A Thermally-Driven Heat Pump Having a Heat Exchanger Located Between Displacers

Abstract

A thermally driven heat pump is disclosed in which at least most of the warm heat exchanger is disposed within the cylinder between the hot and cold displacers. Such an arrangement is not suitable for a prior art heat pump in which movement of the displacers is based on a crank because it would lead to too much dead volume in the system. However, with mechatronically-controlled displacers in which the displacers are independently controlled, the displacers can reciprocate up to the heat exchanger. Such a configuration reduces dead volume compared to prior art Vuilleumier heat pumps in which the warm exchanger occupies a portion of an annular space between the cylinder in which the displacers move.

1 . A heat pump, comprising:
 a heat pump housing having: a hot cap, a cold cap, a hot cylinder portion proximate the hot cap, and a cold cylinder portion proximate the cold cap;   a cold displacer disposed within the cold cylinder portion;   a hot displacer disposed within the hot cylinder portion; and   a substantially disk-shaped warm heat exchanger between the hot cylinder portion and the cold cylinder portion wherein:
 the cold displacer reciprocates between the warm heat exchanger and the cold cap; and 
 the hot displacer reciprocates between the warm heat exchanger and the hot cap. 
   
     
     
         2 . The heat pump of  claim 1 , further comprising:
 a post coupled to the cold cap and extending toward the hot cap along a centerline of the cold cylinder portion wherein:   an opening is defined in the warm heat exchanger to accommodate the post; and   a diameter of the opening in the warm heat exchanger is less than a diameter of the cold displacer.   
     
     
         3 . The heat pump of  claim 1 , further comprising:
 a hot heat exchanger located proximate the hot cap and fluidly coupled to the hot cylinder portion; and   a hot regenerator having one end fluidly coupled to the hot heat exchanger and one end fluidly coupled to the cold cylinder portion.   
     
     
         4 . The heat pump of  claim 1 , further comprising:
 a cold heat exchanger fluidly coupled to the cold cylinder portion; and   a cold regenerator having one end fluidly coupled to the cold heat exchanger and one end fluidly coupled to the hot cylinder portion.   
     
     
         5 . The heat pump of  claim 1 , further comprising:
 a hot regenerator arranged outside the hot cylinder portion; and   a cold regenerator arranged outside the cold cylinder portion.   
     
     
         6 . The heat pump of  claim 5 , further comprising:
 a hot chamber delimited by the hot cylinder portion, the hot displacer, and the hot cap;   a hot warm chamber delimited by the hot cylinder portion, the hot displacer, and the warm heat exchanger;   a cold warm chamber delimited by the cold cylinder portion, the cold displacer, and the warm heat exchanger;   a cold chamber delimited by the cold cylinder portion, the cold displacer, and the cold cap; and   a hot heat exchanger fluidly coupled to the hot chamber and to the hot regenerator;   a cold heat exchanger fluidly coupled to the cold chamber and to the cold regenerator, wherein:
 the hot regenerator is fluidly coupled to the hot heat exchanger and the cold warm chamber; and 
 the cold regenerator is fluidly coupled to the cold heat exchanger and the hot warm chamber. 
   
     
     
         7 . The heat pump of  claim 1 , further comprising:
 a hot heat exchanger disposed in the hot cap; and   a cold heat exchanger annularly arranged around the cold cylinder portion.   
     
     
         8 . The heat pump of  claim 1  wherein:
 the warm heat exchanger comprises at least one tube wrapped in a spiral; 
 adjacent turns of the spiral are separated by at most a predetermined distance; and 
 a working fluid within the hot and cold cylinder portions pass through the separations between adjacent turns of the spiral in response to movement of the displacers. 
 
     
     
         9 . The heat pump of  claim 1 , further comprising:
 a hot heat exchanger proximate the hot cap and fluidly coupled to a hot chamber within the hot cylinder portion;   a cold heat exchanger fluidly coupled to a cold chamber within the cold cylinder portion;   an annular-shaped hot regenerator arranged outside the hot cylinder portion; and   an annular-shaped cold regenerator arranged outside the cold cylinder portion wherein:   a first end of the hot regenerator is fluidly coupled to the hot heat exchanger;   a second end of the hot regenerator is fluidly coupled to a cold warm chamber within the cold cylinder portion;   a first end of the cold regenerator is fluidly coupled to the cold heat exchanger; and   a second end of the cold regenerator is fluidly coupled to a hot warm chamber within the hot cylinder portion.   
     
