JP2604722B2 - Flying ube type heat exchanger - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fin tube type heat exchanger used for air conditioning, freezing, refrigeration, etc., for transferring heat between a refrigerant and a fluid such as air.

2. Description of the Related Art As shown in a perspective view of FIG. 7, a conventional fin tube type heat exchanger of this type has a plurality of plate-shaped fins 1 arranged in parallel at regular intervals and a right angle to the plate-shaped fin group 1. The airflow 3 flows between the plate-like fin groups 1 and exchanges heat with the refrigerant flowing through the heat transfer tube group 2. In recent years, such fin tube type heat exchangers have been required to be small and high performance, but since the air flow velocity between the fins is suppressed from the viewpoint of noise and the like, the heat resistance inside the heat transfer tubes is reduced. The heat resistance on the air side is high. Therefore, at present, the heat transfer area on the air side is enlarged so as to reduce the difference with the heat resistance inside the heat transfer tube. However, enlarging the heat transfer surface has physical limitations, and also has problems in terms of economy, space saving, and the like. It is an important issue in heat exchangers.

FIG. 8 to FIG. 11 show an example of a conventional fin tube type heat exchanger. 8 and 10 show partial side views. 9 and 11 show CC ′ and D−, respectively.
The D 'sectional drawing is shown. The conventional example shown in FIGS. 8 and 9 is a so-called flat fin having a staggered pipe arrangement, and the air flow three-way tube row pitch {L ^′ ₁ ▼} of the heat transfer tube 2 is changed to the outer diameter of the heat transfer tube 2. The outer diameter D ₀ ′ of the heat transfer tube 2 is set to about 2.2 times D ₀ ′ (D ₀ ≒ 10 mm) and the pipe step pitch L ₂ ′ perpendicular to the air flow 3.
It is about 2.2 to 2.5 times. The conventional example shown in FIGS. 10 and 11 is called a slit fin. Based on the flat fin, a large number of slit-shaped cut-and-raised portions 5a to 5d are provided between the heat transfer tubes 2 of the plate-like fin 1. It is a thing. In this fin shape, many cut-and-raised 5a ~ 5d
In this case, a thin temperature boundary layer is formed, and the heat transfer performance at the cut and raised portion is good due to the so-called boundary layer leading edge effect.
Note that the heat transfer tube 2 is made to penetrate the plate-like fin 1 via a fin collar 4 provided integrally.

Problems to be Solved by the Invention However, conventionally, there is no idea to evaluate the heat transfer performance by the air-side general transmission based on the same fan power, and the row pitch and the step pitch are determined by another impractical evaluation method. Therefore, for the flat fins, an optimal heat transfer tube arrangement that maximizes the overall heat transfer coefficient on the air side with the same fan power reference taking into account the airflow flow resistance ΔP has not been realized, resulting in an uneconomical design. ing. This includes the outer diameter of the heat transfer tube
Since D ₀ ′ is as large as 10 mm, a large ΔP also has an effect. Further, regarding the slit fins based on this, not only the uneconomical effect of the base itself but also other problems arise. That is, in the cut-and-raised portions 5a and 5b on the upstream side of the airflow 3, the boundary layer leading edge effect is large and the heat transfer performance is high, but in the cut-and-raised portions 5c and 5d on the downstream side of the airflow 3, the cut-and-raised portions 5a and 5b in the front row are The heat exchange performance is low because the heat exchanged gas does not mix with other gases, that is, 5c to 5d enter the temperature boundary layer generated in 5a and 5b. In addition, a large dead water area 6 where gas does not flow is generated downstream of the heat flow 3 of the heat transfer tube 2, and the heat transfer performance in this portion is low, so that the fin heat transfer performance is not significantly improved. Had a point.

Therefore, in view of the above problems, the present invention is based on the same fan power standard by devising the tube arrangement and the tube diameter of the heat transfer tubes.
Maximize the overall heat transfer coefficient on the air side of the flat fins, further promote the mixing of gas in the cut-and-raised section of the slit fins, and reduce dead water generated in the wake of the heat transfer tubes. Accordingly, the present invention provides a fin tube type heat exchanger in which the overall heat transfer coefficient on the air side is dramatically increased.

