JPWO2020178977A1 - Heat exchanger, heat exchanger unit, and refrigeration cycle equipment - Google Patents

Abstract

It is an object of the present invention to obtain a heat exchanger, a heat exchanger unit, and a refrigeration cycle device in which water does not easily stay in the gaps between flat tubes and the drainage property is improved. The present invention comprises a first flat tube and a second flat tube in which the tube axes are arranged in parallel, the first flat tube having a first side surface facing the second flat tube, and the first The flat tube 2 has a second side surface facing the first flat tube. The first side surface of the first flat tube is arranged to face the second side surface of the second flat tube, and the hydrophilic region which is at least a part of the first side surface is larger than the second side surface. Highly hydrophilic.

Description

The present invention relates to a heat exchanger, a heat exchanger unit including a heat exchanger, and a refrigeration cycle device, and particularly to a structure of fins attached to a flat tube.

Conventionally, heat exchangers that circulate a refrigerant inside and evaporate or condense the refrigerant to exchange heat with a fluid such as air have been widely used in various fields such as air conditioners and refrigerators. It is a heat exchanger that is used in various applications such as cooling heat-generating equipment and heating working fluids, but in every field, improvement in heat exchange performance and compactness is always required, and both of these are compatible with heat exchange. It goes without saying that it has an advantage for the device itself on which the vessel is mounted.

Currently, there is a fin and tube heat exchanger as one of the typical heat exchangers. This fin-and-tube heat exchanger is manufactured by passing a plurality of tubes through a plurality of thin plate-shaped fins in a direction perpendicular to the fin surface, expanding these tubes, and attaching the fins to the tubes. The fin-and-tube heat exchanger is characterized by allowing a refrigerant to flow inside the pipe and exchanging heat with air using fins with a wide heat transfer area that are in close contact with the outer wall of the pipe as a heat transfer medium, resulting in heat exchange performance and compactness. Various quests have been made so far with the aim of improving the number of people. For example, improvements to fins such as thinning the fins to increase the number of fins or making slits on the fin surface to increase the heat transfer area, and making the inner wall of the pipe uneven to increase the heat transfer area as well. Improvements have been made to such pipes.

On the other hand, in order to pursue further improvement in heat exchange performance and compactness, it is difficult to expect a large effect only by accumulating partial improvements within the category of fin and tube heat exchangers. There is. Against this background, many studies have been conducted on new forms of heat exchangers that replace conventional fin-and-tube heat exchangers. Among them, finless heat exchangers, which are heat exchangers that increase the heat transfer area by densely arranging a large number of tubes and do not use fins that connect a large number of tubes, are attracting attention. The finless heat exchanger has various forms depending on the application, from a regular arrangement of circular tubes to a complicated one in which tubes having a cross section such as a rectangle, an ellipse, or a streamline are arranged irregularly. Things have been devised.

In the finless heat exchanger, in terms of heat exchange performance, there is a risk that the heat exchange performance will be significantly reduced due to the loss of the fins. For example, a fin-and-tube heat exchanger with a tube diameter of about 7 mm, a pitch between fins of about 1 mm, and an air velocity of air sent by a fan of about 1 m / s, such as an indoor heat exchanger of a household air conditioner. If you try to change to a finless heat exchanger that uses a flat tube without changing the heat exchanger size and fan input, the short axis of the cross section of the flat tube, which is the minor axis, is reduced to about 2 to 3 mm. Even if the arrangement pitch of the flat tubes is reduced, the heat transfer area is insufficient, and the heat exchange performance is significantly reduced.

Therefore, in Patent Document 1, in order to provide a heat exchanger for an air conditioner capable of improving heat exchange performance while ensuring compactness without causing an increase in pressure loss, fin and tube heat exchange is performed. The short diameter A of the pipe, which is the short axis of the cross section of the vessel, is formed in the range of 0.31 to 1.40 mm, and the short diameter A and the pitch B of each flat pipe are within a certain numerical range. It has been proposed to arrange each flat tube as described above.

Japanese Patent No. 3264525

However, in the fin-and-tube heat exchanger as shown in Patent Document 1, when it is operated as an evaporator, the condensed water generated by condensing the moisture in the air is generated between the adjacent fins. May stay across. When the pitch B of each flat tube of the finless heat exchanger is arranged at the same level as the fin pitch of the conventional fin-and-tube heat exchanger as shown in Patent Document 1, the finless heat exchanger will also be described above. The phenomenon that the condensed water is retained can occur. In such a finless heat exchanger, since the pitch B of each flat tube is small, heat transfer performance can be ensured, but dew condensation water straddles and stays between adjacent flat tubes. As a result, the finless heat exchanger has a problem that the heat transfer performance and the ventilation performance are impaired when the finless heat exchanger is operated as an evaporator.

The present invention is for solving the above-mentioned problems, and even in a finless heat exchanger in which the distance between flat tubes is narrow, water is less likely to stay in the gap between flat tubes, and heat with improved drainage is achieved. The purpose is to obtain a exchanger, a heat exchanger unit, and a refrigeration cycle device.

The heat exchanger according to the present invention includes a first flat tube and a second flat tube in which tube axes are arranged in parallel, and the first flat tube is a first flat tube facing the second flat tube. The second flat tube has a second side surface facing the first flat tube, and a hydrophilic region that is at least a part of the first side surface is the second side surface. More hydrophilic than.

The heat exchanger unit according to the present invention includes the above heat exchanger.

The refrigeration cycle apparatus according to the present invention includes the above heat exchanger unit.

According to the present invention, since the two opposite side surfaces of the first flat tube and the second flat tube are configured to have different hydrophilicity, when the condensed water straddles the two side surfaces. Move from the less hydrophilic side to the higher side. By moving the dew condensation water, it is possible to suppress the dew condensation water from staying between the two flat pipes, and the drainage property is improved. As a result, even in a heat exchanger in which the intervals between the flat tubes are narrow, deterioration of ventilation performance and heat transfer performance can be suppressed.

