JP3068761B2 - Heat exchanger - Google Patents

Abstract

PURPOSE: To prolong time until frosting causes a clogging. CONSTITUTION: There are arranged a louver part 11 formed by cutting and erecting a louver 10 in a corrugated fin 3 and a flat part 12 with no louver 10 formed. The louver part 11 and the flat part 12 are arranged as opposed to each other sandwiching an air passage 13. An air flow is cooled in contact with the surface of the corrugated fin 3 and the louver 10 to exchange heat. Frosting begins with the louver part 11 by the moisture of the air flow and the flat part 12 is kept from being frosted. At stages of the corrugated fin 3, a part frosted faces that not frosted. This enables the securing of a larger air passage 13 of the corrugated fin 3 thereby prolonging time until the frosting causes a clogging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel flow type heat exchanger used for an outdoor unit in a heat pump room air conditioner or the like.

[0002]

2. Description of the Related Art FIG. 7 shows a heat exchanger 1 of the parallel flow type. As shown in FIG. 7, the heat exchanger 1 includes a plurality of flat tubes 2 arranged in parallel at a predetermined interval, and corrugated fins 3 arranged to be sandwiched between the flat tubes 2.
And a pair of hollow headers 4 and 5 connected to the upper and lower ends of each flat tube 2.
Are alternately stacked at right angles to the air flow direction.

As shown in FIG. 8, a refrigerant is circulated in a pair of hollow headers 4, 5, and the refrigerant flows from the hollow headers 4, 5 to a plurality of refrigerant passages 6 provided in each flat tube 2. , The heat of the refrigerant is transmitted from the flat tubes 2 to the corrugated fins 3, and the air flow passes through the corrugated fins 3 to perform heat exchange. In general, when the heat exchanger 1 is used as an evaporator (heating operation), the refrigerant flows from the lower hollow header 5 to the refrigerant flow path 6 of each flat tube 2 in the direction of the arrow M, and on the other hand, as a condenser. When used (cooling operation), the refrigerant flows in the direction opposite to the M direction to release or absorb heat.

Conventionally, to promote heat exchange, FIG.
As shown in the figure, a plurality of louvers 7 of the same shape formed by cutting and raising the corrugated fins 3 are provided, and the louvers 7 are formed so that the inclination directions thereof are opposite on the upstream side and the downstream side of the air flow. I have.

When the heat exchanger 1 is used as an evaporator in an outdoor unit of a room air conditioner, the refrigerant flowing through the flat tubes 2 absorbs the heat of the airflow through the corrugated fins 3 and evaporates, and the air is evaporated. The stream is absorbed and cooled. At this time, when the moisture held by the air condenses on the surface of the corrugated fin 3 and the surface temperature of the corrugated fin 3 becomes lower than the freezing point, the dew forms ice and forms frost on the surface of the corrugated fin 3. It grows with the passage of time, and eventually the air flow passage is blocked. This is called clogging due to frost formation. In particular, since the louver 7 is provided on the corrugated fin 3, the interval between the steps of the corrugated fin 3 is narrow, and the ventilation passage is blocked more quickly by frost. As a result, the heating capacity is short due to insufficient ventilation. At the same time.

Therefore, in Japanese Patent Application Laid-Open No. Hei 6-147785, the ventilation upstream end of the corrugated fin has no louver, the corrugated fin protrudes upstream from the flat tube end, or the corrugated fin upstream end has the upstream end. A heat exchanger is disclosed in which every other flat tube is replaced with a partition plate, or the shape of the louver is sequentially changed from upstream to downstream.

In Japanese Patent Application Laid-Open No. 6-221787, an upstream louver having a small angle is formed in an upstream portion of the corrugated fin into which an air flow flows, and a downstream portion having a larger angle than the upstream louver is formed in a downstream portion. There is disclosed a heat exchanger in which a louver is formed and an upstream portion of a corrugated fin is a louverless portion having no cut.

[0008]

In the above two heat exchangers, the cross-sectional area of the ventilation passage between the corrugated fins is increased toward the upstream side to delay the closing time of the ventilation passage due to frost on the upstream side of the corrugated fin. Let me. However, although frost formation on the upstream side of the corrugated fin can be suppressed by this, if the interval between the steps of the corrugated fin is widened, the flow velocity of the airflow passing through the ventilation passage becomes slow. For this reason, the heat exchange efficiency between the upstream side and the downstream side of the corrugated fin may be reduced due to the difference in the flow velocity of the airflow, and the heating capacity may be reduced.

