REFRIGERATING MACHINE OIL FOR CARBON DIOXIDE REFRIGERANT AND FLUID COMPOSITION FOR REFRIGERATING MACHINE

摘要

PROBLEM TO BE SOLVED: To obtain both a refrigerating machine oil for a carbon dioxide refrigerant which has a sufficiently wide composition range exhibiting compatibility in mixing with a carbon dioxide refrigerant under a low-temperature condition and excellent lubricating properties and stability and sufficiently prevents a bad lubrication in use in a refrigerating machine for a carbon dioxide refrigerant, with which a sufficiently high heat exchange ratio can be obtained and a fluid composition for a refrigerating machine using the same. SOLUTION: This refrigerating machine oil for carbon dioxide refrigerant is characterized by comprising a polyalkylene glycol represented by general formula (1): R1-(OR3)n-OR2 [R1 and R2 are each a 1-5C alkyl group or a 2-5C acyl group; R3 is a 2-4C alkylene group; n is an integer of making a number- average molecular weight 500-3,000] and having 5-20 mm2/s kinematic viscosity.