Heat exchanger

Abstract

A method for making a heat exchanger includes providing a first outer tube, and an inner tube disposed in the first outer tube; placing a first coiled heat-transfer tube in a space defined between the inner tube and the first outer tube without being fixed to either one of an outer peripheral surface of the inner tube and an inner peripheral surface of the first outer tube, the first coiled heat-transfer tube including a plurality of coiled sections, an inside space of the heat-transfer tube defining a first flow path, a coiled space defined between coiled sections of the heat-transfer tube in the space, defined between the inner tube and the first outer tube, defining a second flow path, wherein heat is exchanged between two fluids.

What is claimed is: 
     
         1 . A method for making a heat exchanger comprising the steps of:
 providing a first outer tube, and an inner tube disposed in the first outer tube;   placing a first coiled heat-transfer tube in a space defined between the inner tube and the first outer tube without being fixed to either one of an outer peripheral surface of the inner tube and an inner peripheral surface of the first outer tube, the first coiled heat-transfer tube including a plurality of coiled sections, an inside space of the heat-transfer tube defining a first flow path for a first fluid, a coiled space defined between coiled sections of the heat-transfer tube in the space, defined between the inner tube and the first outer tube, defining a second flow path for a second fluid, wherein heat is exchanged between the first and second fluids;   exerting an expansion force on the first coiled heat-transfer tube to increase a diameter of the coiled sections of the first coiled heat-transfer tube so as to be larger than the diameter the coiled sections of the first coiled heat-transfer tube naturally have, or a contraction force on the first coiled heat-transfer tube to decrease the diameter of the coiled sections of the first coiled heat-transfer tube so as to be smaller than the diameter the coiled sections of the first coiled heat-transfer tube naturally have;   connecting a first tensioning joint to the first coiled heat-transfer tube, and maintaining a state in which the expansion force or the contraction force is applied to the first coiled heat-transfer tube by the first tensioning joint, such that the first coiled heat-transfer tube is subjected to the expansion force, abutting against, with a pressure, the inner peripheral surface of the first outer tube without contacting the outer peripheral surface of the inner tube, or subjected to the contraction force, abutting against, with a pressure, the outer peripheral surface of the inner tube without contacting the inner peripheral surface of the first outer tube, by an action of the first tensioning joint even when the first coiled heat-transfer tube is not fixed either to the inner peripheral surface of the first outer tube or the outer peripheral surface of the inner tube,   wherein the heat exchange is performed between the first and second fluids in the state in which the expansion force or the contraction force is applied to the first coiled heat-transfer tube by the first tensioning joint.   
     
     
         2 . The method according to  claim 1 , wherein the step of exerting comprises exerting the contraction force on the first coiled heat-transfer tube by fixating a first end of the first coiled heat-transfer tube and pulling a second end of the first coiled heat-transfer tube in a direction away from the first end of the first coiled heat-transfer tube before the second end of the first coiled heat-transfer tube is fixated by the first tensioning joint, or exerting the expansion force on the first coiled heat-transfer tube by fixating the first end of the first coiled heat-transfer tube and pushing the second end of the first coiled heat-transfer tube in a direction toward the first end of the first coiled heat-transfer tube before the second end of the first coiled heat-transfer tube is fixated by the first tensioning joint. 
     
     
         3 . The method according to  claim 1 , wherein the first coiled heat-transfer tube is configured in such a manner that when a load equal to or less than 10 kg is applied in a coil longitudinal axis direction of the coiled heat-transfer tube, a length of the first coiled heat-transfer tube in the longitudinal coil axis direction is varied by 10% in comparison with the length of the first coiled heat-transfer tube when no load being applied therein. 
     
     
         4 . The method according to  claim 1 , wherein the first coiled heat-transfer tube is made of at least a material selected from the group consisting of metals; acrylic resins; fluorine based resins; and an epoxy resin. 
     
     
         5 . The method according to  claim 4 , wherein said metals are stainless steel, metal alloy, titanium, copper, or nickel; said acrylic resins are ABS, polyethylene, polypropylene or PMMA; and said fluorine based resins are polycarbonate, PTFE or PFA. 
     
     
         6 . The method according to  claim 1 , wherein an outer diameter of the first coiled heat-transfer tube itself is equal to or less than 28 mm. 
     
     
         7 . The method according to  claim 1 , wherein the heat exchanger further comprises an upper closing part and a lower closing part, the upper closing part closing the inner tube and the first outer tube at an upper side, the lower closing part closing the inner tube and the first outer tube at a lower side. 
     
