CN111527356B - Heat exchanger and refrigeration cycle device - Google Patents

Abstract

A heat exchanger and a refrigeration cycle device. The heat exchanger of an embodiment has a first head and a second head, and a plurality of heat exchange tubes. The plurality of heat exchange tubes has a first heat exchange tube and a second heat exchange tube. The first heat exchange tubes are flowed with a gas-liquid two-phase refrigerant having a large liquid phase content. The second heat exchange tube communicates with the first heat exchange tube, and flows a gas-liquid two-phase refrigerant having a large gas-phase component. The second heat exchange tube has an upper second heat exchange tube and a lower second heat exchange tube. The upper second heat exchange tube is arranged above the first heat exchange tube. The lower second heat exchange tube is arranged below the first heat exchange tube.

Description

Heat exchanger and refrigeration cycle device

Technical Field

Embodiments of the present invention relate to a heat exchanger and a refrigeration cycle device.

Background

A heat exchanger that performs heat exchange between refrigerant and outside air is used. In the case where the heat exchanger is used as an evaporator of a refrigeration cycle apparatus, frost (frost) adheres to the heat exchanger. When frost is formed on the heat exchanger, the normal operation of the refrigeration cycle apparatus is suspended and the defrosting operation is performed. A heat exchanger capable of performing defrosting in a short defrosting operation is required.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2012-163319

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing a heat exchanger and a refrigeration cycle device that can complete defrosting in a short defrosting operation.

Means for solving the problems

The heat exchanger of an embodiment has a first head (header) and a second head, and a plurality of heat exchange tubes. The first and second headers are formed in a cylindrical shape and arranged so as to be separated from each other. The heat exchange tubes are arranged at intervals in the direction of the central axes of the first seal head and the second seal head, and two end parts of the heat exchange tubes are opened in the first seal head and the second seal head. The plurality of heat exchange tubes has a first heat exchange tube and a second heat exchange tube. The first heat exchange tubes are flowed with a gas-liquid two-phase refrigerant having a large liquid phase content. The second heat exchange tube communicates with the first heat exchange tube, and flows a gas-liquid two-phase refrigerant having a large gas-phase component. The second heat exchange tube has an upper second heat exchange tube and a lower second heat exchange tube. The upper second heat exchange tube is arranged above the first heat exchange tube. The lower second heat exchange tube is arranged below the first heat exchange tube.

Drawings

Fig. 1 is a schematic configuration diagram of a refrigeration cycle apparatus.

Fig. 2 is a front view of the heat exchanger of the first embodiment.

Fig. 3 is a partial perspective view of the heat exchanger of the first embodiment.

Fig. 4 is a partial cross-sectional view taken along line F4-F4 of fig. 2.

Fig. 5 is a schematic configuration diagram of the heat exchanger according to the first embodiment.

Fig. 6 is a schematic configuration diagram of a heat exchanger according to a modification of the first embodiment.

Fig. 7 is a flow chart of a defrost method.

Fig. 8 is a schematic configuration diagram of a heat exchanger according to a second embodiment.

Detailed Description

Hereinafter, a heat exchanger and a refrigeration cycle apparatus according to an embodiment will be described with reference to the drawings.

In the present application, the X direction, the Y direction, and the Z direction are defined as follows. The Z direction is a central axis direction (extending direction) of the first header and the second header. For example, the Z direction is a vertical direction, and the + Z direction is an upward direction. The X direction is a central axis direction (extending direction) of the heat exchange tube. For example, the X direction is a horizontal direction, and the + X direction is a direction from the first head toward the second head. The Y direction is a direction perpendicular to the X direction and the Z direction.

Fig. 1 is a schematic configuration diagram of a refrigeration cycle apparatus.

As shown in fig. 1, the refrigeration cycle apparatus 1 includes a compressor 2, a four-way valve 3, an outdoor heat exchanger (heat exchanger) 4, an expansion device 5, an indoor heat exchanger 6, and a controller 9. The components of the refrigeration cycle apparatus 1 are connected in sequence by a pipe 7. In each of the drawings, the flow direction of the refrigerant during the heating operation is indicated by a broken-line arrow, and the flow direction of the refrigerant during the defrosting (cooling) operation is indicated by a solid-line arrow.

