JPH0420792A - Heat exchanger for air condition - Google Patents

Abstract

PURPOSE:To reduce clogging of a frost layer at the front edge and to restrict the reduction of the amount of air by providing a plurality of notches in said front edge such that they are disposed longitudinally parallely to the direction of the air flow. CONSTITUTION:A plurality of longitudinal notches 3 provided in a fin 1 at a predetermined interval are formed longitudinally parallely to the inflow direction 4 of an air flow and adapted such that air from the notches 3 can pass therethrough even frosting at the front edges of the fins is increased. For the length L of the notch, it is set not to exceed the length K from the fin front edges 7 to the rear part of a heat transfer pipe 2, and frosting is uniformly brought to approach each other and the height of a frost layer is restricted low for relaxation of the reduction of the amount of the air. By providing the notches 3 in the fin 1, air is bypassed to part of the fin front edge without lowering the effect of the fin front edges to keep the amount of the air flow, and further high humidity air can be guided to a heat exchanger rear part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plate-fin-tube heat exchanger used in air conditioning equipment and the like.

[Conventional technology]

Plate-fin-tube heat exchangers used in air conditioning equipment, etc.2. As frost progresses, the #4 resistance of the frost layer increases, and the air volume decreases due to the increase in pressure loss due to the frost layer, resulting in poor heating performance. descend. In order to maintain heating performance, it is first necessary to suppress the decrease in air volume, and the main cause of the decrease in air volume is excessive deposition at the end of the fin in the airflow direction (referred to as the leading edge of the fin). It is necessary to prevent clogging due to frost. For this purpose, for example, a heat exchanger as shown in FIG. 8, which is a plan view showing a fin shape, is used, as shown in Japanese Patent Application Laid-Open No. 62-258997. In the figure, (1) is a fin, (2) is a heat exchanger tube, (13+
is a small hole, (41i) is the airflow direction. FIG. 9 is a sectional view taken along the line IX-IX in FIG. 8.

In the conventional heat exchanger shown in FIG. 8, a large number of small holes a31 are provided at the leading edge of the fin to block the heat flow from the leading edge of the fin toward the heat transfer tube, thereby reducing the heat transfer coefficient at the leading edge of the fin. This effect alleviates clogging caused by excessive frost formation at the leading edge of the fin and suppresses a decrease in air volume.

In addition, the large number of small holes eliminates the heat transfer surface itself, and has the effect of reducing the amount of frost on the leading edge.

RIi reduces air flow by reducing wind resistance due to frost layer! l
We are trying to Furthermore, the provision of two small holes increases the distance from the front heat transfer tube to the leading edge of the fin, which reduces the heat transfer coefficient at the leading edge of the fin and prevents clogging due to frost formation.

[Problem to be solved by the invention]

In the conventional heat exchanger shown in Figure 8, small holes prevent clogging due to frost formation on the leading edges of the fins, but in actual operation, the small holes become clogged due to frost growth, making the effect ineffective. Furthermore, if the diameter of the small holes were increased, the heat transfer coefficient at the leading edge of the fin would become too small, making it impossible to obtain the necessary amount of heat exchange.

This invention was made to solve the above problems, and it alleviates the clogging of the frost layer at the leading edge and suppresses the decrease in air volume without excessively reducing the heat transfer coefficient at the leading edge of the fin. The aim is to obtain a heat exchanger that can

[Means to solve the problem]

In the air conditioning heat exchanger of the present invention, a plurality of notches are provided at the ends (front edges) of the fins in the airflow inflow direction so that the longitudinal direction thereof is parallel to the airflow inflow direction.

[For production]

In the heat exchanger according to the present invention, the notch portion provided on the leading edge of the fin ensures the air volume even after a frost layer grows on the leading edge of the fin, thereby suppressing a decrease in the capacity of the heat exchanger.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing the fin shape of an air conditioning heat exchanger according to an embodiment of the present invention. In FIG. 2, (1) is a fin, (2) is a heat transfer tube, and (3) is a fin (1). A plurality of rectangular notches are provided at regular intervals, and the longitudinal direction thereof is parallel to the airflow inflow direction (4).

Even if there is a lot of frost on the front edge of the fin (7), the notch (3)
The structure allows air to pass through.

Regarding the position of the notch (3), the notch center line (5) is located at the center of the heat exchanger tube (2) and the heat exchanger tube (2).

