Fluid heat exchanger

Abstract

An annular heat exchanger suitable for a Stirling engine is provided. The heat exchanger has helical fins, and an outer reinforcing sleeve about the fins. The sleeve improves the pressure resisting ability of a thin separating wall between a pressurized fluid and an outside working environment, resulting in a high-pressure heat exchanger with high heat transfer efficiency. In addition, the sleeve and helical fins together define fluid passages for the flow of heating fluid. The heat exchanger according to the invention has the ability to resist high pressures at high temperatures without distortion, has improved heat transfer capability, better reliability, and lower production cost than prior art heat exchangers.

1 . A heat exchanger for exchanging heat with a working fluid, comprising: 
 a) a tubular wall having an interior surface and an exterior surface, said interior surface in contact with the working fluid;    b) a plurality of external fins about said exterior surface of said wall;    c) a tubular sleeve having an interior surface about and in contact with said external fins; and    d) a heat exchange fluid in contact with said tubular wall, said external fins, and said interior surface of said sleeve, said heat exchange fluid adapted to exchange heat with the working fluid.    
     
     
         2 . A heat exchanger according to  claim 1 , wherein: 
 said external fins are helical about said exterior surface of said tubular wall.    
     
     
         3 . A heat exchanger according to  claim 1 , wherein: 
 said external fins are one of annular and axial relative to said wall.    
     
     
         4 . A heat exchanger according to  claim 1 , wherein: 
 said external fins taper in thickness from said tubular wall to said sleeve.    
     
     
         5 . A heat exchanger according to  claim 1 , wherein: 
 said wall, said external fins, and said sleeve together define a plurality of fluid passages for said heat exchange fluid.    
     
     
         6 . A heat exchanger according to  claim 1 , wherein: 
 said wall and said external fins are a unitary construct.    
     
     
         7 . A heat exchanger according to  claim 1 , wherein: 
 said external fins and said sleeve are a unitary construct.    
     
     
         8 . A heat exchanger according to  claim 1 , wherein: 
 said external fins and said sleeve are made from stainless steel.    
     
     
         9 . A heat exchanger according to  claim 1 , further comprising: 
 e) internal fins in contact with said interior surface of said tubular wall and the working fluid.    
     
     
         10 . A heat exchanger according to  claim 9 , wherein: 
 said internal fins are axial relative to said wall.    
     
     
         11 . A heat exchanger according to  claim 9 , wherein: 
 said internal fins and said wall are a unitary construct.    
     
     
         12 . A heat exchanger according to  claim 9 , wherein: 
 said external fins and said internal fins are in an orthogonal grillage relationship.    
     
     
         13 . A Stirling engine, comprising: 
 a) a cylinder containing a working fluid;    b) a first heat exchanger means for heating said working fluid;    c) a second heat exchanger means for cooling said working fluid;    d) a regenerator for storing heat energy released by the working fluid; and    e) a means for converting a pressure wave in said working fluid into mechanical energy,    wherein at least one of said first and second heat exchangers includes 
 (i) a tubular wall having an exterior surface, and  
 (ii) a plurality of helical fins about said exterior surface of said wall.  
   
     
     
         14 . A Stirling engine according to  claim 13 , wherein: 
 said at least one of said first and second heat exchangers further includes, 
 (iii) a tubular sleeve about and in contact with said helical fins,  
   wherein said wall, said fins and said sleeve together define a plurality of helical fluid passages.    
     
     
         15 . A Stirling engine according to  claim 14 , wherein: 
 said fins and said sleeve are a unitary construct.    
     
     
         16 . A Stirling engine according to  claim 13 , wherein: 
 said at least one of said first and second heat exchangers further includes, 
 (iii) a plurality of internal fins,  
   wherein said wall and said internal fins are a unitary construct.    
     
     
         17 . A Stirling engine, comprising: 
 a) a cylinder containing a working fluid;    b) a first heat exchanger means for heating said working fluid;    c) a second heat exchanger means for cooling said working fluid;    d) a regenerator for storing heat energy released by the working fluid; and    e) a means for converting a pressure wave in said working fluid into mechanical energy,    wherein at least one of said first and second heat exchangers includes 
 (i) a tubular wall having an exterior surface,  
 (ii) a plurality of external fins about said exterior surface of said wall, and  
 (iii) a tubular sleeve about and in contact with said fins.  
   
     
     
         18 . A Stirling engine according to  claim 17 , wherein: 
 said external fins are one of annular, axial, and helical relative to said wall.    
     
     
         19 . A Stirling engine according to  claim 17 , wherein: 
 said wall, said external fins, and said sleeve together define a plurality of fluid passages.    
     
     
         20 . A heat exchanger according to  claim 17 , wherein: 
 said tubular wall has an interior surface in contact with a plurality of internal fins.    
     
     
         21 . A heat exchanger according to  claim 10 , wherein: 
 said wall, said external fins, said interior fins, and said sleeve are of a unitary construct.