JP2006349208A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat exchange efficiency by adequately forming cut and raised pieces on a fin. <P>SOLUTION: The heat exchanger is provided with a refrigerant tube 11 passing a refrigerant, and a plurality of tabular fins 12 arranged side by side on the refrigerant tube 11 with intervals in a tube axis direction, and heat exchange is carried out between the refrigerant and air flowing along plate faces of the fins 12. The fin 12 is plurally provided with the cut and raised pieces 15 formed by cutting and bending one part of the plate face, and openings 16 formed to penetrate the fin 12 following forming of the cut and raised pieces 15. The cut and raised pieces 15 are bent to alternately protrude from both faces of the fin 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat exchanger in which a plurality of fins are arranged in parallel in a refrigerant pipe.

  An evaporator used for a heat exchanger, for example, a refrigerator or the like, has a plurality of fins arranged in parallel along a tube axis direction at intervals in a refrigerant tube through which a refrigerant flows, and sends air in a direction along a plate surface of the fins. Thus, heat exchange is performed between the air and the refrigerant (for example, see Patent Document 1). In order to improve the efficiency of this heat exchange, various attempts have been made to increase the heat transfer of the refrigerant pipes and fins.

  As a method of increasing the heat transfer of the fins, it is conceivable to increase the surface area in contact with air by forming the corrugations by partially extending the fins. As another method, it is also conceivable to cut and raise a part of the fin to form a cut and raised piece, and to apply the flowing air directly to the cut and raised piece.

JP-A-5-133644

  Generally, the fin used for an evaporator is very thin with a thickness of about 0.15 mm. Therefore, if it is formed into a corrugated shape by overhanging as described above, the fin may be broken, and it is difficult to form a high wave. Therefore, there is a limit to the increase of the surface area, and the improvement of the efficiency of heat exchange cannot be expected.

  Also, in the method of forming the cut-and-raised piece on the fin, depending on the direction and angle of the cut-and-raised piece, the air flow may be hindered, causing air retention or passing through at a high speed with almost no air hitting the cut and raised piece. Or In such a state, sufficient heat exchange between the air and the fins is not possible.

  An object of the present invention is to improve the efficiency of heat exchange by appropriately forming a cut and raised piece on a fin.

  The invention described in claim 1 includes a refrigerant pipe through which a refrigerant flows, and a plurality of plate-like fins arranged in parallel at intervals in the pipe axis direction on the refrigerant pipe. In the heat exchanger for exchanging heat between the air flowing along the refrigerant and the refrigerant, the fin is formed by cutting and bending a part of the plate surface and bending the cut and raised piece A plurality of openings formed so as to penetrate the fins along with the formation are provided in the air flow direction, and the cut and raised pieces are bent so as to alternately protrude on both sides of the fins. Features.

  The invention according to claim 2 is that, in the invention according to claim 1, the cut and raised pieces are inclined so as to gradually move away from the plate surface of the fin from the upstream side to the downstream side in the air flow direction. Features.

  The invention described in claim 3 is characterized in that, in the invention described in claim 1, fins having the same shape are arranged side by side in the same direction.

  In the first aspect of the present invention, the flow of air flowing along the fin plate surface is suppressed by the cut-and-raised piece projecting on one surface of the fin, and the other side of the fin passes through the opening on the upstream side of the cut-and-raised piece. Flowing on the surface. The air that has flowed to the other surface is suppressed by the next cut-and-raised piece, and flows again to the one surface side through an opening adjacent to the upstream side.

  Therefore, according to the first aspect of the present invention, the air can smoothly flow so as to meander on both sides of the fin, and the flow velocity of the air becomes slower than the case where the air flows linearly. The fin can be touched for a long time, and heat exchange can be appropriately performed during that time. Thereby, the efficiency of heat exchange improves.

  According to the invention of claim 2, the air can be flowed more smoothly without excessively suppressing the flow of air.

  According to the invention of claim 3, the air flows substantially uniformly around each fin, and the heat exchange efficiency is stabilized. Moreover, since the kind of fin can be reduced, it leads also to cost reduction.

  FIG. 1 is a front view of a heat exchanger according to an embodiment of the present invention, and FIG. 2 is a partial perspective view of the heat exchanger. The heat exchanger 10 is an evaporator mainly used in a refrigerator, and is spaced from the refrigerant pipe 11 meandering by combining the straight pipe portion 11A and the curved pipe portion 11B, and the straight pipe portion 11A of the refrigerant pipe 11. And a plurality of fins 12 arranged side by side. The refrigerant pipe 11 and the fins 12 are made of aluminum or copper having high thermal conductivity.

  The fin 12 is a rectangular thin plate material. Two refrigerant pipes 11 are passed through and fixed to the upper and lower central portions of the fins 12. A plurality of cut and raised pieces 15 are formed on the fin 12.