In view of the above, it is an object of the present invention to provide a heat exchanger in which the intervals between the corrugated fins are made as wide as possible to increase the time until clogging due to frost formation.

[0010]

Means for solving the problems according to the present invention are, as shown in FIG. 1, a plurality of flat tubes 2 in which a refrigerant flows in parallel and corrugated fins 3 for promoting heat exchange.
Are alternately stacked, and a louver portion 11 formed by cutting and raising a plurality of louvers 10 on the corrugated fin 3 is formed.
And a flat portion 12 where the louver 10 is not formed,
The louver portion 11 and the flat portion 12 are arranged to face each other with the fluid flow path 13 interposed therebetween.

Then, in order to improve the heat exchange efficiency in the flat portion 12, unevenness is formed in the flat portion 12 or the louver portion 1 is formed.
Louver 3 whose cut-and-raise angle is smaller than louver 10 of 1
1 may be formed.

Also, as shown in FIG.
In addition, the first louver portion 42 formed such that the plurality of louvers 41 are cut and raised from the fluid upstream to the downstream and the angle is sequentially increased, and the plurality of louvers 43 are cut and raised from the fluid upstream to the downstream and the angle is sequentially reduced. A second louver portion 44 is provided so that the first louver portion 42 and the second louver portion 44 face each other with the fluid flow path 45 interposed therebetween.

[0013]

In the above-mentioned means for solving the above problems, when the heating operation is started, the refrigerant flowing through the flat tube 2 becomes corrugated fins 3.
The fluid absorbs heat and evaporates through the fluid, and the fluid is cooled by absorbing the heat to perform heat exchange. At this time,
In the corrugated fin 3, the moisture held by the fluid is condensed on the surface of the corrugated fin 3, and when the surface temperature falls below the freezing point, frost adheres to the corrugated fin 3, and the louver portion 11 having particularly high heat exchange efficiency
However, since the heat exchange efficiency is low only in the flat portion 12 due to the passage of the fluid, the fluid is hardly cooled and does not frost.

For this reason, in the corrugated fin 3, the frosted portion and the non-frosted portion are opposed to each other, and the gap between the respective stages of the corrugated fin 3, that is, the flow path 13 is largely secured, and clogging due to frosting is achieved. The time required to reach the state becomes longer, and efficient heating operation can be performed for a long time.

When the flat portion 12 is provided with unevenness or a louver 31 having a smaller angle to be cut and raised than the louver 10 of the louver portion 11, the fluid comes into contact with the unevenness or the louver 31, and the heat exchange efficiency in the flat portion 12 is reduced. It is better than the flat portion 12 where no 10 is provided. As a result, frost is slightly formed on the unevenness or the louver 31, but the time until the clogging due to the frost is not extremely shortened.

A first louver portion 42 and a second louver portion 44 in which the cut-and-raised angles of the louvers 41 and 43 are sequentially changed.
And the gap of each step of the corrugated fin 3,
That is, the flow path 45 is communicated at a constant interval from the fluid upstream side to the downstream side. Therefore, the fluid smoothly passes between the corrugated fins 3 and heat exchange is performed efficiently.

[0017]

【Example】

(First Embodiment) A heat exchanger according to a first embodiment of the present invention is shown in FIG.
A plurality of flat tubes 2 for circulating a refrigerant arranged in parallel at a constant interval in a parallel flow type heat exchanger 1 used for an outdoor unit of a heat pump room air conditioner;
A corrugated fin 3 for promoting heat exchange disposed so as to be sandwiched between the flat tubes 2, and a pair of hollow headers 4, 5 connected to the upper and lower ends of the flat tubes 2 and allowing a refrigerant to flow into the flat tubes 2. A flat tube 2 and a corrugated fin 3
Are alternately stacked. In addition, a compressor, a four-way switching valve, an indoor heat exchanger, a decompression device, and the like (not shown) are connected to the hollow headers 4 and 5 via a connection pipe to form a refrigeration cycle, and a refrigerant circulates through each part. Thus, heating or cooling is performed. An air flow for performing heat exchange is generated by a blower (not shown). Further, the same components as those in the related art are denoted by the same reference numerals.