The compressor 2 has a compressor main body 2A and an accumulator 2B. The compressor body 2A compresses the low-pressure gas refrigerant taken into the interior thereof to form a high-temperature high-pressure gas refrigerant. The accumulator 2B separates the gas-liquid two-phase refrigerant and supplies the gas refrigerant to the compressor body 2A.

The four-way valve 3 reverses the direction of refrigerant flow to switch between heating operation and defrosting operation. During the heating operation, the refrigerant flows through the compressor 2, the four-way valve 3, the indoor heat exchanger 6, the expansion device 5, and the outdoor heat exchanger 4 in this order. At this time, the refrigeration cycle apparatus 1 heats the interior of the room by causing the indoor heat exchanger 6 to function as a condenser and the outdoor heat exchanger 4 to function as an evaporator. During the defrosting operation, the refrigerant flows through the compressor 2, the four-way valve 3, the outdoor heat exchanger 4, the expansion device 5, and the indoor heat exchanger 6 in this order. At this time, the refrigeration cycle apparatus 1 causes the outdoor heat exchanger 4 to function as a condenser, causes the indoor heat exchanger 6 to function as an evaporator, and defrosts the outdoor heat exchanger 4.

The condenser condenses the high-temperature and high-pressure gas refrigerant discharged from the compressor 2 by radiating heat to the outside air, thereby forming a high-pressure liquid refrigerant. The evaporator absorbs heat from the outside air to vaporize the low-temperature low-pressure liquid refrigerant sent from the expansion device 5, thereby forming a low-pressure gas refrigerant. A blower fan 4a is provided in the vicinity of the outdoor heat exchanger 4. The blower fan 4a sends outside air to the outdoor heat exchanger 4.

The expansion device 5 reduces the pressure of the high-pressure liquid refrigerant sent from the condenser to form a low-temperature low-pressure liquid refrigerant.

The control unit 9 controls the operations of the compressor 2, the four-way valve 3, the expansion device 5, and the like.

In this manner, in the refrigeration cycle apparatus 1, the refrigerant as the working fluid circulates while changing the phase between the gas refrigerant and the liquid refrigerant, radiates heat in the process of changing the phase from the gas refrigerant to the liquid refrigerant, and absorbs heat in the process of changing the phase from the liquid refrigerant to the gas refrigerant. The heat dissipation and heat absorption can be used to perform heating, defrosting, and the like.

(first embodiment)

Fig. 2 is a front view of the heat exchanger of the first embodiment. Fig. 3 is a partial perspective view of the heat exchanger of the first embodiment. The heat exchanger 4 of the embodiment is used as the outdoor heat exchanger 4 of the refrigeration cycle apparatus 1. The heat exchanger 4 of the embodiment may be used as the indoor heat exchanger 6 of the refrigeration cycle apparatus 1. Hereinafter, a case where the heat exchanger 4 of the embodiment is used as the outdoor heat exchanger 4 of the refrigeration cycle apparatus 1 will be described as an example.

As shown in fig. 2, the heat exchanger 4 has a first header 10, a second header 20, heat exchange tubes 30, and fins 40.

The first header 10 is formed of a material having high thermal conductivity and small specific gravity, such as aluminum or aluminum alloy. The first head 10 is formed in a cylindrical shape, for example, a cylindrical shape having a circular cross section. Both ends of the first header 10 in the Z direction are closed. A plurality of through holes into which the heat exchange tubes 30 are inserted are formed in the outer circumferential surface of the first header 10.

The second head 20 is formed in the same manner as the first head 10. The first head 10 and the second head 20 are arranged so as to be separated from each other in the X direction.

The heat exchange tubes 30 are made of a material having high thermal conductivity and low specific gravity, such as aluminum or an aluminum alloy. As shown in fig. 3, the heat exchange tube 30 is formed in a flattened tubular shape. That is, the heat exchange tube 30 has a predetermined width in the Y direction, is thin in the Z direction, and extends long in the X direction.

