Refrigeration system

Abstract

A refrigeration system ( 1 ) includes first to third compressors ( 11 a , 11 b , 11 c ) connected in parallel and an oil separator for separating a refrigeration oil from a refrigerant discharged from the compressors ( 11 a , 11 b , 11 c ). A main suction pipe ( 55 ) in which a refrigerant to be sucked into the compressors ( 11 a , 11 b , 11 c ) flows includes a primary curved portion ( 101 ) and a primary branch element ( 102 ) assembled to part of the main suction pipe ( 55 ) downstream of a junction with an oil return pipe ( 71 ) for returning the refrigeration oil separated by the oil separator. The main suction pipe ( 55 ) is branched by the primary branch element ( 102 ) into a first suction pipe branch ( 61 a ) of the first compressor ( 11 a ) and a connecting suction pipe ( 56 ). In the primary branch element ( 102 ), the first suction pipe branch ( 61 a ) is at the bottommost position and the outermost position in the direction of a radius of curvature of the primary curved portion ( 101 ).

1 . A refrigeration system comprising a refrigerant circuit ( 10 ) including a plurality of compressors ( 11   a ,  11   b ,  11   c ) connected in parallel and an oil separator ( 70 ) for separating a refrigeration oil from a refrigerant discharged from the compressors ( 11   a ,  11   b ,  11   c ),
 the refrigerant circuit ( 10 ) including a main suction pipe ( 55 ) in which a refrigerant to be sucked into the compressors ( 11   a ,  11   b ,  11   c ) flows, suction pipe branches ( 61   a ,  61   b ,  61   c ) for distributing the refrigerant in the main suction pipe ( 55 ) to the compressors ( 11   a ,  11   b ,  11   c ) and an oil return pipe ( 71 ) for returning the refrigeration oil separated by the oil separator ( 70 ) to the main suction pipe ( 55 ), wherein   a primary flow biasing element ( 110 ) for biasing the flow of the refrigeration oil is assembled to part of the main suction pipe ( 55 ) downstream of a junction of the main suction pipe ( 55 ) and the oil return pipe ( 71 ) so that a larger amount of the refrigeration oil flows into the suction pipe branch ( 61   a ) of the first compressor ( 11   a ) previously chosen from the compressors ( 11   a ,  11   b ,  11   c ).   
   
   
       2 . A refrigeration system comprising a refrigerant circuit ( 10 ) including a plurality of compressors ( 11   a ,  11   b ,  11   c ) connected in parallel and an oil separator ( 70 ) for separating a refrigeration oil from a refrigerant discharged from the compressors ( 11   a ,  11   b ,  11   c ),
 the refrigerant circuit ( 10 ) including a main suction pipe ( 55 ) in which a refrigerant to be sucked into the compressors ( 11   a ,  11   b ,  11   c ) flows, suction pipe branches ( 61   a ,  61   b ,  61   c ) for distributing the refrigerant in the main suction pipe ( 55 ) to the compressors ( 11   a ,  11   b ,  11   c ) and an oil return pipe ( 71 ) for returning the refrigeration oil separated by the oil separator ( 70 ) to the main suction pipe ( 55 ), wherein   a primary curved portion ( 101 ) and a primary branch element ( 102 ) for branching the main suction pipe ( 55 ) into the suction pipe branches ( 61   a ,  61   h ,  61   c ) are assembled to part of the main suction pipe ( 55 ) downstream of a junction of the main suction pipe ( 55 ) and the oil return pipe ( 71 ), the primary branch element ( 102 ) being located downstream of the primary curved portion ( 101 ), and   the suction pipe branch ( 61   a ) of the first compressor ( 11   a ) previously chosen from the compressors ( 11   a ,  11   b ,  11   c ) is at the outermost position in the primary branch element ( 102 ) in the direction of a radius of curvature of the primary curved portion ( 101 ).   
   
   
       3 . A refrigeration system comprising a refrigerant circuit ( 10 ) including a plurality of compressors ( 11   a ,  11   b ,  11   c ) connected in parallel and an oil separator ( 70 ) for separating a refrigeration oil from a refrigerant discharged from the compressors ( 11   a ,  11   b ,  11   c ),
 the refrigerant circuit ( 10 ) including a main suction pipe ( 55 ) in which a refrigerant to be sucked into the compressors ( 11   a ,  11   b ,  11   c ) flows, suction pipe branches ( 61   a ,  61   b ,  61   c ) for distributing the refrigerant in the main suction pipe ( 55 ) to the compressors ( 11   a ,  11   b ,  11   c ) and an oil return pipe ( 71 ) for returning the refrigeration oil separated by the oil separator ( 70 ) to the main suction pipe ( 55 ), wherein   the suction pipe branch ( 61   a ) of the first compressor ( 11   a ) previously chosen from the compressors ( 11   a ,  11   b ,  11   c ) is at the bottommost position in a primary branch element ( 102 ) for branching the main suction pipe ( 55 ) into the suction pipe branches ( 61   a ,  61   b ,  61   c ).   
   
