JPS6082784A - Heat exchanger with fin - Google Patents

Abstract

PURPOSE:To improve a heat transfer rate on the air side, and to miniaturize a heat exchanger with fins and enhance its performance by alternately forming cut and erected sections opposite to an air current and cut and erected sections opening in the direction of the air current to the plate fins among heat transfer tubes. CONSTITUTION:I-shaped cut and erected sections 8 opposite to an air current, louver- shaped cut and erected sections 10 opening in the direction of the air current, I-shaped cut and erected sections 9 and louver-shaped cut and erected sections 11 are arranged in the order to fins 5 in clearance sections among heat transfer tubes 7 adjacent in the stepped direction of a heat exchanger with the fins from the upstream side of the air current. A plurality of small holes 12 are formed to the I-shaped cut and erected sections 8, 9. The fins 5 short in the direction of the air current and the louver-shaped cut and erected sections 10, 11 are positioned under an arranged state, and thin thermal boundary layers are formed severally. The disturbance of the air current on the downstream side is promoted by blow-off flows passing in the small holes 12. Peeling from the heat transfer tubes 7 of the air current in the surroundings of the heat transfer tubes 7 is prevented by flows crossing the side surface sections 9a of the I-shaped cut and erected sections 9, and a heat transfer rate on the air side is improved remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat exchanger with fins for gas-gas-liquid two-phase fluid (or liquid), which is widely used in evaporators, condensers, etc. in the field of air conditioning equipment. It is related to.

Conventional configurations and their problems In recent years, as air conditioning equipment has become less noisy, there has been a growing tendency to design heat exchangers with front wind speeds of 1 m/sec or less.
Improving the performance of heat exchangers in such low wind speed ranges is an issue.

Conventionally, this kind of heat exchanger, as shown in FIG. Air flows between the fins in the direction of the arrow and exchanges heat with the fluid inside the pipe. The thermal fluid characteristics around the heat transfer tube group 2 between the fin group 1 are as shown in Figure 1. When a low wind velocity airflow flows through the heat transfer tube 2 in the direction of the arrow, When the angle θ is 70 to 80', the flow separates and a dead area 3 shown by diagonal lines is created at the downstream part of the heat exchanger tube, so the air side heat transfer coefficient in this dead area 3 decreases significantly, making it difficult to use as a heat exchanger. It had the disadvantage of low heat transfer performance.

In addition, as shown in Figure 1C, the thickness of the temperature boundary layer 4 on the heat transfer surface of the fin group 1 increases in proportion to the square basis of the distance from the airflow inlet, so the air side heat transfer coefficient The heat transfer performance as a heat exchanger deteriorates significantly as the distance from the airflow inlet increases, resulting in a disadvantage that the heat transfer performance as a heat exchanger is low.

3. Purpose of the Invention The present invention eliminates the above-mentioned conventional drawbacks. In particular, the dead area downstream of the heat transfer tube and the temperature boundary layer thickness on the fin heat transfer surface are reduced by the fin shape, Furthermore, the purpose of this invention is to promote airflow turbulence by the blowout flow, thereby significantly improving the air-side heat transfer coefficient, and thereby achieving a smaller size and higher performance of the finned heat exchanger.

Structure of the Invention The finned heat exchanger of the present invention consists of flat plate fins arranged in parallel at regular intervals and through which air flows, and heat transfer tubes inserted at right angles to the flat plate fins and through which fluid flows. , in the part of this flat fin located between the heat transfer tubes,
I-shaped cut-and-raised portions having a plurality of small holes facing the airflow and louver-shaped cut-and-raised portions having openings at both ends in the airflow direction are alternately provided.

With this configuration, short fins are lined up in the air flow direction, and a temperature boundary layer is formed in each of these short fins, so that the thickness of the boundary layer becomes thin.

In addition, the airflow that has passed through all the small holes of the I-shaped cut-and-raised portion and the flow that has passed over the upper part re-attaches to the downstream fin, which promotes airflow turbulence.

Furthermore, the airflow around the heat exchanger tube remains at I
Since it is prevented from separating from the heat exchanger tube due to the flow over the side surface of the cut-and-raised shape, the dead area downstream of the heat exchanger tube is reduced.

Therefore, the air side heat transfer coefficient is significantly improved, and the finned heat exchanger can be made smaller and have higher performance.

DESCRIPTION OF EMBODIMENTS A finned heat exchanger according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a plan view, and FIG. 3 is a cross-sectional view of FIG. 2.