As shown in FIG. 1, the flat tube 2 has a plurality of refrigerant channels 6 through which the refrigerant flows.
Are communicated with the two hollow headers 4 and 5. And when this heat exchanger 1 is used as an evaporator (heating operation)
The refrigerant flows from the lower hollow header 5 into the refrigerant flow path 6 of each flat tube 2, flows through the refrigerant flow path 6, and flows into the upper hollow header 4. On the other hand, when it is used as a condenser (cooling operation), it flows from the upper hollow header 4 to the lower hollow header 5 via the refrigerant flow paths 6 of the flat tubes 2.

The corrugated fins 3 are formed by bending a corrugated metal plate made of aluminum or the like having a high heat transfer coefficient into a wave shape, and the bent portions are fixed to the flat tubes 2 located on both sides. And the depth length of the corrugated fin 3 is
A louver portion 11 formed by cutting and raising a plurality of louvers 10 for promoting heat exchange with an air flow is formed on the surface of each step other than the bent portion of the corrugated fins 3. And a flat portion 12 on which the louver 10 is not formed. The louver portion 11 and the flat portion 12 are provided at each stage of the corrugated fin 3 at one of the louver portion 11 from the center to the front side, which is the upstream side of the air flow, or from the center to the rear side, which is the downstream side. A flat portion 12 is provided on one of the other, and the louver portion 11 and the flat portion 12 are arranged so as to face each other with the air flow path 13 interposed therebetween by bending the corrugated fin 3.

The louver 10 of the louver section 11 is shown in FIG.
As shown in the figure, the cutout is made at the same shape and at the same angle θ1 with a constant interval, and all the inclination directions are set to the same direction. The air flow comes into contact with the perforations 14 formed by the louver 10 and the louver 10, thereby promoting heat exchange. Then, the gap between the tip of the louver 10 of the louver portion 11 and the flat portion 12 of the opposite step is kept uniform,
This space is an air flow path 13 through which the air flows.

Here, the inclination direction of the louvers 10 of the louver portion 11 is all the same. For example, the inclination directions are alternately changed as shown in FIG. May be divided into a plurality of groups, and the inclination direction may be changed for each group, so that these do not adversely affect the heat exchange in the louver portion 11. These corrugated fins 3 are formed by pressing and bending a single metal plate, and each step can be performed continuously.

Since the basic operation of the heat exchanger 1 configured as described above is well known, only the characteristic operation of the present embodiment will be described below. First, when the heating operation of the room air conditioner is started, the refrigerant decompressed by the decompression device (not shown) flows from the lower hollow header 5 into the refrigerant flow path 6 of each flat tube 2, and the upper hollow header 4. Flows to Then, the airflow from the blower flows in from the front side of the heat exchanger 1, passes through the corrugated fins 3, and flows to the rear side. At this time,
The air flow is applied to the surface of the corrugated fin 3 or the louver 10.
, The heat of the air flow is absorbed by the refrigerant through the corrugated fins 3 and cooled, and the refrigerant absorbs the heat of the air flow and evaporates to perform heat exchange.

When the air flow is cooled, the moisture contained in the air condenses on the surface of the corrugated fin 3, and when the surface temperature of the corrugated fin 3 falls below freezing, the dew forms ice and the corrugated fin 3 becomes condensed. The frost starts from the louver portion 11 having particularly high heat exchange efficiency. At this time,
In the corrugated fins 3, the frost on the louver portion 11 grows with the passage of time. However, in the flat portion 12, since the air flow only passes and the heat exchange efficiency is low, the air flow is hardly cooled and no frost is formed. .

As described above, since the louver portion 11 and the flat portion 12 are opposed to each other with the air flow path 13 interposed therebetween, the frosted portion and the non-frosted portion are opposed to each other. The gap, that is, the air flow path 13 is larger than between the steps, and the closing time of the air flow path 13 due to frosting can be lengthened. Therefore, even if the flow rate of the air flow passing through the corrugated fins 3 does not extremely decrease, and even if the heat exchange efficiency in the flat portion 12 is low, the heat exchange efficiency of the heat exchanger 1 does not suddenly decrease, so that the heating capacity is reduced. A drastic decrease can be prevented, and efficient heating operation can be performed for a long time.

Furthermore, since the front and rear sides of the corrugated fins 3 are at the same distance between the respective stages, the air passing through the corrugated fins 3 is not frosted on the surface of the corrugated fins 3. The flow rate and flow rate of the stream do not change and do not reduce the heat exchange efficiency. Further, the louver portion 11 and the flat portion 12 of the corrugated fin 3 can be easily formed from one metal plate, and the productivity is not inferior to the conventional case.