Means for Solving the Problems In order to solve the above problems, a fin tube type heat exchanger of the present invention is provided with a plurality of plate-like fins arranged in parallel at regular intervals, between which a gas flow flows, and Jo fin outer diameter D is inserted at right angles to _{0 (3mm ≦ D 0 ≦ 7.5mm} ) 1.2D 0 ≦ L 1 the airflow direction tube row pitch L ₁ of the configured heat exchanger tube and a heat exchanger tube
≦ 1.8D ₀ , the pipe stage pitch L ₂ perpendicular to the air flow is 2.6D ₀ ≦ L ₂ ≦
3.5D _0, and a leg for joining a slit-shaped or louver-shaped cut-and-raised group opened and cut between two heat transfer tubes of the plate-shaped fins at the two sides facing the air flow with the fins of the cut-and-raised group. A configuration is provided in which the rows are arranged at an angle to the normal direction of the front edge of the plate-like fin.

Operation The operation of this technical means will be described with reference to FIGS.

FIG. 5 and FIG. 6 show that heat transfer tubes having an outer diameter D ₀ are inserted at right angles into a large number of plate-like fins arranged in parallel at regular intervals, and the line pitch of the heat transfer tubes in the airflow direction is L ₁ , in the fin tube heat exchanger tube stage pitch airflow direction perpendicular and L _2, L _1, L ₂ and performs experiments and analyzes the airflow velocity U _F as a parameter, the same fan power? Pu _F ([Delta] P is the heat exchanger The heat transfer performance was evaluated by the air-side overall heat transfer α _{O based} on the flow resistance of the air flow passing through the vessel).

FIG. 5 is intended to outer diameter D ₀ is viewed impact tube row pitch L ₁ when using the heat transfer tube of 7.3 mm. Although not shown, it has been confirmed that the same tendency as in the characteristic diagram of FIG. 5 appears even in the case where the conventional D ₀ ≒ 10 mm.

Strictly speaking, FIG. 5 shows the characteristics when the value of L ₂ / D ₀ is 3.0, but when 2.6 ≦ (L ₂ / D ₀ ) ≦ 3.5,
The characteristic diagram is almost the same as the diagram. As (L ₂ / D ₀ ) becomes smaller than 2.6, and as (L ₂ / D ₀ ) becomes larger than 3.5, the peak of the peak of the characteristic diagram becomes lower.

Figure 6 is obtained by viewing the effect of Kandan pitch L ₂ when the outer diameter D ₀ is used heat transfer tube of 7.3 mm. Although not shown, it has been confirmed that the same tendency as in the characteristic diagram of FIG. 6 appears even in the case where the conventional D ₀ ≒ 10 mm.

Note that FIG. 6 shows the characteristics strictly when the value of L ₁ / D ₀ is 1.5, but when 1.2 ≦ (L ₁ / D ₀ ) ≦ 1.8
The characteristic diagram is almost the same as the diagram. As (L ₁ / D ₀ ) becomes smaller than 1.2 and (L ₁ / D ₀ ) becomes larger than 1.8, the peak of the peak of the characteristic diagram becomes lower.

When the pipe row pitch L ₁ and the pipe step pitch L ₂ increase, the heat transfer coefficient on the fin surface improves, but the fin efficiency decreases.
Further, the flow resistance ΔP of the air flow is represented by a pipe row pitch L ₁ , a pipe step pitch L
_The smaller ₂ is, the larger the value. Therefore, the air side overall heat transfer α _O
There is a peak at _{L 1 ≒ 1.3D 0, L 2} ≒ 2.9D 0 but the heat transfer performance is maximized _{by, 1.2D 0 ≦ L 1 ≦ 1.8D} 0, 2.6D 0 ≦ L 2 ≦ 3.5D 0
Then, it can be seen that the heat transfer performance is sufficiently practical.

The conventional _{ones, (L 1 / D 0)} = 2.2, (L 2 / D 0) = 2.2~2.5
5 and 6, it can be seen that the column pitch and the step pitch having poor characteristics were employed.

In addition, the outer diameter D ₀ of the heat transfer tube is increased by 3 mm from the conventional D ₀ ≒ 10 mm.
By setting ≦ D ₀ 7.5 mm, the dead water area formed downstream of the heat transfer tube is reduced, and the flow resistance ΔP of the air flow is also reduced.