The notch width (H) is set to a size that prevents water droplets from bridging during defrosting, and prevents the notch (3) from being blocked by frost growth. Also.

The length of the notch (L) should not exceed the length (K) from the front edge of the fin (7) to the rear of the heat transfer tube (2) to reduce frost formation and keep the height of the frost layer low. The left side is designed to alleviate the decrease in air volume.

According to this embodiment, by providing the notch (3) in the fin (1), air can be bypassed to a part of the leading edge of the fin that would impair the effect of the leading edge of the fin, thereby maintaining the air volume.

In addition, highly humid air can be introduced to the rear of the heat exchanger.

Observing the frost formation on the heat exchanger, we found that there was significant frost formation on the leading edges of the fins, and the thickness of the frost layer was thinner in the area behind the heat exchanger tubes, indicating that heat transfer at the rear of the heat exchanger was poor. It is necessary to improve the frost formation as much as possible, to bring it as close as possible to a -like frost formation, and to suppress the decrease in air volume by minimizing the increase in air path resistance. In the embodiment of FIG.

This not only prevents the air volume from being reduced due to clogging at the leading edge of the fins, but also allows humid air to bypass the rear part of the heat exchanger as described above, thereby improving heat exchange at the rear part. Due to this effect, a portion of the amount of frost can be shared by the rear part of the heat exchanger, and frost formation can be approached.

The above synergistic effect can alleviate the reduction in air volume and increase the amount of heat exchange.

In the above embodiment, the position of the center line (5) of the notch (3) formed in the fin (1) is between the heat exchanger tube (2) and the heat exchanger tube (
2), but on the extension of the center line (5) of the notch (3a) formed in the fin (1a) as shown in the plan view showing the fin shape of another embodiment in Figure 2. Heat exchanger tube (
2) may be positioned.

In addition, FIG. 3 shows the fin (1) (denoted as fin A) having the shape shown in FIG. 1, and the fin (1a) (denoted as fin A) having the shape shown in FIG.
FIG. 7 is a plan view showing a fin shape of still another embodiment in which fins (denoted as fins B) are alternately inserted into the heat exchanger tube.

4 is a side view showing the state seen from directly above FIG. 3. FIG. Notch f31. The position of (3a) is the fin (11, (l)
a) Because of the difference, the fin pitch is apparently doubled near the notch (31, (3a)), and the NH thickness is thicker at the leading edge of fin A (1) (even though it is thicker than that of fin B (la)). Because of the notch (3a), air path resistance can be suppressed.In this way, the heat exchanger having the configuration shown in FIG. 3 can also be expected to have a kind of staging effect.

In addition to B, a plan view showing the fin shape in Fig. 5, and its VI-
■As shown in Figure 6, which shows a line cross-section, a fin (1b) with a slit-shaped cut-out 8) at the rear of the fin B in Figure 2 is used for heat transfer at the rear of the heat exchanger. The heat exchange rate can be increased and the amount of heat exchanged can be increased. The slit length (M) does not have to be the same, and the slit at the rear may be longer as shown in FIG. Further, the number of rows of heat exchanger tubes in the heat exchanger may be plural, and the plan view showing the fin shape of FIG. 7 shows an embodiment of a heat exchanger with two rows. The fin in Figure 7 (IC
) is provided with a slit-like cut 8) on the fin in Figure 2.

and two rows.

〔Effect of the invention〕

As expected, the air conditioning heat exchanger of the present invention has a plurality of notches whose longitudinal direction is parallel to the airflow inflow direction at the end of the fin in the airflow inflow direction. It is possible to maintain the replacement amount and extend the time until defrosting.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the fin shape of an air conditioning heat exchanger according to one embodiment of the present invention, and FIGS. 4 is a side view in FIG. 3, FIG. 6 is a sectional view taken along the line M-M in FIG. 5, FIG. 8 is a plan view showing the fin shape of the conventional example, and FIG.
The figure is a sectional view taken along the line ■--■ in FIG. In the figure, (1), (], a), (Ib), (
lc) is a heat exchanger tube, (2) is a heat exchanger tube, f31. f3a
) is the notch, and (4) is the airflow direction. Note that in the two figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In an air conditioning heat exchanger consisting of a heat exchanger tube and a plurality of fins arranged in parallel on the heat exchanger tube, a notch is provided at the end of the fin on the side in the airflow inflow direction so that the longitudinal direction thereof is parallel to the airflow inflow direction. An air conditioning heat exchanger characterized by having multiple units.