Fig. 4 is a partial cross-sectional view taken along line F4-F4 of fig. 2. The heat exchange tube 30 is formed in an oblong shape in outer shape. A plurality of refrigerant flow paths 34 are formed inside the heat exchange tubes 30 in a row in the Y direction. The adjacent refrigerant flow paths 34 are separated by flow path walls 35 parallel to the XZ plane. The plurality of refrigerant flow paths 34 penetrate the heat exchange tubes 30 in the X direction.

As shown in fig. 2, the plurality of heat exchange tubes 30 are arranged at intervals in the Z direction. Both ends of the heat exchange tube 30 are inserted into through holes formed in the outer circumferential surfaces of the first header 10 and the second header 20. Thus, both ends of the refrigerant flow path 34 of the heat exchange tube 30 are open inside the first header 10 and the second header 20. The first end socket 10 and the second end socket 20 are hermetically fixed to the heat exchange tube 30 by brazing or the like.

The heat sink 40 is made of a material having high thermal conductivity and low specific gravity, such as aluminum or an aluminum alloy. As shown in fig. 2 and 3, the heat sink 40 is a plate-shaped heat sink formed in a flat plate shape. The heat sink 40 is arranged parallel to the YZ plane. The length of the heat sink 40 in the Z direction is equal to or slightly shorter than the length of the first header 10 and the second header 20 in the Z direction.

As shown in fig. 4, the width of the fin 40 in the Y direction is larger than the width of the heat exchange tube 30 in the Y direction. Notches 43 are formed in the-Y direction from the + Y direction end edges of the heat sink 40. The heat exchange tubes 30 are inserted in the notches 43. The heat exchange tubes 30 and the fins 40 are fixed to each other by brazing or the like.

As shown in fig. 2, the plurality of fins 40 are arranged at intervals in the X direction.

An outside air flow path extending in the Y direction is formed between adjacent heat exchange tubes 30 and between adjacent fins 40. The heat exchanger 4 circulates outside air through the outside air flow path by a blower fan 4a (see fig. 1). The heat exchanger 4 exchanges heat between the outside air flowing through the outside air flow path and the refrigerant flowing through the refrigerant flow path 34. The heat exchange is performed indirectly via the heat exchange tubes 30 and the fins 40. The heat sink 40 may be provided with irregularities. The unevenness generates turbulence in the outside air flowing through the outside air flow path, thereby improving heat exchange efficiency.

The fins 40 of the embodiment are plate fins, but may be corrugated fins. The corrugated fin is formed in a wave shape and is disposed between adjacent heat exchange tubes 30.

The internal structure of the heat exchanger 4 will be explained.

Fig. 5 is a schematic configuration diagram of the heat exchanger 4 of the first embodiment. In fig. 5, the heat exchange tube 30 is represented by a box. In one block of fig. 5, a plurality of heat exchange tubes 30 arranged adjacently and having the same function are included.

The first head 10 has a plurality of partition members. The partition member is disposed parallel to the XY plane and partitions the inside of the first header 10 in the Z direction. The plurality of partition members divide the interior of the first head 10 into a plurality of chambers. The plurality of partition members include an upper partition member 15H, a lower partition member 15L, and an intermediate partition member 15 s.

The upper partition member 15H is disposed above (+ Z direction), and the lower partition member 15L is disposed below (-Z direction). Inside the first head 10, a first chamber 11 is formed between the upper partition member 15H and the lower partition member 15L. A second chamber 12 is formed between the upper partition member 15H and the upper end of the first header 10. A lowermost second chamber 12z is formed between the lower partition member 15L and the lower end of the first header 10.

The intermediate partition member 15s is disposed in the first chamber 11 between the upper partition member 15H and the lower partition member 15L. The plurality of intermediate partition members 15s divide the first chamber 11 into a plurality of first small chambers 11a, 11 z. In the example of fig. 5, the four intermediate partition members 15s divide the first chamber 11 into five first small chambers 11a, 11 z. In the example of fig. 5, the heights in the Z direction of the five first cells 11a, 11Z are equal.

The second head 20 has a plurality of partition members, like the first head 10. The plurality of partition members include an upper partition member 25H, a lower partition member 25L, and an intermediate partition member 25 s.

The upper partition member 25H is disposed at the same height as the upper partition member 15H of the first header 10. The lower partition member 25L is disposed above the lower partition member 15L of the first header 10. The lower partition member 25L is disposed at the same height as the lowermost intermediate partition member 15s disposed in the first chamber 11 of the first header 10.

