Refrigeration system

Abstract

A refrigerant circuit ( 11 ) in an air conditioner ( 10 ) includes a compressor ( 20 ) and an expander ( 30 ). In the compressor ( 20 ), refrigerant compressed by a compression mechanism ( 21 ) is discharged into the internal space of a compressor casing ( 24 ). In the compressor ( 20 ), refrigeration oil which has accumulated in the bottom of the compressor casing ( 24 ) is supplied to the compression mechanism ( 21 ). The refrigeration oil in the bottom of the compressor casing ( 24 ) is directly introduced into an expansion mechanism ( 31 ) of the expander ( 30 ) through an oil supply pipe ( 41 ).

1 . A refrigeration system, comprising a refrigerant circuit ( 11 ) including a compressor ( 20 ) and an expander ( 30 ), the refrigeration system performs a refrigeration cycle by circulating refrigerant in the refrigerant circuit ( 11 ), wherein
 the compressor ( 20 ) includes a compressor casing ( 24 ) in the shape of a sealed vessel and a compression mechanism ( 21 ) housed in the compressor casing ( 24 ) and configured to compress sucked refrigerant and to discharge the compressed refrigerant into the compressor casing ( 24 ), and supplies lubricating oil stored in the compressor casing ( 24 ) to the compression mechanism ( 21 ),   the expander ( 30 ) includes an expansion mechanism ( 31 ) for generating power by expansion of inflow refrigerant and an expander casing ( 34 ) housing the expansion mechanism ( 31 ), and   an oil supply passageway ( 41 ) for supplying the lubricating oil stored in the compressor casing ( 24 ) to the expansion mechanism ( 31 ) is provided such that the expansion mechanism ( 31 ) is lubricated with the lubricating oil supplied through the oil supply passageway ( 41 ).   
   
   
       2 . The refrigeration system of  claim 1 , further comprising an oil supply pipe ( 41 ) having an end connected to a bottom of the compressor casing ( 24 ) and another end connected to the expansion mechanism ( 31 ), wherein
 the oil supply pipe ( 41 ) forms the oil supply passageway.   
   
   
       3 . The refrigeration system of  claim 1 , further comprising an oil return passageway ( 42 ) for returning lubricating oil which has accumulated in the expander casing ( 34 ) to the compressor ( 20 ). 
   
   
       4 . The refrigeration system of  claim 3 , wherein the oil return passageway ( 42 ) is configured to introduce lubricating oil to a suction side of the compression mechanism ( 21 ). 
   
   
       5 . The refrigeration system of  claim 1 , further comprising a cooling heat exchanger ( 46 ) for cooling lubricating oil flowing in the oil supply passageway ( 41 ) by performing heat exchange with refrigerant sucked into the compression mechanism ( 21 ). 
   
   
       6 . The refrigeration system of  claim 3 , further comprising a cooling heat exchanger ( 47 ) for cooling lubricating oil flowing in the oil supply passageway ( 41 ) by performing heat exchange with lubricating oil flowing in the oil return passageway ( 42 ). 
   
   
       7 . The refrigeration system of  claim 1 , further comprising a cooling heat exchanger ( 48 ) for cooling lubricating oil flowing in the oil supply passageway ( 41 ) by performing heat exchange with outdoor air. 
   
   
       8 . The refrigeration system of one of  claims 1  to  7 , wherein the refrigerant circuit ( 11 ) includes a first suction-side passageway ( 17 ) for establishing communication between an evaporator of the refrigerant circuit ( 11 ) and internal space of the expander casing ( 34 ), and a second suction-side passageway ( 18 ) for establishing communication between the internal space of the expander casing ( 34 ) and a suction side of the compression mechanism ( 21 ), and
 the expander casing ( 34 ) is configured to separate refrigerant from the first suction-side passageway ( 17 ) into gas refrigerant and liquid refrigerant, and to send the gas refrigerant to the second suction-side passageway ( 18 ).   
   
   
       9 . The refrigeration system of  claim 8 , wherein the expander ( 30 ) includes an electric generator ( 33 ) housed in the expander casing ( 34 ) and driven by the expansion mechanism ( 31 ), and
 the first suction-side passageway ( 17 ) communicates with a portion of the internal space of the expander casing ( 34 ) below the electric generator ( 33 ), whereas the second suction-side passageway ( 18 ) communicates with a portion of the internal space of the expander casing ( 34 ) above the electric generator ( 33 ).