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Phase equilibrium and diffusivities of hydrofluorocarbons in a synthetic polyol ester lubricant
Author(s) -
Morais Ana Rita C.,
Simoni Luke D.,
Douglas Justin T.,
Scurto Aaron M.,
Shiflett Mark B.
Publication year - 2020
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16241
Subject(s) - refrigerant , lubricant , thermodynamics , fluorocarbon , diffusion , chemistry , solubility , sorption , thermal diffusivity , unifac , refrigeration , gravimetric analysis , activity coefficient , materials science , chemical engineering , organic chemistry , adsorption , aqueous solution , gas compressor , physics , engineering
Detailed knowledge about the thermophysical properties of refrigerant/lubricant systems, such as solubility and diffusivity, are required for the design, operation, and long‐term reliability of heating, ventilation, air‐conditioning, and refrigeration equipment. Herein, vapor–liquid equilibrium of hydrofluorocarbons (HFCs) 1,1,1,2‐tetrafluoroethane (R‐134a), pentafluoroethane (R‐125), and difluoromethane (R‐32) in a polyol ester oil (ISO VG 32) were measured using a gravimetric microbalance at temperatures ranging from 248.15 to 348.15 K and up to 1.0 MPa of pressure. The experimental solubility data of each refrigerant/lubricant system were successfully modeled using the nonrandom two liquid activity coefficient model. A one‐dimensional diffusion equation was applied on time‐dependent absorption data to determine binary diffusion coefficients ( D ) for the refrigerants in the ISO VG 32 lubricant. Finally, Stokes–Einstein diffusing radius calculations support the hypothesis that HFCs dissolve into ISO VG 32 lubricant as individual molecules rather than associated complexes.