It is a perspective view which shows the heat exchanger unit which concerns on Embodiment 1. FIG. It is a front view which shows the heat exchanger which concerns on Embodiment 1. FIG. It is explanatory drawing of the refrigeration cycle apparatus 1 to which the heat exchanger according to Embodiment 1 is applied. It is explanatory drawing of the cross-sectional structure of the heat exchanger of FIG. It is a figure which shows the hydrophilicity property of the surface of the plurality of flat tubes of the heat exchanger of Embodiment 1. FIG. It is explanatory drawing in the case of water droplets adhering to the surface of the plurality of flat tubes of the heat exchanger of the first embodiment. It is a schematic diagram of the heat exchanger which is the comparative example of the heat exchanger of Embodiment 1. FIG. It is a schematic diagram of the heat exchanger which is the comparative example of the heat exchanger of Embodiment 1. FIG. It is a schematic diagram which shows the behavior of water of the outdoor heat exchanger of Embodiment 1. It is a schematic diagram which shows the behavior of water of the outdoor heat exchanger of Embodiment 1. It is a schematic diagram which shows the behavior of water of the outdoor heat exchanger of Embodiment 1. It is explanatory drawing in the case of water droplets adhering to the surface of the plurality of flat tubes of the heat exchanger of the first embodiment. It is explanatory drawing of the cross-sectional structure of the heat exchanger which is the modification of the heat exchanger which concerns on Embodiment 1. FIG. It is explanatory drawing of the cross-sectional structure of the heat exchanger which concerns on Embodiment 2. FIG. It is a figure which shows the hydrophilicity property of the surface of the plurality of flat tubes of the heat exchanger which concerns on Embodiment 2. FIG. It is a figure which shows the hydrophilicity property of the surface of the plurality of flat tubes of the heat exchanger which is the modification of the heat exchanger which concerns on Embodiment 2. FIG. It is a figure which shows the hydrophilicity property of the surface of the plurality of flat tubes of the heat exchanger which concerns on Embodiment 3. FIG. It is a figure which shows the hydrophilicity property of the surface of the plurality of flat tubes of the heat exchanger which concerns on Embodiment 4. FIG. It is a figure which shows the hydrophilicity property of the surface of the plurality of flat tubes of the heat exchanger according to the fifth embodiment. It is explanatory drawing of the cross-sectional structure of the heat exchanger which concerns on Embodiment 6. It is explanatory drawing of the cross-sectional structure of the heat exchanger which is the modification of the heat exchanger which concerns on Embodiment 6.

Hereinafter, embodiments of a heat exchanger, a heat exchanger unit, and a refrigeration cycle device will be described. The form of the drawings is an example, and does not limit the present invention. In addition, those having the same reference numerals in the respective figures are the same or equivalent thereof, which are common to the entire text of the specification. Further, in the drawings below, the relationship between the sizes of the constituent members may differ from the actual one.

Embodiment 1.
FIG. 1 is a perspective view showing a heat exchanger unit 101 according to the first embodiment. FIG. 2 is a front view showing the heat exchanger 100 according to the first embodiment. FIG. 3 is an explanatory view of the refrigeration cycle apparatus 1 to which the heat exchanger 100 according to the first embodiment is applied. The heat exchanger unit 101 shown in FIG. 1 is an example, and here corresponds to the outdoor unit 8 of the air conditioner. Further, the heat exchanger 100 shown in FIG. 2 is mounted inside the heat exchanger unit 101 of FIG. 1, and schematically represents a structure viewed from the front. The heat exchanger 100 is mounted on a refrigerating cycle device 1 such as an air conditioner or a refrigerator, and can be used as an outdoor heat exchanger 5 or an indoor heat exchanger 7 in the refrigerating cycle device 1. As shown in FIG. 3, in the refrigeration cycle device 1, the compressor 3, the four-way valve 4, the outdoor heat exchanger 5, the expansion device 6, and the indoor heat exchanger 7 are connected by a refrigerant pipe 90 to form a refrigerant circuit. It was done. For example, when the refrigeration cycle device 1 is an air conditioner, the refrigerant flows in the refrigerant pipe 90, and the flow of the refrigerant is switched by the four-way valve 4 to perform a heating operation, a refrigeration operation, or a defrosting operation. Can be switched.

The outdoor heat exchanger 5 mounted on the outdoor unit 8 and the indoor heat exchanger 7 mounted on the indoor unit 9 are provided with a blower 2 in the vicinity. In the outdoor unit 8, the blower 2 sends outside air to the outdoor heat exchanger 5. The outdoor heat exchanger 5 exchanges heat between the outside air and the refrigerant. Further, in the indoor unit 9, the blower 2 sends indoor air to the indoor heat exchanger 7. The indoor heat exchanger 7 exchanges heat between the indoor air and the refrigerant to harmonize the temperature of the indoor air. Further, the heat exchanger 100 according to the first embodiment can be used as the outdoor heat exchanger 5 mounted on the outdoor unit 8 and the indoor heat exchanger 7 mounted on the indoor unit 9 in the refrigeration cycle device 1. Functions as a condenser or evaporator. Equipment such as the outdoor unit 8 and the indoor unit 9 on which the heat exchanger 100 is mounted is particularly referred to as a heat exchanger unit 101. The heat exchanger unit 101 shown in FIG. 1 is an example of an outdoor unit 8 on which the heat exchanger 100 is mounted. The arrow shown in FIG. 1 indicates the flow direction of the air flow. The heat exchanger unit 101 takes in the outside air from the back surface into the housing, exchanges heat between the outside air and the refrigerant with the heat exchanger 100, and blows out the heat-exchanged air from the front surface.

The heat exchanger 100 shown in FIG. 2 includes a plurality of flat tubes 20. The plurality of flat tubes 20 are arranged in parallel in the X direction, and one of the plurality of flat tubes 20 adjacent to each other is referred to as a first flat tube 20a and the other is referred to as a second flat tube 20b. The plurality of flat tubes 20 have their respective tube axes arranged along the Z direction, and are arranged in parallel along the X direction. In the first embodiment, the opposite directions in the Z direction coincide with the direction of gravity, but the heat exchanger 100 may be arranged so that the Z axis is inclined in the direction of gravity.

The plurality of flat tubes 20 are connected to the lower end header 80 at the lower end in the Z direction and are connected to the upper end header 81 at the upper end in the Z direction. The lower end header 80 and the upper end header 81 are connected to the refrigerant pipe 90 of the refrigerating cycle device 1, and the refrigerant flowing through the refrigerant circuit flows into one of the lower end header 80 and the upper end header 81 to form a plurality of flat pipes 20. It passes through and flows out from the other side to the refrigerant pipe 90. The plurality of flat tubes 20 are so-called finless heat exchangers in which fins connecting between the plurality of flat tubes 20 are not provided other than the lower end header 80 and the upper end header 81. Furthermore, the plurality of adjacent flat tubes 20 are not provided with a member that connects between the first side surface 25a and the second side surface 25b that face each other.