  FIG. 3 is a front view (partial cross-sectional view) of the fin, and FIG. 4 is a side view of the fin. The cut-and-raised pieces 15 are formed at the upper and lower three positions of the upper, middle, and lower stages of the fin 12, and are further formed at the front and rear three positions so as to avoid the two refrigerant pipes 11. All the cut and raised pieces 15 have a rectangular shape, and the lower side is connected to the plate surface of the fin 12. The cut and raised pieces 15 are inclined with respect to the fins 12 at an angle of about 45 °.

  In FIG. 3, the upper cut-and-raised piece 15U protrudes to the right side of the fin 12, the middle cut-and-raised piece 15M protrudes to the left side, and the lower cut-and-raised piece 15L protrudes to the right side. That is, the cut and raised pieces 15U, 15M, and 15L protrude alternately on both surfaces of the fin 12.

  The fin 12 has an opening 16 penetrating left and right by forming a cut and raised piece 15.

  As shown in FIG. 3, air flows through the evaporator 10 from below to above as indicated by an arrow X. The cut-and-raised piece 15 is inclined so as to gradually move away from the plate surface of the fin 12 from the upstream side to the downstream side when viewed in the air flow direction X.

[Operation of this embodiment]
Hereinafter, the operation of the present embodiment will be described mainly focusing on the fins 12 </ b> B arranged in the center of FIG. 3. In the figure, the leftmost fin is labeled 12A, the middle fin is labeled 12B, and the right fin is labeled 12C.

  The air flowing on the left side of the fin 12B is diverted and suppressed by the cut and raised pieces 15L on the lower stage of the fin 12A and the cut and raised pieces 15M on the middle stage of the fin 12B, and the flow direction X of the cut and raised pieces 15M on the middle stage of the fin 12B. It flows to the right side of the fin 12B through the opening 16L on the upstream side (arrow b1).

  Further, the air flow is diverted and suppressed by the cut and raised piece 15M in the middle stage of the fin 12C and the cut and raised piece 15U in the upper stage of the fin 12B, and the opening on the upstream side in the flow direction X of the cut and raised piece 15U in the upper stage of the fin 12B. After 16M, it returns again to the left side of the fin 12B (arrow b2). Thereafter, it flows upward as it is, or is turned to the cut and raised piece 15U on the upper stage of the fin 12A, flows to the right side of the fin 12B through the opening 16U, and exits upward from the fin 12B.

  Therefore, the air flows so as to meander on both sides of the fin 12 through the opening 16. As the air meanders in this manner, the flow velocity becomes slower than when the air flows linearly, and heat exchange with the fins 12 is appropriately performed during that time.

  In addition, the flow of air does not meander through the openings 16 as described above, but also flows through the fins 12 as they are. Also in this case, the fluid flows while meandering by the cut and raised pieces 15 protruding between the fins 12.

  The cut and raised piece 15 is inclined so as to gradually move away from the plate surface of the fin 12 from the upstream side to the downstream side in the air flow direction X, so that the air flow is not excessively suppressed, and the air Can be smoothly meandered.

  As shown in FIG. 3, the fins 12 have the same shape and are arranged in the same direction. Thereby, air flows substantially uniformly around each fin 12, and stable heat exchange can be performed. Further, since the fins 12 can be constituted by one type, the cost can be reduced.

[Simulation analysis of this embodiment]
The applicant of the present application performed a simulation on the computer and analyzed the performance of the fins 12 of the present embodiment. The simulation conditions are as follows.

(1) In order to verify the effectiveness of the fins 12 of this embodiment, the shapes shown in FIGS. 7A to 7F were also analyzed as comparative examples. The fins 12 of (A) to (F) have the following shapes, respectively.
(A) is a smooth shape without cut and raised pieces and irregularities.
(B) is an example in which peaks (waves) 17 are overhanged on the upper, middle and lower stages to increase the surface area.
(C) is the same as a projecting mountain, but the mountain is higher than (B).
(D) is a cut-and-raised piece 15 which is inclined so as to gradually move away from the fin 12 from the upstream side to the downstream side with respect to the air flow direction, and projects to one side of the fin 12.
(E) is a cut-and-raised piece 15 that inclines so as to gradually approach the fin 12 from the upstream side to the downstream side in the air flow direction and projects to one side of the fin 12.
(F) shows a cut-and-raised piece 15 that is orthogonal to the fin 12 protruding from one side of the fin 12.

(2) The shape of (A) was used as a basic model, and (B) to (F) and the present invention were evaluated as a comparison with this.

(3) As shown in FIG. 5 and FIG. 6, it is assumed that one fin 12 is installed in a virtual box (cabinet) 20 that is vertically penetrated and blown from below the cabinet 20.

(4) The fin material was A1050 (thermal conductivity: 231 W / mK), and the dimensions were length 28 × width 60 × thickness 0.15 (mm). The fin pitch was equivalent to 5 mm.

(5) The copper pipe (refrigerant pipe) 11 was made into a copper block (thermal conductivity: 395 W / mK) having an outer diameter of 8.35 mm, and two copper pipes (refrigerant pipe) were arranged. The temperature was fixed at 80 ° C.

