JPS59210296A - Heat exchanger with fin - Google Patents

Abstract

PURPOSE:To improve heat transfer rate in an air side heat transfer surface remarkably by decreasing ventilating resistance due to stagnant water zone in the after-stream of heat transfer tube and condensed water upon cooling by the configuration of the fin. CONSTITUTION:The fins 1 around the heat transfer tube 2 are provided with wavy flow regulating grooves 4, realizing the shapes of ideal stream line around the heat transfer tube 2 and preventing the separation of airstream in a low airflow velocity zone, while parts, positioning orthogonally with respect to the inflow direction of air, are provided with water outflow grooves 5. When the airstream flows into the arrow sign direction, the airstream, which tried to separate from the tube at a place having an angle theta of + or -70-80 deg. from the stagnation poit of the surface of heat transfer tube, is prevented from separating by the wavy airflow regulating grooves 4 and flows along the surface of the heat transfer tube 2, therefore, the stagnant water zone 3 after the heat transfer tube 2 is reduced remarkably. Accordingly, heat exchange between the heat transfer tube 2 and the airstream may be effected sufficiently in the zone of backwash of the heat transfer tube 2, therefore, the heat transfer performance of the heat exchanger may be improved remarkably.

Description

[Detailed Description of the Invention] In recent years, with the reduction in noise from air conditioning equipment, there has been a growing tendency to design heat exchangers with front wind speeds of 1 m/s or less, and the performance of heat exchangers in such low wind speed ranges has increased. Improvement is an issue.

The present invention proposes a structure of a heat exchanger that satisfies the above-mentioned demands, and in particular reduces the ventilation resistance due to the dead zone following the heat transfer tube and condensed water during cooling by using the fin shape.
This aims to significantly improve the heat transfer coefficient on the air side heat transfer surface.

2 B-7 Conventionally, this type of heat exchanger has a flat plate fin group 1 arranged vertically at regular intervals as shown in Fig. 1a, and this fin group 1.
It consists of a group of tubes 2 inserted at right angles to the fins, and air flows between the fins in the direction of the arrow to exchange heat with the fluid inside the tubes. The thermo-fluid characteristics of the tube 2 between the fins 1 and 2 are as shown in Figure 1. When a low wind speed airflow flows through the tube 2 in the direction of the white arrow, the angle θ from the stagnation point on the tube surface is ±70. ~8
At oO, the flow separates, creating a dead area 3 shown in perspective at the trailing end of the pipe.As a result, the air-side heat transfer coefficient in this dead area 3 decreases significantly, resulting in poor heat transfer performance as a heat exchanger. It had some drawbacks.

The present invention solves the above problems.

A detailed explanation will be given below with reference to FIGS. 2a and 2b.

FIG. 2a is a cross-sectional view of a finned heat exchanger showing an embodiment of the present invention, in which heat exchanger tubes 2 are inserted into fin collar portions 1a that are barred at regular intervals on the fins 1. The fins 1 around the heat exchanger tubes 2 are provided with wave-shaped rectifying grooves 4 that realize an ideal 3-Heno streamline shape around the heat exchanger tubes 2 and prevent separation of airflow in the low wind speed region. A water outflow groove 6 is provided in the wave-shaped rectifying groove 4 around the heat exchanger tube 2, that is, in a portion located perpendicular to the wind inflow direction. FIG. 2 is a sectional view taken along the line AA' in FIG. 2a, showing the shape of the wave-shaped rectifying groove 4.

When the airflow flows in the direction of the white arrow in the finned heat exchanger consisting of the fins 1 and the heat transfer tubes 2, the thermal fluid characteristics for the heat transfer tubes 2''!f are as follows. The angle θ from the stagnation point on the surface of the heat tube is ±70 to 8o.
The airflow that was about to be separated at 0 is prevented from separating by the wave-shaped rectifying grooves 4 provided over the fins 1 around the heat exchanger tube 2, and flows along the surface of the heat exchanger tube 2, so that it flows into a dead area 3 downstream of the heat exchanger tube 2. decreases significantly. Therefore, even in the downstream region of the heat exchanger tubes 2, sufficient heat exchange between the heat exchanger tubes 2 and the airflow can be performed, so that the heat transfer performance of the heat exchanger is significantly improved.

In addition, the wave-shaped rectifying grooves 4 create an ideal streamline shape around the surface of the heat transfer tube 2 and prevent separation of the airflow, allowing the airflow to pass between the fins 1 without disturbing the airflow. pressure loss can be reduced.

Furthermore, when the heat exchanger is used as a cooler, condensed water generated near the heat exchanger tubes 2 on the surface of the flat fins falls,
Wave-shaped straightening groove 40 In the direction of gravity, the water flows along the wave-shaped straightening groove 4 on the lower side of the heat exchanger tube 2, but since the wave-shaped straightening groove 4 is on a substantially circular arc concentric with the heat exchanger tube 2, condensed water is not transferred. The water flows toward a point where the angle θ from the stagnation point on the surface of the heat tube 2 is 'f900, and flows out from the water outflow groove 5. Therefore, even when used as a cooler, the air flow path formed by the wave-shaped rectifying grooves 4 is not blocked by condensed water and the air flow passes through it, without increasing ventilation resistance as well as heat dissipation characteristics. Heat transfer performance can be significantly improved.

In this embodiment, the cross-sectional shape of the rectifying groove 4 is a sawtooth shape, but it is clear that other shapes, such as a groove shape, will have the same effect.

As described above, the present invention provides wave-shaped rectifying grooves 4 to prevent separation of airflow in the fins around the fin group arranged in parallel at regular intervals and the 5 Beno tube group inserted at right angles to the fin group. This is a finned heat exchanger in which water outflow grooves 6 are provided in the wave-shaped rectifying grooves 4 around the adjacent heat transfer tubes 2, that is, in the portions located perpendicular to the wind inflow direction.
The dead area 3 downstream of the heat exchanger tube 2 is reduced, and the heat exchanger tube 2
Since separation of the airflow on the surface is prevented, the airflow is not disturbed, and the pressure loss of the airflow passing between the fins 1 can be reduced, the heat transfer performance of the heat exchanger is greatly improved.

In addition, when used as a cooler, the air flow path formed by the wave-shaped rectifying grooves 4 is not blocked by condensed water and the air flow flows, allowing heat transfer without increasing ventilation resistance, similar to the heat dissipation property. Performance can be significantly improved.

Furthermore, since the wave-shaped rectifying grooves 4 and the water outflow grooves 5 are symmetrical with respect to the step direction line at the center of the heat transfer tubes 2, the same heat transfer performance can be obtained regardless of whether the airflow flows from the forward or reverse direction. The installation has many features such as being able to erase time errors.

[Brief explanation of drawings]

6 b. Fig. 1a is a perspective view of a conventional heat exchanger, Fig. 1 is a thermal fluid characteristic diagram around a tube between fins, and Fig. 2a is a cross section of a finned heat exchanger showing an embodiment of the present invention. Figure, 2nd figure, 2nd figure
It is a sectional view taken along the line AA/ in figure a. 1...Fin, 1a...Part of fin collar, 2...'...Heat transfer tube, 3...Dead area, 4...Wave shape Rectification groove, 6...Water outflow groove. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure (ts, n) Figure 2 (0-n475-

Claims (1)

[Claims] A wave-shaped rectifying groove that 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 prevents separation of airflow in the group of fins around the group of heat exchanger tubes. A finned heat exchanger, wherein water outflow grooves are provided in the wave-shaped rectifying grooves around the heat exchanger tubes in the direction of adjacent stages.