Ejector

Abstract

An ejector ( 200; 300; 400; 600 ) has a primary inlet ( 40 ), a secondary inlet ( 42 ), and an outlet ( 44 ). A primary flowpath extends from the primary inlet to the outlet. A secondary flowpath extends from the secondary inlet to the outlet. A mixer convergent section ( 114 ) is downstream of the secondary inlet. A motive nozzle ( 100 ) surrounds the primary flowpath upstream of a junction with the secondary flowpath. The motive nozzle has an exit ( 110 ). A secondary inlet passageway along the secondary flowpath has a terminal portion oriented to discharge a secondary flow along the secondary flowpath at an angle of less than 75° off-parallel to a local direction of the primary flowpath.

1 . An ejector ( 200 ;  300 ;  400 ;  600 ) comprising:
 a primary inlet ( 40 );   a secondary inlet ( 42 );   an outlet ( 44 );   a primary flowpath from the primary inlet to the outlet;   a secondary flowpath from the secondary inlet to the outlet;   a mixer convergent section ( 114 ) downstream of the secondary inlet; and   a motive nozzle ( 222 ) surrounding the primary flowpath upstream of a junction with the secondary flowpath and having an exit ( 110 );   
       wherein:
 a secondary inlet passageway ( 218 ;  218 A,  218 B;  218 ′A,  218 ′B;  218 ″A,  218 ″B) has a terminal portion oriented to discharge a secondary flow along the secondary flowpath at an angle (θ) of 10-75° off-parallel to a local direction of the primary flowpath; and 
 a center of an outlet of the terminal portion is at a radius (R 1 ) from an axis ( 500 ) of the motive nozzle and axially recessed by a distance (L 1 ) relative to the exit ( 110 ) of the motive nozzle. 
 
     
     
         2 . The ejector ( 200 ;  300 ;  600 ) of  claim 1  wherein:
 the motive nozzle is mounted in a first bore; and 
 the secondary inlet passageway is at least partially defined by a fitting mounted in a second bore. 
 
     
     
         3 . The ejector ( 600 ) of  claim 2  wherein:
 the fitting protrudes into a chamber ( 232 ) surrounding the motive nozzle. 
 
     
     
         4 . The ejector of  claim 2  wherein:
 the second bore is 30-60° off perpendicular to the first bore. 
 
     
     
         5 . The ejector of  claim 1  wherein:
 L 1  is less than 40 mm and R 1  is less than 45 mm. 
 
     
     
         6 . The ejector of  claim 1  wherein:
 said angle is 35-55°. 
 
     
     
         7 . The ejector ( 300 ;  400 ;  600 ) of  claim 1  wherein:
 there are at least two said secondary inlet passageways ( 218 A,  218 B;  218 ′A,  218 ′B;  218 ″A,  218 ″B). 
 
     
     
         8 . The ejector of  claim 1  further comprising:
 a needle ( 132 ) mounted for reciprocal movement along the primary flowpath between a first position and a second position; and 
 a needle actuator ( 134 ) coupled to the needle to drive said movement of the needle relative to the motive nozzle. 
 
     
     
         9 . The ejector of  claim 1  wherein:
 an outer member comprises an end-to-end axial assembly of a plurality of sections. 
 
     
     
         10 . The ejector of  claim 9  wherein the sections include:
 an upstream section ( 202 ) at least partially surrounding the motive nozzle; 
 one or more intermediate sections ( 204 ) at least partially defining a convergent portion ( 214 ) and a mixing portion ( 216 ); and 
 at least one downstream section ( 206 ) at least partially defining a divergent portion ( 118 ). 
 
     
     
         11 . The ejector of  claim 10  wherein:
 an interface of at least two of said sections ( 204 ,  206 ) comprises a boss of one section protruding into a compartment in the other section. 
 
     
     
         12 . A vapor compression system comprising:
 a compressor ( 22 );   a heat rejection heat exchanger ( 30 ) coupled to the compressor to receive refrigerant compressed by the compressor;   the ejector ( 200 ;  300 ;  400 ;  600 ) of  claim 1 ;   a heat absorption heat exchanger ( 64 ); and   a separator ( 48 ) having:
 an inlet ( 50 ) coupled to the outlet of the ejector to receive refrigerant from the ejector; 
 a gas outlet ( 54 ); and 
 a liquid outlet ( 52 ). 
   
     
     
         13 . A method for operating the system of  claim 12  comprising:
 compressing the refrigerant in the compressor; 
 rejecting heat from the compressed refrigerant in the heat rejection heat exchanger; 
 passing a flow of the refrigerant through the primary ejector inlet; and 
 passing a secondary flow of the refrigerant through the secondary inlet to merge with the primary flow. 
 
     
     
         14 . The method of  claim 13  wherein:
 the refrigerant comprises at least 50% CO 2  by weight. 
 
     
     
         15 . An ejector comprising:
 a primary inlet ( 40 );   a secondary inlet ( 42 );   an outlet ( 44 );   a primary flowpath from the primary inlet to the outlet;   a secondary flowpath from the secondary inlet to the outlet;   a convergent section ( 114 ) downstream of the secondary inlet;   a motive nozzle ( 222 ) surrounding the primary flowpath upstream of a junction with the secondary flowpath and having:
 a throat ( 106 ); and 
 an exit ( 110 ); and 
   means for efficiently promoting mixing of the secondary flow into the primary flow.   
     
     
         16 . The ejector of  claim 15  wherein:
 the means comprises an off-radially directed terminal portion of of a secondary passageway from the secondary inlet. 
 
     
     
         17 . The ejector of  claim 15  wherein:
 a center of an outlet of the terminal portion is at a radius (R 1 ) from an axis ( 500 ) of the motive nozzle and axially recessed by a distance (L 1 ) relative to the exit ( 110 ) of the motive nozzle. 
 
     
     
         18 . The ejector of  claim 17  wherein:
 L 1  is at least 5 mm. 
 
     
     
         19 . The ejector of  claim 1  wherein:
 an axis of an outlet of the terminal portion intersects an axis of the motive nozzle at a location upstream of the exit of the motive nozzle. 
 
     
     
         20 . The ejector of  claim 1  wherein:
 L 1  is at least 5 mm.