The heat exchanger tubes 7 are inserted into the fin collar portions 6 that are barred at regular intervals on the flat plate fins 5, and the gaps between the adjacent heat exchanger tubes 7 in the direction perpendicular to the airflow flowing in the direction of the arrow, that is, in the step direction. The fin 5 has an I-shaped cut-out portion 8°9 facing the airflow and openings 10 at both ends in the airflow direction.
a, 10b.

5 Pe=-' Louver-shaped cut 9 raised part 10.1 having 11a and 11bi
A plurality of 1 are provided, and the I-shaped cut-out part 8, the louver-shaped cut-out part 10, the I-shaped cut-out part 9, and the louver-shaped cut-out part 11 are arranged in order from the upstream side of the airflow. The cut-out parts of the shape are arranged alternately. Further, a plurality of small holes 12 are provided in the I-shaped cut-and-raised portion 8.9.

Next, the action and effects will be explained.

First, by providing the I-shaped cut-and-raised portions 8 and 9 and the louver-shaped cut-and-raised portion 10.11i on the flat plate fin 6, the top of the louver-shaped cut-and-raised portion 10.11 functions as a fin parallel to the airflow. However, the flat fin 6 has short fins 6 and louver-shaped cut-out parts 10 and 11 lined up in the airflow direction, and there is always an I-shaped cut-out part between the louver-shaped cut-out parts 10 and 11. Since the cut-out portions 8 and 9 are provided, a thin temperature boundary layer is always formed on the short fins 5 and the louver-shaped cut-out portions 10 and 11. For example, the louver-shaped cut-out portion 11 on the downstream side The temperature boundary layer 6/"-elm" formed in the side louver-shaped cut-out portion 10 does not become buried in the temperature boundary layer 6/"-elm".

In addition, the blowout flow that has passed through the plurality of small holes 12 of the I-shaped cut-and-raised portions 8 and 9 and the flow that has passed over the upper part re-adheres to the louver-shaped cut-and-raised portion 10.11 and the flat plate fin 6 on the downstream side. This promotes airflow turbulence, and the blowout flow that has passed through the plurality of small holes 12 causes the pI-shaped cut and raised portion 8 to
, 9 are also effective.

In addition, since the cut-and-raised part 9 is provided at the rear, which is more than 90 degrees from the stagnation point on the surface of the heat exchanger tube, the airflow of the heat exchanger tube 7 is directed to the heat exchanger tube 7 inserted into the fin collar part 6. Even after the collision, the flow over the side surface 91Li of the I-shaped cut-and-raised portion 9 due to the damming effect of the I-shaped cut-and-raised portion 9 can prevent it from separating from the heat exchanger tube 7 and enter the downstream region of the heat exchanger tube 7. Reduce dead areas.

From the above, the heat transfer coefficient on the air side is significantly improved, and the finned heat exchanger can be made smaller and have higher performance.

Effect of the invention 7 --- As described above, the finned heat exchanger of the present invention has flat plate fins that are arranged in parallel at regular intervals and through which air flows, and a flat plate fin that is inserted at right angles to the flat plate fins and that allows fluid to flow inside. The flat plate fin between the heat exchanger tubes has a plurality of small holes facing the airflow, and a louver-shaped cutout has openings at both ends in the airflow direction. ■The short fins are lined up in the airflow direction, and since there is a louver-shaped raised part between the louver-shaped raised parts, these short fins have A necessary temperature boundary layer is formed.

(2) The blowout flow that passes through all the small holes of the square-shaped cut-and-raised part and the flow that crosses over the upper part re-attaches to the downstream louver-shaped cut-and-raised part and the flat plate fin, promoting airflow turbulence.

■The airflow around the heat transfer tube can be prevented from separating from the heat transfer tube due to the side flow caused by the damming effect of the cut-and-raised part provided at the rear of the heat transfer tube, reducing dead areas.

From the above, the heat transfer coefficient on the air side is significantly improved, and the finned heat exchanger can be made smaller and more efficient.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional finned heat exchanger, FIG. 2 is a front view of a finned heat exchanger according to an embodiment of the present invention, and FIG. 3 is a sectional view taken along line AA in FIG. 2. . 5... Flat plate fin, 7... Heat exchanger tube, 8
, 9......Engineer shape cut-and-raised part, 10, 11...
...louver-shaped cut-and-raised part, 12...small hole. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure (0-) (b) (C) @ 2 Figure 3

Claims (1)

[Claims] Consisting of flat plate fins that are arranged in parallel at regular intervals and through which airflow flows, and heat transfer tubes that are inserted at right angles to the flat plate fins and through which fluid flows inside, the portion of the flat plate fins that is located in the heat transfer tube uD. A heat exchanger with fins is provided with alternating cut-out portions having a plurality of small holes facing the airflow and louver-shaped cut-out portions having openings at both ends in the airflow direction.