   
       4 . The refrigeration system of  claim 2 , wherein
 the suction pipe branch ( 61   a ) of the first compressor ( 11   a ) is at the bottommost position in the primary branch element ( 102 ).   
   
   
       5 . The refrigeration system of  claim 1 , wherein
 the plurality of compressors ( 11   a ,  11   b ,  11   c ) are first to third compressors ( 11   a ,  11   b ,  11   c ),   the main suction pipe ( 55 ) is branched into the suction pipe branch ( 61   a ) of the first compressor ( 11   a ) and a connecting suction pipe ( 56 ) which is branched into the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) and the suction pipe branch ( 61   c ) of the third compressor ( 11   c ), and   a secondary flow biasing element ( 120 ) for biasing the flow of the refrigeration oil in the connecting suction pipe ( 56 ) is provided so that more refrigeration oil flows into the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) than into the suction pipe branch ( 61   c ) of the third compressor ( 11   c ).   
   
   
       6 . The refrigeration system of  claim 2 , wherein
 the plurality of compressors ( 11   a ,  11   b ,  11   c ) are first to third compressors ( 11   a ,  11   b ,  11   c ),   the main suction pipe ( 55 ) is branched by the primary branch element ( 102 ) into the suction pipe branch ( 61   a ) of the first compressor ( 11   a ) and a connecting suction pipe ( 56 ) which is branched by a secondary branch element ( 104 ) into the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) and the suction pipe branch ( 61   c ) of the third compressor ( 11   c ),   the connecting suction pipe ( 56 ) is provided with a secondary curved portion ( 103 ) and   the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) is positioned outside the suction pipe branch ( 61   c ) of the third compressor ( 11   c ) in the secondary branch element ( 104 ) in the direction of a radius of curvature of the secondary curved portion ( 103 ).   
   
   
       7 . The refrigeration system of  claim 2 , wherein
 the plurality of compressors ( 11   a ,  11   b ,  11   c ) are first to third compressors ( 11   a ,  11   b ,  11   c ),   the main suction pipe ( 55 ) is branched by the primary branch element ( 102 ) into the suction pipe branch ( 61   a ) of the first compressor ( 11   a ) and a connecting suction pipe ( 56 ) which is branched by a secondary branch element ( 104 ) into the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) and the suction pipe branch ( 61   c ) of the third compressor ( 11   c ), and   the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) is positioned lower than the suction pipe branch ( 61   c ) of the third compressor ( 11   c ) in the secondary branch element ( 104 ).   
   
   
       8 . The refrigeration system of  claim 6 , wherein
 the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) is positioned lower than the suction pipe branch ( 61   c ) of the third compressor ( 11   c ) in the secondary branch element ( 104 ).   
   
   
       9 . The refrigeration system of  claim 2 , wherein
 the plurality of compressors ( 11   a ,  11   b ,  11   c ) are first to third compressors ( 11   a ,  11   b ,  11   c ),   the main suction pipe ( 55 ) is branched by the primary branch element ( 102 ) into the suction pipe branch ( 61   a ) of the first compressor ( 11   a ) and a connecting suction pipe ( 56 ) which is branched by a secondary branch element ( 104 ) into the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) and the suction pipe branch ( 61   c ) of the third compressor ( 11   c ), and   the suction pipe branch ( 61   b ) of the second compressor ( 11   b ) is positioned outside the suction pipe branch ( 61   c ) of the third compressor ( 11   c ) in the secondary branch element ( 104 ) in the direction of a radius of curvature of the primary curved portion ( 101 ) of the main suction pipe ( 55 ).   
   
   
       10 . The refrigeration system of  claim 1 , further comprising
 oil equalizers ( 72 ,  73 ) for supplying the refrigeration oil accumulated in a casing of the first compressor ( 11   a ) to the other compressors ( 11   b ,  11   c ).   
   
   
       11 . The refrigeration system of  claim 1 , further comprising
 oil equalizers ( 72 ,  73 ,  74 ) for equalizing the amounts of the refrigeration oil accumulated in casings of the compressors ( 11   a ,  11   b ,  11   c ).   
   
   
       12 . The refrigeration system of  claim 5 , further comprising
 a first oil equalization pipe ( 72 ) for supplying the refrigeration oil accumulated in a casing of the first compressor ( 11   a ) to the connecting suction pipe ( 56 ) or the suction pipe branch ( 61   b ) of the second compressor ( 11   b ), a second oil equalization pipe ( 73 ) for supplying the refrigeration oil accumulated in a casing of the second compressor ( 11   b ) to the suction pipe branch ( 61   c ) of the third compressor ( 11   c ) and a third oil equalization pipe ( 74 ) for supplying the refrigeration oil accumulated in a casing of the third compressor ( 11   c ) to the main suction pipe ( 55 ) or the oil return pipe ( 71 ).   
   
