N. K. Dalaouti

Standard Reference Data for the Viscosity of Toluene

Viscosity is an important transport property for the optimum design of a chemical process plant and for the development of molecular theories of the liquid state. A large amount of experimental viscosity data has been produced for all types of liquids, from alternative refrigerants to molten salts and molten metals. The accuracy of these data is related to the operating conditions of the instrument and, for this purpose as well as for the calibration of relative instruments, standard reference data for viscosity are necessary over a wide range of temperatures. New experimental data on the viscosity of liquid toluene along the saturation line have been obtained recently, mostly at low temperatures. The quality of the data is such that recommended values can be proposed with uncertainties of 0.5% (95% confidence level) for 260 K⩽T⩽370 K and 2% for 210 K⩽T<260 K and 370 K<T⩽400 K. A discussion about the uncertainties in the measurements and about the purity of the samples is made. The proposed value for the ...

Reference Correlation for the Viscosity of Liquid Toluene from 213 to 373 K at Pressures to 250 MPa

A correlation in terms of temperature and molar volume is recommended for the viscosity of liquid toluene as a reference for high-pressure viscosity measurements. The temperature range covered is from 213 to 373 K, and the pressure range from atmospheric up to 250 MPa. The standard deviation of the proposed correlation is 1.36%, and, within a 95% confidence limit, the error is 2.7%. It is estimated that for densities up to 920 kg·m−3the uncertainty of the viscosity values generated by this correlation is about ±2%.

Viscosity of Natural-Gas Mixtures: Measurements and Prediction

New measurements of the viscosity of a natural-gas mixture are reported. The measurements were performed in a vibrating-wire viscometer, in the temperature range from 313 to 455 K at a pressure close to atmospheric and in the temperature range from 240 to 353 K at pressures up to 15 MPa. The uncertainty of the reported measurements is estimated to be ±1%. The data were employed to validate further an existing method of predicting the viscosity of mixtures at high pressures.

Viscosity and thermal conductivity of methane, ethane and propane halogenated refrigerants

Abstract In the case of the methane and ethane halogenated refrigerants, the examination of the available viscosity and thermal conductivity measurements, allowed the derivation and recommendation of standard equations for these two properties. Hence, equations for the viscosity of refrigerants R32, R124, R125, R134a, R141b, and R152a in the liquid phase and refrigerants R125, R134a, R142b and R152a in the vapor phase are recommended. In the case of the thermal conductivity, equations for refrigerants R32, R123, R124, R125, R134a, R141b, R142b and R152a in the liquid phase and refrigerants R123, R125, R134a, and R141b in the vapor phase are also recommended. For each refrigerant, the temperature range of application and the uncertainty of the equation, is given. These equations together with those previously derived for the Dymond and Assael hard-sphere model for high pressure, form a very useful tool for the engineer. Very few viscosity and thermal conductivity measurements for the propane-halogenated refrigerants exist. Hence, although no recommended equations could yet be derived, a first estimate of the parameters of the Dymond and Assael hard-sphere model could be derived.

On the correlation of transport properties of liquid mixtures

Abstract The paper describes the application of the theoretically-based scheme of Vesovic–Wakeham, modified by making use of the hard-sphere model of Dymond–Assael, to the prediction of the viscosity and thermal conductivity of liquid mixtures. The purpose of the paper is to examine this scheme in more detail than earlier in order to find out under what circumstances it works well and when it fails. Hence, the scheme is employed to predict for the first time, the viscosity and thermal conductivity of a wide range of mixtures of quite disparate liquids from groups of hydrocarbons, through combinations of alcohols and hydrocarbons, to halogenated refrigerants. It will be shown that, in all cases, provided that the mass ratio of the pure components is close to unity, the predictions show excellent agreement with experiment.

Viscosity of Toluene+Cyclopentane Mixtures: Measurements and Prediction

New measurements of the viscosity of binary mixtures of toluene+cyclopentane are presented. The measurements, performed in a vibrating-wire viscometer, cover the temperature range from 210 to 310 K at pressures up to 25 MPa. The concentrations studied are 60 and 30%, by weight, toluene. The uncertainty of the measurements, confirmed at room temperature and higher temperatures with the measurement of the viscosity of water, is estimated to be ±0.5%, increasing to ±1% at temperatures below 240 K. The present measurements are employed to examine the predictive power of two recent theoretically based schemes proposed for the calculation of the viscosity of mixtures.

Reference Correlation for the Viscosity of Liquid Cyclopentane from 220 to 310 K at Pressures to 25 MPa

A correlation in terms of temperature and molar volume is recommended for the viscosity of liquid cyclopentane as a reference for low-temperature, high-pressure viscosity measurements. The temperature range covered is from 220 to 310 K and the pressure range from atmospheric up to 25 MPa. The standard deviation of the proposed correlation, within a 95% confidence limit, is 1%.

Prediction of the Viscosity of Liquid Mixtures

This paper describes the application of the theoretically based scheme of Vesovic and Wakeham, modified by making use of the hard-sphere model of Dymond and Assael, to the prediction of the viscosity of liquid mixtures. The purpose of the paper is to examine this scheme in more detail than earlier to find out in what circumstances it works well and when it fails. Hence, the scheme is employed to predict, for the first time, the viscosity of a wide range of mixtures of quite disparate liquids from groups of hydrocarbons, through combinations of alcohols and hydrocarbons, to halogenated refrigerants. It is shown that, in all cases, provided that the mass ratio of the pure components is close to unity, the predictions show excellent agreement with experiment.

Thermal Conductivity of Toluene+Cyclopentane Mixtures: Measurements and Prediction

New measurements of the thermal conductivity of toluene, cyclopentane, and a binary mixture of 60 wt% toluene are presented. The measurements cover the temperature range from 235 to 345 K and from the saturation line up to 20 MPa pressure. The measurements were performed with a transient hot-wire instrument. The uncertainty of the measurements is estimated to be ±0.5%. The present results are employed to examine the predictive power of a theoretically based scheme for the calculation of the transport properties of mixtures.

Viscosity and thermal conductivity of halogenated methane and ethane refrigerants

Viscosity and thermal conductivity of liquid halogenated methane and ethane refrigerants from about 200 K to near the critical temperature, at saturation and also at pressures up to 50 MPa, are shown to be satisfactorily correlated on the basis of a scheme developed by Dymond and Assael from consideration of hard-sphere theory. For the 31 refrigerants considered here, from the 1445 viscosity and 1226 thermal conductivity measurements examined only 5.2% were found to deviate by more than 5% from the proposed scheme.