Tubular heat exchanger

Abstract

A tubular heat exchanger includes tubes, each having a plurality of cells inside, stacked in multiple stages and zigzag-bent heat-radiating fins brazed and integrated among the tubes. The gaps among the tubes become progressively wider toward the rear to enable foreign substance to be discharged without being caught by the heat-radiating fins. The upper and lower surfaces are formed of an inclined surface progressively and symmetrically reduced and inclined rearwardly with respect to a tube center line to have the front cell thicker than the end cell. The upper and lower surfaces of the heat-radiating fins are formed of an inclined surface progressively and symmetrically enlarged and inclined rearwardly with respect to a fin center line. A wind direction guiding ribs, tilted toward the upper and lower surfaces of the tubes, protrude from the heat-radiating fins to blow the wind along the upper and lower surfaces of the tubes.

Claims

1. A tubular heat exchanger, comprising: a top; a plurality of tubes stacked in multiple stages to have a front gap among the tubes narrower than a rear gap among the tubes, each tube having: a front cell formed inside; a plurality of middle cells formed inside; an end cell formed inside, wherein the front cell is thicker than the end cell; an upper surface formed of an inclined surface progressively and symmetrically reduced and inclined rearwardly from a front end of said each tube to a rear end of said each tube with respect to a tube center line; and a lower surface formed of an inclined surface progressively and symmetrically reduced and inclined rearwardly from a front end of said each tube to a rear end of said each tube with respect to the tube center line, wherein the tubes are stacked in a tilted position such that the tube center line is tilted in a slope of a predetermined angle to maintain the lower surface horizontally parallel to a wind direction; and a plurality of zigzag-bent heat-radiating fins placed among the tubes, each heat-radiating fin comprising: a horizontal upper surface, wherein the horizontal upper surface is brazed and welded to the lower surfaces of the tubes; and a lower surface formed of an inclined surface progressively enlarged and inclined rearwardly from a front end of said each heat-radiating fin to a rear end of said each heat-radiating fin with respect to a horizontal fin center line, wherein the lower surface is brazed and welded to the upper surfaces of the tubes.

2. The tubular heat exchanger as in claim 1, wherein a front portion of said each heat-radiating fin comprises an indented portion indented toward an inner portion of the front gap among the tubes to reduce airflow resistance at the front gap.

3. The tubular heat exchanger as in claim 1, wherein one of the middle cells of said each tube located at a position corresponding to the indented portion is sized smaller than that of other middle cells due to a reduced heat-radiating area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view showing the configuration of a common tubular heat exchanger;

(2) FIG. 2 is a cross-sectional view of a conventional tube for a heat exchanger;

(3) FIG. 3 is a cross-sectional view of a conventional oval tube for a heat exchanger;

(4) FIG. 4 is a disassembled perspective view of tubes and heat-radiating fins according to an embodiment of the present invention;

(5) FIG. 5 is a process view showing a process of manufacturing a heat-radiating fin according to an embodiment of the present invention;

(6) FIG. 6 is a cross-sectional view of a tubular heat exchanger according to an embodiment of the present invention;

(7) FIG. 7 is an exploded view of an exemplary heat-radiating fin according to an embodiment of the present invention;

(8) FIG. 8 is a flow analysis of a tube according to an embodiment of the present invention and a flow analysis of a conventional tube; and

(9) FIG. 9 is a cross-sectional view of a tubular heat exchanger according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) FIGS. 4 to 6 illustrate a heat exchanger according to an embodiment of the present invention. Tubes 100 are continuously extruded. During the extrusion process, quadrilateral middle cells 102 are formed inside by a plurality of partition walls 101, and a front cell 103 and an end cell 104, both having a streamlined cross-section, are formed at front and rear portions. Upper surfaces 105 and lower surfaces 106 of the tubes 100 are formed of an inclined surface progressively and symmetrically reduced and inclined with respect to a tube center line TL toward the rear, and the front cell 103 is thicker than the end cell 104.

(11) According to an embodiment of the present invention, a tube is 16 mm from a front end to a rear end. The thickness of the front cell 103 is 3 mm, and that of the end cell 104 is 1.5 mm. Also, the interval among the tubes 100 is approximately 9.8 mm with respect to the tube center line TL.

(12) Heat-radiating fins 200 placed in the gaps among the tubes are manufactured as in FIG. 5. A rolled plate is unrolled, and an indented portion 201 is cut and formed at a front portion of the plate with respect to a virtual bending line BL. After the indented portion 201 is formed on the plate, the plate is passed between a pair of an upper roller 300 and a lower roller 301. Here, the bending line BL is vertically bent to form the zigzag heat-radiating fins 200. While the heat-radiating fins 200 are zigzag-bent, wind direction guiding ribs 202 are also bent together. The wind direction guiding ribs 202 may be manufactured with the indented portion 201 before the heat-radiating fins 200 are bent. The upper roller 300 and the lower roller 301 are manufactured in the shape of a cone. The shafts of the upper roller 300 and the lower roller 301 are not in parallel and are tilted toward each other. Accordingly, a rear portion forms a greater area than a front portion if the heat-radiating fins 200 are manufactured.

