JPH09310940A - Heat exchange device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the ice from being formed on the peripheral end of a rotation vane of a blower in a heat exchange device for use as an evaporator by providing a water droplet capturing part to capture water droplets flowing into the blower disposed downstream of air stream of a heat exchanger and removing the ice formed on the part using an ice removal means. SOLUTION: A heat exchanger 1 having a water repellent, treated surface in which low temperature refrigerant flows and over the outer side of which air 4 flows and a blower 2 driven by an electric motor 3 provided downstream of air flow of the exchanger 1 are disposed in a unit 5, and a water droplet capturing part 6 is provided around the blower 2 so as to cover the peripheral end of rotation vane of the blower 2. The part 6 is rotated by a motor 7 to scrape off the ice attached and formed on the part 6 by means of a brush. Thus icing on the peripheral end of the wane of the blower 2 can be greatly reduced and the ice formed on the part 6 can be continuously removed, and hence high heating capacity can be obtained for a long period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchange device including a heat exchanger having a heat transfer surface whose surface is subjected to a water repellent treatment, and the heat exchanger is used as an evaporator. .

[0002]

2. Description of the Related Art When a heat pump type air conditioner is operated for heating in winter, a heat exchanger of an outdoor unit that exchanges heat with outdoor air operates as an evaporator. At this time, frost is generated on the heat exchanger due to condensation and freezing of water vapor in the air.
This frost narrows the air flow path between the fins and increases the ventilation resistance to the air flow, so that the air flow rate gradually decreases and the heat transfer performance deteriorates. Therefore, conventionally, it has been necessary to periodically perform a defrosting operation that melts and removes frost.

On the other hand, as a method of suppressing this frost formation, it has been conventionally known that the development of frost formation can be delayed by subjecting the fin surface to a water repellent surface treatment that repels water. When the fin surface is made water repellent, the condensed water droplets become spherical on the fin surface and the degree of supercooling required for freezing increases, so that the time until freezing can be delayed. However, in the conventional water-repellent surface, the water droplets generated on the fin surface move on the fin surface by the air flow, stay at the air flow downstream end of the fin, and grow to bridge between the fins. Therefore, the ventilation resistance to the air flow increases, and the air flow rate gradually decreases. Further, since the water droplet diameter increases as the water droplets collect, the supercooled state cannot be maintained, and as a result, the water droplet freezes and the air flow path is clogged. Therefore, the frost resistance performance of the fin could not be significantly improved only by the water repellent surface treatment.

To solve this problem, the methods disclosed in Japanese Patent Laid-Open Nos. 4-177093, 63-3182, and 7-127991 are considered. In Japanese Patent Laid-Open No. 4-177093, it is possible to prevent water droplets from remaining at the downstream end of the air flow of the fin by making the downstream end of the fin air flow hydrophilic and making other parts of the fin water repellent. 3182
In the publication, the fin row on the air flow inflow side is subjected to a water-repellent treatment, and the fin row on the air flow outflow side is subjected to a hydrophilic surface treatment, and the fin pitch of the fin row on the air flow inflow side is made larger than that of the fin row on the air flow outflow side. As a result, it is possible to prevent the water droplets from remaining at the downstream end of the airflow of the fins and extend the time until the fins are clogged due to frost formation. In addition, JP-A-7-127
In the 991 publication, a water-drop collecting member having a hydrophilic treatment is installed on the downstream side of the air flow of the heat exchanger, and water drops collecting at the downstream end of the fin on the air flow are guided to the water drop collecting member to be removed. It is said that it is possible to prevent water droplets from remaining at the downstream end of the fins in the air flow, and to suppress a decrease in air flow.

On the other hand, according to observation, the condensed water droplets on the water-repellent surface developed by the inventors of the present invention are separated from the fin surface immediately after the water droplets are condensed and adhered to the fin surface, and immediately after the adjacent water droplets are coalesced, the air flow is then generated. It has been clarified that the water will be scattered to the downstream side. The water droplets that accumulate at the downstream end of the fin airflow also drop below the heat exchanger due to their own weight,
The amount of water drops remaining at the downstream end of the fins in the air flow is very small. Therefore, the above-mentioned problems are alleviated, and it is possible to obtain a heat exchange device capable of significantly suppressing the increase in ventilation resistance and frost formation due to the adhered water droplets and capable of supplying a high heating capacity for a long time.

