JPS62147290A - Heat exchanger - Google Patents

Abstract

PURPOSE:To secure gaps between respective cut-and-raised pieces sufficiently to increase the heat exchanging efficiently of a heat exchanger without inviting the increase of passing resistance by a method wherein the louver type cut-and- raised piece is bent into a chevron type at the center thereof. CONSTITUTION:A flat plate type fin 10 is bored with a plurality of heat transfer tube penetrating holes 11 and is formed with a plurality of louver type cut-and- raised pieces 12 between the penetrating holes 11 so as to be orthogonal to the flow direction A of airflow. Respective louver type cut-and-raised pieces 12 are cut and raised so that the front end rims 12 a thereof are raised toward one surface of the fin 10 while the rear end rims 12b thereof are raised toward the other surface of the fin 10. The substantially central part 12c of the fin 10 is formed so as to be biased toward the downstream side of the flow direction A of the air-flow with respect to the boundary of an imaginary plane B connecting the front end rim 12a and the rear end rim 12b. The central part 12c of the louver type cut-and-raised piece 12 is bent so as to have a bent angle beta larger than the inlet angle alpha of the front end rim 12a and is formed so that the sectional surface shows a chevron type configuration.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cross-fin tube type heat exchanger used as an evaporator or condenser in an air conditioner, etc. It is related to.

[Technical Background of the Invention As is well known, a Kokuros fin tube heat exchanger consists of a fin group consisting of a plurality of flat fins arranged parallel to each other at predetermined intervals, and a fin group for this fin group. It consists of a group of heat exchanger tubes that are inserted almost perpendicularly through the tube. In this type of heat exchanger, the heat transfer coefficient of the tube inner side dε body is extremely large compared to the heat transfer coefficient of the fin-air side. For this reason, the surface area of the fins is increased so that the ratio of pipe inner area/fin surface area is generally about 15 to 20, and the fins are provided with louver-like cutouts to promote heat transfer to increase the heat exchange rate. That's what I do. A conventional example thereof is shown in FIGS. 3 and 4.

In the figure, reference numeral 1 denotes a flat fin made of, for example, aluminum, constituting a fin group, and the fin 1 has a plurality of heat exchanger tube insertion holes 2 through which heat exchanger tubes (not shown) are inserted.
... are bored, and a plurality of louver-shaped cut and raised pieces 3 are provided between the heat exchanger tube insertion holes 2, 2.
. is formed so as to be perpendicular to the flow direction A of the airflow. That is, as shown well in Figure 4,
Each louver-shaped cut-and-raised piece 3 has a front end edge 3a cut and raised on one side of the fin 1 when viewed from the flow direction A of the airflow, and a rear end edge 3b cut and raised on the other side. In this case, the entrance angle (inclination angle with respect to the fin plane) at the edge 3a is O1, the gap between each louvered cut piece 3, 3 is W, and the gap between each louvered cut piece 3 is W, and the gap between each louvered cut piece 3 is Let the width of the raised piece 3 be L. Note that this width is a width projected onto a virtual plane parallel to the fin plane, and has the relationship L=QcosO, where Q is the length from the front edge 3a to the rear edge 3b.

When such a heat exchanger is used, for example, as an evaporator, the louver-shaped cut and raised pieces 3,
vXW between them to prevent them from being closed.
Even if hydrophilic treatment is applied, it must be at least approximately 0.5 m long.

On the other hand, in order to improve the heat transfer coefficient, it is preferable to reduce the above width. That is, if the width is large, the thickness of the temperature boundary layer of the airflow becomes thicker, which hinders the improvement of the heat transfer coefficient. In order to reduce this width, it is sufficient to increase the above population angle θ, but
This has the other disadvantage of increasing ventilation resistance.

[Object of the invention] This invention was made in view of the above-mentioned conventional circumstances,
The purpose is to provide a finned heat exchanger that can improve heat exchange performance without increasing ventilation resistance while ensuring sufficient gap width between louver-shaped cut and raised pieces. It is in.

[Embodiment] The present invention will be described in detail below with reference to an embodiment shown in FIGS. 1 and 2.

