Dynamic Viscosity under Pressure for Mixtures of Pentaerythritol Ester Lubricants with 32 Viscosity Grade: Measurements and Modeling

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• 作者：L. Lugo ; X. Canet ; M. J. P. Comu&ntilde ; as ; A. S. Pensado ; J. Ferná ; ndez
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2007
• 出版时间：March 14, 2007
• 年：2007
• 卷：46
• 期：6
• 页码：1826 - 1835
• 全文大小：190K
• 年卷期：v.46,no.6(March 14, 2007)
• ISSN：1520-5045

文摘

The dynamic viscosity under pressure of three mixtures of pentaerythritol ester lubricants (PEs) has beenmeasured using a rolling-ball viscometer for several temperatures with an experimental uncertainty of 3%.The first one is a multicomponent mixture of several PEs named in the present work as PEC5-C9 lubricant;the second one is a binary mixture of pentaerythritol tetra(2-ethylhexanoate), PEB8, and pentaerythritoltetraheptanoate, PEC7, with a PEB8 mole fraction of 0.6670; and the third one is another binary mixture ofPEB8 and pentaerythritol tetrapentanoate, PEC5, with a PEB8 mole fraction of 0.6911. The two binary mixtures,xPEB8 + (1 - x)PEC7 and xPEB8 + (1 - x)PEC5, have been prepared with the same viscosity grade as thePEC5-C9 lubricant (VG32). A total of 1176 experimental measurements of the rolling time have been performedat pressures up to 60 MPa for the determination of 196 dynamic viscosity data points. The viscosities ofthese binary mixtures have been compared with the predicted values obtained by using several viscositymodels (Grunberg-Nissan and Katti-Chaudhri mixing laws, self-referencing model, hard-sphere theory, andfree-volume model). All methods predict dynamic viscosity values for the two binary mixtures that agreewith the experimental data within an average mean deviation of 10% over the entire temperature and pressureranges. The best predictions were found with the free-volume model, for which the average mean deviationfor both mixtures is lower than 4%. Parameter values for the self-referencing model were determined fromexperimental viscosity data of several pure PEs. These parameters permit the estimation of viscosity valuesof PE lubricant of unknown composition, when a viscosity value at any temperature and pressure is available.This model predicts the viscosities of PEC5-C9 lubricant with an average deviation of 4%.