Refrigeration apparatus and use thereof

Abstract

A refrigeration apparatus, including a main refrigerant circuit ( 1 ), including a compressor ( 2 ), a condenser ( 4 ), an expansion valve ( 6 ), and a refrigerant passage ( 61 ) extending within an evaporator ( 8 ), the apparatus including a coolant passage ( 71 ) extending within the evaporator ( 8 ). The refrigeration apparatus further includes a lubrication branch ( 20 ), connected to a supply part ( 4, 16 ) of the main circuit ( 1 ) to derive a lubrication refrigerant flow ( 91 ) for lubrication of said compressor ( 2 ). The refrigeration apparatus further includes a subcooling branch ( 40 ), comprising: a subcooling inlet ( 41 ), connected to the coolant passage ( 71 ), so as to derive a subcooling coolant flow ( 92 ) from the main coolant flow ( 93 ), and a subcooling outlet ( 42 ), connected to the coolant passage ( 71 ), for reintroducing the subcooling coolant flow ( 92 ) into the main coolant flow ( 93 ); and a subcooling heat exchanger ( 31 ).

What is claimed is: 
     
         1 . A refrigeration apparatus, comprising a main refrigerant circuit, including:
 a compressor, including a compressor inlet and a compressor outlet,   a condenser, including a condenser inlet, connected to the compressor outlet, and a condenser outlet,   an expansion valve, including a valve inlet, connected to the condenser outlet and a valve outlet, and   a refrigerant passage, extending at least partially within an evaporator of the refrigeration apparatus, the refrigerant passage including a refrigerant passage inlet, connected to the valve outlet, and a refrigerant passage outlet, connected to the compressor inlet, the refrigeration apparatus also including a coolant passage extending at least partially within the evaporator and including a coolant passage inlet and a coolant passage outlet,   wherein the main refrigerant circuit is configured for a loop circulation of a main refrigerant flow of a refrigerant, successively through the compressor, the condenser, the expansion valve, and the refrigerant passage,   wherein the evaporator is configured for enabling an exchange of heat between the main refrigerant flow circulating through the refrigerant passage and a main coolant flow of a coolant circulating through the coolant passage,   wherein the refrigeration apparatus further comprises a lubrication branch, comprising:   a lubrication inlet, connected to a supply part of the main circuit, the supply part consisting in the condenser, the valve inlet, and any part of the main circuit between the condenser outlet and the valve inlet, the lubrication inlet being configured to derive a lubrication refrigerant flow from the main refrigerant flow circulating through the supply part; and   a lubrication outlet, connected to the compressor so as to feed the compressor with the lubrication refrigerant flow, for lubrication of said compressor with the refrigerant of the lubrication refrigerant flow,   wherein the refrigeration apparatus further comprises:   a subcooling branch, comprising:
 a subcooling inlet, connected to the coolant passage, so as to derive a subcooling coolant flow from the main coolant flow, and 
 a subcooling outlet, connected to the coolant passage, for reintroducing the subcooling coolant flow into the main coolant flow; and 
   a subcooling heat exchanger, being configured for enabling an exchange of heat between the subcooling coolant flow circulating through the subcooling branch and the lubrication refrigerant flow circulating through the lubrication branch, so that the lubrication refrigerant flow may be cooled by the subcooling coolant flow within the subcooling heat exchanger.   
     
     
         2 . The refrigeration apparatus according to  claim 1 , wherein:
 the subcooling inlet is connected to a coolant passage inlet of the coolant passage, so as to derive the subcooling coolant flow from the main coolant flow circulating through the coolant passage inlet, and   the subcooling outlet is connected to a coolant passage outlet of the coolant passage, for reintroducing the subcooling coolant flow into the main coolant flow circulating through the coolant passage outlet.   
     
     
         3 . The refrigeration apparatus according to  claim 1 , wherein:
 the refrigerant passage comprises an evaporator tank of the evaporator, the evaporator tank being connected to the refrigerant passage inlet, for admitting the main refrigerant flow into the evaporator tank, and to the refrigerant passage outlet, for discharging the main refrigerant flow from the evaporator tank; and   the coolant passage comprises at least one heat exchange duct of the evaporator, the heat exchange duct extending within the evaporator tank so as to be surrounded by the main refrigerant flow received within the evaporator tank, the heat exchange duct being connected to the coolant passage inlet, for admitting the main coolant flow into the heat exchange duct, and to the coolant passage outlet, for discharging of the main coolant flow from the heat exchange duct.   
     
