JP2000266486A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the effectiveness of a heat exchanger while the ventilating resistance of the heat exchanger is reduced. SOLUTION: The heat transfer coefficient of a heat exchanger can be improved by suppressing the influence of a thermal boundary layer while the ventilating resistance of the heat exchanger is reduced, when the widths 5h of downstream-side cut-and-raised pieces 4 are made narrower and the separating widths 5'h of the pieces 4 are made larger in the downstream side area of cut-and-raised pieces 6 installed to a heat radiating fin 1 from the center of a heat exchanger pipe 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger used for a condenser and an evaporator of an air conditioner or the like having a refrigeration cycle, and more particularly to a structure of a radiation fin.

[0002]

2. Description of the Related Art Conventionally, in a heat exchanger used for a refrigeration cycle device such as an air conditioner, generally, a plurality of cut-and-raised pieces are formed on a radiation fin as a measure for improving heat exchange capacity.

The average heat transfer coefficient has been increased by dividing the temperature boundary layer, which is to be continuously developed along the flow, on the radiation fins into a plurality of pieces by the cut and raised pieces.

For example, in a heat exchanger used in an indoor unit of an air conditioner, as shown in FIGS. 11 and 12, a cut-and-raised piece 6 'and a separation portion 8' between the cut-and-raised piece are formed. A plurality of heat exchange pipes are formed between the heat exchange pipes so as to be substantially line-symmetric with respect to a center line 7 'connecting the centers of the heat exchange pipes 2' in the longitudinal direction of the radiation fins.

[0005]

However, the air flow actually passing between the heat radiation fins is substantially equal to the center line 7 'in FIG.
On the other hand, when flowing to the downstream side in the air flow direction, the flow rate is increased due to the contraction between the heat exchange pipes. Was causing an increase.

[0006] In addition, the heat transfer effect due to the leading edge effect is sufficient in the downstream cut-and-raised piece due to the influence of the temperature boundary layer developed by the cut-and-raised piece on the upstream side in the air flow direction with respect to the center line 7 '. However, there is a problem that the heat transfer coefficient is reduced as compared with the cut and raised piece on the upstream side.

The present invention has been made in consideration of the above circumstances, and has as its object to provide a heat exchanger that improves the heat exchange rate while reducing ventilation resistance.

[0008]

In order to achieve the above object, a first aspect of the present invention is to provide a heat exchange fin having a plurality of radiating fins stacked at intervals from each other and a heat exchanging through a through hole provided in the radiating fin. In a heat exchanger comprising a pipe, a plurality of cut-and-raised pieces are provided in parallel with the longitudinal direction of the heat-radiating fin, and the width of the cut-and-raised pieces in the airflow direction is the same as that of the heat exchange pipe. Are formed smaller on the downstream side than on the upstream side in the airflow direction with respect to the center line connecting the centers of the fins in the longitudinal direction of the radiating fins.

According to a second aspect of the present invention, in the heat exchanger according to the first aspect, the separation width between the cut and raised pieces is formed to be larger on the downstream side than on the upstream side in the air flow direction. It is.

According to a third aspect of the present invention, in the heat exchanger according to the first or second aspect, the separation width between the cut-and-raised pieces is set to be the width of the cut-and-raised pieces in the airflow-flow direction on the upstream side in the airflow-flow direction. It is characterized by being made larger.

According to a fourth aspect of the present invention, there is provided the heat exchanger according to any one of the first to third aspects, wherein the plurality of cut-and-raised pieces provided in the separated portions between the through-holes allows the airflow to flow with respect to the center line. The present invention is characterized in that the number of cut-and-raised pieces on the downstream side is smaller than that on the upstream side in the flow direction.

According to a fifth aspect of the present invention, in the heat exchanger according to any one of the first to fourth aspects, the cut-and-raised piece is provided at a space between the through holes, and is formed at the space. The number of the raised pieces is three to four.

According to the above-described structure, in the first aspect of the present invention, the width of the air flow in the air flow direction passing through the piece is reduced on the downstream side in the air flow direction, so that the square of the flow velocity is reduced. The ventilation resistance that increases in proportion to the product of the lengths of the raising pieces in the airflow direction can be reduced.

According to the second aspect of the present invention, in addition to the first aspect, the separation width between the cut-and-raised pieces between the upstream cut-and-raised pieces and the downstream cut-and-raised pieces is increased. In addition, it is possible to suppress the influence of the temperature boundary layer developed by the upstream cut-and-raised pieces on the downstream cut-and-raised pieces, and to improve the heat transfer coefficient by the leading edge effect of the downstream cut-and-raised pieces.

