Heat transfer tubes and method for manufacturing

• US 5,052,476 A
• Filed: 08/28/1990
• Issued: 10/01/1991
• Est. Priority Date: 02/13/1990
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Shindoh Company Limited (Mitsubishi Materials Corporation)
• Original Assignee: 501 Mitsubishi Shindoh Company Limited
• Inventors: Sukumoda, Shunroku, Masukawa, Seizo, Kohno, Haruo
• Primary Examiner(s): Rivell, John
• Assistant Examiner(s): LEO, LEONARD R
• Application Number:
  US07/574,490
• Time in Patent Office: 399 Days
• Field of Search: 165/133, 165/179, 165/181, 165/183, 165/184, 138/38
• US Class Current: 165/133
• CPC Class Codes: B21B 1/227 Surface roughening or texturing
• CPC Class Codes: B21C 37/0803 the tubes having a special shape, e.g. polygonal tubes
• CPC Class Codes: B21C 37/083 Supply, or operations combined with supply, of strip material
• CPC Class Codes: B21H 8/00 Rolling metal of indefinite length in repetitive shapes specially designed for the manufacture of particular objects , e.g. checkered sheets
• CPC Class Codes: F28F 1/40 the means being only inside the tubular element
• CPC Class Codes: F28F 13/187 especially adapted for evaporator surfaces or condenser surfaces, e.g. with nucleation sites

Abstract

A heat transfer tube having an inner surface in which are formed primary grooves and secondary grooves. The primary grooves parallel to one another, extending at an angle to the longitudinal direction of the heat transfer tube and secondary grooves parallel to one another, extending an angle to the primary grooves. At the intersections of the primary and secondary grooves is formed a series of pear-shaped grooves whose inner opening dimension is smaller than the dimension of the bottom of the pear-shaped groove.

Claims

1. A heat transfer tube having an inner surface in which are formed:

(a) primary grooves, having a U-shaped cross section and parallel to one another, extending at an angle to the longitudinal direction of the heat transfer tube,

(b) secondary grooves, having a V-shaped cross section and parallel to one another, extending at an angle and intersecting with the primary grooves, and

(c) pear-shaped grooves, having an opening width formed between the intersections of the primary and secondary grooves, having a trapezoidal cross sectional shape, said opening width being smaller than the dimension of their bottom portion, and are distributed regularly and uniformly along the primary grooves.

2. A heat transfer tube according to claim 1 wherein the widths of the opening of the pear-shaped grooves are not wider than about 75% of the widths of the opening of the primary grooves.

3. A heat transfer tube according to claim 2 wherein the widths of the opening of the primary grooves are between about 40% to 140%, inclusive, of the depth of the primary grooves.

4. A heat transfer tube according to claim 2 wherein the primary grooves are equidistantly spaced at a distance about 1.5 to 3 times the width of the opening of the primary grooves.

5. A heat transfer tube according to claim 2 wherein the widths of the opening of the secondary grooves are between about 25% to 90%, inclusive, of the width of the opening of the primary grooves.

6. A heat transfer tube according to claim 2 in which the depth of the secondary grooves are between about 50% to 100%, inclusive, of the depth of the primary grooves.

7. A heat transfer tube according to claim 1 wherein a tube is made of a material selected from the group consisting of copper, copper alloys, aluminum and aluminum alloys.