JPS6146898A - Heat exchanger with fins - Google Patents

Abstract

PURPOSE:To make the thickness of frost which attaches on a plate fin uniform, by providing indented type cutting parts at the up-stream end part of a plate fin for air flow, and recessed parts of the corrugated cut-out parts are situated so as to confront heat transfer pipes. CONSTITUTION:Many parallel plate fins 1 and many heat transfer pipes 2 which intersect at right angles to said plate fins are provided. Corrugate type cut-out parts 9 are provided at the up-stream side end part of plate fins 1 corresponding air flow, and, furthermore, the recessed part of the corrugated type cut-out parts 9 are positioned at fin parts which situate at the upstream side of heat transfer pipes 2 with respect to air flow. As a result, the heat exchange volume near the heat transfer pipes are reduced and the frost attaching volume are reduced. Accordingly, the thickness of frost which attaches on the plate fins becomes uniform, and the choking times between plate fins can be maintained longer than before.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in a heat exchanger for an outdoor unit of an air conditioner, and is aimed at preventing frost formation during heat pump operation. .

Structure of a conventional example and its problems A conventional finned heat exchanger is composed of a large number of parallel plate fins 1 and a large number of heat exchanger tubes 2 orthogonal to the plate fins, as shown in FIG. 3 is an end plate. The heat source fluid flowing in the heat transfer tube and the air flowing in the direction of the arrow exchange heat via this finned heat exchanger.

When such a conventional heat exchanger with fins is used as a heat exchanger for an outdoor unit of an air conditioner and operated as a heat pump, as shown in Figure 6 (view of Figure 5 from the direction of the arrow). , the upstream end 4 of the plate fin 1 with respect to the airflow
As a result, the frost 5 forms on the plate fins 1. Then, as the operating time elapses, frost 5 develops as shown in FIG. 6 and blocks the space between the plate fins 6.

In FIG. 6, 2 is a heat exchanger tube, and the arrow indicates the direction of air flow. FIG. 7 is a view of FIG. 6 viewed from the arrow B, and shows in detail the development of frost forming on the upstream end portion 4 of the plate fin 1.

In the fin section 7 located on the upstream side of the heat exchanger tube 2 with respect to the air flow, the distance from the heat exchanger tube 2 is short, so the plate fin surface temperature is close to the heat exchanger tube temperature, so the temperature difference between the plate fin and the air becomes large. As a result, the amount of local heat exchange on the fin surface becomes large, and the frost 5 develops quickly and becomes thick.

On the other hand, in the fin portion 8 located between the body heat tube 2 and the heat exchanger tube 20, the distance from the heat exchanger tube 2 is long, and therefore the plate fin surface temperature becomes higher than the heat exchanger tube temperature, and the temperature between the plate fin 1 and the air increases. As a result of the smaller difference, the amount of local heat exchange on the fin surface is small, frost does not develop much, and the thickness of the frost is also small. As described above, in the conventional heat exchanger with fins, the thickness of the frost adhering to the plate fins is not uniform, and the frost is locally divided into areas where the thickness is large and areas where the thickness is small.

In areas where the frost is thicker, the spaces between the plate fins tend to become clogged with frost, so the spaces between the fins become clogged with frost quickly.

If the space between the fins becomes clogged with frost, heat exchange between the heat source fluid flowing inside the heat transfer tube and the air becomes impossible, so in order to operate the heat pump continuously, it is necessary to periodically melt the frost that has adhered to the plate fins. There is a need to. As explained in Section L, conventional heat exchangers with fins have the disadvantage that the frost between the fins gets clogged quickly, so the heat pump cannot operate unless the frost is melted about once every hour. It was not good in terms of energy efficiency.

Purpose of the Invention In order to eliminate the above-mentioned conventional drawbacks, the present invention makes the thickness of the frost that forms on the plate fins uniform and prevents frost formation by making the closing time between the plate fins longer than before. The present invention provides a heat exchanger with fins.

Structure of the Invention In order to achieve this object, the present invention provides a convex-concave notch at the upstream end of the plate fin relative to the airflow, and further positions the concave part of the concave-concave notch so as to face the heat exchanger tube. This is what I did.

With this configuration, the amount of heat exchange near the heat exchanger tubes is reduced, and the amount of frost formation is reduced.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, 1 is a large number of parallel plate fins, 2 is a large number of heat exchanger tubes orthogonal to the plate fins, and 3 is an end plate. And the plate fin 1 has a second
As shown in the figure, a concave-convex notch 9 is provided at the upstream end 4.
Furthermore, the concave portion 10 of the uneven notch portion 9 is arranged in the fin portion 7 located on the upstream side of the heat exchanger tube 2 with respect to the air flow.

The operation of the heat exchanger with the above configuration will be explained with reference to FIG.

When a heat exchanger with fins having the above configuration is used in an outdoor unit of an air conditioner to operate a heat pump, the fin area in this part is reduced compared to the conventional one because the fin part 7 is divided into four parts 10. As a result, the amount of local heat exchange in the fin portion 7 is reduced, and the amount of frost formed is also reduced.

Therefore, the development of frost on the fin portion 7 is prevented, and as a result, the third
As shown in the figure, frost 5 forms on the plate fin 1 with a uniform thickness. As a result, the time during which the space between the plate fins 6 is blocked by frost becomes longer, the heat pump operating time becomes longer, the number of times the frost is melted is reduced, and energy efficiency is also dramatically improved.

As another embodiment, it goes without saying that a heat exchanger with fins having a corrugated concave-convex notch 11 as shown in FIG. 4 has the same effect as the embodiment shown in FIG. 2.

As is clear from the detailed description of the invention, the present invention includes a large number of parallel plate fins and a large number of heat transfer tubes perpendicular to the plate fins, and has an uneven cut at the upstream end of the plate fin with respect to the airflow. A notch is provided, and the concave part of the uneven notch is arranged in the fin part located upstream of the heat exchanger tube with respect to the air flow, and such a heat exchanger with fins is used as an outdoor unit of an air conditioner. When operated as a heat pump, the upstream fin portion of the heat transfer tube becomes a concave portion and the fin area is reduced, resulting in a decrease in the amount of local heat exchange in this portion and a reduction in frost formation.

As a result, the development of frost on the fin portions is prevented, and frost forms on the plate fins with a uniform thickness.

Therefore, the time during which the space between the plate fins is blocked by frost becomes longer, the heat pump operating time becomes longer, the number of times frost is melted is reduced, and energy efficiency is also dramatically improved.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a heat exchanger with fins according to an embodiment of the present invention, Fig. 2 is a sectional view of the main part of the heat exchanger, and Fig. 3 shows the state of frost on the fins of the heat exchanger. Sectional view shown, No. 4
The figure is a diagram equivalent to Figure 2 showing another embodiment of the present invention, Figure 5 is a perspective view of a conventional finned heat exchanger, and Figure 6 is a cross section showing the frosting state of a conventional finned heat exchanger. 7 are cross-sectional views showing the frosting state of a conventional finned heat exchanger viewed from different angles. 1... Plate fin, 2... Heat exchanger tube, 9/11... Concave and convex cutout portion. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 (2) Brush 3 Figure 4 Figure 5

Claims (1)

[Claims] A large number of parallel plate fins and a large number of heat transfer tubes perpendicular to the plate fins are provided, an uneven cutout is provided at the upstream end of the plate fin with respect to the air flow, and a concave and convex cutout is provided on the upstream side of the heat transfer tube with respect to the air flow. A heat exchanger with fins, in which a concave portion of the uneven cutout portion is arranged in a fin portion.