JPS61243289A - Finned heat exchanger - Google Patents

Abstract

PURPOSE:To secure heat exchanging capacity and lengthen a permissible time to continue the operation of the heat exchanger even when frosting is caused by a method wherein a plurality of cut-up pieces are arranged on a flat sheet fin between heat transfer tubes and at the upstream side of the heat transfer tubes. CONSTITUTION:The cut-up pieces 9a, 9b, 9c are provided on the flat sheet fin 5 in the area of upstream side of airflow 8 with respect to the heat transfer tubes 7 so as to be slanted with respect to the flow direction of the airflow while the cut-up pieces 10a, 10b are provided at the down-stream side area of the cut-up pieces 10a, 10b are provided at the down-stream side area of the same so as to be slanted to a direction reverse to the inclinations of the cut-up pieces 9a, 9b, 9c. On the other hand, slit type or louver type cut-ups 11a, 11b, in which two sides, opposing to the airflow, are cut up and opened, are provided on the flat sheet fin 5 at the leading edge thereof. The flow of heat from the upstream side leading edge of the flat sheet fin 5 to the heat transfer tube 7 is limited, therefore, temperature at the leading edge part in the upstream side of the heat transfer tube is comparatively high and the amount of frosting in this area may be reduced. When the airflow collides against the cut-up pieces, another airflow having whirling component is generated, therefore, the heat transfer coefficient at the airflow side of the flat sheet fin 5 may be increased by the turbulent flow promoting effect of the whirling airflow.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a finned heat exchanger used in air conditioners, refrigerators, and the like.

BACKGROUND ART In heating operation of a heat pump type air conditioner using air as a heat source, an outdoor heat exchanger functions as an evaporator. here,
As shown in Figure 4, a conventional finned heat exchanger consists of a group of heat transfer tubes 1 that are installed horizontally and through which refrigerant flows;
It is composed of a plurality of flat plate fins 3 inserted vertically at regular intervals through which air flows in the two directions of the arrows.

Problems to be Solved by the Invention In the configuration as described above, when the surrounding air temperature decreases, the evaporation temperature does not reach 0°C or lower, and water vapor in the air adheres to the flat fins 3 and freezes, causing the water vapor to freeze on the flat fins. A frost layer 4 is formed. This frost layer 4 has a shape as shown in FIG. 5, and the frost is thickest at the front edge portion of the flat fin 3. This frost layer 4
This especially develops at the leading edge of the fins, causing fin clogging, which reduces the amount of air flowing between the fins of the flat fins 3, and also reduces the heat of the finned heat exchanger due to the insulation effect of the frost layer. Replacement capacity will be significantly reduced and defrosting will be required. Therefore, it is not possible to downsize the heat exchanger in order to ensure the full heating capacity, and there is a problem in that the duration of the heating operation is shortened.

The present invention solves the above-mentioned problems of the prior art and provides a small, high-performance finned heat exchanger that ensures heat exchange capability during frosting and has a long operating time.

Means for Solving the Problems The finned heat exchanger of the present invention is composed of flat plate fins arranged in parallel at predetermined intervals and a heat exchanger tube passing through the flat plate fins perpendicularly. In the side region, a plurality of cut and raised pieces Bi are provided on the flat plate fin so as to be inclined to the flow direction of the airflow, and in the downstream region, a plurality of cut and raised pieces Bi are provided on the flat plate fin and are inclined in the opposite direction to the cut and raised pieces Bi. It is something. Further, a slit-shaped or louver-shaped cut-and-raised C was provided on the flat-plate fin between the heat exchanger tube and the front edge of the flat-plate fin, with two sides facing the airflow opened and raised.

Effects According to the above configuration, as shown in FIG. 5, frost does not accumulate on the leading edges of the fins and the fins are prevented from becoming clogged. That is, since a plurality of cut and raised pieces B and C are arranged between the heat exchanger tubes in the step direction of the flat fin and at the upstream part of the heat exchanger tubes, the openings of these cut and raised pieces allow the front edge of the fin to be The heat flow from the fin to the heat transfer tube is restricted, and the temperature difference between the surface temperature of the fin leading edge and the air temperature is small, resulting in less frost formation. In addition, heat flow is restricted between the heat exchanger tubes in the step direction of the flat fins in the same way as described above, and the amount of frost formation is small, so an airflow passage is secured in this portion.

Next, regarding the heat exchange capacity, it is better to cut and raise the heat exchange capacity.

B induces an airflow with a swirling component in the air flowing between the inlets, and this promotes turbulence, increasing the heat exchange capacity. Furthermore, due to the leading edge effect of the boundary layer at the openings of the cut and raised sections C9 and the cut and raised sections B, the heat exchange capacity in these parts is also large.

As described above, as a result of making it possible to exchange heat with a small temperature difference in a heat exchanger with fins, ensuring heat exchange capacity, and preventing frost formation from concentrating on the leading edge of the fins, the heat exchanger with fins This made it possible to make the device smaller and more efficient, and to extend its operating time.

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

FIG. 1 is a plan view of fins in a finned heat exchanger according to an embodiment of the present invention, and FIG. 2 is a plan view of the fins shown in FIG.
It is a line sectional view, and FIG. 3 is a perspective view of the same fin.

As shown in FIG. 1, heat transfer tubes T are inserted into fin collar portions 6 that are barred at predetermined intervals on the flat fins 5, and air flows in from the direction of arrow 8.

