Flat heat transfer tube

Abstract

A flat heat transfer tube has upper and lower walls and fluid channels. Two to five inner fins are formed on each of two surfaces of the flat walls facing each fluid channel. The tube height is 1.8 mm or less; the tube width is 20 mm or less; the fluid channel height is 1.0 mm or less; the fluid channel width w 1 is 2.0 mm or less; the fluid diameter is 0.3 to 1.2 mm; and the thickness t of each wall is 0.4 mm or less. The ratio h 2 /t of the fin height h 2 to the wall thickness t satisfies the relation 0.5≦h 2 /t≦2.0. The ratio p 1 /w 1 of the fin pitch p 1 to the fluid channel width w 1 satisfies the relation 0.15≦p 1 /w 1 ≦1/n (where n is the number of the inner fins formed on one of the two surfaces).

1 : A flat heat transfer tube which assumes a flat form having a pair of flat walls facing each other and has a plurality of fluid channels arranged along the width of the flat heat transfer tube; in which an inner fin in the form of an elongated projection extending along the length of the flat heat transfer tube is formed on each of two surfaces of the respective flat walls, the two surfaces facing each of the fluid channels; and which has a tube height H of 1.8 mm or less, a tube width W of 20 mm or less, a height h 1  of the fluid channel of 1.0 mm or less, a width w 1  of the fluid channel of 2.0 mm or less, and a fluid diameter Dh of 0.3 mm to 1.2 mm;
 wherein a thickness t of each of the flat walls is 0.4 mm or less; two to five inner fins are formed on at least one of the two surfaces of the respective flat walls, the two surfaces facing at least one fluid channel; a ratio h 2 /t or h 2   a/t , which is the ratio of a height h 2  or h 2   a  of the inner fin to the thickness t of the flat wall, satisfies a relation 0.5≦h 2 /t≦2.0 or 0.5≦h 2   a/t ≦2.0, respectively; and a ratio p 1 /w 1 , p 2 /w 1 , or p 3 /w 1 , which is the ratio of a fin pitch p 1 , p 2 , or p 3  of the plurality of inner fins to the width w 1  of the fluid channel, satisfies a relation 0.15≦p 1 /w 1 ≦1/n, 0.15≦p 2 /w 1 ≦1/n, or 0.15≦p 3 /w 1 ≦1/n, respectively (where n is the number of the inner fins formed on at least one of the two surfaces of the respective flat walls).   
   
   
       2 : A flat heat transfer tube according to  claim 1 , wherein a plurality of the inner fins are formed on each of the two surfaces of the respective flat walls, the two surfaces facing each of the fluid channels, and the number of the inner fins is the same between the two surfaces. 
   
   
       3 : A flat heat transfer tube according to  claim 2 , wherein the ratio of the height h 2  or h 2   a  of the inner fin to the height h 1  of the fluid channel satisfies a relation h 2 /h 1 <0.5 or h 2   a /h 1 <0.5, respectively, and the positions of the inner fins along the width of each of the fluid channels are the same between the two surfaces of the respective flat walls. 
   
   
       4 : A flat heat transfer tube according to  claim 2 , wherein the ratio of the height h 2  or h 2   a  of the inner fin to the height h 1  of the fluid channel satisfies a relation h 2 /h 1 ≧0.5 or h 2   a /h 1 ≧0.5, respectively, and the positions of the inner fins along the width of each of the fluid channels differ between the two surfaces of the respective flat walls. 
   
   
       5 : A flat heat transfer tube according to  claim 1 , wherein a plurality of the inner fins are formed on each of the two surfaces of the respective flat walls, the two surfaces facing each of the fluid channels, and the number of the inner fins differs between the two surfaces. 
   
   
       6 : A flat heat transfer tube according to  claim 5 , wherein the positions of the inner fins along the width of each of the fluid channels differ between the two surfaces of the respective flat walls. 
   
   
       7 : A flat heat transfer tube according to  claim 2 , wherein the height h 2   a  of at least one of the inner fins formed on at least one of the two surfaces of the respective flat walls, the two surfaces facing each of the fluid channels, differs from the height h 2  of the remaining inner fins. 
   
   
       8 : A flat heat transfer tube which assumes a flat form having a pair of flat walls facing each other and has a plurality of fluid channels arranged along the width of the flat heat transfer tube; in which an inner fin in the form of an elongated projection extending along the length of the flat heat transfer tube is formed on each of two surfaces of the respective flat walls, the two surfaces facing each of the fluid channels; and which has a tube height H of 1.8 mm or less, a tube width W of 20 mm or less, a height h 1  of the fluid channel of 1.0 mm or less, a width w 1  of the fluid channel of 2.0 mm or less, and a fluid diameter Dh of 0.3 mm to 1.2 mm;
 wherein a thickness t of each of the flat walls is 0.4 mm or less; a single inner fin is formed on at least one of the two surfaces of the respective flat walls, the two surfaces facing at least one fluid channel; a ratio h 2 /t, which is the ratio of a height h 2  of the inner fin to the thickness t of the flat wall, satisfies a relation 0.5≦h 2 /t≦2.0; and a ratio w 2   c /w 1 , which is the ratio of a distance w 2   c  between the single inner fin and a side surface of the fluid channel to the width w 1  of the fluid channel, satisfies a relation 1/4≦w 2   c /w 1 ≦1/2.   
   
   
       9 : A flat heat transfer tube according to  claim 8 , wherein a single inner fin is formed on each of the two surfaces of the respective flat walls, the two surfaces facing each of the fluid channels; the ratio of the height h 2  of the inner fin to the height h 1  of the fluid channel satisfies a relation h 2 /h 1 <0.5; and the position of the inner fin along the width of each of the fluid channels is the same between the two surfaces of the respective flat walls. 
   
   
       10 : A flat heat transfer tube according to  claim 8 , wherein a single inner fin is formed on each of the two surfaces of the respective flat walls, the two surfaces facing each of the fluid channels; the ratio of the height h 2  of the inner fin to the height h 1  of the fluid channel satisfies a relation h 2 /h 1 ≧0.5; and the position of the inner fin along the width of each of the fluid channels differs between the two surfaces of the respective flat walls. 
   
   
       11 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 1 .   
   
   
       12 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 2 .   
   
   
       13 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 3 .   
   
   
       14 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 4 .   
   
   
       15 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 5 .   
   
   
       16 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 6 .   
   
   
       17 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 7 .   
   
   
       18 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 8 .   
   
   
       19 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 9 .   
   
   
       20 : A heat exchanger including a pair of header tanks arranged apart from each other; a plurality of flat heat exchange tubes extending between the two header tanks, arranged at predetermined intervals along the length of the header tanks, and having opposite end portions brazed to the header tanks after being inserted into respective tube insertion holes formed in the header tanks; and corrugate fins each disposed between and brazed to the adjacent heat exchange tubes;
 wherein each of the heat exchange tubes is the flat heat transfer tube according to  claim 10 .