However, in the unit structure in which the blower is arranged on the downstream side of the heat exchanger with respect to the air flow, supercooled water droplets scattered to the downstream side along with the air flow adhere to the blower and are frozen. FIG. 13 shows how ice accretes on the blades of the blower. The ice accretion 17 concentrates on the peripheral edge portion of the blade of the blower 2 and is formed into an ice column. This ice accretion gradually grows with the attachment of the water droplets, and when it reaches a certain size, it acts on the centrifugal force and comes into contact with members such as the compressor cover 11 around the blower 2,
It will be separated from the wing surface. The released ice collides with the heat exchanger 1 and the like in the unit 5 to damage the fins, or when the ice is not released uniformly from the blade surface, the rotation of the blower 2 becomes unbalanced and the blower is damaged. I was afraid.

Also for hydrophilic heat exchangers, water droplets may be scattered from the heat exchanger when used under conditions of high airflow velocity or when heating operation is restarted after defrosting operation. Regarding the processing method described in JP-A-4-334511 and JP-A-6-123588, the methods are considered.

In the method disclosed in Japanese Patent Laid-Open No. 4-334511, when a large amount of water droplets such as molten water after defrosting operation remains on the fins, the water droplets are scattered by the air flow when the heating operation is restarted. The purpose is to prevent the water from adhering to the blower, etc., and to install a filter on the suction side of the blower to capture water droplets scattered from the heat exchanger. The filter is a mesh formed of metal wires, resin, fibers, etc., and is provided with a heating means by an electric heater in case the water droplets captured by the filter freeze.

Further, in the method disclosed in Japanese Patent Laid-Open No. 6-123588, condensed water droplets are scattered to the downstream side of the air flow when used under conditions of high air flow velocity, so that a flat heat transfer tube and fins are used. A trap plate for trapping scattered water droplets is integrally formed at the end of the heat transfer tube of the heat exchanger that is downstream of the air flow. The water droplets flowing out of the heat exchanger will be scattered in the flow direction of the air flow, but since they are captured by the trap plate integrally formed with the heat transfer tube, it is possible to prevent the water droplets from scattering to the downstream side of the air stream. .

However, under the condition that the water droplets scattered from the heat exchanger are in a supercooled state, if the mesh-shaped member as described above is used as the water droplet capturing member, clogging due to icing occurs as the water droplets are captured. , The air flow rate gradually decreases and the heat transfer performance decreases. Further, on the water-repellent surface developed by the inventors, water droplets are constantly scattered during the heating operation. Therefore, it is necessary to frequently use a heating means such as an electric heater to prevent clogging of the water droplet capturing member. come.
Therefore, just installing the mesh-like member on the suction side of the blower as in the above-mentioned embodiment requires extra heating energy, which is an energy disadvantage. Also,
In the method of forming a part of the heat transfer tube into the trap plate, the trap plate is cooled by the heat conduction from the heat transfer tube, so the amount of frost at this location locally increases, and the air flow path is short-timed. It will be blocked within.

[0011]

In view of the above problems, the present invention provides a heat exchanger having a heat exchanger having a water-repellent surface and a blower, wherein the blower sucks and blows air. Prevents icing on the peripheral edge of the
It is to provide a heat exchange device that can obtain a high heating capacity for a long time.

[0012]

A heat exchange device according to the present invention is a fan in which a heat-repellent surface treatment is applied to a heat exchanger and a fan is installed around a rotary blade of a fan installed on a downstream side of an air flow of the heat exchanger. Is provided with a water droplet trapping portion for trapping water droplets flowing into the peripheral edge portion of the rotor blade, and the water droplet trapping portion is rotatable about the same center as the rotation center of the rotor blade. The solution is to install a removal device for the continuous removal of ice.

According to the present invention, the water-repellent surface treatment developed by the inventors is applied under the frosting condition in which the water vapor in the air stream condenses to form water droplets and then the condensed water droplets are frozen. By doing so, frost formation in the heat exchanger can be significantly delayed, and water droplets scattered from the heat exchanger and trying to flow into the blower are trapped by the water droplet trapping section arranged around the blower, and are further generated in the water droplet trapping section. Since the ice accretion is continuously removed from the water droplet catcher by the removing device, it is possible to achieve a heat exchanging device capable of obtaining a high heating capacity for a long time.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Each embodiment of the present invention will be described in detail below.

FIG. 1 is a top view of a heat exchange device according to an embodiment of the present invention, and FIG. 2 is a partial detailed view of the heat exchange device.
Inside the unit 5, a heat exchanger 1 having a water-repellent surface treatment in which a low-temperature refrigerant (not shown) flows inside and an air 4 flows outside, and an electric motor is provided downstream of the heat exchanger. The blower 2 driven by the motor 3 is installed. A water droplet trapping unit 6 is installed around the blower so as to cover the peripheral edge of the rotary blade of the blower, and a motor 7 for rotating the water droplet trapping unit 6 as shown in FIG. 2 and the water droplet trapping unit 6 are provided. The brush 8 which contacts is installed.