     
         8 . The method according to  claim 7 , further comprising the steps of:
 fixing the first coiled heat-transfer tube to the upper closing part at an upper fixing point via an upper part of the first tensioning joint; and   fixing the first coiled heat-transfer tube to the lower closing part at a lower fixing point via a lower part of the first tensioning joint,   wherein the first coiled heat-transfer tube is fixed to the upper and lower closing parts in a manner such that the coiled sections of the first coiled heat-transfer tube between the upper fixing point and the lower fixing point have the diameter larger than or smaller than the diameter the coiled sections of the first coiled heat-transfer tube naturally have.   
     
     
         9 . The method according to  claim 1 , further comprising the steps of:
 providing a second outer tube outside of the first outer tube;   placing a second coiled heat-transfer tube in a space defined between the first outer tube and the second outer tube without being fixed to either one of the outer peripheral surface of the first outer tube and an inner peripheral surface of the second outer tube, the second coiled heat-transfer tube including a plurality of coiled sections, and defining a third flow path for a third fluid, wherein heat is exchanged between the second and third fluids;   exerting an expansion force on the second coiled heat-transfer tube to increase a diameter of the coiled sections of the second coiled heat-transfer tube so as to be larger than the diameter the coiled sections of the second coiled heat-transfer tube naturally have, or a contraction force on the second coiled heat-transfer tube to decrease the diameter of the coiled sections of the second coiled heat-transfer tube so as to be smaller than the diameter the coiled sections of the second coiled heat-transfer tube naturally have; and   connecting a second tensioning joint to the second coiled heat-transfer tube, and maintaining a state in which the expansion force or the contraction force is applied to the second coiled heat-transfer tube by the second tensioning joint, such that the second coiled heat-transfer tube is subjected to the expansion force, abutting against, with a pressure, the inner peripheral surface of the second outer tube without contacting the outer peripheral surface of the first outer tube, or subjected to the contraction force, abutting against, with a pressure, the outer peripheral surface of the first outer tube without contacting the inner peripheral surface of the second outer tube, by an action of the second tensioning joint even when the second coiled heat-transfer tube is not fixed either to the inner peripheral surface of the second outer tube or the outer peripheral surface of the first outer tube,   wherein coiled diameters of the first coiled heat-transfer tubes and the second coiled heat-transfer tube are concentric, and   wherein the heat exchange is performed between the second and third fluids in the state in which the expansion force or the contraction force is applied to the first coiled heat-transfer tube by the first tensioning joint, and in the state in which the expansion force or the contraction force is applied to the second coiled heat-transfer tube by the second tensioning joint.   
     
     
         10 . The method according to  claim 9 , wherein the step of exerting comprises exerting the contraction force on the second coiled heat-transfer tube by fixating a first end of the second coiled heat-transfer tube and pulling a second end of the second coiled heat-transfer tube in a direction away from the first end of the second coiled heat-transfer tube before the second end of the second coiled heat-transfer tube is fixated by the second tensioning joint, or exerting the expansion force on the second coiled heat-transfer tube by fixating the first end of the second coiled heat-transfer tube and pushing the second end of the second coiled heat-transfer tube in a direction toward the first end of the second coiled heat-transfer tube before the second end of the second coiled heat-transfer tube is fixated by the second tensioning joint. 
     
     
         11 . The method according to  claim 9 , wherein the heat exchanger further comprises an upper closing part and a lower closing part, the upper closing part closing the inner tube and the second outer tube at an upper side, the lower closing part closing the inner tube and the second outer tube at a lower side. 
     
     
         12 . The method according to  claim 11 , further comprising the steps of:
 fixing the first and second coiled heat-transfer tubes to the upper closing part at different upper fixing points via the upper part of the first tensioning joint and an upper part of the second tensioning joint, respectively; and   fixing the first and second coiled heat-transfer tubes to the lower closing part at different lower fixing points via the lower part of the first tensioning joint and a lower part of the second tensioning join, respectively,   wherein the first coiled heat-transfer tube is fixed to the upper and lower closing parts in a manner such that the coiled sections of the first coiled heat-transfer tube between the upper fixing points and the lower fixing points have the diameter larger than or smaller than the diameter the coiled sections of the first coiled heat-transfer tube naturally have, and the second coiled heat-transfer tube is fixed to the upper and lower closing parts in a manner such that the coiled sections of the second coiled heat-transfer tube between the upper fixing points and the lower fixing points have the diameter larger than or smaller than the diameter the coiled sections of the second coiled heat-transfer tube naturally have, and   wherein the diameter of the coiled sections of the first coiled heat-transfer tube between the upper fixing points and lower fixing points is smaller than the diameter of the coiled sections of the second coiled heat-transfer tube between the upper fixing points and lower fixing points.