The carbon dioxide (R-744) as a natural refrigerant has been an attractive alternative
refrigerant to replace HFC (hydrofluorocarbon) refrigerants currently used in air conditioning
systems, due to the environmental concerns. Because new compressors with CO2 are going to be
operated under the high pressure, the tribology of sliding surfaces in the compressor becomes very
important. To develop new compressor, especially scroll type, the friction and wear characteristics
of sliding surfaces between a fixed scroll and an orbiting scroll in the scroll compressor were
investigated in this paper. The sliding tests of pin-on-disk type were carried out between scroll
surfaces under various sliding speeds, normal loads, surface roughness, and refrigerant pressures.
Two types of lubricants were used, namely POE (polyol ester) oil and PAG (polyalkylene glycol)
oil. The friction forces, wear amounts and surface temperatures were monitored during the tests.
Test results showed that the wear amounts increased with increasing normal load and rotating
speed, and also decreased with decreasing surface roughness. Also, the results of the sliding tests
showed that using PAG oil has an advantage over POE oil in CO2 environment. As the pressure of
CO2 refrigerant became higher, the amount of wear and coefficient of friction became larger in
CO2/POE mixed environment, but wear and friction remained constant in CO2/PAG mixed
environment. The wear coefficients in CO2/PAG and CO2/POE mixed environment were 8.60×10-9
㎣/N·m and 2.35×10-8 ㎣/N·m, respectively.
The carbon dioxide (CO2) is investigated as an alternative refrigerant to replace HFC
(hydro fluorocarbon) refrigerants in refrigerators and air conditioning systems due to the
environmental concerns. Because new compressors with the carbon dioxide are going to be
operated under the high pressure, the tribology of sliding surfaces in the compressor becomes very
important. To develop new compressors, especially rotary type, the friction and wear characteristics
of sliding surfaces between a vane and a roller in the rotary compressor were evaluated in this
paper. Several hard coatings, such as TiN, CrN, and WC/C, were applied on vane surfaces in order
to improve the tribological characteristics, and their performances were evaluated experimentally.
The vane-on-disk type sliding tests were carried out under the various sliding speeds, normal loads,
and carbon dioxide pressures with an exclusive high pressure wear tester. From the tests wear
volume of vane surfaces applied various coatings were compared. During the tests coefficients of
friction and surface temperatures were monitored. Test results showed that WC/C coatings showed
good tribological properties. TiN and CrN coated vanes showed good wear resistance properties but
produced high friction.
The CO2 was investigated as an alternative refrigerant to replace HFC
(hydrofluorocarbons) refrigerant in air conditioning systems due to the environmental concerns.
Because new compressors with CO2 are going to be operated under the high pressure, the tribology
of sliding surfaces in the compressor becomes very important. To develop new compressor,
especially rotary type, the friction and wear characteristics of sliding surfaces between a vane and a
roller in the rotary compressor were evaluated in this paper. Several hard coatings, such as TiN,
CrN and WC/C, were applied on vane surfaces in order to improve the tribological characteristics,
and their performances were evaluated experimentally. Two types of lubricants were used, namely
POE (polyol ester) oil and PAG (polyalkylene glycol) oil. The vane-on-disk type sliding tests were
performed with an exclusive high pressure wear tester. From the tests, wear volumes of vane
surfaces applied various coatings were compared. Test results showed that WC/C and CrN coatings
showed good tribological properties. Also, the results of the sliding tests showed that using PAG oil
has an advantage over POE oil in CO2 environment.
Due to the environmental concerns, especially the greenhouse effect and GWP (Global
Warming Potential), the carbon dioxide was investigated as an alternative natural refrigerant to
replace HFCs (HydroFluoroCarbons) in refrigerator or air conditioning systems. To develop new
compressor, especially rotary type, the friction and wear characteristics of sliding surfaces between
vane and flange in the rotary compressor were evaluated in this paper. Several hard coatings, such
as TiN, CrN and WC/C, were applied on vane surfaces in order to improve the tribological
characteristics, and their performances were evaluated experimentally. The vane-on-flange type
lubricated sliding tests were performed with a high pressure wear tester using HFC (R410A) and
carbon dioxide. From the tests, wear volumes of vane surfaces applied with various coatings were
compared each other.
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