. A modified Chueh et al. equation has been used to fit the experimental volumetric results with a root-mean-square error better than 0.10 per cent. The results have been further processed to evaluate the fugacity of liquid dibenzofuran.

Correlation for prediction of vapor pressures of pure fluids incorporating renormalization group formulations with corresponding-states principle

Abstract A simple correlation for predicting the vapor pressures of coal liquids between the freezing and critical points, and extending to normal fluids, has been developed on the basis of renormalization group theory and phenomenological scaling theory. The Clapeyron equation has been reduced to the integral form to represent vapor pressure using a generalized correlation developed by Sivaraman et al. (1983) for the prediction of latent heats of vaporization of normal fluids and coal-liquid model compounds. L*, the dimensionless latent heat of vaporization, andΔz, the difference between the compressibility factors of the saturated vapor and liquid, are given by the corresponding-states correlations and based on the formulations of Pitzer et al. (1955). A simple expression for the latent heat of vaporization developed by Torquato and Stell (1982) is incorporated into this correlation. The vapor-pressure correlation has been tested successfully for 23 pure-component systems including aromatic and heterocyclic compounds often found in coal liquids and shale oil in the region 0 〈 e = (Tc-T)/Tc 〈 0.69. The deviations in the predicted vapor pressures are in the range 0.11–5.45%.