JPS5923981Y2 - Heat exchanger with fins - Google Patents

Description

[Detailed description of the idea] In recent years, with the reduction in noise from air conditioning equipment, there has been a growing trend to design heat exchangers with front wind speeds of 1 m/s or less. Improving performance is an issue.

The present invention proposes a structure of a heat exchanger that satisfies the above-mentioned demands.In particular, the dead area downstream of the heat transfer tubes is reduced by the fin shape, and the heat transfer coefficient on the air side heat transfer surface is significantly improved. This is what we aim to do.

Conventionally, this type of heat exchanger, as shown in FIG. The fluid flows between the fins 1' in the direction of the white arrow and exchanges heat with the fluid in the tube 2'.

The thermal fluid characteristics around the tube 2' between the fins 1' are:
As shown in Figure 1, when a low wind velocity airflow flows through the pipe 2' in the direction of the white arrow, the angle θ from the stagnation point on the pipe surface
The flow separates between 70 and 80°, creating a dead area 3 shown by diagonal lines in the front and downstream parts.As a result, the air side heat transfer coefficient in this dead area decreases significantly, so it is difficult to conduct heat as a heat exchanger. It had the disadvantage of low performance.

The present invention has been developed by considering the above-mentioned problems and solving them.

Hereinafter, one embodiment of the present invention will be explained in detail with reference to FIGS. 2a and 2).

FIG. 2a is a cross-sectional view of a finned heat exchanger showing an embodiment of the present invention, in which heat transfer tubes 5 are inserted into fin collar portions 4a that are barred at regular intervals on the fins 4, and the airflow The fins 4 partially surrounding the heat exchanger tubes 5 along the
Wave-shaped rectifying grooves 6 are provided around the heat exchanger tubes 5 in a low wind speed region to realize an ideal streamline shape and at the same time prevent separation of airflow.

A protrusion 7 protruding in the same direction as the rectifying groove is provided on the fin at a position between the heat exchanger tubes in the direction of adjacent stages and adjacent to the rectifying groove.

FIG. 2 is a sectional view taken along line AA' in FIG. 2a, and shows the wave-shaped rectifying groove 6. The cross-sectional shape of the protrusion 7 is shown.

When the airflow flows in the direction of the white arrow in the finned heat exchanger composed of the fins 4 and the heat exchanger tubes 5, the heat exchanger tubes 5
The surrounding thermal fluid characteristics are as follows.

That is, the speed of air is highest when it passes between the heat exchanger tubes 5 in the direction of adjacent stages and through a position where adjacent rectifying grooves 6 are close to each other.

At that position, it collides with the protrusion 7 that protrudes in the same direction as the rectifying groove, so that a vortex is generated.

Furthermore, the generated eddy current is regulated to flow along the rectifying grooves protruding in the same direction in close proximity, so that it is further activated.

As a result, the thickness of the boundary layer on the fin surface and the heat exchanger tube surface becomes thinner, and the heat transfer coefficient between the fluid and the fin surface and the heat exchanger tube surface increases significantly.

After that, the angle from the stagnation point on the surface of the heat exchanger tube 5 ±70 to 80
The airflow that was about to be separated at the temperature of The dead area 8 of the stream is significantly reduced.

Therefore, the vortex generated by colliding with the protrusion 7 is caused by the fin 4
The fluid flows over the surface to reduce the thickness of the boundary layer on the surfaces of the fins 4 and the heat exchanger tubes 5, significantly improving the heat transfer coefficient between the fluid and the fins 4 and the heat exchanger tubes 5, and preventing separation of airflow. The wave-shaped rectifying grooves 6 significantly reduce the dead area in the downstream region of the heat exchanger tubes 5, and sufficient heat exchange between the heat exchanger tubes 5 and the airflow can be performed, so that the heat transfer performance of the heat exchanger is greatly improved.

In addition, the wave-shaped rectifying grooves 6 create an ideal streamline shape around the surface of the heat exchanger tube 5, and prevent separation of the airflow, so the pressure loss of the airflow passing between the fins 4 is small. can.

In this embodiment, the cross-sectional shape of the rectifying groove 3 is a sawtooth shape, but it is clear that other shapes, such as a groove shape, can also have the same effect.

As described above, the present invention consists of a group of fins arranged in parallel at regular intervals and a group of heat exchanger tubes inserted at right angles to the group of fins. In addition to providing grooves, protrusions protruding in the same direction as the rectifying grooves are provided on the fins at positions where adjacent rectifying grooves are close to each other between the heat exchanger tubes in the direction of adjacent stages, thereby generating a vortex flow by the protrusions. By reducing the thickness of the boundary layer on the fin surface, the heat transfer coefficient between the fluid and the fins can be significantly increased, and in addition, the wave-shaped rectifying grooves prevent the airflow from separating, allowing it to flow through the tube group. By imparting a momentum change to the mainstream and the heat transfer tube side, the dead zone downstream of the heat transfer tube can be reduced, which further increases the improvement in the heat transfer coefficient between the fluid and the fins, making it suitable for use as a heat exchanger. This can have many practical effects.

[Brief explanation of drawings]

Fig. 1a is a perspective view of a conventional heat exchanger, Fig. 1 is a thermal fluid characteristic diagram of the heat exchanger tube, Fig. 2a is a sectional view of a finned heat exchanger showing an embodiment of the present invention, Figure 2 is A- in Figure 2 a.
It is a sectional view taken along the A' line. 4...fins, 5...heat exchanger tubes, 6...
... Rectifying groove, 7... Protrusion.

Claims (1)

[Scope of utility model registration request] It is composed of a group of fins arranged in parallel at regular intervals and a group of heat exchanger tubes inserted at right angles to the group of fins, and a wave-shaped rectifying groove is provided in the group of fins around the group of heat exchanger tubes, and a groove is provided between adjacent stages. A heat exchanger with fins, wherein protrusions projecting in the same direction as the flow straightening grooves are provided on the fins at positions where adjacent flow straightening grooves are close to each other and between the heat exchanger tubes in the direction.