System and Method for Manufacturing and Operating a Coaxial Tube Heat Exchanger

Abstract

A coaxial heat exchanger is provided. Embodiments of the present disclosure relate to a coaxial heat exchanger for use in water source heat pumps or other applications involving fluid to fluid heat transfer. Embodiments of the present disclosure allow for the use of pre-existing engineered tubing with a textured or riffled interior surface and a folded fin intermediate member. Some methods of the present disclosure involve annealing and hydrostatically expanding the engineered tubing to increase contact and thermal transfer between the inner tube and the intermediate member. Additional systems, devices, and methods are also disclosed.

1 . A coaxial heat exchanger for water source heat pumps comprising:
 an inner tube, wherein the inner tube has a textured interior surface and a textured exterior surface;   an intermediate member positioned outboard of the inner tube; and   an outer jacket comprising an interior and exterior, wherein the outer jacket is positioned outboard of the intermediate member.   
     
     
         2 . The coaxial heat exchanger of  claim 1 , wherein the inner tube comprises copper or a copper bearing alloy. 
     
     
         3 . The coaxial heat exchanger of  claim 1 , wherein the exterior surface of the inner tube is configured to increase heat transfer to a condensing or evaporating fluid and the interior surface of the inner tube is configured to increase heat transfer to a single-phase fluid. 
     
     
         4 . The coaxial heat exchanger of  claim 1 , wherein the intermediate member comprises a folded fin. 
     
     
         5 . The coaxial heat exchanger of  claim 1 , wherein the outer jacket comprises steel and is brazed to the inner tube. 
     
     
         6 . The coaxial heat exchanger of  claim 1 , wherein the intermediate member is configured to create an axial gap portion, wherein the exterior surface of the inner tube is not covered by the intermediate member in the axial gap portion. 
     
     
         7 . The coaxial heat exchanger of  claim 6 , further comprising a spacer positioned axially parallel to the inner tube in the volume between the inner tube and the outer jacket. 
     
     
         8 . The coaxial heat exchanger of  claim 1 , wherein the intermediate member comprises more than one intermediate member section. 
     
     
         9 . The coaxial heat exchanger of  claim 1 , wherein the inner tube is annealed and hydrostatically expanded within the intermediate member. 
     
     
         10 . The coaxial heat exchanger of  claim 1 , wherein the heat exchanger is coiled and has about a ten-inch diameter. 
     
     
         11 . A method for manufacturing a coaxial heat exchanger, the method comprising:
 obtaining an engineered inner tube comprising an interior surface and an exterior surface, wherein the interior surface and exterior surface of the engineered inner tube are textured;   positioning an intermediate member comprising an interior and an exterior axially outboard of the engineer inner tube;   positioning the intermediate member and engineered inner tube within an outer jacket; and   deforming at least one of the engineered inner tube, intermediate member, or outer jacket to increase thermal transfer between the engineered inner tube and the intermediate member.   
     
     
         12 . The method of  claim 11 , further comprising annealing the engineered inner tube. 
     
     
         13 . The method of  claim 11 , wherein the deforming comprises expanding the engineered inner tube using hydrostatic pressure. 
     
     
         14 . The method of  claim 11 , wherein the deforming comprises shrinking the intermediate member or outer jacket. 
     
     
         15 . The method of  claim 11 , wherein the interior surface of the engineered inner tube is rifled. 
     
     
         16 . The method of  claim 11 , wherein the engineered inner tube comprises copper or copper bearing alloy. 
     
     
         17 . The method of  claim 11 , wherein the intermediate member comprises extruded aluminum. 
     
     
         18 . The method of  claim 11 , wherein the intermediate member comprises a folded fin. 
     
     
         19 . The method of  claim 11 , further comprising brazing the outer jacket to the intermediate member. 
     
     
         20 . A water source heat pump comprising:
 a compressor in fluid communication with a refrigerant line;   a reversing valve configured to adjust the direction of refrigerant flowing in at least a portion of the refrigerant line;   a water line wherein the water line is in thermal communication with the outside environment; and   a coaxial heat exchanger comprising:
 an inner tube in fluid communication with the water line, wherein the inner tube has a textured interior and exterior surface; 
 an intermediate member positioned outboard of the inner tube wherein the intermediate member has a folded fin structure; and 
 an outer jacket positioned outboard of the intermediate member to define a volume between intermediate member and the outer jacket, the volume being in fluid communication with the refrigerant line.