JPS62284196A - Heat exchanger - Google Patents

Abstract

PURPOSE:To provide high thermal conductivity throughout a whole range from a fin on the upper stream side to a fin on the downstream side, by a method wherein, plural slit pieces risen in a direction in which a front edge part is positioned opposite to an air current are formed in a fin surface, and a reference surface, formed on the fin left non-risen between the adjoining slit pieces, is inclined based on the direction of the air current. CONSTITUTION:Fins 4 are formed between straight tube parts 1' of a flat tube 1. Slit pieces 5, secured in a waveform manner to the flat tube 1 at intervals of a specified distance, are formed on the fin 4 surface, and are risen from the fin 4 with a width C so that a front edge part 5' is positioned opposite to an air current B and a rise surface 5'' is extended in parallel to the air current B direction, and are continuously formed in the direction B. Further, a reference surface 6, left non-risen between the slit pieces 5, of the fin 4 is inclined based on the air current B direction. When heat exchange takes place between the air current B and a heating medium flowing through the flat tube 1, development of a temperature boundary layer (d) of the air current B is disconnected, and the temperature boundary layer (d), leaving a tail, can be prevented from extending to the slit piece 5 on the downstream side.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a heat exchanger used in air conditioning equipment, refrigeration equipment, etc.

BACKGROUND OF THE INVENTION In recent years, there has been a remarkable improvement in the performance of heat exchangers, and heat exchangers equipped with wave-shaped fins characterized by a large heat transfer area on the air side have already been put into practical use.

The conventional heat exchanger mentioned above will be explained below with reference to the drawings.

FIG. 5 shows a schematic shape of a heat exchanger according to the present invention, and FIGS. 6 and 7 show fin shapes of a conventional heat exchanger. In FIGS. 6 and 7, reference numeral 1- denotes a meanderingly bent flat tube, with straight tube portions 1' substantially parallel to each other. 2
fins are provided between the opposing straight pipe portions 1' of the flat tube 1, and are fixed to the flat tube 1 at regular intervals in a wave shape. Reference numeral 3 denotes a slit 6 provided on the surface of the fin 2, which is cut and raised from the fin 2 so that its front edge 3' faces the airflow A and the cut and raised surface 3'' is parallel to the air inflow direction. The slit pieces 3 are continuously provided on the surface of the fin 2 at intervals of a slit width a so as to alternate vertically in the air inflow direction.

The operation of the heat exchanger constructed as above will be explained below with reference to FIGS. 6 to 9.

Heat exchange is performed between the airflow A flowing between the fins of the fins 2 and the heat medium flowing inside the flat tube 1 via the fins 2 and the flat tube 1. At that time, airflow A generated on the surface of the fin 2
The development of the temperature boundary layer S is separated, and airflow A and fin 2
A relatively large heat transfer coefficient was obtained between the two.

Problems to be Solved by the Invention However, in the above configuration, as shown in FIG. In order to reduce the temperature, the temperature boundary layer is not completely separated and gradually increases as it goes downstream, and as shown in FIG. There was a problem in that the value decreased. Also, this problem is that if the slit width a is made large, the distance between the slit pieces 3 will increase, so the slit pieces 3 on the downstream side will not be affected by the slit pieces 3 on the upstream side, and will move toward the downstream side. This can prevent the heat transfer coefficient from decreasing as much as possible, but on the other hand, because the slit width is made large, the individual slit pieces 3 and the airflow A
There was a problem in that the heat transfer coefficient between the two ends decreased, making it impossible to obtain a large heat transfer coefficient even on the upstream side.

In view of the above-mentioned problems, the present invention provides a heat exchanger that can obtain high thermal conductivity throughout the entire region from the upstream fins to the downstream fins.

Means for Solving the Problems In order to solve the above problems, the heat exchanger of the present invention is provided with a plurality of slit pieces on the fin surface whose front edges are cut and raised in the direction opposite to the airflow. A reference surface of the fin remaining without being cut and raised is provided between slit pieces adjacent in the direction, and this reference surface is inclined with respect to the airflow direction.

Effect of the Invention With the above-described configuration, the present invention uses the inclined reference plane to change the flow direction of the airflow, so even if the distance between the slits is small, the temperature boundary layer formed by the upstream slit pieces does not extend to the downstream slit pieces. This results in completely suppressing the development of a thermal boundary layer from upstream to downstream, and maintaining an extremely high heat transfer coefficient between the airflow and the fins.

EXAMPLE Hereinafter, a heat exchanger according to an example of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show the fin shape of a heat exchanger in an embodiment of the present invention. Figure 1.

