Oil Separation in a Cooling Circuit

Abstract

The invention concerns a method and a cooling system for oil separation in a cooling circuit, including compression means ( 4 ) that supply coolant under a first high pressure through means for oil separation ( 10 ) and further on through condensing means ( 12 ), from where coolant is applied restriction means ( 16 ), from where coolant is conducted to flooded evaporation means ( 18 ), from where the compression means ( 4 ) suck gaseous coolant back, where remaining oil in the flooded evaporation means is returned to the cooling circuit through an oil removal circuit ( 26 ). It is the purpose of the invention to achieve an efficient oil separation from a flooded evaporator ( 18 ). This may be attained by the cooling system according to the invention, in that the oil removal circuit ( 26 ) includes a pump ( 24 ), the suction side of which being connected to the flooded evaporator ( 18 ), where the pressure outlet of the pump is connected to a pressure connection ( 9 ) between the pressure outlet of the compressor ( 4 ) and the oil separator ( 10 ).

1 . A method for oil separation in a cooling circuit ( 2 ), including compression means ( 4 ) that deliver coolant under a first high pressure through means for oil separation ( 10 ) and further on through condensing means ( 12 ), from where coolant in liquid state is applied restriction means ( 16 ), from where coolant under a second lower pressure is conducted to at least one flooded evaporation means ( 18 ), from where coolant, which is mainly in gaseous state, is conducted to the suction side of the compression means ( 4 ), where remaining oil in the flooded evaporation means ( 18 ) is returned to the cooling circuit ( 2 ) through an oil removal circuit ( 22 ,  24 ,  26 ,  28 ,  30 ), characterised in that the oil removal circuit ( 22 ,  24 ,  26 ,  28 ,  30 ) includes means ( 24 ) for pumping oil from the flooded evaporation means ( 18 ) and to a point ( 9 ) in a pressure connection forming a coolant connection between the pressure outlet of the compression means ( 4 ) and at least one oil separation means ( 10 ). 
   
   
       2 . A cooling system ( 2 ) containing at least one compressor ( 4 ) having a pressure outlet ( 6 ), which is connected to an oil separator ( 10 ), where the oil separator ( 10 ) is further connected to at least one condenser ( 12 ), from where the coolant is conducted through a coolant line ( 14 ) to at least one restriction element ( 16 ) communicating with at least one flooded evaporator ( 18 ), from where primarily gaseous coolant flows to the suction side ( 6 ) of the compressor, where an oil removal circuit ( 22 ,  24 ,  26 ,  28 ,  30 ) connected to the coolant circuit ( 2 ) is provided in connection with the flooded evaporator ( 18 ), characterised in that the oil removal circuit ( 22 ,  24 ,  26 ,  28 ,  30 ) includes a pump ( 24 ), the suction side ( 22 ) of which being connected to the flooded evaporator ( 18 ), where the pressure outlet of the pump is connected to a point ( 9 ) in a pressure connection between the pressure outlet of the compressor ( 8 ) and the oil separator ( 10 ). 
   
   
       3 . Cooling system according to  claim 1 , characterised in that the outlet ( 8 ) of the pump ( 24 ) communicates with pressure control valves ( 28 - 32 ), from where excess coolant is conducted to the flooded evaporator ( 18 ) via pressure control valves ( 32 ). 
   
   
       4 . Coolant ( 2 ) according to  claim 1 , characterised in that the cooling system ( 2 ) contains a number of compressors ( 4 ) having coolant communication through oil separators ( 10 ) and further on through at least one condenser ( 12 ) to a number of expansion elements ( 16 ), from where coolant is conducted to a number of independent evaporators ( 18 ) where flooded evaporators ( 18 ) are connected to the oil removal circuit ( 22 ,  24 ,  26 ), where an outlet connection ( 26 ) from the oil removal circuit forms a connection to a central oil distribution circuit, where oil is conducted to the active compressors depending on the actual oil level in each individual compressor. 
   
   
       5 . Cooling system according to  claim 1 , characterised in that the mixture of oil and fluid and/or gaseous coolant flows through a preheater ( 42 ) before the mixture is supplied to the pressure connection ( 8 ) between the pressure outlet of the compressor and the oil separator ( 110 ). 
   
   
       6 . Cooling system according to  claim 5 , characterised in that the preheater ( 42 ) is contained in the oil separator ( 110 ).