Heat Exchanger

Abstract

Newly-developed manufacturing techniques have opened up new possibilities in fabricating designs of components that were previously infeasible. One such component is a heat exchanger. A crossflow heat exchanger is disclosed that includes a plurality of internal passages for conducting a first fluid. The internal passages that form a spiral with adjacent passages separated by a gap of a predetermined distance or less. The second fluid passes through the gaps. The internal passages may be a plurality of parallel passages arranged along a first line. From upstream to downstream, each of the passages form an inlet spiral connected to an inner ring connected to an outlet spiral. The gaps are less than a predetermined distance related to a Reynolds number that is less than that at which laminar flow exists.

We claim: 
     
         1 . A crossflow heat exchanger, comprising:
 an inlet for a first fluid;   an outlet for the first fluid;   an inlet spiral having a plurality of passages therein;   an inlet manifold fluidly coupling the inlet with the plurality of passages of the inlet spiral;   an outlet spiral having a plurality of passages therein; and   an outlet manifold fluidly coupling the outlet with the plurality of passages of the outlet spiral, wherein:
 the passages of the inlet spiral are fluidly coupled to the passages of the outlet spiral; 
 interior walls of the passages of the inlet and outlet spirals are in contact with the first fluid; 
 the exterior walls of the inlet and outlet spirals are in contact with a second fluid; 
 the inlet spiral is nested with the outlet spiral; and 
 a gap between adjacent turns of the inlet and outlet spirals is less than a predetermined distance. 
   
     
     
         2 . The crossflow heat exchanger of  claim 1  wherein the predetermined distance is less than a distance at which a predetermined Reynolds number exists. 
     
     
         3 . The crossflow heat exchanger of  claim 2  wherein the predetermined Reynolds number is that which is defined to lead to laminar flow for the given geometry of the gaps. 
     
     
         4 . The crossflow heat exchanger of  claim 1 , further comprising: a plurality of braces mechanically coupling adjacent turns of the inlet and outlet spirals. 
     
     
         5 . The crossflow heat exchanger of  claim 1  wherein the passages of the inlet spiral and the passages of the outlet spiral are fluidly coupled via a collector ring. 
     
     
         6 . The crossflow heat exchanger of  claim 1  wherein the passages of the inlet spiral and the passages of the outlet spiral are coupled via a transition section. 
     
     
         7 . The crossflow heat exchanger of  claim 1  wherein the passages of the inlet spiral are arranged along a first line; the passages of the outlet spiral are arranged along a second line; and the first line and the second line are parallel. 
     
     
         8 . The crossflow heat exchanger of  claim 1  wherein a cross section of the passages of the inlet and outlet spirals are one of: circular, elliptical, and polygonal. 
     
     
         9 . A crossflow heat exchanger, comprising:
 an inlet spiral having a rectangular cross section and defining a plurality of passages arranged longitudinally;   an inlet manifold coupled to an upstream end of the inlet spiral with the inlet spiral defining an inlet volume that fluidly couples with the plurality of passages of the inlet spiral;   an outlet spiral having a rectangular cross section and defining a plurality of passages arranged longitudinally;   an outlet manifold coupled to a downstream end of the outlet spiral with the outlet spiral defining an outlet volume that fluidly couples with the plurality of passages of the outlet spiral;   a collector ring having a rectangular cross section and defining a plurality of passages longitudinally, wherein:
 the plurality of passages of the collector ring have inlets and outlets; 
 the inlets of the passages in the collector ring couple with downstream ends of the plurality of passages in the inlet spiral; and 
 the outlets of the passages in the outer ring couple with upstream ends of the plurality of passages in the outlet spiral. 
   
     
     
         10 . The heat exchanger of  claim 9  wherein turns of the inlet spiral interleave with turns of the outlet spiral and the inlet and outlet spirals have a least one kink around the circumference. 
     
     
         11 . The heat exchanger of  claim 10  wherein a gap between adjacent turns of the inlet and outlet spirals is less than a predetermined distance. 
     
     
         12 . The heat exchanger of  claim 10  wherein:
 turns of the inlet spiral interleave with turns of the outlet spiral; and 
 a gap exists between adjacent turns, the heat exchanger further comprising:
 a plurality of braces mechanically coupling adjacent turns. 
 
 
     
     
         13 . The heat exchanger of  claim 10  wherein:
 turns of the inlet spiral interleave with turns of the outlet spiral; and 
 a gap exists between adjacent turns, the heat exchanger further comprising:
 a plurality of braces extending radially and mechanically coupling a plurality of turns. 
 
 
     
     
         14 . The heat exchanger of  claim 10  wherein a fluid flows from the inlet manifold into passages in the inlet spiral into passages in the inlet ring into passages in the outlet spiral into the outlet manifold. 
     
     
         15 . The heat exchanger of  claim 14  wherein the fluid is a liquid. 
     
     
         16 . The heat exchanger of  claim 9  wherein:
 a gap exists between adjacent turns; and 
 a gas flows through the gaps. 
 
     
     
         17 . A heat pump, comprising:
 a cylinder;   a hot displacer disposed in the cylinder;   a cold displacer disposed in the cylinder; and   a crossflow heat exchanger disposed between the hot displacer and the cold displacer, the crossflow heat exchanger comprising:
 an inlet spiral having a rectangular cross section and defining a plurality of passages arranged longitudinally; 
 an inlet manifold coupled to an upstream end of the inlet spiral with the inlet spiral defining an inlet volume that fluidly couples with the plurality of passages of the inlet spiral; 
 an outlet spiral having a rectangular cross section and defining a plurality of passages arranged longitudinally; and 
 an outlet manifold coupled to a downstream end of the outlet spiral with the outlet spiral defining an outlet volume that fluidly couples with the plurality of passages of the outlet spiral, wherein the passages of the inlet spiral are fluidly coupled to the passages of the outlet spiral. 
   
     
     
         18 . The heat pump of  claim 17  wherein the passages of the inlet spiral are coupled to the passages of the outlet spiral via a transition section. 
     
     
         19 . The heat pump of  claim 17  wherein:
 turns of the inlet spiral interleave with turns of the outlet spiral; 
 gaps exists between adjacent turns; 
 the cylinder is filled with a working fluid; and 
 reciprocation of one of the displacers in the cylinder causes the working fluid to pass through the gaps. 
 
     
     
         20 . The heat pump of  claim 17  wherein:
 turns of the inlet spiral interleave with turns of the outlet spiral; and 
 a gap exists between adjacent turns, the heat exchanger further comprising: 
 a plurality of braces mechanically coupling adjacent turns.