According to the third aspect of the present invention, in addition to the first or second aspect of the present invention, the gap between all the cut-and-raised pieces is increased, so that it is difficult for the boundary layers to influence each other and the heat transfer coefficient is improved. Can be done.

According to the invention of claim 4, in addition to the invention of any of claims 1 to 3, since the number of cut and raised pieces on the downstream side is reduced, the ventilation resistance can be further reduced.

According to a fifth aspect of the present invention, in addition to any one of the first to fourth aspects of the present invention, the number of cut-and-raised pieces is set to three to four to reduce ventilation resistance and improve heat transfer coefficient. It is possible to obtain the conflicting effects with a good balance.

[0018]

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

As shown in FIG. 1, the heat exchanger according to the present invention comprises a compressor 11, an outdoor heat exchanger 12, a pressure reducer 13 comprising a capillary tube or an electronic expansion valve, and an indoor heat exchanger 14 in order. This is used for an indoor heat exchanger of an air conditioner having a heat pump refrigeration cycle connected by a refrigerant pipe 15.

FIG. 2 shows a cross section of an indoor unit 21 of the air conditioner. The indoor unit has indoor air suction ports 22 and 23 on the front and top surfaces, respectively, and further has an air conditioning air discharge port on the lower front. 24.

The indoor unit 21 includes the suction ports 22, 2
A ventilation path 25 is formed from 3 to the discharge port 24, and an indoor heat exchanger 26 and a cylindrical indoor fan 27 are sequentially installed in the ventilation path 25 along the ventilation direction.

The indoor heat exchanger 26 constructed as described above
When air is blown from the direction indicated by the arrow in FIG. 1 by the rotational drive of the indoor fan 27, air passes between the radiation fins.

The indoor heat exchanger 26 is, as shown in FIG.
A heat dissipating fin laminated portion 31 in which a plurality of heat dissipating fins 1 are stacked at intervals from each other; a heat exchange pipe 2 penetrating through holes 3 provided in the heat dissipating fin 1 in two rows in a staggered manner;
Consists of two.

As shown in FIG. 4, the heat radiation fin 1 is provided with a cut-and-raised piece 6 at a space between the heat exchange pipe through holes 3. The cut-and-raised pieces 6 are provided so as to project in a direction substantially perpendicular to the radiation fin surface, and four cut-and-raised pieces 6 are provided along the ventilation direction.

As shown in FIG. 4 and FIG. 5 which shows a cross section taken along the line AA in FIG. 4, the cut and raised piece 6 has an airflow of the cut and raised piece 4 on the upstream side of the air flow with respect to the center line 7. The width 5h of the cut-and-raised piece 5 on the downstream side of the airflow in the airflow distribution direction is smaller than the width 4h in the circulation direction.

The separation width 5'h between the cut-and-raised pieces on the downstream side is set to be larger than the separation width 4'h between the cut-and-raised pieces on the upstream side.

The airflow flowing into the radiating fins is contracted between the heat exchange pipes, the flow velocity increases, and reaches the cut-and-raised piece 5 on the downstream side. Generally, the ventilation resistance increases in proportion to the product of the square of the flow velocity and the length of the object in the airflow direction.

Therefore, by reducing the width 5 h of the cut-and-raised piece on the downstream side in the direction of airflow by the increase in the flow velocity on the downstream side, an increase in ventilation resistance can be prevented.

On the other hand, since the temperature difference between the air and the radiating fins is small on the downstream side, the amount of heat exchange is small, and even if the width 5′h of the cut-and-raised piece on the downstream side in the airflow direction is reduced, a large heat is generated. No reduction in transmissibility occurs.

Further, the temperature boundary layer developed by the upstream cut-and-raised pieces 4 affects the downstream cut-and-raised pieces 5 and reduces the heat transfer coefficient at the downstream cut-and-raised pieces 5. The effect of the boundary layer is suppressed by increasing the separation width 5'h between the cut-and-raised pieces on the downstream side, and the heat transfer coefficient is improved by the leading edge effect at the leading edge 5t of the cut-and-raised piece on the downstream side.

The present invention is not limited to the above-described embodiment. For example, as shown in FIGS.
The number of the cut-and-raised pieces may be smaller on the downstream side than on the upstream side of the airflow. Further, as shown in FIGS. 9 and 10, the heat exchange pipe rows can be arranged in a row.

According to the experiment, as shown in FIG.
A radiating fin provided with four cut-and-raised pieces according to the conventional configuration;
Compared with the radiating fins (four cut and raised pieces) according to the present embodiment, the radiating fin according to the present embodiment has a large average heat transfer coefficient and a small ventilation resistance.