Inside the second head 20, a first chamber 21 is formed between the upper partition member 25H and the lower partition member 25L. A second chamber 22 is formed between the upper partition member 25H and the upper end of the second head 20. A lowermost chamber 20z is formed between the lower partition member 25L and the lower end of the second header 20.

The intermediate partition member 25s is disposed in the first chamber 21 between the upper partition member 25H and the lower partition member 25L. The plurality of intermediate partition members 25s divide the first chamber 21 into a plurality of first small chambers 21 a. In the example of fig. 5, three intermediate partition members 25s divide the first chamber 21 into four first small chambers 21 a. In the example of fig. 5, the heights in the Z direction of the four first cells 21a are equal. The height of the first chambers 11a, 11z of the first head 10 is equal to the height of the first chamber 21a of the second head 20.

The intermediate partition member 25s is also disposed in the second chamber 22 between the upper partition member 25H and the upper end portion of the second header 20. The plurality of intermediate partition members 25s divide the second chamber 22 into a plurality of second small chambers 22 a. In the example of fig. 5, three intermediate partition members 25s divide the second chamber 22 into four second small chambers 22 a. In the example of fig. 5, the heights in the Z direction of the four second cells 22a are equal. The height of the second cell 22a is greater than the height of the first cell 21 a.

The heat exchange tube 30 has a first heat exchange tube 31 and a second heat exchange tube 32. The first heat exchange tubes 31 are arranged below the center of the heat exchanger 4 in the Z direction. Second heat exchange tube 32 has an upper second heat exchange tube 32u and a lower second heat exchange tube 32 z. The upper second heat exchanger tube 32u is disposed above the first heat exchanger tube 31. The lower second heat exchanger tube 32z is disposed below the first heat exchanger tube 31 and at the lowermost portion of the plurality of heat exchanger tubes 30.

A first end of the first heat exchange tube 31 in the-X direction opens into the first chamber 11 of the first header 10. A plurality of first heat exchange tubes 31 are opened in each of a plurality of first small chambers 11a, 11z formed in the first chamber 11. In the example of fig. 5, the same number of first heat exchange tubes 31 are opened for the plurality of first cells 11a, 11z, respectively. Among the plurality of first cells 11a, 11z, the lowermost first heat exchanger tube 31z is open in the lowermost first cell 11 z. The lowermost first heat exchanger tube 31z is disposed lowermost in the first heat exchanger tube 31. Therefore, the lowermost first heat exchange tube 31z is closest to the lower second heat exchange tube 32 z.

The second end portion in the + X direction of the first heat exchange tube 31 opens into the first chamber 21 or the lowermost chamber 20z of the second header 20. The lowermost of the first heat exchange tubes 31z opens to the lowermost chamber 20 z. The upper first heat exchanger tube 31u disposed above the lowermost first heat exchanger tube 31z opens into the first chamber 21. In the plurality of first small chambers 21a formed in the first chamber 21, a plurality of upper first heat exchange tubes 31u are opened, respectively. The number of the first heat exchange tubes 31u opening above the first cells 11a of the first header 10 is the same as the number of the first heat exchange tubes 31u opening above the first cells 21a of the second header 20.

The first end of the upper second heat exchange tube 32u in the-X direction opens into the second chamber 12 of the first header 10.

the-X direction first end of the lower second heat exchange tube 32z opens into the lowermost second chamber 12z of the first header 10.

The second end of the upper second heat exchange tube 32u in the + X direction is open to the second chamber 22 of the second header 20. In the plurality of second small chambers 22a formed in the second chamber 22, a plurality of upper second heat exchange tubes 32u are opened, respectively. In the example of fig. 5, the same number of upper second heat exchange tubes 32u are opened with respect to the four second small chambers 22a, respectively. The number of the second heat exchange tubes 32u opening above the second small chamber 22a is larger than the number of the first heat exchange tubes 31u opening above the first small chamber 21 a.

The second end in the + X direction of the lower second heat exchange tube 32z opens to the lowermost chamber 20z of the second header 20. The number of the lower second heat exchange tubes 32z is the same as that of the lowermost first heat exchange tubes 31z or is greater than that of the lowermost first heat exchange tubes 31 z.