(6) The ambient temperature was 25 ° C., and the wind speed into the cabinet 20 was 0.5 m / s (inlet temperature 25 ° C.). The flow field was a laminar flow model for smooth fins. The time dependence was assumed to be a steady analysis, and the flow field (velocity / pressure) and temperature field were analyzed. The fluid region was an air layer and thermal radiation was ignored.

(7) From the simulation analysis results, the heat flow rate at the lower part (inlet) and the upper part (outlet) of the cabinet 20 was obtained, and the difference was taken as the total heat flow rate.

  FIG. 8 is a table showing the analysis results, and FIG. 9 is a graph showing the analysis results. The fins 12 of the comparative examples and the present invention have the same dimensions, but the surface area of the fins 12 is larger for the corrugated fins (comparative examples B and C) than the smooth fins (comparative example A), and the others are the same. ing.

  Hereinafter, a comparison between the smooth fin of the comparative example (A) and the other fins (B) to (F) will be described. In the comparative example (B), the area ratio is increased by 3%, 1.03, and the total heat quantity ratio is increased by 1.05, 5%, compared with the comparative example (A). In Comparative Example (C), the area ratio is increased by 12% and the heat ratio is increased by 8% compared to Comparative Example (A).

  In Comparative Examples (B) and (C), some improvement in efficiency was recognized from the analysis results. However, the rate of increase in the heat ratio is lower than the increase in the area ratio between the comparative example (B) and the comparative example (C). Therefore, even if the height of the mountain 17 is further increased, it is considered that an increase in the heat quantity ratio cannot be expected. Further, in order to form the high peak 17 on the fin 12 which is a thin plate material by overhanging processing, there is a processing limit, and the improvement of the efficiency of heat exchange reaches the limit at a low level.

  In Comparative Example (D), there was almost no difference in the caloric ratio as compared with Comparative Example (A). This is because, as shown in FIG. 7D, the air flow is cut and raised, blocked by the pieces 15 and divided into the left and right sides of the fins 12, and comes out straight at a relatively high speed (arrows y1, y2). It is considered that air retention Z occurs between the cut and raised pieces 15. That is, it is considered that the air flowing at high speed does not appropriately exchange heat because the time for touching the fins is shortened, and the heat exchange is not promoted with the retained air.

  The comparative example (E) has substantially the same caloric ratio as the comparative example (A). Also in this case, as in Comparative Example D, air flows at high speed on both the left and right sides of the fin 12 (y1, y2), and a stay Z occurs between the cut and raised pieces 15.

  Also for the comparative example (F), the heat quantity ratio is substantially the same as that of the comparative example (A). In this case as well, as in the comparative example (D), air flows at high speed on both the left and right sides of the fin 12 (y1, y2), and a stay Z occurs between the cut and raised pieces 15.

  In the case of the present invention, the area ratio was the same as that of Comparative Example (A), but the heat quantity ratio was about 1.16, and an improvement in heat exchange efficiency of about 16% was recognized. In the present invention, as shown in FIG. 6, a slight stay Z is seen on the lower side of the cut-and-raised piece 15, but since air snakes on the left and right of the fin 12 through the opening 16, It is considered that heat exchange is appropriately performed.

[Other Embodiments]
(1) As shown in FIG. 10, the cut and raised piece 15 can be inclined so as to gradually approach the plate surface of the fin 12 from the upstream side to the downstream side with respect to the air flow direction.

  (2) Further, as shown in FIG. 11, the cut and raised pieces 15 can be provided orthogonal to the fins.

  (3) The heat exchanger of the present invention does not need to form cut-and-raised pieces on all the fins, and may be one in which fins having cut-and-raised pieces and smooth fins are alternately arranged in parallel. .

It is a front view of the heat exchanger which concerns on embodiment of this invention. It is a fragmentary perspective view of the same heat exchanger. It is a front view (partial sectional view) of a fin. It is a side view of a fin. It is a perspective view which shows the model of simulation. It is a front view which shows the model of the simulation. It is a front view which shows the model of the comparative example of the simulation. It is a table | surface which shows the analysis result of the simulation. It is a graph which shows the analysis result of the simulation. It is a front view (partial sectional view) of a fin showing a second embodiment. It is a front view (partial sectional view) of a fin showing a third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Heat exchanger 11 Refrigerant tube 12 Fin 15 Cut and raised piece 16 Opening

Claims (3)

A refrigerant pipe through which the refrigerant flows, and a plurality of plate-like fins arranged in parallel at intervals in the pipe axis direction on the refrigerant pipe, and the air flowing along the plate surface of the fin and the refrigerant In heat exchangers that exchange heat between
The fin has a cut-and-raised piece formed by cutting and bending a part of the plate surface, and an opening formed so as to penetrate the fin when the cut-and-raised piece is formed. A heat exchanger comprising: a plurality of cut-and-raised pieces in a direction, wherein the cut-and-raised pieces are bent so as to alternately protrude on both sides of the fin.   The heat exchanger according to claim 1, wherein the cut-and-raised piece is inclined so as to gradually move away from the plate surface of the fin from the upstream side to the downstream side in the air flow direction. The heat exchanger according to claim 1, comprising fins having the same shape arranged side by side in the same direction.

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