     
         10 . The heat pump of  claim 1  wherein the warm heat exchanger is housed within a warm heat exchanger cylinder portion; and the hot cylinder portion, the cold cylinder portion, and the warm heat exchanger cylinder portion are of the same diameter. 
     
     
         11 . The heat pump of  claim 1  wherein the warm heat exchanger is housed within a warm heat exchanger portion; and the warm heat exchanger has an inlet that pierces the warm heat exchanger cylinder portion and an outlet that pierces the warm heat exchanger cylinder portion. 
     
     
         12 . A heat pump, comprising:
 a housing having a hot cap on one end of the housing and a cold cap on the other end of the housing;   a cylinder within the housing;   a substantially disk-shaped warm heat exchanger disposed within the housing and roughly centrally located between the hot cap and the cold cap;   a hot displacer disposed in a portion of the cylinder between the warm heat exchanger and the hot cap; and   a cold displacer disposed in a portion of the cylinder between the warm heat exchanger and the cold cap.   
     
     
         13 . The heat pump of  claim 12  wherein the cylinder has a hot cylinder portion and a cold cylinder portion, the heat pump further comprising:
 a hot chamber delimited by the hot cap, the hot cylinder portion, and the hot displacer; 
 a cold chamber delimited by the cold cap, the cold cylinder portion, and the cold displacer; 
 a hot warm chamber delimited by the warm heat exchanger, the hot cylinder portion, and the hot displacer; 
 a cold warm chamber delimited by the warm heat exchanger, the cold cylinder portion, and the cold displacer; 
 a hot heat exchanger proximate fluidly coupled to the hot chamber; 
 a cold heat exchanger fluidly coupled to the cold chamber; 
 a hot regenerator; and 
 a cold regenerator, wherein: 
 a first end of the hot regenerator is fluidly coupled to the hot heat exchanger; 
 a second end of the hot regenerator is fluidly coupled to a cold warm chamber; 
 a first end of the cold regenerator is fluidly coupled to the cold heat exchanger; and 
 a second end of the cold regenerator is fluidly coupled to a hot warm chamber. 
 
     
     
         14 . The heat pump of  claim 13  wherein:
 the hot regenerator is annularly arranged outside the cylinder near the hot cap; and 
 the cold regenerator is annularly arranged outside the cylinder near the cold cap. 
 
     
     
         15 . A heat pump, comprising:
 a heat pump housing having: a hot cap, a cold cap, a hot cylinder portion proximate the hot cap, and a cold cylinder portion proximate the cold cap;   a cold displacer disposed within the cold cylinder portion;   a hot displacer disposed within the hot cylinder portion; and   a substantially disk-shaped warm heat exchanger wherein:   the warm heat exchanger is located between the hot and cold displacers.   
     
     
         16 . The heat pump of  claim 1 . 5  wherein:
 the warm heat exchanger is housed within a warm heat exchanger cylinder portion; and 
 the hot cylinder portion, the cold cylinder portion, and the warm heat exchanger cylinder portion are of the same diameter. 
 
     
     
         17 . The heat pump of  claim 15  wherein the warm heat exchanger has an inlet that pierces the warm heat exchanger cylinder portion and an outlet that pierces the warm heat exchanger cylinder portion. 
     
     
         18 . The heat pump of  claim 15  wherein:
 the warm heat exchanger comprises at least one tube wrapped in a spiral; 
 adjacent turns of the spiral are separated by at most a predetermined distance; and 
 a working fluid within the hot and cold cylinder portions pass through the separations between adjacent turns of the spiral in response to movement of the displacers. 
 
     
     
         19 . The heat pump of  claim 15 , further comprising:
 a hot heat exchanger located proximate the hot cap and fluidly coupled to a chamber within the hot cylinder portion;   a hot regenerator having one end fluidly coupled to the hot heat exchanger and one end fluidly coupled to a chamber within the cold cylinder portion.   
     
     
         20 . The heat pump of  claim 15 , further comprising:
 a hot heat exchanger proximate the hot cap and fluidly coupled to a hot chamber within the hot cylinder portion;   a cold heat exchanger fluidly coupled to a cold chamber within the cold cylinder portion;   an annular-shaped hot regenerator arranged outside the hot cylinder portion; and   an annular-shaped cold regenerator arranged outside the cold cylinder portion wherein:   a first end of the hot regenerator is fluidly coupled to the hot heat exchanger;   a second end of the hot regenerator is fluidly coupled to a cold warm chamber within the cold cylinder portion;   a first end of the cold regenerator is fluidly coupled to the cold heat exchanger; and   a second end of the cold regenerator is fluidly coupled to a hot warm chamber within the hot cylinder portion.