(13) As shown in FIG. 7, the heat-radiating fins manufactured by the above-mentioned method are closely attached and brazed to the upper surfaces 105 and the lower surfaces 106 among the tubes 100 stacked in multiple stages after a filler agent is applied on the surfaces of the heat-radiating fins to integrate the tubes 100 with the heat-radiating fins 200 in order to manufacture a heat exchanger.

(14) As in FIG. 6, the heat exchanger manufactured by the above-mentioned method includes the tubes 100 placed in such a way that the tube center lines TL are parallel to each other, and the upper surfaces 105 and the lower surfaces 106 formed of an inclined surface reduced and inclined toward the rear, thereby causing the front gaps among the tubes 100 to relatively be narrower than the rear gaps. Since the rear gaps are wide, foreign substance is immediately discharged without being accumulated on the upper surfaces 105 of the tubes 100.

(15) Also, the indented portion 201 is formed at the front portion of the heat-radiating fins 200 to prevent the front gaps among the tubes 100 from being blocked. Accordingly, wind may easily pass through the narrowed front gaps, thereby reducing airflow resistance at the front gaps and guiding the wind not to be stagnant at the front gaps and to be blown toward the inner portion. Since a heat-radiating area w of the middle cell 102, placed at a position corresponding to the indented portion 201, is reduced, the middle cell 102 is preferably manufactured to have a relatively smaller heat-radiating area w, and the reduced heat-radiating area w is complemented by enlarging the heat-radiating area w in the front cell 103 and the end cell 104. As in FIG. 6, the front cell 103 is a portion directly coming in contact with the wind, thereby having a relatively greater heat exchange amount than other portions. Also, the area of each of the heat-radiating fins 200 corresponding to the end cell 104 is enlarged compared with other portions, thereby complementing the insufficient heat-radiating area w from the front cell 103 and the end cell 104.

(16) Also, the wind direction guiding ribs 202 are disposed at a rear portion of each of the heat-radiating fins 200 to guide the wind to be blown along the upper surfaces 105 and the lower surfaces 106 of the tubes 100. As in FIG. 8, the tubes 100 according to an embodiment of the present invention have a weakness, wherein the wind is more deviated from the tube surfaces toward the rear compared with a conventional tube, thereby degrading the air-cooling performance at the tube surfaces. However, each of the wind direction guiding ribs 202 has a slope fighting against the wind, thereby enhancing the air-cooling performance at the tube surfaces as the wind is blown along the upper surfaces 105 and the lower surfaces 106 of the tubes 100. Also, the wind direction guiding ribs 202 are partially cut from the heat-radiating fins 200, thereby increasing the heat-radiating area.

(17) FIG. 9 illustrates a heat exchanger according to another embodiment of the present invention which extrudes and manufactures the tubes 100 using the same method as the previous embodiment of the present invention. That is, the upper surfaces 105 and the lower surfaces 106 are formed of an inclined surface progressively reduced and inclined with respect to the tube center line TL toward the rear to have the front cell 103 thicker than the end cell 104.

(18) However, the another embodiment of the present invention tilts the tube center line TL in a slope α of a predetermined angle to enable the lower surfaces 106 to maintain the state of being horizontally parallel to the wind direction when the tubes 100 are stacked in multiple stages. Here, the upper surfaces 105 become more tilted downward than the time when the tubes 100 are manufactured, and the heat-radiating fins 200 are manufactured to be in close contact with the upper surfaces 105 and the lower surfaces 106 among the tubes 100. The heat-radiating fins 200 also become tilted to be enlarged and inclined downward from a fin center line PL parallel to an upper portion and horizontal to a lower portion, wherein the front portion forms the indented portion 201 to reduce the airflow resistance at the front portion and guide the wind toward the inner portion.

(19) The another embodiment of the present invention configured as such has a strength, wherein the heat exchange performance at the tube surfaces is not degraded due to the lower surfaces 106 of the tubes 100 being parallel to the wind direction. Also, the upper surfaces 105 become more tilted downward than in the previous embodiment of the present invention due to the slope α, thereby enabling foreign substance to easily be discharged by being dropped downward. The wind insufficient on the upper surfaces 105 is complemented by the wind direction guiding ribs 202, thereby not degrading the air-cooling performance at the tube surfaces.