FIG. 4 is an explanatory view of the cross-sectional structure of the heat exchanger 100 of FIG. FIG. 4 shows a cross section perpendicular to the pipe axis of the plurality of flat pipes 20, and is an explanatory view of the structure of the cross section corresponding to the AA cross section of FIG. In FIG. 4, a part of the plurality of flat tubes 20 is shown. The plurality of flat tubes 20 are formed in a flat shape having a long axis and a short axis in a cross-sectional shape perpendicular to the tube axis. The plurality of flat tubes 20 are arranged so that the long axis faces the Y direction and the short axis faces the X direction. That is, the Y direction is the major axis direction of the flat tube 20, and the X direction is the minor axis direction of the flat tube 20. The flow direction of the airflow passing through the heat exchanger 100 is substantially the same as the Y direction. Further, the plurality of flat pipes 20 have a first end portion 21 which is an end portion located on the windward side in the flow direction of the air flow and a second end portion 22 which is an end portion located on the leeward side.

The plurality of flat tubes 20 include a first flat tube 20a and a second flat tube 20b arranged adjacent to the first flat tube 20a. Here, in the first flat tube 20a, the side surface facing the X direction is referred to as the first side surface 25a, and the side surface facing the opposite direction in the X direction is referred to as the second side surface 25b. Further, in the second flat tube 20b, the side surface facing the X direction is referred to as the first side surface 25a, and the side surface facing the opposite direction in the X direction is referred to as the second side surface 25b. That is, the first flat tube 20a and the second flat tube 20b have a first side surface 25a which is a side surface along the major axis direction and a second side surface 25b which is located on the opposite side of the first side surface 25a. Has. The first flat tube 20a and the second flat tube 20b have a first side surface 25a which is a side surface facing the minor axis direction and a second side surface 25b which is located on the opposite side of the first side surface 25a. .. The first flat tube 20a and the second flat tube 20b are arranged adjacent to each other, and the first side surface 25a and the second side surface 25b are arranged so as to face each other. The plurality of flat tubes 20 may be composed of only two types of the first flat tube 20a and the second flat tube 20b, or may include other flat tubes having different configurations.

Each of the plurality of flat tubes 20 is made of a metal material having thermal conductivity. As a material constituting each of the plurality of flat tubes 20, for example, aluminum, an aluminum alloy, copper, or a copper alloy is used. Each of the plurality of flat tubes 20 is manufactured by extruding a heated material from a hole in a die to form a plurality of refrigerant flow paths 24 shown in FIG. Each of the plurality of flat tubes 20 may be manufactured by a drawing process in which a material is pulled out from a hole in a die to form a cross section shown in FIG. Each manufacturing method of the plurality of flat tubes 20 can be appropriately selected according to the cross-sectional shape.

FIG. 5 is a diagram showing the hydrophilicity of the surface of the plurality of flat tubes 20 of the heat exchanger 100 of the first embodiment. FIG. 5 shows the same cross section as that of FIG. 4, and schematically represents regions having different hydrophilicity on the surfaces of the plurality of flat tubes 20 in different patterns. The plurality of flat tubes 20 are configured by arranging the first flat tube 20a and the second flat tube 20b side by side. The first flat tube 20a and the second flat tube 20b differ in the hydrophilicity of the two side surfaces along the major axis direction. In FIG. 5, the first side surface 25a has high hydrophilicity, and the second side surface 25b has low hydrophilicity. In the first embodiment, the first flat tube 20a and the second flat tube 20b have the same hydrophilicity as the first side surface 25a and the second side surface 25b, respectively. It is not limited to this. The first side surface 25a and the second side surface 25b may have regions having different hydrophilicity. However, the first side surface 25a and the second side surface 25b are configured so that the hydrophilicity of the facing surfaces is different at least in a part.

FIG. 6 is an explanatory view when water droplets adhere to the surfaces of the plurality of flat tubes 20 of the heat exchanger 100 of the first embodiment. FIG. 6 shows an example of the state of water droplets adhering to the first side surface 25a or the second side surface 25b of the plurality of flat tubes 20. When water droplets such as condensed water adhere to the surfaces of the plurality of flat tubes 20, the shape of the water droplets changes depending on the degree of hydrophilicity of the surfaces. The contact angle θ is generally used as an index showing the affinity between the surface of an object and water. The contact angle θ is the angle formed by the water droplets dropped on the surface of the object and the surface. When the surface of the object is highly hydrophilic, the contact angle θ is small, and when the surface of the object is low in hydrophilicity, the contact angle θ is large. When the hydrophilicity is high, the water droplets tend to spread thinly on the surfaces of the plurality of flat tubes 20, and when the hydrophilicity is low, the water droplets are rounded due to surface tension. When the hydrophilicity is low, it is also called high water repellency. Generally, the contact angle θ is used as an index showing the affinity between the surface of a solid and water. The contact angle θ is defined as the angle formed by the contact surface between the surface of the solid and the water droplet when the water droplet is dropped on the surface of the solid.

When water is dropped on the surface of the member, the water is rounded by its own surface tension γw. When the surface tension of the solid is γs and the interfacial tension between the surface of the solid and the surface of water is γsw, the relationship of γs = γw · cosθ + γsw is established between the water dropped on the surface of the solid and the surface. That is, the surface tension γs of the solid is balanced with the surface direction component of the solid of the surface tension γw of water and the resultant force of the interfacial tension γsw between the surface of the solid and water, and at this time, the angle formed by the surface of water and the solid surface is in contact with each other. The angle θ.

FIG. 7 is a schematic view of the heat exchanger 1100, which is a comparative example of the heat exchanger 100 of the first embodiment. FIG. 7 shows a part of the heat exchanger 1100, and schematically shows a state in which water droplets are attached to the first side surface 1025a and the second side surface 1025b of the plurality of flat tubes 1020. The plurality of flat tubes 1020 are configured by arranging the first flat tube 1020a and the second flat tube 1020b side by side. The plurality of flat tubes 1020 of the heat exchanger 1100, which is a comparative example, have the same hydrophilicity as the first side surface 1025a and the second side surface 1025b, and are in a state of high water repellency. That is, the surfaces of the plurality of flat tubes 1020 have a large contact angle θ, and in particular, the contact angle θ ≧ 90 °. Further, in the heat exchanger 1100 of the comparative example, the relationship between the contact angle θ1 of the first side surface 1025a and the contact angle θ2 of the second side surface 1025b is θ1 = θ2.