     
         4 . The refrigeration apparatus according to  claim 1 , wherein the subcooling heat exchanger is positioned outside of the evaporator. 
     
     
         5 . The refrigeration apparatus according to  claim 1 , wherein the subcooling heat exchanger comprises:
 a heat exchange tank, belonging to the lubrication branch and being configured so that the lubrication refrigerant flow circulates through the heat exchange tank, and   a heat exchange passage, belonging to the subcooling branch, being positioned within the heat exchange tank and being configured so that the subcooling coolant flow circulates through the heat exchange passage.   
     
     
         6 . The refrigeration apparatus according to  claim 5 , wherein the lubrication branch comprises:
 an inlet duct, connecting the lubrication inlet to the heat exchange tank, for circulation of the lubrication refrigerant flow from the lubrication inlet to the heat exchange tank, and comprising an open inlet end positioned within the heat exchange tank for admission of the lubrication refrigerant flow into the heat exchange tank; and   an outlet duct, connecting the heat exchange tank to the lubrication outlet, for circulation of the lubrication refrigerant flow from the heat exchange tank to the lubrication outlet, and comprising an open outlet end positioned within the heat exchange tank, at a lower height than the open inlet end.   
     
     
         7 . The refrigeration apparatus according to  claim 5 , wherein the heat exchange tank is positioned at a higher height than the lubrication outlet, so that the compressor is fed with the lubrication refrigerant flow by gravity. 
     
     
         8 . The refrigeration apparatus according to  claim 5 , wherein the heat exchange tank comprises at least one liquid level sensor, detecting the presence of liquid refrigerant at a respective height within the heat exchange tank. 
     
     
         9 . The refrigeration apparatus according to  claim 5 , wherein the heat exchange passage is a coil duct. 
     
     
         10 . The refrigeration apparatus according to  claim 1 , wherein, for being connected to the supply part, the lubrication inlet is connected to a bottom part of the condenser. 
     
     
         11 . The refrigeration apparatus according to  claim 1 , wherein the compressor is a positive displacement-type compressor. 
     
     
         12 . The refrigeration apparatus according to  claim 1 , wherein:
 the compressor is a screw compressor comprising two meshing screw rotors and bearings, the screw-rotors being supported by the bearings, and   the lubrication outlet is connected to the compressor so as to feed the bearings and the screw rotors with the lubrication refrigerant flow, for lubrication of said bearings and screw rotors.   
     
     
         13 . A refrigeration system, comprising a refrigeration apparatus according to  claim 1 , and comprising a main coolant circuit, including the coolant passage and at least one client device to be cooled by the main coolant flow, the main coolant circuit being configured for loop circulation of the main coolant flow through the main coolant circuit, successively through the coolant passage and said at least one client device. 
     
     
         14 . The refrigeration system according to  claim 13 , wherein the coolant of the main coolant flow comprises water. 
     
     
         15 . A use of the refrigeration apparatus according to  claim 1 , the use including:
 closed loop circulation of the main refrigerant flow successively through the compressor inlet, the compressor, the compressor outlet, the condenser inlet, the condenser, the condenser outlet, the valve inlet, the expansion valve, the valve outlet, the refrigerant passage inlet, the refrigerant passage, and the refrigerant passage outlet;   derivation of the lubrication refrigerant flow from the main refrigerant flow circulating through the supply part, by the lubrication inlet,   circulation of the lubrication refrigerant flow through the lubrication branch, successively through the lubrication inlet, the subcooling heat exchanger and the lubrication outlet,   derivation of the subcooling coolant flow from the main coolant flow circulating through the coolant passage, by the subcooling inlet,   circulation of the subcooling coolant flow through the subcooling branch, successively through the subcooling inlet, the subcooling heat exchanger and the subcooling outlet,   exchange of heat between the subcooling coolant flow and the lubrication refrigerant flow in the subcooling heat exchanger, so that the lubrication refrigerant flow is cooled by the subcooling coolant flow,   feeding of the compressor, by the lubrication outlet, with the lubrication refrigerant flow that was cooled by the subcooling coolant flow in the subcooling heat exchanger, for lubrication of the compressor, and   reintroduction, by the subcooling outlet, of the subcooling coolant flow that has cooled the lubrication refrigerant flow in the subcooling heat exchanger, into the main coolant flow circulating through the coolant passage.