The first head 10 has a first refrigerant port 17, a second refrigerant port 18, and a temperature sensor 14.

The first refrigerant port 17 is constituted by a first refrigerant port 17a and a lowermost first refrigerant port 17z, the first refrigerant ports 17a are formed in the plurality of first small chambers 11a constituting the first chamber 11, respectively, and the lowermost first refrigerant port 17z is formed in the lowermost first small chamber 11 z. The first refrigerant port 17a of the first refrigerant port 17 constituting the heat exchanger 4 and the lowermost first refrigerant port 17z are joined by the connecting pipe 17b and connected to the same component of the refrigeration cycle apparatus 1. In the example of fig. 1, the first refrigerant port 17 of the outdoor heat exchanger 4 is connected to the expansion device 5.

The second refrigerant port 18 is constituted by a second refrigerant port 18a formed above (upper half) the second chamber 12, and a lowermost second refrigerant port 18z formed in the lowermost second chamber 12 z. The second refrigerant port 18a constituting the second refrigerant port 18 of the heat exchanger 4 and the lowermost second refrigerant port 18z merge together via the connection pipe 18b and are connected to the same constituent components of the refrigeration cycle apparatus 1. In the example of fig. 1, the second refrigerant port 18 of the outdoor heat exchanger 4 is connected to the four-way valve 3.

The temperature sensor 14 is connected to a lowermost first refrigerant port 17z constituting the first refrigerant port 17. The temperature sensor 14 outputs a signal corresponding to the temperature of the refrigerant flowing through the first refrigerant port 17 to the control unit 9 of the refrigeration cycle device 1. The control unit 9 detects the temperature of the refrigerant flowing through the first refrigerant port 17 based on a signal input from the temperature sensor 14.

The second head 20 has a connection flow path 26. The connection channel 26 connects the first chamber 21 and the second chamber 22. Connection flow paths 26a are formed between the plurality of first small chambers 21a formed in the first chamber 21 and the plurality of second small chambers 22a formed in the second chamber 22, respectively. In the example of fig. 5, the connection channel 26a connects the nth (n is a natural number) first cell 21a from above the first chamber 21 and the nth second cell 22a from below the second chamber 22. This can avoid the intersection of the plurality of connection channels 26 and simplify the layout. The connection channel 26a may connect the first small chamber 21a and the second small chamber 22a in a combination other than the above.

Fig. 6 is a schematic configuration diagram of a heat exchanger 104 according to a modification of the first embodiment. The configuration of the modification other than the configuration described below is the same as that of the first embodiment.

The heat exchanger 104 does not have the intermediate partition members 15s, 25s in the first header 10 and the second header 20. That is, the first chamber 11 of the first closure 10 is not divided into a plurality of first cells. The first chamber 21 of the second head 20 is also not divided into a plurality of first cells. The second chamber 22 of the second head 20 is also not divided into a plurality of second cells.

The first refrigerant port 17 is formed below the first chamber 11 of the first header 10. The connection flow path 26 connects the upper side of the first chamber 21 of the second head 20 and the lower side of the second chamber 22. Thereby, the gas-liquid two-phase refrigerant containing a large amount of liquid-phase component flows out from below and flows in, and the gas-liquid two-phase refrigerant containing a large amount of gas-phase component flows out from above. Therefore, the shortage of the refrigerant due to the retention of the refrigerant can be suppressed.

The heat exchanger 104 of the modification also has the same operational effects as the heat exchanger 4 of the first embodiment.

A refrigerant flow path in the heat exchanger 4 according to the first embodiment will be described.

As described above, in fig. 5, the flow direction of the refrigerant during the heating operation is indicated by the broken-line arrow, and the flow direction of the refrigerant during the defrosting operation is indicated by the solid-line arrow.

A description will be given of a refrigerant flow path in the case where the refrigeration cycle apparatus 1 performs a heating operation.

