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Refrigeration lubricant structure effect on the foaming phenomenon in the POE-refrigerant mixture.

Number: 1384

Author(s) : CHEN Y. K., WANG Y. H., HUNG J. T.

Summary

POE refrigeration lubricants are synthesized by different polyols and fatty acids, these various combinations can create different lubricant properties to meet requirements from different refrigeration systems. As global phase down schedule of HFCs, refrigeration lubricant makers focus on modifying structures of incumbent lubricants to apply for alternative refrigerant, such as expanding miscibility range in R32, or reducing viscosity-dilution in R1234ze. However, the modifications usually focus on the miscibility, solubility and working viscosity, there are no many attentions on the other properties, such as refrigerant absorption, desorption, heat transfer, and foaming. Our goal in this paper is to check the effect on foaming property from related structure modification.
Foaming is important phenomenon in refrigeration system, it affects not only oil return, but lead to start-up problem. To detailed describing foaming phenomenon, two stages of bubble life mechanisms must be taken into consideration: bubble generation stage and bubble stable/collapse stage. After investigating a lot of parameters, such as refrigerant solubility in lubricant, surface tension, contact angle, viscosity, density, saturated pressure, temperature and vapor pressure, we find each parameter can play a different role on bubble generation and collapse stage. We try to give a preliminary look on how lubricant chemical structure effect on these parameters, and further checking foaming phenomenon of refrigerant-lubricant mixture through conducting experiments.
In this study, fully branched and fully linear POE with ISO32 and ISO55 were chosen to mix with traditional HFCs, and alternative low GWP refrigerants by different ratios, and conducted foaming tests under different pressure. We also discuss viscosity effect by comparing different viscosity grades range from ISO32 to ISO170. Results show the path that lubricant type influencing foaming phenomenon is through altering solubility and working viscosity of refrigerant-lubricant mixture, then following resulting different foam characteristics. The investigation could provide a better understanding of foaming mechanism, and the direction to well-design lubricants to overcome foaming issue in refrigeration system.

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  • Original title: Refrigeration lubricant structure effect on the foaming phenomenon in the POE-refrigerant mixture.
  • Record ID : 30033612
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 27th International Compressor Engineering Conference at Purdue.
  • Publication date: 2024/07/18

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