When water adheres to the surfaces of a plurality of flat tubes 1020 having low hydrophilicity, that is, high water repellency, such as the heat exchanger 1100 of the comparative example, water droplets are formed on either the first side surface 1025a or the second side surface 1025b. It is easy to stay as. Further, especially when the water droplets adhering to both side surfaces 1025a and 1025b come into contact with each other, the same force acts on the water droplets from the side surfaces 1025a and 1025b of the two opposing flat tubes, so that the water droplets act on either side surface 1025a and 1025b. There is no bias. Here, when there is not enough water to overcome the force received from the surfaces of both side surfaces 1025a and 1025b, the water is bridged between the first side surface 1025a and the second side surface 1025b. There is a problem that water is easily retained because it is retained without flowing down. The retention of water between the plurality of flat tubes 1020 increases resistance to the flow of air passing between the plurality of flat tubes 20. Then, the load of the blower 2 is increased, and the flow rate of air passing through the heat exchanger 1100 is reduced. Further, the water droplets in the gaps between the plurality of flat tubes 1020 become thermal resistance for heat transfer between the air flowing through the gaps and the refrigerant flowing in the plurality of flat tubes 1020, and the heat exchange efficiency is lowered.

FIG. 8 is a schematic view of the heat exchanger 2100, which is a comparative example of the heat exchanger 100 of the first embodiment. FIG. 8 shows a part of the heat exchanger 2100, and schematically shows a state in which water droplets are attached to the first side surface 2025a and the second side surface 2025b of the plurality of flat tubes 2020. The plurality of flat tubes 2020 are configured by arranging the first flat tube 2020a and the second flat tube 2020b side by side. The plurality of flat tubes 2020 of the heat exchanger 2100, which is a comparative example, have the same hydrophilicity as the first side surface 2025a and the second side surface 2025b, and are in a highly hydrophilic state. That is, the surfaces of the plurality of flat tubes 2020 have a small contact angle θ, and in particular, the contact angle θ <90 °. Further, in the heat exchanger 1100 of the comparative example, the relationship between the contact angle θ1 of the first side surface 2025a and the contact angle θ2 of the second side surface 2025b is θ1 = θ2.

When water adheres to the surfaces of a plurality of flat tubes 2020 in a highly hydrophilic state, the water tends to form a film on the surface and stay there. The water adhering to the first side surface 2025a or the second side surface 2025b spreads thinner than the water droplets staying on the highly water-repellent side surfaces 1025a and 1025b, so that the gaps between the plurality of flat tubes 2020 are not bridged. The ventilation resistance passing through the heat exchanger 2100 is unlikely to increase. However, water adheres so as to partially cover the surface of the first side surface 2025a or the second side surface 2025b, and is heat resistant to heat transfer between the air flowing through the gap and the refrigerant flowing in the plurality of flat pipes 2020. Therefore, the heat exchange efficiency is reduced.

The heat exchangers 1100 and 2100 according to the comparative example need to be operated with frost formation and defrosting when used under conditions where the outside air temperature is low. When operating in a state where the heat exchangers 1100 and 2100 are frosted, the water adhering to the plurality of flat tubes 1020 and 2020 freezes. Therefore, when defrosting the heat exchangers 1100 and 2100, it is necessary to melt the frozen water, and the amount of heat input to the heat exchangers 1100 and 2100 during the defrosting operation increases, so that the time for defrosting is increased. It will increase. The air conditioner during the defrosting operation generally stops the heating operation. Therefore, since the heat exchangers 1100 and 2100 according to the comparative example are frequently defrosted, there are problems that the comfort in the room is lowered and the operating efficiency of the refrigeration cycle device 1 is lowered when heating the room. ..

In the heat exchanger 100 according to the first embodiment, the relationship of θ1 <θ2 is satisfied when at least the contact angle of the first side surface 25a is θ1 and the contact angle of the second side surface 25b is θ2. That is, it can be said that the first side surface 25a having a surface having a small contact angle θ1 is more hydrophilic than the second side surface 25b. Further, it can be said that the second side surface 25b having a surface having a large contact angle θ2 has higher water repellency than the first side surface 25a.

9 to 11 are schematic views showing the behavior of water in the outdoor heat exchanger 10 of the first embodiment. 9 to 11 show views seen from the upstream side of the airflow passing through the heat exchanger 100. In the heat exchanger 100 of the first embodiment, the contact angle θ1 of the first side surface 25a and the contact angle θ2 of the second side surface 25b satisfy the relationship of θ1 <θ2. As shown in FIGS. 9 to 11, when the contact angles θ of the side surfaces 25a and 25b forming the gaps of the plurality of flat tubes 20 are different, the water droplets 70a and 70b adhering to the two surfaces forming the gaps come into contact with each other. Then, the water droplet 70b staying on the second side surface 25b having high water repellency easily moves to the side of the first side surface 25a having high hydrophilicity. Therefore, the amount of water adhering to the first side surface 25a increases, and the downward force applied to the water droplet 70 due to the gravity G also increases. If the water is completely transferred from the second side surface 25b to the first side surface 25a, the weight is further increased.

On the other hand, as shown in FIG. 7, in the heat exchanger 1100 of the comparative example, the water droplets 1070 are attached to both of the two side surfaces 1025a and 1025b forming the gap, and therefore, from the two side surfaces 1025a and 1025b. It receives the interfacial tension γsw between solid and water, the surface tension γs of solid, and the surface tension γw of water. Here, when the gravity G applied to the water droplet 1070 exceeds the resultant force of the forces received from the side surfaces 1025a and 1025b, the water falls. However, in the heat exchanger 100 according to the first embodiment and the heat exchangers 1100 and 2100 according to the comparative example, the first flat tubes 20a, 1020a, 2020a and the second flat tubes 20b, 1020b, 2020b The interval is narrow. Therefore, the downward force applied to the water droplets 70, 1070, and 2070 by the gravity G is small. Therefore, when the force received by the water droplets 70, 1070, 2070 from the first flat pipes 20a, 1020a, 2020a and the second flat pipes 20b, 1020b, 2020b is strong, the water droplets 70, 1070, 2070 are flattened. It tends to stay between the tubes 20, 1020, and 2020. Therefore, in the heat exchanger 1100 of the comparative example shown in FIG. 7, the water droplet 1070 receives a force from both of the two side surfaces 1025a and 1025b forming the gap, and therefore tends to stay in the gap.