From the above, the fin tube type heat exchanger according to the present invention improves the air side overall heat transfer α _{O based} on the same fan power ΔPU _F by 40 to 50% as compared with the conventional one.

Further, according to the slit fin having the above-described configuration, a portion of the cut-and-raised portion provided on the downstream side of the airflow to enter the temperature boundary layer generated by the upstream-raised portion is reduced, and the boundary layer leading edge effect at the cut-and-raised portion is sufficiently increased. The heat transfer performance of the fins is improved. Further, since the cut-and-raised legs are provided at an angle to the airflow, the cut-and-raised airflow flowing inside and outside are mixed, and the heat transfer can be promoted by this mixing effect. Furthermore, the airflow having a swirl component induced by the legs enhances the mixing effect described above, and is effective in reducing dead water in the downstream part of the heat transfer tube, thereby increasing the effective heat transfer area of the fins. The performance improvement is also large.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 and 3 are partial side views of a fin tube type heat exchanger according to an embodiment of the present invention. FIGS. 2 and 4 are AA 'and B of FIGS. 1 and 3, respectively. FIG. Reference numeral 11 denotes plate-like fins arranged in parallel at predetermined intervals. Reference numeral 12 denotes a heat transfer tube having an outer diameter D ₀ of 7.3 mm. The tube row pitch L ₁ in the direction of air flow 13 is set to 13.0 mm where (L ₁ / D ₀ ) = 1.78.
Vertical Kandan pitch L ₂ in 13 direction, and a 21.0mm as the _{(L 2 / D 0) =} 2.88. The heat transfer tube 12 is inserted at right angles into a fin collar 14 provided in the plate-like fin 11 by burring or the like, and is fixed by pipe expansion or brazing. In addition, the plate-shaped fin 11 has an airflow between the heat transfer tubes 12.
The legs 17a, 17b, which join the plate-shaped fins 11 of the cut-and-raised group 16 with two side portions 15a, 15b opposed to the 13 direction, make an angle with the normal direction of the front edge of the plate-shaped fins 11. It is provided.

A table comparing the dimensions and performance of the fin tube type heat exchanger of the present embodiment with those of the conventional one is shown below.

According to this table, finned tube heat exchanger of this embodiment, as compared with the conventional, the same fan power? Pu _F reference air side overall heat transfer alpha _O of, from 60/120 to 90/120 1.
5 times, the weight of the heat exchanger is 33% lighter,
The weight is reduced, and the cost can be reduced by about 30%.

The operation according to the present embodiment is as follows. First, the airflow
For 13 direction of the pipe string pitch L ₁ is _{1.2D 0 ≦ L 1 ≦ 1.8D 0} , the airflow 13 perpendicular to the direction Kandan pitch L ₂ is _{2.6D 0 ≦ L 2 ≦ 3.5D 0} ,
As described above, the base flat fin can enhance the air-side heat transfer performance most on the basis of the same fin power. At this time, since the outer diameter D _{0 of the} heat transfer tube is 3 mm ≦ D ₀ ≦ 7.5 mm, the conventional product D ₀ =
The air-side heat transfer performance is improved by about 40 to 50% for the 10 mm one because the flow resistance of the airflow and the dead water area 18 are small.

Furthermore, since the two side portions 15a and 15b of the slit-shaped or louver-shaped cut-and-raised opening are provided offset from each other, the cut-and-raise on the downstream side of the airflow 13 is caused by the cut-and-raise on the upstream side of the airflow 13. There is always a portion located outside the temperature boundary layer, and the heat transfer performance in that portion is good. Further, since the cut-and-raised group 16 is provided at an angle to the front edge of the plate-like fin 11 between the heat transfer tubes 12, the airflow flowing inside the cut-and-raised and the airflow flowing outside are different from each other. The direction is different, slip occurs between the air flows, turbulence occurs,
Improve heat transfer performance. Furthermore, the cut and raised legs 17a, 17b
Since the airflow is provided at an angle to the direction of the airflow 13, an airflow having a swirl component due to the secondary flow is induced from the legs 17a and 17b. This air flow has a function of mixing the gas exchanged with the heat exchanged in the cut-and-raised portion and the fresh gas, and has a swirl component to the air flow 13 downstream of the heat transfer tube 12, so that the dead water area 18 is further more than a flat fin. As a result, the effective heat transfer area of the plate-like fin 11 is increased, and the heat transfer performance is dramatically improved.
Further, in the fin tube type heat exchanger of this embodiment, since the outer diameter of the heat transfer tube is smaller than that of the conventional heat exchanger, the thickness of the heat transfer tube can be reduced, and the cost can be reduced by about 30% compared to the conventional case.