Water vapor in the air stream condenses to form water droplets,
Under the condition of being frozen thereafter, due to the water-repellent effect developed by the present inventors, some of the condensed water droplets are released into the airflow before freezing, and the water droplets attached to the heat exchanger 1 are minute. Therefore, the frost formation in the heat exchanger 1 can be significantly delayed. At this time, the separated water droplets are scattered along the air flow to the downstream side of the air flow and flow to the blower 2. However, the water droplet trapping unit 6 installed around the blower 2 causes the circumference of the rotating blades of the blower 2 to move. Water droplets in the air stream flowing into the ends are captured. Further, the water droplet catching unit 6 rotates at a low rotation speed, and the brush 8 in contact with the water droplet catching unit 6 scrapes off the icing that has adhered to the water droplet catching unit 6 and is frozen. Water droplets can be captured over time. Therefore, the ice accretion at the peripheral edge of the rotor blade of the blower 2 can be significantly reduced, the ice that separates from the rotor blade surface disappears, and the ice accretion on the water droplet trapping portion 6 is continuously removed, so that the ice accumulator can be removed for a long time. It is possible to achieve a heat exchange device that achieves a high heating capacity throughout.

As the member used for the water drop catching section 6,
A mesh-shaped member or a linear member made of metal, resin, fiber or the like is suitable, and it is desirable to coat the surface thereof with polytetraethylene or the like, which has a low adhesion to ice. Further, the mesh pitch or the line pitch of the water drop catching unit 6 is set to 1 in order to effectively catch the flying water drops.
Must be less than mm.

Regarding the installation position of the brush 8 for removing the ice accretion formed on the water drop catching portion 6, as shown in FIG. 3, the water drop is so arranged that the ice accreting on the water drop catching portion can be efficiently removed to the outside of the water drop catching portion. It may be installed between the capturing unit 6 and the blower 2.

The water drop catching unit 6 is driven by a small electric motor 7 or the like, but since the rotation speed may be several times per minute, the required power is small and the power consumption is small. In addition, heat exchanger 1
If the temperature of the air flow flowing out of the water is 0 ° C. or higher, the scattered water droplets will not freeze, so that it is not necessary to rotate the water droplet capturing unit 6.

As another method of rotating the water droplet catching section 6, there is a method of providing the blade 18 for rotating the water droplet catching section 6 by the air flow as shown in FIG. In this case, the electric motor required to rotate the water droplet catching unit 6 becomes unnecessary.

In the above embodiment, the water drop catching portion is provided so as to cover the peripheral edge of the rotary blade of the blower, but as shown in FIG. 5, the water drop catching portion is provided so as to cover the entire airflow inflow portion of the blower. May be.

FIG. 6 shows a heat exchange device according to another embodiment of the present invention. The difference from the previous embodiment is in the method of removing the ice removed by the brush. A water droplet catcher 6 is arranged around the blower 2, and the water droplet catcher 6 is rotated at a low speed by an electric motor 7. A brush 8 is installed so as to be in contact with the water droplet catcher, and a collector 1 provided with a heating means (not shown) below the brush.
There is 0.

The ice accretion generated in the water droplet catching section 6 is scraped off by a brush 8 installed so as to be in contact with the water droplet catching section 6, and collected in a collecting section 10. Since the collection unit 10 is provided with a heating means, the ice 13 accumulated on the collection unit 10
Is melted, and after melting, it becomes water and is discharged to a drain pan (not shown) at the bottom of the unit case.

As a heating means, as shown in FIG. 7, a part of a compressor cover 11 that covers the compressor 12 is molded into a collecting part 10 to utilize the exhaust heat from the compressor 12, or an electric heater. Alternatively, there is a method in which a refrigerant pipe through which a high-temperature refrigerant flows is arranged in the collection unit 10.

In the above-mentioned embodiment, the brush 8 for mechanically removing the icing adhering to the water droplet catching portion 6 is provided. However, as another method, as shown in FIG. A method of melting the ice accretion of the water droplet catching portion 6 passing through this location by providing the arc-shaped member 9 below the water droplet catching portion and providing the member 9 with a heating means is effective.
As the heating means, a method of forming the member 9 with a part of a compressor cover and utilizing exhaust heat from the compressor, or a method of installing an electric heater or a refrigerant pipe through which a high-temperature refrigerant flows in the member 9 There is. Further, it is effective to use a hydrophilic member for the water droplet catching portion 6 or perform a hydrophilic surface treatment so that the water droplets after melting do not remain on the water droplet catching portion 6.