In the heat exchanger 100 according to the first embodiment, as shown in FIG. 11, the upward force applied to the water droplet 70 acts only from the first side surface 25a having high hydrophilicity. Therefore, the amount of water droplets 70 staying between the plurality of flat tubes 20 of the heat exchanger 100 is smaller than that of the heat exchanger 1100 of the comparative example shown in FIG. Further, in the heat exchanger 100 according to the first embodiment, the amount of water droplets 70b on the second side surface 25b moves to the first side surface 25a and adheres to the highly hydrophilic first side surface 25a. Will increase. Therefore, the downward force applied to the water droplet 70 becomes stronger, and it is easier to move downward than the water droplet 2070 existing in the gap between the plurality of flat tubes 2020 of the heat exchanger 2100 of the comparative example. Therefore, the amount of water droplets 70 staying between the plurality of flat tubes 20 of the heat exchanger 100 is smaller than that of the heat exchanger 2100 of the comparative example shown in FIG.

As described above, the heat exchanger 100 according to the first embodiment includes a first flat tube 20a and a second flat tube 20b in which the tube axes are oriented in the vertical direction and arranged in parallel. The first flat tube 20a and the second flat tube 20b are located on opposite sides of the first side surface 25a, which is a side surface along the long axis direction in the cross section perpendicular to the tube axis, and the first side surface 25a. The second side surface 25b and the like are provided. The first side surface 25a of the first flat tube 20a is arranged so as to face the second side surface 25b of the second flat tube 20b. The hydrophilic region, which is at least a part of the first side surface 25a, is more hydrophilic than the second side surface 25b. With this configuration, water droplets 70 such as dew condensation water in the gaps between the plurality of flat tubes 20 can easily move from the second side surface 25b to the facing first side surface 25a, and the plurality of flat tubes 20 can easily move. The amount of water that stays in between is reduced. Therefore, the heat exchanger 100 according to the first embodiment has improved drainage property, reduced ventilation resistance and thermal resistance between air and the refrigerant, and thus removed, as compared with the heat exchangers 1100 and 2100 of the comparative example. The frost operation time can be reduced. Specifically, the contact angle θ1 of the hydrophilic region of the first side surface 25a is smaller than the contact angle θ2 of the region of the second side surface 25b facing the hydrophilic region.

Desirably, the contact angle θ1 of the hydrophilic region of the first side surface 25a is lower than 90 °, and the contact angle θ2 of the region of the second side surface 25b facing the hydrophilic region is 90 ° or more. This is because one surface of the facing surface has low hydrophilicity, that is, the water repellency is increased, so that the water droplet 70b of the second side surface 25b can easily move to the first side surface 25a having higher hydrophilicity.

FIG. 12 is an explanatory view when water droplets adhere to the surfaces of the plurality of flat tubes 20 of the heat exchanger 100 of the first embodiment. In FIG. 12, the surfaces of the plurality of flat tubes 20 are in an inclined state. When the water droplets on the surface of an object are gradually tilted from a horizontal state, the tilt angle α when the water droplets start to slide down is called the fall angle. It can be said that the surface of an object having a small fall angle has weak adhesion to water droplets, and the water droplets can be easily removed from the surface of the object. Therefore, on the surface of an object to which the same amount of water is attached, the smaller the fall angle, the higher the water detachability. Therefore, in the first embodiment, the second side surface 25b may be configured so that the fall angle is smaller than that of the hydrophilic region of the first side surface 25a. In other words, the fall angle of the hydrophilic region of the first side surface 25a may be larger than the fall angle of the region of the second side surface 25b facing the hydrophilic region. This makes it easier for water to concentrate from the second side surface 25b, which has high water releasability, to the first side surface 25a, which has relatively low water releasability. When water is concentrated on the first side surface 25a, the water spreads on the first side surface 25a, and the water adhering to the plurality of flat pipes 20 easily flows down due to the weight of the water itself. As a result, the heat exchanger 100 according to the first embodiment can further reduce the amount of water staying between the plurality of flat tubes 20.

FIG. 13 is an explanatory view of a cross-sectional structure of the heat exchanger 100A, which is a modification of the heat exchanger 100 according to the first embodiment. As shown in FIG. 13, the cross-sectional shape of the plurality of flat pipes 120 is a shape that is bent at the center in a cross section perpendicular to the pipe axis, and the two portions extending in a straight line are formed at a predetermined angle. It has a shape that is held and connected. That is, the plurality of flat pipes 120 do not have a shape extending linearly in the long axis direction in a cross section perpendicular to the pipe axis, but have a shape bent on the way from one end 21 to the other end 22. There is. In the plurality of flat tubes 120, the major axis direction means a direction in which a straight line connecting the end portion 21 and the end portion 22 extends. The plurality of flat tubes 120 are not limited to the form shown in FIG. For example, the shape may be such that a plurality of points are bent in the middle of the plurality of flat tubes 120, and the bending angle can be appropriately set.

Embodiment 2.
The heat exchanger 200 according to the second embodiment is a modification of the structure of a plurality of flat tubes 20 with respect to the heat exchanger 100 according to the first embodiment. In the second embodiment, the changes to the first embodiment will be mainly described.

FIG. 14 is an explanatory view of a cross-sectional structure of the heat exchanger 200 according to the second embodiment. FIG. 14 shows a cross section perpendicular to the tube axis of the plurality of flat tubes 20. Each of the plurality of flat pipes 20 extends in the Y direction from the refrigerant flow section 50 provided with a plurality of refrigerant flow paths 24 through which the refrigerant flows, and the end portion 21 of the refrigerant flow section 50 in the long axis direction. The fin portion 51 provided is provided. The fin portion 51 is a plate-shaped portion that protrudes from the end portion 21 in the Y direction and is installed along the pipe axes of the plurality of flat pipes 20. In the second embodiment, the fin portion 51 extends parallel to the major axis direction of the refrigerant flow section 50, that is, the Y direction, but the fin portion 51 is not limited to this embodiment. For example, the fin portion 51 may extend from the end portion 21 at a predetermined angle with respect to the Y direction.

