Heat exchanger

Abstract

A small heat exchanger can efficiently exchange heat, and can be produced at low cost in comparison with a conventional heat exchanger. In the heat exchanger, a heat-transfer tube can be easily replaced so that the heat exchanger can be used for a treatment which requires a low flow rate. A heat-transfer tube produced in the form of a coil is attached to, for example, a lower closing portion and an inner tube, which are integrally produced. The heat-transfer tube is pulled in the U-direction to reduce the diameter of the coiled portions and, thus, is closely bonded or welded to the inner tube. An outer tube and an upper closing portion are attached so that there is a slight gap between the outer tube and the outer diameter of the heat-transfer tube.

1 . A heat exchanger comprising a coiled heat-transfer tube placed in a space defined between an inner tube and an outer tube, an inside space of the heat-transfer tube being used as one of flow paths, a coiled space defined between coiled sections of the heat-transfer tube in the space being used as the other flow path, and heat being exchanged between one fluid and the other fluid, the heat exchanger further comprising:
 a tensioning mechanism for keeping an expansion or contraction force acting to expand or contract a diameter of the coiled heat-transfer tube than a diameter the heat-transfer tube naturally has,   wherein the heat is exchanged between one fluid and the other fluid while the expansion or contraction force is applied to the heat-transfer tube by the tensioning mechanism.   
     
     
         2 . The heat exchanger of  claim 1 , wherein the heat-transfer tube is not fixed to either one of an outer peripheral surface of the inner tube or an inner peripheral surface of the outer tube, and
 wherein the diameter of the coiled heat-transfer tube is expanded or contracted than the diameter the heat-transfer tube naturally has, and the heat-transfer tube is brought into close contact with or pressure contact against the inner tube or the outer tube by the expansion or the contraction.   
     
     
         3 . The heat exchanger of  claim 1 , wherein a load applied in a coil axis direction of the heat-transfer tube is equal to or less than 10 kg when a length of the coiled heat-transfer tube in the coil axis direction is varied by 10% in comparison with a length the coiled heat-transfer tube naturally has. 
     
     
         4 . The heat exchanger of  claim 3 , wherein the heat-transfer tube is made of at least a material selected from the group consisting of metals such as stainless steal, hastelloy, inconel, titanium, copper, and nickel; acrylic resins such as ABS, polyethylene, polypropylene, PMMA; fluorine based resins such as polycarbonate, PTFE, and PFA; and an epoxy resin. 
     
     
         5 . The heat exchanger of  claim 4 , wherein the outer diameter of the heat-transfer tube  1  is equal to or less than 28 mm. 
     
     
         6 . A heat exchanger comprising a coiled heat-transfer tube placed in a space defined between an inner tube and an outer tube, an inside space of the heat-transfer tube being used as one of flow paths, and a coiled space defined between coiled sections of the heat-transfer tube in the space being used as the other flow path, heat being exchanged between one fluid and the other fluid,
 wherein the coiled heat-transfer tube is elastically deformed from its natural state to be brought into close contact with or pressure contact against the inner tube or the outer tube, and the heat is exchanged between one fluid and the other fluid while the heat-transfer tube is elastically deformed.   
     
     
         7 . The heat exchanger of  claim 2 , wherein a load applied in a coil axis direction of the heat-transfer tube is equal to or less than 10 kg when a length of the coiled heat-transfer tube in the coil axis direction is varied by 10% in comparison with a length the coiled heat-transfer tube naturally has.