Corrugated fin type heat exchanger

Abstract

In a corrugated fin type heat exchanger a flat tube can be replaced, to improve heat exchange performance thereof. A characteristic part of the heat exchanger lies in a projection having been formed on the ascending surface and the descending surface of the corrugated fin of respective tube elements.

Claims

1. A corrugated fin type heat exchanger, comprising: a flat tube having a pair of even flat surface portions whose horizontal sections face each other, and a pair of joining portions that link both the flat surface portions; a corrugated fin having pairs of flat ascending surfaces and descending surfaces arranged alternately, and a bottom portion and top portion each joining respective surfaces in a wavy pattern; a plurality of tube elements in which the bottom portions alone of the corrugated fin are joined to each of a pair of the flat surface portions of the flat tube; and a pair of tanks into which both ends of the flat tube of respective tube elements are inserted, wherein: the respective tube elements are arranged with the top portions of each corrugated fin separated one another; and on each of the ascending surface and on the descending surface, a respective projection configured to guide an air flow is formed only at a location near to the top portion, the projection being parallel to a ridgeline of wave of the corrugated fin and extending continuously over substantially an entire length of the ridgeline.

2. The corrugated fin type heat exchanger according to claim 1, wherein the projections are formed on an outer side of the ascending surface of the wave, and on an inner side of the descending surface of the wave, respectively.

3. The corrugated fin type heat exchanger according to claim 1, wherein the projections are formed on an outer side of the ascending surface of the wave, and on an outer side of the descending surface of the wave, respectively.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1(A) illustrates an explanatory perspective view of a state of a gas flowing through a tube element of a heat exchanger of a first embodiment of the invention in this application, and FIG. 1(B) a cross-sectional view seen along a B-B arrow in FIG. 1(A).

(2) FIG. 2 illustrates an assembled perspective view of the tube element of the same heat exchanger.

(3) FIG. 3 illustrates a front view of the same heat exchanger.

(4) FIG. 4 is an expanded cross-section perspective view of IV part in FIG. 3.

(5) FIG. 5 illustrates a main part cross-sectional view of a tube element of a heat exchanger of a second embodiment of the invention in this application.

(6) FIG. 6 illustrates a comparative view of heat exchange performance between a conventional type corrugated fin and the corrugated fin according to the present application.

(7) FIG. 7 illustrates an explanatory view of a state of a gas flowing through a tube element of a conventional corrugated fin type heat exchanger.

DESCRIPTION OF EMBODIMENTS

(8) Next, embodiments of the present invention will be explained on the basis of the drawings.

(9) The heat exchanger of the present invention is a corrugated fin type heat exchanger for use, mainly, in large-scaled working machines such as mining working machines and construction working machines that are used in places with much dust, and has, in particular, such a construction that a plurality of flat tubes inserted into a pair of tanks can independently be removed and replaced.

(10) The flat tube 2 of this heat exchanger has, as shown in FIG. 2, a pair of even flat surface portions 2a facing each other, a pair of joining portions 2b that link both the flat surface portions 2a, and cylinder-like portions 2c with a circular cross-section, each being formed at both ends of the flat tube 2.

(11) As shown in FIG. 1(A), FIG. 1(B), the corrugated fin 3 has a shape such that a wave shape continues along the direction of an axis line connecting open ends of the flat tube 2. In other words, a waved corrugated fin is formed with a pair of the ascending surfaces 3d and descending surfaces 3e arranged alternately, and the bottom portion 3b and the top portion 3c connecting between surfaces 3d, 3e in a wavy pattern.

(12) The tube element 5 has been formed, as shown in FIG. 2, by joining the bottom portion 3b alone of the corrugated fin 3 with the pair of flat surface portions 2a of the flat tube 2.

(13) As shown in FIG. 3, the cylinder-like portions 2c of the flat tube 2 of respective tube elements 5 have been detachably inserted into tube insertion holes of the pair of tanks 1 via a tubular bush. In this instance, the flat tube 2 and the corrugated fin 3 of the tube element 5 have previously been brazed and joined in a high temperature furnace.

(14) Adjacent tube elements 5 are separated from each other in top portions 3c of respective corrugated fins 3, and can be set arranged in a zigzag form as shown in FIG. 4.

(15) A characteristic part of the present invention lies in the projection 4 having been formed on the ascending surface 3d and the descending surface 3e of the corrugated fin 3 of respective tube elements 5.

(16) As shown in FIG. 1(A) and FIG. 2, the projection 4 being parallel to the ridgeline 3a of the wave of the corrugated fin is formed in a location near to the top portion 3c on the ascending surface 3d and on the descending surface 3e of the corrugated fin 3. This projection 4 works as a barrier for preventing an air flow from escaping from the surface of the corrugated fin 3 to a gap 8. As shown in FIG. 1(B), the projection 4 formed on the ascending surface 3d projects to the outer side of the ascending surface 3d, and the projection 4 formed on the descending surface 3e projects to the inner side of the descending surface 3e (the projecting directions of the projections 4 are the same).

(17) Next, FIG. 5 shows a second embodiment of the projection 4 that is the characteristic part of the present invention.

(18) This second embodiment differs from the first embodiment in the projection directions of the projections 4. In other words, as illustrated in FIG. 5, each of projections 4 equipped on the ascending surface 3d and on the descending surface 3e projects in directions facing each other. Therefore, they work as barriers that prevent effectively an air flow leakage to the gap 8.

(19) FIG. 6 illustrates graphs that compare respectively percentages (%) of heat release quantity and percentages (%) of pressure loss, among corrugated fins 3 of the first embodiment (middle graph) and the second embodiment (right graph), and a straight type corrugated fin of a conventional technology (left graph). The straight type is used as the reference (100%). The analysis was conducted under conditions of 80° C. of tube internal wall temperature, 45° C. of gas temperature, and 8 m/s of gas flow speed.

(20) As shown in FIG. 6, the first embodiment showed 8% increase in heat release quantity and, on the other hand, 27% increase in pressure loss, relative to the conventional technology. The second embodiment showed 5% increase in the heat release quantity and, on the other hand, 19% increase in the pressure loss, relative to the conventional technology.

(21) In both first embodiment and second embodiment, the pressure loss slightly increases, but improvement in the heat release quantity is surely recognized, and improvement in heat release performance can be recognized in a heat exchanger in which tube replacement is possible.

REFERENCE SIGNS LIST

(22) 1: tank 2: flat tube 2a: flat surface portion 2b: joining portion 2c: cylinder-like portion 3: corrugated fin 3a: ridgeline 3b: bottom portion 3c: top portion 3d: ascending surface 3e: descending surface 4: projection 5: tube element 6: core 6a: first row core 6b: second row core 6c: third row core 6d: fourth row core 7: outlet/inlet pipe 8: gap 9: air flow