The present invention as described above the effect of the invention, the outer diameter _{D 0 (3mm ≦ D 0 ≦} 7.5mm) 1.2D 0 ≦ L 1 ≦ 1.8D 0 airflow direction row pitch L ₁ of the heat transfer tube, air flow and vertical the Kandan pitch L ₂ and _{2.6D 0 ≦ L 2 ≦ 3.5D 0} , further, a slit-shaped and open to the airflow direction between heat transfer tubes mutual plate fin or the raised louvers shape cutting, the legs raised this cut is, The flat fins are provided so as to form an angle with the leading edge, so that the flat fins can improve the air-side heat transfer performance by 40% to 50% based on the same fan power standard. Induced flow and turbulence with a swirl component in the airflow flowing between them, the airflow mixing effect, turbulence promotion effect, dead water area reduction effect, and boundary layer leading edge effect are fully exhibited, and the air-side heat transfer performance is improved. Can be greatly improved. Further, since the heat transfer tube outside diameter D ₀ is small, it is possible to reduce the thickness, conventional respect attained about 30% of the cost.

[Brief description of the drawings]

FIG. 1 is a partial side view showing a fin tube type heat exchanger according to one embodiment of the present invention, FIG. 2 is a sectional view taken along line AA 'of FIG. 1, and FIG. FIG. 4 is a partial side view showing the fin tube type heat exchanger, and FIG.
-B 'is a sectional view, FIGS. 5 and 6 are characteristic diagrams showing the operation of the present invention, FIG. 7 is a perspective view showing a conventional fin tube type heat exchanger, and FIG. 8 is a conventional fin tube type heat exchanger. 9 is a partial side view showing the exchanger, FIG. 9 is a sectional view taken along the line CC 'of FIG. 8, and FIG.
The figure is a partial side view showing another conventional fin tube type heat exchanger, and FIG. 11 is a sectional view taken along the line DD 'of FIG. 11 ...... plate fin, 12 ...... heat transfer tube, D ₀ ...... outer diameter of the heat transfer tube, L ₁ ...... tube row pitch, L ₂ ...... Kandan pitch, 13 ...... airflow, 15a, 15b ...... sides Division, 16 ... Cut-and-raised group, 17a, 17b
……leg.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hachiro Koma, Inventor 3-22, Takaidahondori, Higashiosaka-shi Matsushita Refrigerator Co., Ltd. (72) Inventor Shigeo Aoyama 3-22, Takaidahondori, Higashiosaka-shi Matsushita Refrigeration Co., Ltd (72) Inventor Hiroyoshi Tanaka 1006 Kadoma Kadoma, Matsushita Electric Industrial Co., Ltd. (72) Inventor Makoto Obata 1006 Odaka Kadoma, Kadoma City Matsushita Electric Industrial Co., Ltd. (56) References JP-A 61-61 62794 (JP, A) JP-A-60-202296 (JP, A) Japanese Utility Model Laid-Open No. 57-100079 (JP, U)

Claims (2)

(57) [Claims] 1. A plate-like fin which is arranged in parallel at regular intervals and through which air flows, and an outer diameter D ₀ (3 mm ≦ D ₀₎ through which a fluid flows through an inside of the plate-like fin inserted at right angles to the plate-like fin. ≤7.5
mm), and the air flow direction tube row pitch L ₁ of the heat transfer tubes is set to 1.2D ₀ ≦ L ₁ ≦ 1.8D ₀ , and the air flow and the vertical tube step pitch L ₂ are set to 2.6D ₀ ≦ L ₂ ≦ 3.5D ₀ fin tube type heat exchanger. 2. A leg for joining a slit-shaped or louver-shaped cut-and-raised group, which is opened by cutting and raising two sides of the plate-shaped fin facing the air flow between the heat transfer tubes, with the fins of the respective cut-and-raised groups. The fin tube type heat exchanger according to claim 1, wherein the rows are provided so as to form an angle with the normal direction of the leading edge of the plate-like fin.