FIG. 15 is a diagram showing the hydrophilicity of the surface of the plurality of flat tubes 20 of the heat exchanger 200 according to the second embodiment. The first flat tube 20a and the second flat tube 20b constituting the plurality of flat tubes 20 include a first side surface 25a and a second side surface 25b, respectively. The first side surface 25a of the first flat tube 20a and the second side surface 25b of the second flat tube 20b do not have the same hydrophilicity in the entire area. In the first side surface 25a, the entire surface of the refrigerant flow portion 50 and the surface of the fin portion 51 is a region having high hydrophilicity. The second side surface 25b is configured such that the surface of the refrigerant flow portion 50 is less hydrophilic than the first side surface 25a, and the fin portion 51 is a region having high hydrophilicity like the first side surface 25a. It has become. With this configuration, it is possible to suppress the retention of water droplets in the gaps between the refrigerant flow portions 50 of the plurality of flat pipes 20 having a narrow interval.

In the heat exchanger 200, since the gap between the portions where the fin portions 51 face each other is relatively wide, the fin portions 51 may have a great influence on the ventilation resistance regardless of whether the hydrophilicity is high or low. No. However, as shown in FIG. 15, by making the fin portion 51 a highly hydrophilic region, water droplets move from the fin portion 51 located on the windward side to the refrigerant flow portion 50 having low hydrophilicity located on the leeward side. It becomes difficult to do. Therefore, it is possible to prevent water droplets from staying in the gaps between the refrigerant flow portions 50 having a narrow interval.

FIG. 16 is a diagram showing the hydrophilicity of the surfaces of the plurality of flat tubes 20 of the heat exchanger 200a, which is a modification of the heat exchanger 200 according to the second embodiment. As shown in FIG. 16, the fin portions 51 of the plurality of flat tubes 20 also have high hydrophilicity on the first side surface 25a and low hydrophilicity on the second side surface 25b, similarly to the refrigerant flow section 50. Is also good. With this configuration, the plurality of flat tubes 20 of the heat exchanger 200 are the same as those in the first embodiment when the difference in thickness between the refrigerant flow section 50 and the fin section 51 is small or the same thickness. It is possible to suppress the retention of water droplets.

Embodiment 3.
The heat exchanger 300 according to the third embodiment is a modification of the structure of the plurality of flat tubes 20 with respect to the heat exchanger 100 according to the first embodiment. In the third embodiment, the changes to the first embodiment will be mainly described.

FIG. 17 is a diagram showing the hydrophilicity of the surface of the plurality of flat tubes 20 of the heat exchanger 300 according to the third embodiment. The plurality of flat tubes 20 of the heat exchanger 200b are formed by joining the refrigerant flow section 50 and the fin section 51 manufactured as separate members. The plate-shaped member 60 forming the fin portion 51 is formed by bending, for example, a metal plate material, and is joined to the end portion 21 of the refrigerant flow portion 50 with a joining means such as brazing. The hydrophilicity of the entire surface of the plate-shaped member 60 forming the fin portion 51 is lower than that of the surface of the refrigerant flow portion 50. With this configuration, of the second side surfaces 25b of the plurality of flat tubes 20, only the region F in which the plate-shaped member 60 and the refrigerant flow portion 50 face each other faces the different hydrophilic surfaces. There is. Therefore, the gaps formed by the region F and the plate-shaped member 60 have different hydrophilic surfaces facing each other, and the retention of water droplets is suppressed as in the gaps of the plurality of flat tubes 20 of the first embodiment. Can be done.

In the third embodiment, the plurality of flat tubes 20 have different hydrophilic surfaces facing each other only in a part of the first side surface 25a and the second side surface 25b. However, when the heat exchanger 300 is used as an evaporator, it is possible to suppress the retention of water droplets on the wind side where dew condensation is most likely to occur, which is advantageous over the heat exchangers 1100 and 2100 of the comparative example. Further, even when the region F is arranged on the leeward side, water droplets that have moved to the leeward side due to the air flow are easily discharged in the region F, which is advantageous over the heat exchangers 1100 and 2100 of the comparative example. ..

In the third embodiment, the refrigerant flow unit 50 is a region having low hydrophilicity as a whole, but is different between the first side surface 25a side and the second side surface 25b side as in the first embodiment. It may be configured to be hydrophilic. However, like the plurality of flat tubes 20 of the heat exchanger 300 according to the third embodiment, the entire surface of the refrigerant flow portion 50 is a low hydrophilic surface, and the entire surface of the fin portion 51 is a highly hydrophilic surface. This has the advantage that the plate-shaped member 60 forming the refrigerant flow section 50 and the fin section 51 can be easily manufactured.

Embodiment 4.
The heat exchanger 400 according to the fourth embodiment is a modification of the structure of the plurality of flat tubes 20 with respect to the heat exchanger 100 according to the first embodiment. In the fourth embodiment, the changes to the first embodiment will be mainly described.

FIG. 18 is a diagram showing the hydrophilicity of the surface of the plurality of flat tubes 20 of the heat exchanger 400 according to the fourth embodiment. The plurality of flat tubes 20 of the heat exchanger 400 include a refrigerant flow section 50 provided with a plurality of refrigerant flow paths 24 through which the refrigerant flows, and a long axis end portion 21 of the refrigerant flow section 50 in the Y direction. A fin portion 51 extending toward the end and a fin portion 52 extending in the opposite direction in the Y direction from the end portion 22 are provided. The fin portion 52 is a plate-shaped portion that protrudes from the end portion 22 in the opposite direction in the Y direction and is installed along the pipe axes of the plurality of flat pipes 20.

The plurality of flat tubes 20 of the heat exchanger 400 are configured by joining the refrigerant flow section 50 manufactured as a separate member and the plate-shaped member 460. The plate-shaped member 460 forming the fin portion 51 and the fin portion 52 is formed by bending a metal plate material, for example, and is attached so as to cover one side surface of the refrigerant flow portion 50 to provide a joining means such as brazing. It is joined to the refrigerant flow unit 50. The hydrophilicity of the entire surface of the plate-shaped member 460 forming the fin portion 51 and the fin portion 52 is lower than that of the surface of the refrigerant flow portion 50. On the other hand, the hydrophilicity of the entire surface of the refrigerant flow section 50 is higher than that of the surface of the plate-shaped member 460. Desirably, the surface of the plate-shaped member 460 has a contact angle of θ1 <90 °, and the surface of the refrigerant flow section 50 has a contact angle of θ2 ≧ 90 °. The plate-shaped member 460 and the refrigerant flow section 50 have an advantage that they can be easily manufactured because their respective surfaces are configured to have the same hydrophilicity.

