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Solution properties of polyol ester lubricants designed for use with R-32 and related low-GWP refrigerant blends.

Number: pap. 1491

Author(s) : URREGO R., BENANTI T., HESSELL E.

Summary

The purpose of this paper is to compare thermophysical properties of refrigerant-lubricant mixtures containing traditional POE lubricants to those containing advance (or optimized) POEs. The general methods for data acquisition and processing, along with creation of Daniel charts were in accord with those developed by Seeton (2009). The results of measurements involving mixtures of traditional POEs with R-32 or R-410A show that lubricant viscosities in the compressor at various conditions within the normal operating envelope decrease by as much as 25-54%. This illustrates the excessive lubricant viscosity dilution of R-32 relative to R-410A with traditional POEs used today with HFCs refrigerants. The solution property measurement technique was also used to develop a class of advanced ester POE lubricants optimized for R-32 to eliminate the viscosity dilution problem. Significant energy savings can be achieved through proper optimization of lubricant/refrigerant solution properties to provide the best balance of lubrication in the compressor while maintaining excellent heat transfer in the refrigeration cycle. Miscibility between new low Global Warming Potential (GWP) refrigerants and POE lubricants is a property that has to be considered, since a miscibility gap at concentrations between 10% to 20% (or higher to 30%) in volume may become an issue in oil return in refrigeration systems and its performance evaluated as Coefficient of Performance (COP). The advanced ester POE lubricants show improvement in the miscibility and viscosity issues. The miscibility gap was eliminated such that the new products are fully miscible from -20°C to 40°C. Viscosity dilution was limited to closely match the typical viscosity dilution shown in the baseline pair of R410A and an ISO 32 traditional POE. Finally, a comparison of concentrations and solution viscosities of traditional and advanced ester POE lubricants with R410A and R32 refrigerants, using actual conditions measured in a three ton air conditioning system, show a solution viscosity improvement when as ISO grade increases, with lower concentrations of refrigerant in oil than in the baseline of R410A and an ISO 32 traditional POE.

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Pages: 10 p.

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Details

  • Original title: Solution properties of polyol ester lubricants designed for use with R-32 and related low-GWP refrigerant blends.
  • Record ID : 30014113
  • Languages: English
  • Source: 2014 Purdue Conferences. 22nd International Compressor Engineering Conference at Purdue.
  • Publication date: 2014/07/14

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