Elsevier

Fluid Phase Equilibria

Volume 236, Issues 1–2, 20 September 2005, Pages 229-236
Fluid Phase Equilibria

Influence of the molecular structure on the viscosity of some alkoxyethanols

https://doi.org/10.1016/j.fluid.2005.02.009Get rights and content

Abstract

This work reports new measurements of the viscosity of some monoethylene glycol alkyl ether liquids: monoethylene glycol methyl ether (MEGME), monoethylene glycol ethyl ether (MEGEE) and monoethylene glycol iso-propyl ether (iso-MEGPE), up to 100 MPa at seven temperatures ranging from 293.15 to 353.15 K. The measurements at atmospheric pressure have been performed with an Ubbelohde-type glass capillary tube viscometer with an uncertainty of ±1%. At pressures up to 100 MPa the viscosity was determined with a falling-body viscometer with an uncertainty of ±2%. Using previous density data obtained at the laboratory, current measurements were used to study the dependence of the viscosity and of the molecular parameters of hard-sphere scheme and free-volume model on the molecular structure.

Introduction

Our research concerning polyalkylene glycol polyalkyl ethers aims to create a complete database of experimental thermodynamic and transport properties for these fluids, which could be used to develop models able to accurately represent the behaviour with both temperature and pressure of the thermophysical properties of these interesting compounds. As a part of our studies on polyalkylene glycol polyalkyl ethers, the density and dynamic viscosity of several polyethylene glycol dimethyl ethers [1], [2], [3], [4], [5], [6] (diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether) are reported up to 60 and 100 MPa, respectively. Moreover, densities for several diethylene glycol monoalkyl ethers (diethylene glycol monomethyl ether and diethylene glycol monoethyl ether) up to 25 MPa, and the speed of sound of triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether up to 100 MPa have recently been published [7], [8]. The present work was undertaken with the aim to complete our database.

More precisely, the present work was undertaken with the aim to analyse the high-pressure viscosity behaviour of the three monoethylene glycol monoalkyl ethers also called alkoxyethanols obeying the formula CnH2n+1OCH2CH2OH: monoethylene glycol methyl ether (MEGME; n = 1), monoethylene glycol ethyl ether (MEGEE; n = 2) and monoethylene glycol iso-propyl ether (iso-MEGPE; n = 3) which have been actively studied for various applications. For example, the phase equilibrium behaviour of alkoxyethanols, such as monoethylene glycol ethyl ether, with CO2 is essential to process development in the food and cosmetic industries [9], [10]. In the last years, measurements of the viscosity of monoethylene glycol alkyl ethers under pressure have become important because of the use of these data in studying the reliability of these fluids as lubricants in refrigeration compressors and as absorbents for absorption systems. However, the database for transport properties of these compounds is scarce and available at very limited temperature and pressure conditions. Most measurements have been made at atmospheric pressure and at temperatures between 293.15 and 323.15 K. Thus, while there are abundant data for these compounds describing the temperature dependence of the viscosity at 0.1 MPa [11], [12], [13], [14], studies versus pressure are less frequent. With respect to other thermophysical properties, density values of these compounds have been studied by us [15].

To complete our experimental and theoretical studies of some physical properties of monoethylene glycol alkyl ethers, in this paper new viscosity data at temperatures from 293.15 to 353.15 K and at pressures up to 100 MPa are reported. These experimental values are used to test the correlation ability of the hard-sphere scheme and free-volume model.

Section snippets

Measurement techniques

At atmospheric pressure, the kinematic viscosities, ν, were measured with an Ubbelohde-type glass capillary tube viscometer with a Schott-Geräte automatic measuring unit (model AVS 350) in a thermostated bath, which regulates the temperature to within an accuracy of ±0.01 K. After multiplication by the density at atmospheric pressure, the dynamic viscosity, η, is obtained with a relative uncertainty lower than 1%. The calibration has been checked with certified calibrated Cannon oil.