When the refrigeration cycle apparatus 1 shown in fig. 1 performs a heating operation, the outdoor heat exchanger 4 functions as an evaporator. At this time, the liquid refrigerant flowing out of the expansion device 5 is equally distributed by the refrigerant distribution mechanism (not shown), and flows into the first refrigerant port 17a and the lowermost first refrigerant port 17z constituting the first refrigerant port 17 of the heat exchanger 4 shown in fig. 5 via the connection pipe 17 b.

The refrigerant flows from the first refrigerant port 17a into the first small chamber 11a constituting the first chamber 11 of the first header 10, and flows from the lowermost first refrigerant port 17z into the lowermost first small chamber 11 z.

The refrigerant flows from the first small chamber 11a into the upper first heat exchange tube 31u, and flows from the lowermost first small chamber 11z into the lowermost first heat exchange tube 31 z. During the circulation in the first heat exchange tubes 31, the refrigerant absorbs heat from the outside air. Thereby, the liquid refrigerant becomes a gas-liquid two-phase refrigerant containing a large amount of liquid-phase components. That is, the gas-liquid two-phase refrigerant containing a large amount of liquid component flows through the first heat exchange tubes 31.

The refrigerant flows into the first small chamber 21a from the upper first heat exchange tube 31u, and flows into the lowermost chamber 20z from the lowermost first heat exchange tube 31 z.

The refrigerant flows from the first cell 21a through the connection flow path 26a and flows into the second cell 22 a.

The refrigerant flows from the second small chamber 22a into the upper second heat exchange tube 32u, and flows from the lowermost chamber 20z into the lower second heat exchange tube 32 z. During circulation in the second heat exchange tubes 32, the refrigerant absorbs heat from outside air. Thereby, the gas-liquid two-phase refrigerant containing a large amount of liquid phase component is changed into a gas-liquid two-phase refrigerant containing a large amount of gas phase component. That is, the gas-liquid two-phase refrigerant having a large gas-phase component flows through the second heat exchange tubes 32.

The refrigerant flows into the second chamber 12 from the upper second heat exchange tubes 32u, and flows into the lowermost second chamber 12z from the lower second heat exchange tubes 32 z.

The refrigerant flows out of the heat exchanger 4 from the second refrigerant port 18a and the lowermost second refrigerant port 18 z. The gas refrigerant flowing out of the outdoor heat exchanger 4 shown in fig. 1 flows into the compressor 2 via the four-way valve 3.

As described above, the refrigerant flows through the first cell 11a of the first header 10, the upper first heat exchange tube 31u, the first cell 21a of the second header, the connecting flow path 26a, the second cell 22a of the second header, and the upper second heat exchange tube 32 u. The refrigerant flows through the lowermost first small chamber 11z of the first header 10, the lowermost first heat exchange tubes 31z, the lowermost chamber 20z of the second header, the lower second heat exchange tubes 32z, and the lowermost second chamber 12z of the first header 10. These refrigerant flow paths constitute modules. A plurality of modules are arranged in parallel in the heat exchanger 4.

A refrigerant flow path in the case where the refrigeration cycle apparatus 1 performs the defrosting operation will be described.

The refrigerant flows in the case of performing the defrosting operation in reverse to the case of performing the heating operation. When the refrigeration cycle apparatus 1 shown in fig. 1 performs the defrosting operation, the outdoor heat exchanger 4 functions as a condenser. At this time, the gas refrigerant flowing out of the compressor 2 via the four-way valve flows into the second refrigerant port 18 of the heat exchanger 4 shown in fig. 5.

The refrigerant flows from the second refrigerant ports 18a, 18z into the second chamber 12 of the first head 10 and the lowermost second chamber 12 z. The refrigerant flows into the second heat exchange tubes 32 from the second chamber 12 and the lowermost second chamber 12 z. During the circulation in the second heat exchange tubes 32, the refrigerant radiates heat to the outside air. Thereby, the gas refrigerant becomes a gas-liquid two-phase refrigerant having a large gas-phase component. That is, the gas-liquid two-phase refrigerant having a large gas-phase component flows through the second heat exchange tubes 32.

The refrigerant flows from the second heat exchange tubes 32 into the second chamber 22 of the second head 20 and the lowermost chamber 20 z. The refrigerant flows from the second chamber 22 through the connecting passage 26 and flows into the first chamber 21.

