Heat exchanger

Abstract

A heat exchanger has tubes defining refrigerant passages therein and fins disposed between the tubes. The tubes have tube main walls opposed to each other. The fins are joined to the tube main walls. The tube main walls have projections that project inside of the tubes and define recesses on outer sides of the tubes. Each of the tubes has an outer dimension, in a direction perpendicular to the tube main walls, in a range between equal to or greater than 0.8 mm and equal to or less than 1.9 mm.

1 . A heat exchanger for performing heat exchange between a refrigerant and an external fluid, comprising:
 tubes defining passages therein for allowing the refrigerant to flow, the tubes having tube main walls opposed to each other; and   fins disposed between the tubes and joined with the tube main walls, wherein   the tube main walls have projections that project inside of the tubes and define recesses outside of the tubes for allowing the external fluid to flow, and   each of the tubes has a tube outer dimension in a range between at least 0.8 mm and at most 1.9 mm, in a direction perpendicular to the tube main walls.   
   
   
       2 . The heat exchanger according to  claim 1 , wherein
 the tube outer dimension is in a range between at least 1.0 mm and at most 1.6 mm.   
   
   
       3 . The heat exchanger according to  claim 2 , wherein
 the tube outer dimension is in a range between at least 1.2 mm and at most 1.4 mm.   
   
   
       4 . The heat exchanger according to  claim 1 , wherein
 the projections are arranged at a predetermined pitch with respect to a longitudinal direction of the tube, and   the predetermined pitch is in a range between at least 1.0 mm and at most 6.5 mm.   
   
   
       5 . The heat exchanger according to  claim 4 , wherein
 the predetermined pitch is in a range between at least 1.6 mm and at most 5.7 mm.   
   
   
       6 . The heat exchanger according to  claim 5 , wherein
 the predetermined pitch is in a range between at least 2.3 mm and at most 5.0 mm.   
   
   
       7 . The heat exchanger according to  claim 1 , wherein
 each of the fins has a fin outer dimension in a range between at least 2.0 mm and at most 9.0 mm, in the direction perpendicular to the tube main walls.   
   
   
       8 . The heat exchanger according to  claim 7 , wherein
 the fin outer dimension is in a range between at least 3.0 mm and at most 7.3 mm.   
   
   
       9 . The heat exchanger according to  claim 8 , wherein
 the fin outer dimension is in a range between at least 4.0 mm and at most 6.0 mm.   
   
   
       10 . The heat exchanger according to  claim 1 , wherein
 the projections extend continuously from upstream ends to downstream ends of the tubes with respect to a flow direction of the external fluid flowing outside of the tubes.   
   
   
       11 . The heat exchanger according to  claim 1 , wherein
 each of the tubes has a first tube member and a second tube member joined with the first tube member, and the tube main walls of each tube are included in the first and second tube members.   
   
   
       12 . The heat exchanger according to  claim 11 , wherein
 the first tube member and the second tube member have an identical shape.   
   
   
       13 . The heat exchanger according to  claim 1  wherein
 each of the tubes has a separation wall for separating an inner space of the tube into a plurality of spaces in a direction perpendicular to a longitudinal direction of the tube, and   the separation wall is integrated with the tube main walls.   
   
   
       14 . The heat exchanger according to  claim 1 , wherein
 the projections have curved shapes extending along the tube main walls in a meandering manner in a direction perpendicular to a longitudinal direction of the tubes.   
   
   
       15 . The heat exchanger according to  claim 1 , wherein
 the projections have straight shapes extending along the tube main walls and obliquely with respect to a longitudinal direction of the tubes.   
   
   
       16 . The heat exchanger according to  claim 1 , wherein
 the projections have V-shapes that extend along the tube main walls and diverging in a longitudinal direction of the tubes.   
   
   
       17 . The heat exchanger according to  claim 1 , wherein
 the projections are meshed along the tube main walls.   
   
   
       18 . The heat exchanger according to  claim 1 , wherein
 the projections have side walls extending perpendicular to outer surfaces of the tube main walls, and   the side walls define edged corners with the outer surfaces of the tube main walls.   
   
   
       19 . The heat exchanger according to  claim 1 , wherein
 the projections have side walls extending perpendicular to outer surfaces of the tube main walls, and   the side walls define curved corners with the outer surfaces of the tube main walls.   
   
   
       20 . The heat exchanger according to  claim 1 , wherein
 the fins are corrugated fins including first fin walls and second fin walls connecting the first fin walls, and   the first fin walls are flat and joined with outer surfaces of the tube main walls.   
   
   
       21 . The heat exchanger according to  claim 20 , wherein
 the second fin walls have louvers that are angled with respect to a flow direction of the external fluid flowing through the fins.   
   
   
       22 . The heat exchanger according to  claim 1 , wherein the external fluid is air for cooling the refrigerant.