   
       13 . The refrigeration system of  claim 1 , wherein
 the first compressor ( 11   a ) is a capacity invariable compressor.   
   
   
       14 . The refrigeration system of  claim 1 , wherein
 each of the compressors ( 11   a ,  11   b ,  11   c ) is so configured that the refrigeration oil is accumulated in high pressure space in the casing.   
   
   
       15 . The refrigeration system of  claim 1 , wherein
 liquid injection pipes ( 86 ,  86   a ,  86   b ,  86   c ) for introducing a portion of a liquid refrigerant flowing in a liquid pipe ( 84 ) on a high pressure side of the refrigerant circuit ( 10 ) to the suction pipe branches ( 61   a ,  61   b ,  61   c ) of the compressors ( 11   a ,  11   b ,  11   c ) are connected to the suction pipe branches ( 61   a ,  61   b ,  61   c ).   
   
   
       16 . The refrigeration system of  claim 1 , further comprising
 oil collecting pipes ( 75 ,  76 ,  77 ) connected to the suction pipe branches ( 61   a ,  61   b ,  61   c ) of the compressors ( 11   a ,  11   b ,  11   c ) at one end, respectively, and connected to each other at the other end.   
   
   
       17 . A refrigeration system comprising a refrigerant circuit ( 10 ) including a plurality of compressors ( 11   a ,  11   b ,  11   c ) connected in parallel and an oil separator ( 70 ) for separating a refrigeration oil from a refrigerant discharged from the compressors ( 11   a ,  11   b ,  11   c ),
 the refrigerant circuit ( 10 ) including a main suction pipe ( 55 ) in which a refrigerant to be sucked into the compressors ( 11   a ,  11   b ,  11   c ) flows, suction pipe branches ( 61   a ,  61   b ,  61   c ) for distributing the refrigerant in the main suction pipe ( 55 ) to the compressors ( 11   a ,  11   b ,  11   c ) and an oil return pipe ( 71 ) for returning the refrigeration oil separated by the oil separator ( 70 ) to the main suction pipe ( 55 ), wherein   oil collecting pipes ( 75 ,  76 ,  77 ) connected to the suction pipe branches ( 61   a ,  61   b ,  61   c ) of the compressors ( 11   a ,  11   b ,  11   c ) at one end, respectively, and connected to each other at the other end are provided.   
   
   
       18 . The refrigeration system of  claim 16 , wherein
 each of the suction pipe branches ( 61   a ,  61   b ,  61   c ) has an oblique portion ( 59 ) extending obliquely upward in the downstream direction from a certain position of a barrel of the suction pipe branch ( 61   a ,  61   b ,  61   c ) and an oil storing portion ( 58 ) formed upstream of the oblique portion ( 59 ) and   the one ends of the oil collecting pipes ( 75 ,  76 ,  77 ) are connected to the oil storing portions ( 58 ).   
   
   
       19 . The refrigeration system of  claim 17 , wherein
 the suction pipe branch ( 61   a ,  61   b ,  61   c ) has an oblique portion ( 59 ) extending obliquely upward in the downstream direction from a certain position of a barrel of the suction pipe branch ( 61   a ,  61   b ,  61   c ) and an oil storing portion ( 58 ) formed upstream of the oblique portion ( 59 ) and   the one ends of the oil collecting pipes ( 75 ,  76 ,  77 ) are connected to the oil storing portions ( 58 ).   
   
   
       20 . The refrigeration system of  claim 6 , further comprising
 a first oil equalization pipe ( 72 ) for supplying the refrigeration oil accumulated in a casing of the first compressor ( 11   a ) to the connecting suction pipe ( 56 ) or the suction pipe branch ( 61   b ) of the second compressor ( 11   b ), a second oil equalization pipe ( 73 ) for supplying the refrigeration oil accumulated in a casing of the second compressor ( 11   b ) to the suction pipe branch ( 61   c ) of the third compressor ( 11   c ) and a third oil equalization pipe ( 74 ) for supplying the refrigeration oil accumulated in a casing of the third compressor ( 11   c ) to the main suction pipe ( 55 ) or the oil return pipe ( 71 ).   
   
   
       21 . The refrigeration system of  claim 7 , further comprising
 a first oil equalization pipe ( 72 ) for supplying the refrigeration oil accumulated in a casing of the first compressor ( 11   a ) to the connecting suction pipe ( 56 ) or the suction pipe branch ( 61   b ) of the second compressor ( 11   b ), a second oil equalization pipe ( 73 ) for supplying the refrigeration oil accumulated in a casing of the second compressor ( 11   b ) to the suction pipe branch ( 61   c ) of the third compressor ( 11   c ) and a third oil equalization pipe ( 74 ) for supplying the refrigeration oil accumulated in a casing of the third compressor ( 11   c ) to the main suction pipe ( 55 ) or the oil return pipe ( 71 ).