FIG. 9 shows a heat exchange device according to another embodiment of the present invention. The difference from the above embodiment is that a member 15 is installed on the bottom of the heat exchanger 1 so that the bottom of the heat exchanger 1 is higher than the bottom 14 of the unit case, and the unit on the air flow outflow side of the heat exchanger 1 is provided. The heating means is provided on the bottom surface 14 of the case.

In the water-repellent heat exchanger 1 developed by the present inventors, a part of the water droplets in which the water vapor in the air stream is condensed is immediately released after being condensed and scattered to the downstream side of the air stream, but the remaining condensed water droplets are self-weighted. Falls to the bottom of the heat exchanger 1 and freezes there. In addition, when the heating operation is continuously performed for a long time, defrosting operation needs to be performed because frost is gradually generated in the heat exchanger, but when the defrosting operation is performed, the heat exchanger 1 is generated. The frost is dropped to the lower part of the heat exchanger 1 in a frosted state. Therefore, the unit case bottom surface 14 on the air flow downstream side of the heat exchanger 1
Frost accumulates with the passage of time, and since this frost is exposed to cold air during heating operation and is also thermally cut off from the heat exchanger 1, it does not melt during defrosting operation and is gradually higher. Grows in a layer of frost. This frost blocks the air flow passage at the bottom of the heat exchanger 1, so that heat exchange is not performed at this location, which causes a reduction in the amount of heat exchanged. In this embodiment, since the member 15 is installed at the bottom of the heat exchanger 1, it is possible to prevent the frost that has fallen and accumulated from coming into direct contact with cold air. Further, since the heating means is provided on the unit case bottom surface 14 on the air flow outflow side of the heat exchanger 1, it is possible to melt the accumulated frost even during the heating operation. After melting, it will be discharged as water to the drain pan 16 at the bottom of the unit case.
It is possible to suppress the accumulation of frost on the downstream side of the air flow.

As the heating means, the compressor cover 1
A method of using a part of No. 1 on the unit case bottom surface 14 on the air flow downstream side of the heat exchanger to utilize the exhaust heat from the compressor, or a method of installing an electric heater or a refrigerant pipe for flowing a high-temperature refrigerant is used. is there.

FIG. 10 shows the details of a heat exchange device showing another embodiment of the present invention. The difference from the above-mentioned embodiment is that the drain pan 16 is extended on the upstream side of the air flow of the heat exchanger 1 having a water repellent surface treatment.

Water-repellent heat exchanger 1 developed by the present inventors
Then, although the condensed water droplets are scattered from the heat transfer surface as described above, some of the water droplets are scattered and fall toward the upstream side of the airflow of the heat exchanger 1. Therefore, when the water-repellent heat exchanger 1 is incorporated in the conventional unit 5 that uses a hydrophilic heat exchanger, the air flow inflow side of the unit 5 becomes submerged. Therefore, as shown in this embodiment, a part of the drain pan 16 is extended to the upstream side of the air flow of the heat exchanger 1,
When the water droplets scattered or dropped upstream of the heat exchanger 1 are captured on the drain pan 16, the air inlet side of the unit 5 will not be flooded.

FIG. 11 shows a method of operating a heat exchange device according to another embodiment of the present invention. During the heating operation, the blower rotating at the rotation speed N ₀ has a rotation speed N ₁ (<N ₀ ) when the defrosting operation is started.
When it is decelerated to, the defrosting operation is terminated, and the heating operation is restarted, the motor rotates again at the rotation speed N ₀ .

When the heating operation is performed for a long time, frost forms on the heat exchanger. At this time, icing is also caused in the blower by the water droplets that have passed through the water droplet capturing portion and the water droplets that flow in from the portion not covered by the water droplet capturing portion. It is necessary to perform a defrosting operation to remove this frost and ice. In the defrosting operation, a method is usually adopted in which a high-temperature refrigerant from a compressor is caused to flow inside the heat exchanger to melt the frost formed on the heat exchanger. In the present embodiment, during the defrosting operation for removing frost on the heat exchanger, the blower is rotated at a low speed to remove icing on the blower at the same time. As described above, the frost formed on the water-repellent heat exchanger developed by the inventors is removed from the heat exchanger in the frost state during the defrosting operation. This means that in order to remove the frost on the heat exchanger, it is not necessary to apply the thermal energy required to melt all the frost. Therefore, during the defrosting operation, the blower is rotated at a low speed to create a flow of airflow, and part of the thermal energy is guided to the blower located downstream of the airflow, and the heat exchanger defrosts and the rotor blades of the blower. The icing on the surface can be removed.