(Second Embodiment) In the heat exchanger 1 of the first embodiment, the corrugated fin 3 is provided with the flat portion 12 in which the louver 10 is not formed, and the air flow path 13 is secured. If the heat exchange efficiency at 12 becomes too low, there is a possibility that the heating capacity will be reduced. Therefore, in the corrugated fin 3 of the heat exchanger 1 according to the present embodiment, as shown in FIG.
1 is formed. The height h of the undulations 21 of the flat portion 12 is set lower than the height j of the louver 10 from the flat portion 12 (h <j). The other configuration is the same as that of the first embodiment.

When the air flow flows into the corrugated fins 3, the air flow comes into contact with the undulations 21 in the flat portion 12 and heat exchange is performed, so that the heat exchange efficiency is improved as compared with the flat portion 12 of the first embodiment. I do. In addition, the undulations 21 of the flat portion 12
Is lower than the louver 10 of the louver part 11,
Although frost is formed on the undulations of the flat portion 12, the frost is less than that of the louver portion 11, and the closing time of the air flow path 13 due to the frost is not extremely shortened, and the same effect as that of the first embodiment is obtained. be able to.

Third Embodiment In the corrugated fin 3 of the heat exchanger 1 of the present embodiment, as shown in FIG. 5, a plurality of louvers 31 are cut and formed in the flat portion 12. The louver 31 of the flat portion 12 has a cut-and-raised angle θ2 smaller than the cut-and-raised angle θ1 of the louver 10 of the louver portion 11, and its height k is lower than the height j of the louver 10 of the louver portion 11. Is set (k <j), and is the same as the height h of the undulations 21 of the flat portion 12 of the second embodiment (k =
h). Although the inclination direction of the louver 31 of the flat portion 12 is set to be opposite to the inclination direction of the louver 10 of the louver portion 11, even if the louver 10 is inclined in the same direction as the louver 10 of the louver portion 11, heat exchange is not hindered. Will not give. Other configurations are the same as those of the second embodiment.

As described above, the louver 3 having the cut-and-raised angle θ2 smaller than the louver 10 of the louver portion 11 is formed on the flat portion 12.
By providing 1, the heat exchange efficiency in the flat portion 12 is increased as compared with the flat portion 12 without the louver 10 of the first embodiment, and the same effect as in the second embodiment is obtained.

(Fourth Embodiment) In the first to third embodiments, the front side and the rear side of the corrugated fin 3 are divided into the louver portion 11 and the flat portion 12, but in this case, the air flow is reduced. When the air flows from the louver portion 11 to the flat portion 12 or from the flat portion 12 to the louver portion 11, the air flow may be disturbed at the boundary and affect heat exchange. Therefore, in the corrugated fins 3 of the heat exchanger 1 of the present embodiment, as shown in FIG. 6, a plurality of louvers 41 are formed in one stage of the corrugated fins 3 so as to be cut and raised from the front side to the rear side so that the angles are sequentially increased. A first louver part 42,
At one stage of the corrugated fin 3, there is provided a second louver portion 44 formed such that a plurality of louvers 43 are cut and raised from the front side to the rear side and the angle is sequentially reduced. The first louver portion 42 and the second louver portion 44 are arranged so as to face each other with the air flow path 45 interposed therebetween by bending the corrugated fin 3.

Note that the maximum cut-and-raised angle θ3 and the minimum cut-and-raised angle θ4 of each of the louver portions 42 and 44 are the cut-and-raised angle θ of the louver 10 of the louver portion 11 of the third embodiment.
1 (θ3 = θ1) and the same angle as the cut-and-raised angle θ2 (θ4 = θ2) of the louver 31 of the flat portion 12 are set. That is, θ3 = θ1, θ4 = θ2, and
The minimum height 1 and the maximum height n of each of the louvers 41 and 43 of each of the louver sections 42 and 44 are also different from those of the louver section 11 of the third embodiment.
Of the louver 10 of the flat portion 12 and the louver 31 of the flat portion 12 (l = k, n = j). Other configurations are the same as in the first embodiment.

As described above, by making the first louver portion 42 and the second louver portion 44 face each other, an air flow path 45 having no boundary is formed from the front side to the rear side of the corrugated fin 3, and a predetermined interval is provided. Is communicated with. Moreover, the frost in the first louver portion 42 is smaller at the front side and gradually increases toward the rear side, and the second louver portion 44 has more frost on the front side and gradually decreases toward the rear side. The closing time of the air passage 45 is not extremely reduced. Therefore, the air flow smoothly flows from the front side to the rear side of the corrugated fin 3, and heat exchange is performed efficiently.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention. For example, in the first embodiment, one step of the corrugated fin 3 is divided into the louver part 11 and the flat part 12, but the louver part 11, the flat part 12, and the louver part 11 are divided into three parts or the louver part. Part 11, flat part 12, louver part 11, flat part 1
It may be divided into four, such as 2, or more, and arranged to face each other.