In the heat exchanger 400, the first flat tube 20a and the second flat tube 20b have at least one refrigerant flow section 50 having a refrigerant flow path 24 for passing a refrigerant inside, and an end 21 of the refrigerant flow section 50. , 22 and two fin portions 51 and 52 extending in the major axis direction. Therefore, since the fin portion 51 and the fin portion 52 extend from both ends of the refrigerant flow portion 50, the contact area with the air passing between the plurality of flat pipes 20 increases, and the heat exchange efficiency becomes high. .. Then, the plate-shaped member 460 forming the fin portions 51 and 52 forms the first side surface 25a of the first flat tube 20a, and forms a part of the second side surface 25b of the second flat tube 20b. It faces the distribution unit 50. With this configuration, in the heat exchanger 400, the first side surface 25a having high hydrophilicity and the second side surface 25b having low hydrophilicity are arranged so as to face each other, and the refrigerant flow section 50 having the narrowest interval is arranged. In the gap between the two, the retention of water droplets can be suppressed as in the first embodiment.

The plurality of flat tubes 20 of the heat exchanger 400 are formed by joining the refrigerant flow section 50 and the separate plate-shaped member 460, but the refrigerant flow section 50 and the fin portions 51 and 52 are integrated. May be manufactured in. In this case, the plurality of flat tubes 20 are manufactured by, for example, extrusion processing or drawing processing. However, when the refrigerant flow section 50 and the fins 51, 52 are integrated in the plurality of flat tubes 20 of the heat exchanger 400, at least the first side surface 25a side and the second side surface 25b side of the refrigerant flow section 50 are integrated. It is necessary to form the hydrophilic properties of the surface differently.

Embodiment 5.
The heat exchanger 500 according to the fifth embodiment is obtained by changing the arrangement of a plurality of flat tubes 20 with respect to the heat exchanger 200 according to the second embodiment. In the fifth embodiment, the changes to the second embodiment will be mainly described.

FIG. 19 is a diagram showing the hydrophilicity of the surface of the plurality of flat tubes 520 of the heat exchanger 500 according to the fifth embodiment. In the first flat pipe 520a constituting the plurality of flat pipes 520 of the heat exchanger 500, the fin portion 51 extends in the opposite direction in the Y direction from the end portion 21 of the refrigerant flow portion 50. Further, in the second flat pipe 520b constituting the plurality of flat pipes 520, the fin portion 52 extends in the Y direction from the end portion 22 of the refrigerant flow portion 50. The refrigerant flow section 50 of the first flat tube 520a and the second flat tube 520b is not parallel to each other in the X direction, and the refrigerant flow section 50 of the second flat tube 520b is located at a position deviated in the Y direction. Have been placed. That is, the fin portion 51 of the first flat pipe 520a and the refrigerant flow portion 50 of the second flat pipe 520b face each other, and the refrigerant flow portion 50 of the first flat pipe 520a and the fin portion of the second flat pipe 520b It is arranged so as to face the 52. In other words, the first flat pipe 520a and the second flat pipe 520b are arranged so that one refrigerant flow portion 50 and the other fin portions 51 and 52 face each other.

The plurality of flat tubes 520 of the heat exchanger 500 are configured such that the fin portions 51 and 52 have high hydrophilicity and the refrigerant flow portion 50 has low hydrophilicity. As a result, in the gap formed by the adjacent first flat tube 520a and the second flat tube 520b, the facing surfaces have different hydrophilic properties, so that the heat exchanger 500 has the same hydrophilicity as that of the first embodiment. It is possible to suppress the retention of water droplets.

Embodiment 6.
The heat exchanger 600 according to the sixth embodiment is obtained by modifying the structure and arrangement of the plurality of flat tubes 20 with respect to the heat exchanger 100 according to the first embodiment. In the sixth embodiment, the changes to the first embodiment will be mainly described.

FIG. 20 is an explanatory view of a cross-sectional structure of the heat exchanger 600 according to the sixth embodiment. FIG. 20 shows a cross section perpendicular to the tube axis of the plurality of flat tubes 20. The plurality of flat tubes 620 are composed of a first flat tube 620a and a second flat tube 620b. The plurality of flat pipes 620 are each provided with a plurality of refrigerant flow units 50, and are formed by connecting the end 21 of one refrigerant flow unit 50 and the end 22 of the other refrigerant flow unit 50 with fin portions 53. ing. Further, in the plurality of flat pipes 620, fin portions 51 and 52 extend from ends 21 and 22 that are not connected to other refrigerant flow portions 50.

Similar to other embodiments, the plurality of flat tubes 620 have a first side surface 25a and a second side surface 25b facing each other. The first side surface 25a is configured to have high hydrophilicity, and the second side surface 25b is configured to have low hydrophilicity at least in the gap between the refrigerant flow portions 50 having a narrow interval. With this configuration, the heat exchanger 600 can suppress the retention of water droplets as in the first embodiment while having a large heat exchange capacity.

FIG. 21 is an explanatory view of a cross-sectional structure of the heat exchanger 600a, which is a modification of the heat exchanger 600 according to the sixth embodiment. Similar to the heat exchanger 600, the plurality of flat pipes 620 of the heat exchanger 600a are configured by connecting the plurality of refrigerant flow portions 50 by fin portions 53. The heat exchanger 600a is positioned so that the refrigerant flow section 50 of the second flat tube 620b is displaced in the Y direction with respect to the refrigerant flow section 50 of the first flat tube 620a. That is, the fin portion 51 and the fin portion 53 of the first flat pipe 620a and the refrigerant flow portion 50 of the second flat pipe 620b face each other, and the refrigerant flow portion 50 and the second flat pipe of the first flat pipe 620a face each other. The fin portion 52 of the 620b is arranged so as to face the fin portion 52. In other words, the first flat pipe 620a and the second flat pipe 620b are arranged so that one refrigerant flow portion 50 and the other fin portions 51, 52, 53 face each other.

The plurality of flat tubes 620 of the heat exchanger 600a are configured such that the surface hydrophilicity of the fin portions 51, 52, 53 is high and the hydrophilicity of the surface of the refrigerant flow portion 50 is low. With this configuration, the facing surfaces have different hydrophilic properties in the gap formed by the adjacent first flat tube 520a and the second flat tube 520b. Therefore, the heat exchanger 600a can suppress the retention of water droplets as in the first embodiment while having a large heat exchange capacity.

