Ejectors and Methods of Use

Abstract

An ejector has: a motive flow inlet ( 40 ); a secondary flow inlet ( 42 ); an outlet ( 44 ); a motive flow nozzle ( 242 ) having an outlet ( 110 ); a primary flowpath from the motive flow inlet through the motive flow nozzle to the ejector outlet; a secondary flowpath from the secondary flow inlet to the ejector outlet, merging with the primary flowpath at the motive nozzle outlet; a control needle ( 200; 300; 400 ) shiftable along a range of motion between a first condition and a second condition and seated against the motive nozzle in the second condition. The needle comprises: a main shaft ( 210 ); a tip ( 204 ); a first portion ( 220; 320 ) converging toward the tip; and a shoulder portion ( 214; 314; 422 ) between the first portion and the main shaft and seated against the motive nozzle in the second condition and converging toward the tip at a greater angle ( ?1; ?1 2 ) than an angle ( ?2; ?2 2 ) of the first portion.

What is claimed is: 
     
         1 . An ejector comprising:
 a motive flow inlet ( 40 );   a secondary flow inlet ( 42 );   an outlet ( 44 );   a motive flow nozzle ( 242 ) having an outlet ( 110 );   a primary flowpath from the motive flow inlet through the motive flow nozzle to the ejector outlet;   a secondary flowpath from the secondary flow inlet to the ejector outlet, merging with the primary flowpath at the motive nozzle outlet;   a control needle ( 200 ;  300 ;  400 ) shiftable along a range of motion between a first condition and a second condition and seated against the motive nozzle in the second condition,   
       wherein the needle comprises:
 a main shaft ( 210 ); 
 a tip ( 204 ); 
 a first portion ( 220 ;  320 ) converging toward the tip; and 
 a shoulder portion ( 214 ;  314 ;  422 ) between the first portion and the main shaft and seated against the motive nozzle in the second condition and converging toward the tip at a greater angle (θ 1 ; θ 1-2 ) than an angle (θ 2 ; θ 2-2 ) of the first portion. 
 
     
     
         2 . The ejector of  claim 1  wherein:
 the shoulder portion angle (θ 1 ) is 15° to 75°; and 
 the first portion angle (θ 2 ) is 5° to 60°. 
 
     
     
         3 . The ejector of  claim 1  wherein:
 the shoulder portion angle (θ 1-2 ) is 75° to 115°; and 
 the first portion angle (θ 2-2 ) is 5° to 60°. 
 
     
     
         4 . The ejector of  claim 1  wherein:
 the shoulder portion angle (O f ) is 10° to 30° greater than the first portion angle (θ 2 ). 
 
     
     
         5 . The ejector of  claim 1  wherein:
 the shoulder portion angle (θ 1-2 ) is 5° to 80° greater than the first portion angle (θ 2-2 ). 
 
     
     
         6 . The ejector of  claim 1  wherein:
 a throat of the motive nozzle has clearance relative to the needle in the second condition. 
 
     
     
         7 . The ejector of  claim 1  wherein:
 the motive nozzle is made of stainless steel; and 
 the needle is made of stainless steel. 
 
     
     
         8 . The ejector of  claim 1  wherein:
 the needle comprises a transition section ( 330 ) between the first portion and the second portion and being closer to cylindrical than the first portion and the second portion. 
 
     
     
         9 . The ejector of  claim 1  wherein:
 the motive nozzle is a convergent-divergent nozzle. 
 
     
     
         10 . The ejector of  claim 1  further comprising:
 a mixer comprising a convergent portion at least partially downstream of the motive nozzle; and 
 a divergent diffuser portion downstream of the convergent portion. 
 
     
     
         11 . 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 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 ). 
   
     
     
         12 . A method for operating the system of  claim 11 , the method 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.   
     
     
         13 . A method for operating the ejector of  claim 1 , the method comprising:
 driving a motive flow along the primary flowpath; and   shifting the needle to the second condition so as to stop the motive flow.