Further, when comparing the heat dissipating fin provided with five cut and raised pieces according to the conventional configuration with the heat dissipating fin provided with three cut and raised pieces according to the present embodiment, the average heat transfer coefficient is as follows. It can be seen that even with substantially the same, the radiation fins according to the present embodiment greatly reduce the ventilation resistance.

Since the load of the indoor fan provided opposite to the heat exchanger can be reduced by reducing the ventilation resistance as described above, the power consumption can be reduced.

Further, from the experimental results, the heat transfer coefficient is low when the cut and raised pieces are two, and the ventilation resistance is large when the cut and raised pieces are five, although there is no large difference in the heat transfer coefficient from the case where the cut and raised pieces are four. You can see that. Therefore, it was confirmed that the case where the number of the cut-and-raised pieces applied to one cut-and-raised group was set to 3 to 4 was efficient.

As is evident from the above results, the present invention reduces the width of the cut-and-raised pieces on the downstream side and increases the separation width between the cut-and-raised pieces to reduce the ventilation resistance and reduce the temperature boundary. The heat transfer coefficient can be improved by suppressing the influence of the layer.

[0037]

As described above, according to the present invention, the width of the cut-and-raised piece provided on the radiation fin in the direction of air flow is:
On the downstream side in the airflow direction by forming the center of the heat exchange pipe smaller on the downstream side than the upstream side in the airflow direction with respect to the center line connected in the longitudinal direction of the radiation fins,
The ventilation resistance that increases in proportion to the square of the flow velocity can be reduced, and a heat exchanger having high heat exchange performance can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a refrigeration cycle according to the present invention.

FIG. 2 is a sectional view showing an air conditioner indoor unit according to the present invention.

FIG. 3 is a perspective view showing a heat exchanger according to the present invention.

FIG. 4 is a front view showing the embodiment of the present invention.

FIG. 5 is a sectional view taken along line AA in FIG.

FIG. 6 is a graph showing an average heat transfer coefficient with respect to ventilation resistance.

FIG. 7 is a front view showing another embodiment.

FIG. 8 is a sectional view taken along line BB in FIG. 7;

FIG. 9 is a front view showing an embodiment in which the heat exchange pipe rows are arranged in one row.

FIG. 10 is a sectional view taken along line CC in FIG. 9;

FIG. 11 is a front view showing a conventional heat radiation fin.

FIG. 12 is a sectional view taken along the line DD in FIG. 11;

[Description of Signs] 1, 1 ': heat dissipating fins 2, 2': heat exchange pipe 3, 3 ': through hole 4: upstream cut and raised piece 4h: width of upstream cut and raised piece in air flow direction 4 ': Separated portion between the cut-and-raised pieces on the upstream side 4'h ... Separation width between the cut-and-raised pieces on the upstream side 5 ... Cut-and-raised piece on the downstream side 5h ... Airflow circulation of the cut-and-raised piece on the downstream side Width in the direction 5 ': Separation portion between cut-and-raised pieces on the downstream side 5'h ... Separation width between cut-and-raised pieces on the downstream side 5t ... Front edge of cut-and-raised pieces on the downstream side 6, 6' ... Cut-and-raised piece 7, 7 '... center line of heat exchange pipe 8' ... Separated portion between cut-and-raised pieces 14, 26, ... indoor heat exchanger 21 ... indoor unit 31 ... radiating fin laminated portion 32 ... end plate

Claims (5)

[Claims] 1. A heat exchanger comprising: a plurality of radiating fins stacked at intervals from each other; and a heat exchange pipe penetrating a through hole provided in the radiating fin, wherein the radiating fin extends in a longitudinal direction thereof. A plurality of cut-and-raised pieces are provided substantially in parallel and separated from each other, and the width of the cut-and-raised pieces in the airflow direction is formed to be smaller on the downstream side of the center of the heat exchange pipe than on the upstream side. And heat exchanger. 2. The heat exchanger according to claim 1, wherein a separation width between the cut-and-raised pieces is made larger on the downstream side than on the upstream side in the airflow direction. 3. The method according to claim 1, wherein the width of the cut-and-raised pieces is larger than the width of the cut-and-raised pieces in the airflow direction on the upstream side in the airflow direction. Heat exchanger. 4. A plurality of cut-and-raised pieces provided in a space between the through-holes to reduce the number of cut-and-raised pieces on the downstream side from the upstream in the air flow direction with respect to the center line. The heat exchanger according to claim 1, wherein: 5. The cut-and-raised piece is provided in a space between the through holes, and the number of the cut-and-raised pieces formed in the space is three to four. The heat exchanger according to any one of claims 1 to 4.