In the upstream region of the airflow 8 with respect to the heat transfer tube 7 in the flat plate fin 6, cut and raised pieces 91L, 9b are provided in the downstream region. , 90 and cut and raised piece B101L.

10b is provided. Also cut and raised piece B101L.

Cut and raised pieces D121L and 12b are provided on the downstream side of the airflow of 10b so as to be inclined with respect to the flow direction of the airflow. Further, slit-shaped or louver-shaped cut and raised 011a and 11b are provided in the flat plate fin 6 between the heat transfer tube 7 and the front edge of the flat plate fin 5 with two sides facing the airflow opened and raised.

The effects of this embodiment are as follows. (1) Since the slit-shaped or louver-shaped cut-and-raise C11&, 11b is provided on the airflow upstream side of the heat transfer tube 7, the flat fin 6
Since the heat flow from the upstream front edge of the heat exchanger tube 7 to the heat exchanger tube 7 is restricted, the temperature at the upstream side front edge of the heat exchanger tube is relatively high, and the temperature difference from the temperature of the inflowing air is small. therefore,
As shown in FIG. 6, the amount of frost is reduced at the leading edge of the fins on the upstream side of the heat transfer tube 7, where frost develops quickly and fin clogging occurs earliest, making it difficult for the fins to become clogged. . In addition, cut-and-raise pieces 9, gb, and sc are provided between the heat transfer tubes in the stage direction, so the heat flow is restricted in the same way as above, and the fin front in this area is At the edges, the amount of frost is small and clogging due to frost is less likely to occur.

(2) Slit type or louver type cutting and raising 011
In the wing portions 1L and 11b (portions cut and raised from the flat plate fins 6), the air side heat transfer coefficient is large due to the boundary layer leading edge effect. As described in (1), this part also requires small temperature difference heat exchange, and although the heat exchange capacity is large, the amount of frost formation is relatively small, and clogging is difficult to occur.

(3) On the flat plate fin 6 between the heat exchanger tubes in the 0-stage direction, a plurality of cut and raised pieces 9a, sb, 5cB1oa, 10b and DI2a are provided at an angle with the flow direction of the airflow 8.
, b are installed, so when the airflow collides with these cut and raised pieces, an airflow having a swirling component that has the function of destroying the temperature boundary layer on the surface of the flat fin 6 is induced. Due to the effect of promoting turbulence due to this air flow, the air side heat transfer coefficient of the flat plate fins 5 is high. The effect of promoting turbulent flow due to the airflow having a swirling component becomes larger toward the downstream side of the airflow due to the interaction between the cut and raised pieces, B, and O. This means that the flat fin 6
The local heat transfer performance of the airflow increases toward the downstream side of the airflow. Here, even if the local heat transfer performance of the flat fins is uniform, the moisture in the air decreases toward the downstream side of the airflow, resulting in a frost thickness distribution as shown in FIG. However, in the fin shape of the present invention in which the local heat transfer performance increases toward the downstream side of the airflow as described above, the frost thickness becomes relatively uniform from the leading edge to the trailing edge of the fin. Therefore, clogging of the fins is less likely to occur, and operation can be continued for a long time.

As described above, the heat exchanger with fins improves the heat transfer performance by the boundary layer leading edge effect and the turbulence promotion effect.

Achieved a compact and high-performance converter, and made the fins less likely to clog.

Effects of the Invention The present invention has the above-described structure to ensure heat exchange ability even when frost forms on the fins of a heat exchanger with a sifter-in, and prevents frost from concentrating on the leading edges of the fins and causing clogging. This makes it possible to prevent this from occurring and extend the period of continuous operation.

[Brief explanation of drawings]

FIG. 1 is a plan view of a fin according to an embodiment of the finned heat exchanger of the present invention, FIG. 2 is a sectional view taken along the line If-I' in FIG. 1,
FIG. 3 is a perspective view of the same fin, FIG. 4 is a perspective view of a conventional finned heat exchanger, and FIG. 5 is a side view of a main part of the conventional finned heat exchanger. 5... Flat plate fin, 6... Fin collar, 7... Heat exchanger tube, 8... Air flow, 91
．． 9b, 90...Yamakiri Shiori Katamu, 10 &, 10
b...Cut and raised piece B, 111L, 1
l b---...Cut and raised piece C, 12&. 12'O... Name of the cut and raised piece D0 agent
Patent attorney Toshio Nakao (1 person) Figure 1
5111 Hand liquid, Awa212. Finklag 1. Yes, it's true. 81. Air flow (? a, b, c ,,, f-7J Riko Nishi! A
10a, b...Lηsujjisegoshiυ) BIfα
b ・・78 rise St throat C l2a,b, Neguri A Nigo Lノ”rDFigure 2Figure 3Figure 4

Claims (2)

[Claims] (1) Consisting of flat plate fins arranged in parallel at predetermined intervals and heat exchanger tubes perpendicularly passing through the flat plate fins, the flat plate is arranged in an upstream region of the airflow with respect to the heat exchanger tubes at an angle with the flow direction of the airflow. A plurality of cut and raised pieces are provided on the fin, and the cut and raised piece A is provided in the downstream region with respect to the heat transfer tube.
A plurality of cut and raised pieces B are provided on the flat fin so as to be inclined in the opposite direction, and two sides facing the airflow are opened on the flat fin between the heat exchanger tube and the front edge of the flat fin. A heat exchanger with fins equipped with a raised slit or louver shaped raised C. (2) The finned heat exchanger according to claim 1, wherein a plurality of cut and raised pieces D are provided downstream of the cut and raised pieces B with respect to the airflow.