In FIGS. 1 and 2, reference numeral 10 denotes a flat fin made of, for example, aluminum, constituting the fin group of this heat exchanger, and this fin 10 has a plurality of heat exchanger tube insertion holes 11 as in the conventional case. A plurality of louver-shaped cut and raised pieces 12 are formed at positions between the insertion holes 11 so as to be perpendicular to the flow direction A of the airflow. As best shown in FIG.
is cut and raised on one side of the fin 10, and the rear edge 1
2b is cut and raised on the other side, but according to the present invention, each louver-shaped cut and raised piece 12 is different from the conventional straight line shape, and its approximately central portion 12c is connected to the front edge 12a and the rear side. It is formed so as to be slightly biased toward the downstream side in the flow direction A of the airflow with the virtual plane B connecting the end edge 12b as a boundary. That is, in this embodiment, if the artificial angle (inclination angle with respect to the fin plane) of the front edge 12a is α, the central part 12c of the louver-shaped cut and raised piece 12 is bent at an angle β larger than the artificial angle α. The cross section is formed so as to have an angular shape.

° As a result, the width L' of the louver-shaped cut and raised piece 12 is
By increasing the entrance angle α, it becomes shorter than the conventional linear width, and the gap W between each cut and raised piece 12 is reduced.
' is wider than Hw in the past. This means that it is possible to increase the number of cut and raised pieces 12 installed without increasing the artificial angle α compared to the past, or if the number of installed pieces is the same, the entrance angle α can be made smaller to reduce the ventilation resistance. This means that by appropriately selecting the angles α, β and the bending position, it is possible to satisfy both conditions at the same time.

Furthermore, by making the width L' short, the development of a temperature boundary layer is suppressed due to the leading edge effect at the front end edge 12a, and a separation effect occurs due to the bent portion of the central portion 12c, which reduces airflow. This will hinder stratification. Furthermore, since the airflow is guided further downward and exits from the rear edge 12b, the turbulence of the airflow flowing between each fin 10 is further promoted, and the heat exchange efficiency is improved overall. I can figure it out.

In the above embodiment, the substantially central portion 12c of the louver-shaped cut and raised piece 12 is clearly bent into a U-shape, but the same effect can be obtained even if it is bent in a gentle arch shape. . Further, although the fins 10 in the above embodiment are relatively narrow and the heat exchanger tube insertion holes 11 are arranged in a line along the longitudinal direction, the present invention is limited to such fins. It goes without saying that the present invention is also applicable to a fin in which transmission holes are arranged in a staggered manner, as shown in FIG. 3, for example.

[Effects] As is clear from the description of the embodiments described above, according to the present invention, by bending the approximately central portion of the louver-shaped cut and raised pieces into a │ shape, there is a gap between each cut and raised piece. Heat exchange efficiency can be further improved while ensuring a sufficient gap and without causing an increase in wire passing resistance. Further, according to the present invention, for example, Japanese Patent Laid-Open Nos. 57-192764 and 57-192764
7-192765, it is not subject to strict dimensional restrictions.

Actual manufacturing is relatively easy. Furthermore, by forming the bent portion as described above, the mechanical strength of the entire fin is increased, the thickness of the fin can be reduced, and handling during the production process is excellent, contributing to improved production efficiency. The effect is remarkable.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a part of the fin applied to the heat exchanger of the present invention, Fig. 2 is an enlarged cross-sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a plan view showing a part of the conventional fin. FIG. 4 is a plan view similar to that shown in FIG. 1, and FIG. 4 is a cross-sectional view taken along line iv-rv in FIG. In the figure, 10 is a fin, 11 is a heat exchanger tube insertion hole, 12 is a louver-shaped cut and raised piece, 12a is a front edge, 12b is a rear edge, 1
2c is the central portion.

Claims (3)

[Claims] (1) It has a fin group in which a plurality of flat fins are arranged parallel to each other at predetermined intervals so that airflow can flow between them, and the heat exchanger tube is arranged approximately perpendicular to the fin group. A heat exchanger inserted through the fins, the front end edge of the fin is cut and raised on one side of the fin when viewed from the flow direction of the airflow, and the rear end edge is cut and raised on the other side of the fin. In a device in which a plurality of louver-shaped cut and raised pieces are formed, the louver-shaped cut and raised pieces are arranged so that the substantially central part of the louver-shaped cut and raised pieces is connected to the imaginary plane connecting the front end edge and the rear end edge. A heat exchanger characterized in that it is formed so as to be biased toward the downstream side. (2) In claim (1), the louver-shaped cut-and-raised piece is characterized in that a substantially central portion thereof is bent into a U-shape at an angle greater than the entrance angle at the front edge. Heat exchanger. (3) The heat exchanger according to claim (1), wherein a substantially central portion of the louver-shaped cut and raised piece is bent into an arch shape with a predetermined curvature.