Solubility of HFCs in Pentaerythritol Tetraalkyl Esters

Abstract

difluoroethane (HFC152a) in pentaerythritol tetranonanoate, pentaerythritol tetra-2-ethylbutanoate, and pentaerythritol tetra-2-ethylhexanoate have been measured at temperatures between 303 and 363 K and pressures between 0.07 and 2.1 MPa. Henry's constant and the activity coefficient for HFCs at infinite dilution were derived for measurements below 0.34 MPa. The measurements were made by an isochoric method with an uncertainty of <2% for Henry's constant and <3% at high pressure. Within the investigated temperature range, solubilities for HFCs in pentaerythritol tetraalkyl esters decrease in the following order: HFC152a > HFC134a > HFC32 > HFC125 > HFC143a. The experimental data have been correlated with a Flory-Huggins model with an extended temperature dependence, which is able to describe the data with a deviation from measured data of <2.7%.

Phase equilibrium and diffusivities of hydrofluorocarbons in a synthetic polyol ester lubricant

“…Similar results were obtained by Grebner, who found that both R‐134a and R‐125 showed mixed negative and positive deviations from Raoult's law in POE 32 oils, depending on the refrigerant mole fraction 28 . Also, Wahlström and Vamling reported that R‐32 in pentaerythritol tetraalkyl esters showed negative deviation from Raoult's law over a temperature range of 303.15–363.15 K 7 . The two distinct solubility behaviors demonstrate the complexity of these refrigerant/oil mixtures, thus molecular simulation studies should be performed to better understand the intermolecular interactions responsible for those solubility behaviors.…”

“…While most of the studies in this field focus on the determination of thermodynamic and physical properties of pure HFC refrigerants, few studies are documented in the open literature on the phase behavior, thermodynamic, and transport properties of HFC/lubricant binary mixtures, namely at low temperatures. Wahlström and Vamling investigated the solubility of R‐134a, R‐32, and R‐125 in a linear chained pure component POE, that is, pentaerythritol tetrapentanoate ester (PEC5), at temperatures between 303.15 and 363.15 K, and pressures ranging from 0.07 to 2.1 MPa 7 . Among the HFCs studied, R‐134a was found to be the most soluble refrigerant in PEC5 oils followed by R‐125 and R‐32 at a given temperature and pressure.…”

Solubility of carbon dioxide in 2-methylbutyric, 2-methylvaleric and 2-methylhexanoic ester oils

“…Few data are available on the thermophysical properties of the refrigerant + lubricant systems [1][2][3][4][5][6][7][8][9][10][11], and most of them refer to hydrofluorocarbons (HFC) and commercial oils. However, the structure and composition of the commercial oils is usually not defined, since they are mixtures of different components and additives, and this complicates the development of reliable thermodynamic models able to predict the behaviour of the lubricant + refrigerant mixtures.…”

Solubility of Carbon Dioxide in Pentaerythritol Tetrabutyrate (PEC4) and Comparison with Other Linear Chained Pentaerythritol Tetraalkyl Esters

“…Moreover, the regression of these models requires a large number of experimental data to determine the dependence of the solubility on pressure, temperature, and molecular structure. Unfortunately, in the literature there is a lack of such information, except for few systematic works, as [1][2][3][4][5][6][7]. For this reason, our group is involved in a research program to provide experimental measurements and the development of a general predictive model focused on the phase behavior of lubricant + refrigerant blends, with particular attention to systems of POE precursors and CO 2 [8][9][10][11][12][13][14].…”