The refrigerant flows into the first heat exchange tubes 31 from the first chamber 21 and the lowermost chamber 20z of the second header 20. The refrigerant radiates heat to the outside air while circulating through the first heat exchange tubes 31. Thereby, the gas-liquid two-phase refrigerant containing a large amount of gas-phase components is changed into a gas-liquid two-phase refrigerant containing a large amount of liquid-phase components. That is, the gas-liquid two-phase refrigerant containing a large amount of liquid component flows through the first heat exchange tubes 31.

The refrigerant flows from the first heat exchange tubes 31 into the first chamber 11 of the first header 10. The refrigerant flows from the first chamber 11 into the first refrigerant port 17. The refrigerant flows out of the heat exchanger 4 from the first refrigerant port 17. The liquid refrigerant flowing out of the outdoor heat exchanger 4 shown in fig. 1 flows into the expansion device 5.

In this way, in both the heating operation and the defrosting operation, the gas-liquid two-phase refrigerant containing a large amount of liquid component flows through the first heat exchange tubes 31, and the gas-liquid two-phase refrigerant containing a large amount of liquid component flows through the second heat exchange tubes 32. That is, the gas-liquid two-phase refrigerant having a liquid phase component larger than that in the second heat exchange tubes 32 flows through the first heat exchange tubes 31. The gas-liquid two-phase refrigerant having a gas phase component larger than that in the first heat exchange tubes 31 flows through the second heat exchange tubes 32.

During the defrosting operation, the gas-liquid two-phase refrigerant containing a large amount of gas-phase components flows into the second heat exchange tubes 32. In the process of flowing through the second heat exchange tubes 32, the refrigerant radiates heat to the outside air, and therefore the liquid-phase component of the gas-liquid two-phase refrigerant increases. The upper second heat exchange tubes 32u occupying most of the second heat exchange tubes 32 are arranged above the first heat exchange tubes 31. Therefore, the liquid-phase component of the refrigerant flows through the first heat exchange tubes 31 from the upper second heat exchange tubes 32u with gravity. This can suppress the shortage of the refrigerant caused by the retention of the refrigerant.

A defrosting method of the heat exchanger 4 of the embodiment will be described.

Fig. 7 is a flow chart of a defrost method. The control unit 9 of the refrigeration cycle apparatus 1 performs the heating operation (S02). The control unit 9 switches the four-way valve 3 and causes the refrigerant to flow through the compressor 2, the four-way valve 3, the indoor heat exchanger 6, the expansion device 5, and the outdoor heat exchanger 4 in this order.

When the refrigeration cycle apparatus 1 performs a heating operation, the outdoor heat exchanger 4 functions as an evaporator. At this time, the refrigerant flowing through the heat exchange tubes 30 absorbs heat from the outside air flowing through the outside air flow path. Therefore, dew condensation water adheres to the fins 40 and the heat exchange tubes 30 constituting the external air flow path. The dew condensation water flows downward along the plate-shaped fins 40 and stays at the lowermost portion of the heat exchanger 4. When the outside air temperature is low, dew condensation water freezes and frost adheres thereto. Therefore, frost is likely to adhere to the lowermost portion of the heat exchanger 4.

When frost is formed on the outside air flow path of the heat exchanger 4, the refrigerant is less likely to absorb heat from the outside air, and the heat exchange efficiency is reduced. If the temperature of the refrigerant is lower than the outside air, the refrigerant easily absorbs heat from the outside air, and the heat exchange efficiency is improved. Therefore, the control unit 9 reduces the temperature of the refrigerant by throttling the expansion device 5. When frost is formed on the outside air flow path of the heat exchanger 4, the refrigerant temperature is reduced to less than 0 ℃.

The control unit 9 determines whether or not the detected refrigerant temperature Te is less than 0 deg.c based on the signal from the temperature sensor 14 (S04).

If the determination at S04 is yes, the control unit 9 substitutes Te into Te0 (S06). The controller 9 determines whether or not the difference Δ Te between the previously detected refrigerant temperature Te0 and the newly detected refrigerant temperature Te exceeds the predetermined value α (S08). The predetermined value α is set to, for example, 3 to 10 ℃. When the difference Δ Te exceeds the predetermined value α, the refrigerant temperature rapidly decreases. When frost is formed on the outside air flow path of the heat exchanger 4, the controller 9 abruptly decreases the refrigerant temperature.

