Method of expanding corrugated tube and manufacturing a heat exchanger with expansion tube

Abstract

A method of manufacturing a heat exchanger coil, the method comprising the steps of reconfiguring the cross-sectional shape of an elongate tube from a substantially round cross-sectional shape having a first outer circumference to a reduced or corrugated cross-sectional shape having a second outer circumference which is less than the first outer circumference, forming a plurality of u-shaped hairpin tubes from the elongate tube, the u-shaped hairpin tubes each having a pair of parallel legs, inserting each of the parallel legs of the hairpin tube through a predetermined opening in at least one fin plate, attaching a plurality of return bends to the u-shaped hairpin tubes to form a predetermined circuitry and then incrementally applying fluid pressure from a fluid pressure source to an internal channel of the circuitry to incrementally expand the circuitry to form a tight heat transfer bond between the circuitry and at least one wall of the predetermined opening.

What is claimed is: 
     
         1 . A method of manufacturing a heat exchanger coil, the method comprising the steps of:
 reconfiguring a cross-sectional shape of an elongate tube from a substantially round cross-sectional shape having a first outer circumference to one of a reduced and a corrugated cross-sectional shape having a second outer circumference less than said first outer circumference;   forming a plurality of u-shaped hairpin tubes from said elongate tube, said u-shaped hairpin tubes each having a pair of parallel legs;   inserting each of said parallel legs through a predetermined opening in at least one fin plate;   attaching a plurality of return bends to said u-shaped hairpin tubes to form a predetermined circuitry; and   incrementally applying fluid pressure from a fluid pressure source to an internal channel of said circuitry to incrementally expand said circuitry to form a tight heat transfer bond between said circuitry and at least one wall of said predetermined opening.   
     
     
         2 . The method according to  claim 1 , wherein an end of said circuitry is sealed prior to said application of said fluid pressure. 
     
     
         3 . The method according to  claim 1 , wherein said at least one fin plate is a plurality of fin plates. 
     
     
         4 . The method according to  claim 1 , wherein said substantially round cross-sectional shape is one of substantially circular-shaped and substantially oval-shaped. 
     
     
         5 . The method according to  claim 1 , wherein said attachment of said plurality of return bends to said u-shaped hairpin tubes is by brazing. 
     
     
         6 . The method according to  claim 1 , wherein said at least one fin plate is a plurality of fin plates and said predetermined opening is a plurality of predetermined openings in said plurality of fin plates, said predetermined openings being arranged in a predefined arrangement. 
     
     
         7 . The method according to  claim 1 , wherein said application of fluid pressure one of incrementally expands said reduced shape and unfolds said corrugated shape to re-form said substantially round cross-sectional shape. 
     
     
         8 . The method according to  claim 1 , wherein said elongate tube is sealed prior to said application of fluid pressure. 
     
     
         9 . The method according to  claim 1 , wherein said fluid pressure is applied such that an internal pressure of said hairpin tube is up to approximately 2,500 PSI. 
     
     
         10 . The method according to  claim 9 , wherein said fluid pressure is applied such that said internal pressure of said hairpin tube is up to approximately 2,100 PSI. 
     
     
         11 . The method according to  claim 1 , wherein said fluid pressure source is one of a hand pump, a hydraulic pump, an electric pump and a gas pump. 
     
     
         12 . The method according to  claim 1 , wherein a fluid used in said application of said fluid pressure is leak detectable. 
     
     
         13 . The method according to  claim 1 , wherein each of said pair of parallel legs of said u-shaped hairpin tubes includes an end portion which is not corrugated. 
     
     
         14 . The method according to  claim 1 , wherein said u-shaped hairpin tube includes a u-shaped portion between said pair of parallel legs, said u-shaped portion not being corrugated. 
     
     
         15 . A method of manufacturing a HVAC heat exchanger coil, the method comprising the steps of:
 reconfiguring a cross-sectional shape of a plurality of elongate tubes from a substantially round cross-sectional shape having a first circumference to one of a reduced and a corrugated cross-sectional shape having a second circumference less than said first circumference;   bending each of said elongate tubes into a hairpin-shaped tube having a pair of parallel legs;   inserting each of said pair of parallel legs of said hairpin tubes through a predetermined opening in at least one fin plate;   coupling at least one leg of said pair of parallel legs with a return bend to form a predefined circuitry;   incrementally applying fluid pressure from a fluid pressure source to an internal channel of said circuitry to expand said circuitry to said first outer circumference and said substantially round cross-sectional shape and form a tight heat transfer bond between said elongate tube and at least one wall of said predetermined opening.   
     
     
         16 . A method of manufacturing a heat exchanger coil, the method comprising the steps of:
 reconfiguring a cross-sectional shape of an elongate tube from a substantially round cross-sectional shape having a first outer circumference to a corrugated cross-sectional shape having a second outer circumference less than said first outer circumference;   forming a plurality of tube sections, said tube sections including at least one of straight tubes, u-shaped hairpin tubes and return bends;   forming a predefined circuitry from said at least one of said straight tubes, said u-shaped hairpin tubes and said return bends;   incrementally applying fluid pressure from a fluid pressure source to an internal channel of said circuitry to pressure inflate and radially expand said circuitry to continuously contact a wall of said predetermined opening and form a tight heat transfer bond between said circuitry and said predetermined opening.