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Refrigerant and oil mixture has an impact on compressors' performance.

Le mélange, huile et fluide frigorigène, a une influence sur le rendement des compresseurs.

Author(s) : WUJEK S. S., BOWERS C. D., OKARMA P., et al.

Type of article: Article

Summary

Lubricants are utilized on compressors to lower friction thus increasing efficiency while decreasing wear and increasing longevity. While pure lubricant properties are commonly cited in literature due to more readily available property data, far more meaningful results are obtained when lubricant-refrigerant mixture properties are utilized. The most critical of these properties are the vapor-liquid equilibrium data, which relate temperatures, pressures, and concentrations, to other intensive properties such as density and viscosity. To determine the impact of fundamental refrigerant-lubricant mixture properties on compressor performance, a series of lubricants, having known mixture properties, were utilized in a semi-hermetic transcritical carbon dioxide compressor. This compressor was installed in a calorimeter which allowed compressor electrical power consumption to be accurately measured. Likewise, refrigerant temperatures, pressures, and mass flows were measured. As this calorimeter utilized the full refrigeration cycle with both a gas-cooler and evaporator, it was possible to accurately determine the oil circulation ratio (OCR) via the sample based method given by ASHRAE Standard 41.4. The compressor was operated at a series of suction and discharge pressures and temperatures which were near the edge of the operating envelope. Combining the property information with experimental data from the calorimeter experiments allow for analysis of the impact of refrigerant-lubricant mixture properties on compressor efficiencies. Due to the relatively small changes in performance, it was necessary to properly account for the presence of lubricant in the definitions of isentropic and volumetric efficiencies. After accounting for these properties, multivariate least square curve fitting was utilized to understand the relative impact of mixture properties and OCR on compressor efficiency. The analysis is furthered to show the impact of compressor efficiency on system performance for the purpose of pointing towards selecting lubricants to minimize energy consumption.

Details

  • Original title: Le mélange, huile et fluide frigorigène, a une influence sur le rendement des compresseurs.
  • Record ID : 30021438
  • Languages: French
  • Source: Revue générale du Froid & du Conditionnement d'air - n.1160
  • Publication date: 2016/11

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