Patent ID: 7334426

Claim:
A refrigerating apparatus comprising: a heat source side circuit ( 11 ) which is provided with a compressor ( 21 ) and a heat source side heat exchanger ( 24 ) and which is connected to a user side heat exchanger ( 33 ) by means of an existing liquid side communication pipe ( 60 ) and an existing gas side communication pipe ( 70 ), the refrigerating apparatus performing cleaning operation for removing refrigerating machine oil for an old refrigerant from the existing liquid side communication pipe ( 60 ) and the existing gas side communication pipe ( 70 ) by operating the compressor ( 21 ), wherein an operation condition in the cleaning operation is set based on a Froude number Fr expressed by an expression Fr=(d g /d l )×(U 2 /gD) where U is a velocity of a gas refrigerant flowing through the gas side communication pipe ( 70 ), D is an inner diameter of the gas side communication pipe ( 70 ), d g is a density of the gas refrigerant flowing through the gas side communication pipe ( 70 ), d l is a density of a liquid existing in the gas side communication pipe ( 70 ), and g is a gravitational acceleration.