A

Experimental results

The experimental dynamic viscosity values for MEGME, iso-MEGPE and MEGEE, at different pressures and temperatures are listed in Table 1. To our knowledge, there are no literature viscosities for these fluids at pressures different from atmospheric. Our experimental kinematic viscosity values for MEGME at atmospheric pressure agree with published measurements of Pal and Sharma [23], [24] at 298.15 and 308.15 K, with an average deviation of 1.3%, with the data of Muhuri and Hazra [25] at 298.15 K

Modified Andrade representation

The experimental data of viscosity on an isotherm, η(P), can be fitted for each isotherm to the following Tait-like equation:η(P)=AexpBlnC+PC+0.1MPaand on an isobar, η(T), can be fitted for isobar to the following Andrade's equation [31]:η(T)=AexpBTCBoth previous equations can be combined in order to fit the viscosity as a function of temperature and pressure. Then, we have proposed [2] the following equation:η(P,T)=η0(T)expDlnE(T)+PE(T)+0.1MPawhere η0(T) is the temperature

Conclusion

The dynamic viscosity of some monoethylene glycol alkyl ethers has been measured up to 100 MPa in the temperature range 293.15–353.15 K. The experimental uncertainty for the viscosity measurements is less than 2%, except at 0.1 MPa where the uncertainty is 1%. It follows from the discussion that some simple viscosity approaches with a strong physical and theoretical background (the hard-sphere scheme, the free-volume model) are able to model the viscosity of these compounds (MEGME, MEGEE and iso

Acknowledgements

This work was supported by Spanish Science and Technology Ministry (PPQ2001-3022), European Union (FEDER), Xunta de Galicia (PGIDIT03PXIC20609PN) and Spanish–French Joint Action (HF 2001-0101 and 04238PG).

References (38)

  • M.J.P. Comuñas et al.

    Fluid Phase Equilib.

    (2002)
  • A. Baylaucq et al.

    Fluid Phase Equilib.

    (2002)
  • S.N. Joung et al.

    Fluid Phase Equilib.

    (2001)
  • A. Staby et al.

    Fluid Phase Equilib.

    (1993)
  • M. Kanti et al.

    Fluid Phase Equilib.

    (1991)
  • M.J. Assael et al.

    Fluid Phase Equilib.

    (1992)
  • M.J.P. Comuñas et al.

    Int. J. Thermophys.

    (2000)
  • M.J.P. Comuñas et al.

    Int. J. Thermophys.

    (2001)
  • M.J.P. Comuñas et al.

    J. Chem. Eng. Data

    (2002)
  • M.J.P. Comuñas et al.

    J. Chem. Eng. Data

    (2003)
  • E.R. López et al.

    J. Chem. Eng. Data

    (2003)
  • E.R. López et al.

    J. Chem. Eng. Data

    (2004)
  • H.C. Ku et al.

    J. Chem. Eng. Data

    (2000)
  • A. Pal et al.

    J. Chem. Eng. Data

    (1999)
  • A. Conesa et al.

    Int. J. Thermophys.

    (1998)
  • T.M. Aminabhavi et al.

    J. Chem. Eng. Data

    (1994)
  • M.J.P. Comuñas et al.

    J. Chem. Eng. Data

    (2004)
  • D. Ducoulombier et al.

    J. Phys. Appl.

    (1985)
  • F.J. Vieira dos Santos et al.

    Int. J. Thermophys.

    (1997)
  • Cited by (19)

    • Viscosity of oxygenated fuel: A model based on Eyring's absolute rate theory

      2019, Fuel
      Citation Excerpt :

      Viscosity has a significant impact on the spray characteristics and combustion of the fuel [13]. For decades, the experimental viscosity of oxygenated compounds has been widely reported [14–33] often with significant scatter. In addition to the provision of accurate data, a rigid theoretical model for the viscosity of oxygenated fuels is required to further our knowledge and assist applications.

    • Study of molecular interactions of binary mixtures DEC with alkoxyalkanols at various temperatures

      2017, Journal of Chemical Thermodynamics
      Citation Excerpt :

      The long-standing interest in mixed solvents is largely due to their importance as tuneable reaction media. Accurate knowledge of various thermophysical properties such as excess molar volume, density, speed of sound and refractive index of mixtures of organic liquids is essential for the right design of several types of relevant industrial equipment [1–3]. From molecular perspective, binary liquid mixtures are also interesting because they often exhibit complex structural and dynamical features, especially when the components are capable of specific interactions with one another, which may result in strong interspecies molecular associations [4].

    • Modeling the thermodynamic and transport properties of decahydronaphthalene/propane mixtures: Phase equilibria, density, and viscosity

      2011, Fluid Phase Equilibria
      Citation Excerpt :

      Values of the pure component parameters for a variety of other hydrocarbons, alcohols, refrigerants, carbon dioxide, and water can be found elsewhere [26]. Parameter values for alkoxyethanols [30], polyethers [31], and polyalkylene glycol dimethylethers have also been reported [29,38]. Tobaly et al. reported spectroscopically measured phase composition data for C3/cis-DHN mixtures [38].

    View all citing articles on Scopus
    View full text