A Bench Evaluation Test for Refrigeration Oils in a Refrigeration System Using a Screw Compressor

Weifeng Wu,Quanke Feng,Zhao Zhang,Xiaolin Wang,Liangwei Yang

doi:10.3390/app9153202

Weifeng Wu, Quanke Feng + Show 3 more

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https://doi.org/10.3390/app9153202

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Abstract

Refrigeration oil has a large effect on the performance of refrigeration systems. However, the physical and chemical indexes of fresh refrigeration oils often fail to reflect the actual operating characteristics, especially with respect to the degradation of refrigeration oils. In this paper, a bench evaluation test of refrigeration oils was carried out to investigate the degradation of synthetic refrigeration oils used with the refrigerant R134a, in a purpose-built, full-scale refrigeration system utilizing a screw compressor. To accelerate the degradation process of the refrigeration oil, the discharge temperature at the exit of the compressor was turned to a high level. Comparison tests of a mature refrigeration oil type A and a newly developed oil type B were performed under the same working conditions with 500 h of operating time. The performance of the screw compressor and refrigeration system was analyzed. The abrasion of the screw rotors and carbon deposition at the discharge port was investigated. Results showed that the bench evaluation test successfully predicted the degradation process of the refrigeration oils. The evolution analysis of the refrigeration oil viscosity and acid value during the bench evaluation test indicated that 15% of the physical and chemical indexes for refrigeration oil drain were too strict. Research work in this paper showed a more practical method to evaluate the performance of refrigeration oils through the bench evaluation test.

Highlights

Refrigeration oil is very important for lubricating, sealing, cooling and clearing the system of unwanted particles in the flow [1] in vapor compression refrigeration systems
An accelerated bench test experimental set up was established to evaluate the performance of the refrigeration oils used in an actual refrigeration system with a screw compressor
A newly developed oil type B were applied in the study with R134a as the working refrigerant

Summary

Introduction

Refrigeration oil is very important for lubricating, sealing, cooling and clearing the system of unwanted particles in the flow [1] in vapor compression refrigeration systems. The oil can decrease the vibration of the compressor [2]. This topic has been widely researched, and several standards have been formulated to select refrigeration oils for different types of compressors. These standards suggested different physical and chemical indexes for compressors under varying operating conditions. Most research focused on the characteristics of fresh refrigeration oil. The physical and chemical indexes of fresh refrigeration oils sometimes failed to reflect the actual operating characteristics [3]. Performance tests of the refrigeration oil in refrigeration systems were often recommended for evaluating refrigeration oils

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