PρT Measurements and Equation of State (EoS) Predictions of Ester Lubricants up to 45 MPa

Abstract

New experimental densities in the compressed liquid state are reported for pentaerythritol tetrapentanoate (PEC5) over the temperature range of 278.15−353.15 K and for pressures up to 45 MPa. Density values (99 experimental data) have been measured with a high-pressure vibrating tube densimeter. A correction factor that was due to the viscosity of the sample was applied to the experimental density values. These data were used to determine isothermal compressibilities, isobaric thermal expansion coefficients, and internal pressures for this compound. Furthermore, the density data corresponding to the homologous series: dialkyl sebacates, 1,10-decanediol diesters, triglycerides, trimethyolethane triesters, pentaerythritol tetraesters, and linear oligomer esters of poly(hexamethylene sebacate) were predicted using the Sako−Wu−Prausnitz (SWP) equation of state (EoS), which is linked to the group contribution approach of Elvassore et al. [Ind. Eng. Chem. Res. 1999, 38, 2110] and compared with experimental data in the literature. In addition, other two EoSthe Soave−Redlich−Kwong (SRK) and Peng−Robinson (PR) equationswere used to predict the densities of some pentaerythritol tetraesters, for which the critical constants and acentric factors have been published in the literature.

Testing the ability of various equations of state to reproduce high-pressure isotherm crossings in the (α, P) plane

“…This behavior has been documented in different papers, mainly by Randzio et al [1][2][3][4][5] and in papers referencing newly measured thermophysical properties of fluids [6,7]. The isobaric expansivity ˛, defined by:…”

The Pressure–Viscosity Coefficient of Several Ionic Liquids

“…9 it can be concluded that a high a/b ratio could be obtained with lubricants of low internal pressure and thermal pressure coefficient, and high scaling coefficient and isothermal compressibility. In Table 4 the a/b, a p and j T values at T = 313.15 K and p = 50 MPa of six ILs, squalane, and four pentaerythritol ester lubricants are presented, together with the scaling exponent c. For all the fluids, the a p and j T values were determined through fits of a Tait equation to the experimental density data of the literature [49][50][51][52][53][54][67][68][69][70] and by obtaining the corresponding analytical derivatives. Roland et al [63] determined the c value for squalane, [C 8 C 1 im]BF 4 , and [C 8 C 1 im]PF 6 , whereas Fandiño et al [71] evaluated the c exponents for the pentaerythritol esters and Pensado et al [65] calculated those of the other ILs.…”

Tris(2-Ethylhexyl) trimellitate (TOTM) a potential reference fluid for high viscosity. Part II: Density measurements at temperatures from (293 to 373)K and pressures up to 68MPa

“…The effect of viscosity on the density measurements made by U-tube densimeters has been extensively studied experimentally [11][12][13][14][15][16][17][18][19] and, recently, the increasing interest in high viscosity liquids has intensified the awareness in this effect [15][16][17][18]. However, to the knowledge of the authors, no theoretical study has been published.…”