As another method for operating the heat exchange device, as shown in FIG. 12, the blower is rotated at the number of revolutions N ₁ (<N ₀ ) from the start of the defrosting operation to the time t1, and thereafter There is a method in which the rotation speed is increased to N ₂ (> N ₁ , <N ₀ ), and when the defrosting operation is finished and the heating operation is restarted, the rotation speed is N ₀ . In this case, the ice formation adhering to the blower is partially melted during the time t1 from the start of the defrosting operation, and then the rotational speed of the blower is increased to centrifuge the partially melted ice formation. It can be removed from the rotor blade surface of the blower by the action of force. In setting the rotation speed N ₂ , it is effective to set the rotation speed near the critical speed of the blower in order to efficiently remove the icing from the rotor blade surface at a low rotation speed. Further, in order to reduce the adhesion between the rotor blades of the blower and the ice, it is also effective to apply a water-repellent treatment to the surface of the blower.

[0034]

As described in detail above, according to the present invention, under the frosting condition in which water vapor in an air stream condenses to form water droplets and then the condensed water droplets are frozen, By applying the developed water-repellent surface treatment, frost formation in the heat exchanger can be significantly delayed, and the water droplets scattered from the heat exchanger and trying to flow into the blower are collected by the water droplet trapping member placed around the blower. Since the ice accretion that is captured and further generated on the water droplet capturing member is continuously removed from the water droplet capturing member by the removing device, it is possible to achieve a heat exchange device that can obtain a high heating capacity for a long time.

[Brief description of drawings]

FIG. 1 is a top view of a heat exchange device according to an embodiment of the present invention.

FIG. 2 is a partial detailed view of a heat exchange device according to an embodiment of the present invention.

FIG. 3 is a partial detailed view of a heat exchange device according to an embodiment of the present invention.

FIG. 4 is a partial detailed view of a heat exchange device according to an embodiment of the present invention.

FIG. 5 is a partial detailed view of a heat exchange device according to an embodiment of the present invention.

FIG. 6 is a heat exchange device according to an embodiment of the present invention.

FIG. 7 is a heat exchange device according to an embodiment of the present invention.

FIG. 8 is a partial detailed view of a heat exchange device according to an embodiment of the present invention.

FIG. 9 is a heat exchange device according to an embodiment of the present invention.

FIG. 10 is a heat exchange device according to an embodiment of the present invention.

FIG. 11 is a method of operating a heat exchange device according to an embodiment of the present invention.

FIG. 12 is a method of operating a heat exchange device according to an embodiment of the present invention.

FIG. 13 is icing that occurs on a blade surface of a blower in a heat exchange device including a heat exchanger having a water-repellent surface.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heat exchanger, 2 ... Blower, 4 ... Air flow, 5 ... Unit, 6 ... Water droplet trapping part, 8 ... Brush, 10 ... Ice trapping part, 1
1 ... Compressor cover, 13 ... Ice, 14 ... Unit case bottom, 16 ... Drain pan.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Muroi 502 Jinritsu-cho, Tsuchiura-shi, Ibaraki Machinery Research Institute, Hiritsu Manufacturing Co., Ltd. (72) Yoshito Watanabe 502 Jinritsu-cho, Tsuchiura-shi, Ibaraki Nitate Manufacturing Mechanical Research Laboratory (72) Inventor Yasuhiro Yoshimura 502 Jinritsucho, Tsuchiura-shi, Ibaraki Hiritsu Manufacturing Co., Ltd.Mechanical Research Laboratory (72) Inventor Hiroshi Kogure 800 Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Prefecture Hitachi Co., Ltd. Tochigi Headquarters (72) Inventor Toshihiko Fukushima 502 Kintatecho, Tsuchiura-shi, Ibaraki Machinery Research Institute, Hitate Works, Ltd. (72) Inventor Toshio Hatada 502, Kintatemachi, Tsuchiura-shi, Ibaraki Machinery Research Center, Hitachi, Ltd.

Claims (1)

[Claims] 1. A heat exchanger having a water-repellent surface on the heat transfer surface on the air side, and a blower arranged downstream of the air flow of the heat exchanger,
In order to capture the water droplets flowing into the blower, a water droplet capturing section rotatably disposed at a center substantially the same as the center of rotation of the blower, and for continuously removing ice formed on the water droplet capturing section. A heat exchange device comprising an ice accretion removing means.