In FIG. 2, reference numeral 1 denotes a flat tube having the same structure as the conventional example, and includes a straight tube portion 1'. Fins 4 are provided between the straight pipe portions 1' of the flat tube 1, and are fixed to the flat tube 1 at regular intervals in a wave shape. Reference numeral 5 denotes a slit piece provided on the surface of the fin 40, which is cut and raised from the fin 4 with a slit width C so that the front edge 6' faces the direction of the airflow B and the cut and raised surface is parallel to the direction of the airflow B. and are provided continuously in the airflow B direction. Further, fins 4 remaining without being cut and raised between the slit pieces 6 that are continuous in the direction of the airflow B
There is a zero reference plane 6, and this reference plane 6 has an inclination with respect to the airflow B direction.

The operation of the heat exchanger configured as above will be explained below using FIGS. 1 to 4.

Heat exchange is performed between the airflow B flowing between the fins of the fins 4 and the heat medium flowing inside the flat tube 1 via the fins 4 and the flat tube 1. At this time, since the slit piece 6 is continuously provided on the surface of the fin 4, the development of the temperature boundary layer d of the airflow B generated on the surface of the fin 4 is interrupted. In addition, as shown in FIG. 3, the temperature boundary layer d of the airflow B formed by the slit piece 5 on the upstream side does not disappear immediately after passing through the slit piece 5, but trails to the downstream side.
Since the flow direction can be changed by the reference surface 6 itself, and the distance between the slits can be made large by the reference surface 6 itself, it is possible to prevent the trailing temperature boundary layer d from being applied to the slit piece 5 on the downstream side. Therefore, as shown in Fig. 4, even if the slit width C is shortened, the temperature boundary layer d is completely separated, and an extremely high heat transfer coefficient can be obtained between the fins 4 and the airflow B from the upstream side to the downstream side. Can be done.

As described above, according to this embodiment, the slit pieces 6 whose front edges 5' are cut and raised in the direction facing the air flow B are provided on the surface of the fin 40, and the slit pieces 5 adjacent to each other in the direction of the air flow B are formed. The reference surface 6 of the fin 40 that remains without being cut and raised is provided in between, and since the reference surface 6 of the parenthesis has an inclination with the direction of the airflow B, a temperature boundary layer d is created from the upstream side to the downstream side. It is possible to suppress the development of heat transfer, obtain an extremely high heat transfer coefficient between the fins 4 and the airflow B, and obtain a heat exchanger with excellent heat transfer performance.

Effects of the Invention As described above, the present invention provides a fin surface with a slit piece whose front edge is cut and raised in a direction opposite to the airflow, and which remains without being cut and raised between adjacent slit pieces in the airflow direction. By providing a reference surface for the fins and having the reference surface slope with the airflow direction, the heat transfer coefficient between the fins and the airflow is maintained high from the upstream side to the downstream side, resulting in heat exchange with excellent heat transfer performance. You can get the equipment.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a main part showing the fin shape of a heat exchanger in an embodiment of the present invention, Fig. 2 is a sectional view of a main part of Fig. 1, and Fig. 3 is a temperature boundary layer of the air flow in Fig. 1. FIG. 4 is a graph showing the local heat transfer coefficient between the fins in FIG. 1 and the airflow; FIG. Fig. 6 is a perspective view of the main part showing the fin shape of a conventional heat exchanger, Fig. 7 is a sectional view of the main part of Fig. 6, and Fig. 8 is a main part showing the state of the temperature boundary layer of the airflow in Fig. 6. The cross-sectional view, FIG. 9, is a graph showing the local heat transfer coefficient between the fins of FIG. 6 and the airflow. 4...Fin, 5...Slit piece, 5
′...Front edge, 5"...Cut and raised surface,
6...Reference surface. Name of agent: Patent attorney Toshio Nakao and 1 other person 4-
m-fin 6-slit piece, 5'-f; spherical surface Fig. 2 Fig. 5- slit piece No. 41!1 Air flow β direction distance fiber (Shinho) Fig. 5 Fig. 6 Fig. I' Fig. 7 Fig. 9 Air flow 8 directional distance

Claims (1)

[Claims] It comprises a flat tube bent in a meandering manner and fins stacked in a wave shape between the flat tubes, and a plurality of slit pieces are provided on the surface of the fins, the front edges of which are cut and raised in the direction opposite to the airflow. , and a reference surface of the fin remaining without being cut and raised is provided between the slit pieces adjacent to each other in the airflow direction, and the reference surface is inclined with respect to the airflow direction.