In the second embodiment, the heat exchange efficiency is increased by providing the zigzag undulations 21 on the flat portion 12.
Not only the undulations 21 but also other shapes such as irregularities or waveforms may be used.

[0035]

As is apparent from the above description, claim 1
According to the invention, since the louver portion and the flat portion face each other across the air flow path, the frosted portion and the non-frosted portion face each other, so that the frosted portion and the non-frosted portion are opposed to each other more than between the conventional corrugated fins. The gap becomes large, and the time until the clogging due to frost formation can be extended. Therefore,
Even if the flow rate of the fluid passing through the corrugated fins does not decrease extremely and the heat exchange efficiency in the flat part is low, the heat exchange efficiency as a heat exchanger does not drop sharply, so it is possible to prevent a drastic decrease in heating capacity An efficient heating operation can be performed for a long time, and a heat exchanger resistant to clogging can be provided.

In addition, since the corrugated fins are at the same intervals between the stages, that is, all the fluid flow paths are at the same intervals,
Even under the condition that the surface of the corrugated fin does not frost, the flow rate and the flow velocity of the fluid passing through the corrugated fin do not change, and the heat exchange efficiency does not decrease.

According to the second and third aspects of the present invention, the flat portion is provided with unevenness or a louver having a cut-and-raised angle smaller than that of the louver of the louver portion. Since the heat exchange efficiency can be improved and the amount of frost formed on the louver portion can be reduced, the time required for clogging due to frost formation is not extremely reduced.

According to the fourth aspect of the present invention, the first louver portion and the second louver portion in which the cut-and-raised angle of the louver is sequentially changed are opposed to each other, so that the fluid flow path is constant from the fluid upstream side to the downstream side. Is maintained, the turbulence of the fluid does not occur between the stages of the corrugated fin, and the heat exchange is performed efficiently.

[Brief description of the drawings]

1A and 1B show a part of a heat exchanger according to a first embodiment of the present invention, wherein FIG. 1A is a cross-sectional view, and FIG.

FIG. 2 is a cross-sectional view of a corrugated fin showing another embodiment of the louver.

FIG. 3 is a sectional view of a corrugated fin showing another embodiment of the louver.

FIG. 4 is a sectional view of a corrugated fin of the heat exchanger of the second embodiment.

FIG. 5 is a sectional view of a corrugated fin of the heat exchanger according to the third embodiment.

FIG. 6 is a cross-sectional view of a corrugated fin of a heat exchanger according to a fourth embodiment.

FIG. 7 is an overall perspective view of a parallel flow heat exchanger.

FIG. 8 is a partially enlarged perspective view of a conventional heat exchanger.

[Explanation of symbols]

 2 Flat tube 3 Corrugated fin 10, 31, 41, 43 Louver 11 Louver part 12 Flat part 13, 45 Air flow path 42 First louver part 44 Second louver part

Claims (4)

(57) [Claims] 1. A heat exchanger in which a plurality of parallel flat tubes through which a refrigerant flows and a corrugated fin for promoting heat exchange are alternately laminated, wherein a plurality of louvers are provided on the corrugated fin. A heat exchanger wherein a cut-and-raised louver portion and a flat portion not forming the louver are provided, and the louver portion and the flat portion are arranged to face each other across a fluid flow path. . 2. The heat exchanger according to claim 1, wherein irregularities are formed on the flat portion. 3. The heat exchanger according to claim 1, wherein a plurality of louvers whose cut-and-raise angles are smaller than those of the louvers of the louver portion are provided on the flat portion. 4. A heat exchanger in which a plurality of parallel flat tubes through which a refrigerant flows and a corrugated fin for promoting heat exchange are alternately stacked, wherein a plurality of louvers are provided on the corrugated fin. A first louver portion formed such that the cut-and-raised angle is gradually increased from the fluid upstream to the downstream, and a second louver portion formed such that a plurality of louvers are cut and raised from the fluid upstream to the downstream and the angle is sequentially reduced. Wherein the first louver portion and the second louver portion are arranged to face each other with the fluid flow path interposed therebetween.