Further, in the sixth embodiment, in the plurality of flat pipes 620, the refrigerant flow portion 50 and the fin portions 51, 52, 53 are integrally molded, but even if they are configured by joining different members to each other. good. For example, as shown in the fourth embodiment, the plurality of flat pipes 620 can be easily manufactured by joining the plate-shaped members forming the fin portions 51, 52, 53 and the refrigerant flow portion 50. There is an advantage of becoming.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the configuration of the above-described embodiments. For example, the plurality of flat pipes 620 have two refrigerant flow units 50, but may have more refrigerant flow units 50. Further, the heat exchangers 100, 200, 200a, 300, 400, 500, 600, 600a may have flat tubes having further different hydrophilic properties. Further, in the above description, the index of hydrophilicity is described by expressing that the case where the contact angle between the water droplet and the surface is large is low hydrophilicity and the case where the contact angle is small is high hydrophilicity. , The size of the fall angle may be used instead of the size of the contact angle. That is, when the rolling angle is small, the hydrophilicity is low (water detachability is high), and when the rolling angle is large, the hydrophilicity is high (water detachability is low), and the surfaces of a plurality of flat tubes are formed. You may. Further, the present invention may be configured by combining each embodiment. For example, the bent cross-sectional shape of the plurality of flat tubes 120 of the heat exchanger 100A, which is a modification of the heat exchanger 100 according to the first embodiment, may be applied to other embodiments. In short, it should be added that the gist (technical scope) of the present invention also includes various modifications, applications, and uses made by those skilled in the art as necessary.

1 Refrigeration cycle device, 2 blower, 3 compressor, 4 four-way valve, 5 outdoor heat exchanger, 6 expansion device, 7 indoor heat exchanger, 8 outdoor unit, 9 indoor unit, 10 outdoor heat exchanger, 20 flat tube, 20a first flat tube, 20b second flat tube, 21 (first) end, 22 (second) end, 24 refrigerant flow path, 25a (first) side surface, 25b (second) side surface. , 50 Refrigerator flow section, 51 fin section, 52 fin section, 53 fin section, 60 plate-shaped member, 70 water droplets, 70a water droplets, 70b water droplets, 80 lower end header, 81 upper end header, 90 refrigerant piping, 100 heat exchanger, 101 Heat exchanger unit, 200 heat exchanger, 200a heat exchanger, 200b heat exchanger, 300 heat exchanger, 400 heat exchanger, 460 plate-shaped member, 500 heat exchanger, 520 flat tube, 520a first flat tube , 520b 2nd flat tube, 600 heat exchanger, 600a heat exchanger, 620 flat tube, 620a 1st flat tube, 620b 2nd flat tube, 1020 flat tube, 1020a 1st flat tube, 1020b 2nd 1025a (first) side surface, 1025b (second) side surface, 1070 water droplets, 1100 heat exchanger, 2020 flat tube, 2020a first flat tube, 2020b second flat tube, 2025a first Side, 2025b Second side, 2070 water droplets, 2100 heat exchanger, A tube minor axis, B pitch, F region, G gravity, γs surface tension, γsw interface tension, γw surface tension, θ contact angle, θ1 contact angle, θ2 contact angle.

Heat exchanger according to the present invention includes a first flat tube and the second flat tube, which is parallel to the tube axis, the first flat tube is first opposed to the second flat tube The second flat tube has a second side surface facing the first flat tube, and a hydrophilic region that is at least a part of the first side surface is the second side surface. hydrophilic rather higher than, the sliding angle of the hydrophilic region of the first side is greater than the sliding angle region opposed to the hydrophilic region of the second side.

Claims (14)

It is provided with a first flat tube and a second flat tube in which the tube axes are arranged in parallel.
The first flat tube has a first side surface facing the second flat tube.
The second flat tube has a second side surface facing the first flat tube.
The hydrophilic region, which is at least a part of the first side surface,
A heat exchanger that is more hydrophilic than the second side surface. The contact angle of the hydrophilic region on the first side surface is
The heat exchanger according to claim 1, which is smaller than the contact angle of the region of the second side surface facing the hydrophilic region. The contact angle of the hydrophilic region of the first side surface is
Less than 90 °
The contact angle of the region of the second side surface facing the hydrophilic region is
The heat exchanger according to claim 2, wherein the temperature is 90 ° or more. The fall angle of the hydrophilic region on the first side surface is
The heat exchanger according to any one of claims 1 to 3, which is larger than the fall angle of the region of the second side surface facing the hydrophilic region. The first flat tube and the second flat tube are
At least one refrigerant flow unit having a refrigerant flow path for passing refrigerant inside,
The heat exchanger according to any one of claims 1 to 4, further comprising at least one fin portion extending in the long axis direction in a cross section perpendicular to the pipe axis from the end portion of the refrigerant flow section. The first flat tube and the second flat tube are
The heat exchanger according to claim 5, wherein one of the refrigerant flow sections and the other fin section are arranged so as to face each other. The first flat tube and the second flat tube are
The heat exchanger according to claim 5, wherein the refrigerant flow portions and the fin portions are arranged so as to face each other. The first flat tube and the second flat tube are
It is formed by joining the fin portion and the refrigerant flow portion.
The fin portion
The heat exchanger according to claim 6 or 7, wherein the heat exchanger is formed by being joined to one of the two side surfaces of the refrigerant flow unit along the long axis direction. The surface of the fin portion
The heat exchanger according to claim 8, which has a hydrophilicity different from that of the surface of the refrigerant flow section. The fin portion
Has multiple fins
The heat exchanger according to any one of claims 5 to 9, which extends in the major axis direction from both ends of the refrigerant flow section in the major axis direction. The refrigerant distribution unit
It has multiple refrigerant distribution units and has multiple refrigerant distribution units.
The ends of two adjacent refrigerant flow sections among the plurality of refrigerant flow sections are
The heat exchanger according to any one of claims 5 to 10, which is connected by the fin portion. The first flat tube and the second flat tube are
The heat exchanger according to any one of claims 1 to 11, wherein a member for connecting between the first side surface and the second side surface is not provided. A heat exchanger unit comprising the heat exchanger according to any one of claims 1 to 12. A refrigeration cycle apparatus comprising the heat exchanger unit according to claim 13.

Images