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Experimental investigation on foaming factors and foaming  characteristics of oil/refrigerant mixtures.

Number: 2523

Author(s) : KATO Y., FUKUTA M., MOTOZAWA M., GOTO S., TAKAKI T.

Summary

Refrigeration oil is used in refrigerant compressors for lubrication, sealing, and cooling. The refrigeration oil has generally good solubility with refrigerants for oil return. In cases where the refrigerant dissolves excessively in the refrigeration oil, the mixture of oil and refrigerant foams easily due to the stirring effect of moving parts such as the rotating shaft and rotor in the compressor. If refrigeration oil flows out from the compressor with refrigerant into a refrigeration cycle by violent foaming, some negative effects may occur. Two such examples are the reduction of heat transfer efficiency at heat exchangers, and the risk of compressor failure as a result of low refrigeration oil level in the compressor. To avoid these problems, the foaming characteristics of the refrigeration oil and refrigerant mixture are necessary to clarify. In this study, the foaming characteristics were examined in a cylindrical vessel with various actions causing the foaming under a wide range of refrigerant concentrations in the oil. R410A and R32 were the refrigerants used, and polyol ester (POE-1, POE-2) oil were used as the refrigeration oils. It was found that the stirring effect was the primary factor of the foaming, as compared to gas blowing and heat input into the oil. The foaming characteristics from the stirring were evaluated by two viewpoints: the foaming height and the collapsing speed of the foam. The results showed that the highest foaming height was obtained in the refrigerant concentration range of 33–40%. In addition, it was found that the foaming generation can be related to the pressure ratio of the pressure of oil/refrigerant mixture to that of saturated refrigerant, even when different types of oil or refrigerant are used.

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  • Original title: Experimental investigation on foaming factors and foaming  characteristics of oil/refrigerant mixtures.
  • Record ID : 30033038
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 20th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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