If the determination at S08 is yes, the controller 9 determines that frost has formed on the heat exchanger 4 (S10). At this time, the control unit 9 stops the operation of the compressor 2. The control unit 9 stops the operation of the blower fan 4a of the heat exchanger 4.

The control unit 9 performs the defrosting operation (S12). The control unit 9 switches the four-way valve to cause the refrigerant to flow through the compressor 2, the four-way valve 3, the outdoor heat exchanger 4, the expansion device 5, and the indoor heat exchanger 6 in this order. The controller 9 starts the operation of the compressor 2. The control unit 9 does not operate the blower fan 4 a.

In the defrosting operation, the high-temperature gas refrigerant flowing out of the compressor 2 flows into the second heat exchange tubes 32 of the heat exchanger 4. The gaseous refrigerant dissipates heat during circulation in the second heat exchange tubes 32. The heat exchanger 4 of the embodiment has, as the second heat exchange tubes 32, lower second heat exchange tubes 32z in addition to the upper second heat exchange tubes 32 u. The high-temperature gas refrigerant melts the lowermost frost attached to the heat exchanger 4 while circulating in the lower second heat exchange tubes 32 z. Even when a large amount of frost adheres to the lowermost portion of the heat exchanger 4, the lower second heat exchange tubes 32z are disposed below the heat exchanger 4, and therefore efficient defrosting can be performed. This enables defrosting to be completed in a short defrosting operation. The water after the frost is melted falls to the lower side of the heat exchanger 4, so that the frost can be prevented from being attached again.

The refrigerant flowing into the lower second heat exchange tubes 32z flows into the lowermost first heat exchange tubes 31z from the lowermost chamber 20z and flows out from the lowermost first refrigerant ports 17 z. When the defrosting is completed, the temperature of the refrigerant flowing out of the lowermost first refrigerant port 17z rises. The controller 9 determines whether or not the refrigerant temperature exceeds a predetermined value β (S14). The predetermined value β is set to, for example, 3 to 15 ℃. The temperature sensor 14 is connected to the lowermost first refrigerant port 17z below the first chamber 11 of the first header 10. Therefore, the controller 9 can accurately determine that defrosting of the lowermost portion of the heat exchanger 4 is completed.

If the determination at S14 is yes, the control unit 9 determines that defrosting is completed (S16). At this time, the control unit 9 stops the operation of the compressor 2.

The controller 9 resumes the heating operation (S18). At this time, the control unit 9 switches the four-way valve 3, and causes the refrigerant to flow through the compressor 2, the four-way valve 3, the indoor heat exchanger 6, the expansion device 5, and the outdoor heat exchanger 4 in this order.

By the above, the process of the defrosting method is completed.

As described above in detail, the heat exchanger 4 of the embodiment includes the first header 10 and the second header 20, and the plurality of heat exchange tubes 30. The first head 10 and the second head 20 are formed in a cylindrical shape and arranged so as to be separated from each other in the X direction. The plurality of heat exchange tubes 30 are arranged at intervals in the central axis direction (Z direction) of the first head 10 and the second head 20, and both end portions are opened inside the first head 10 and the second head 20. The plurality of heat exchange tubes 30 have a first heat exchange tube 31 and a second heat exchange tube 32. The first heat exchange tubes 31 flow the gas-liquid two-phase refrigerant having a large liquid phase component. The second heat exchange tubes 32 communicate with the first heat exchange tubes 31, and flow a gas-liquid two-phase refrigerant having a large gas-phase component. Second heat exchange tube 32 has an upper second heat exchange tube 32u and a lower second heat exchange tube 32 z. The upper second heat exchanger tube 32u is disposed above the first heat exchanger tube 31. The lower second heat exchanger tube 32z is disposed below the first heat exchanger tube 31.

Frost is likely to adhere to the lowermost portion of the heat exchanger 4. The gas-liquid two-phase refrigerant having a large gas-phase component flows through the second heat exchange tubes 32. Second heat exchange tube 32 has a lower second heat exchange tube 32 z. Therefore, the heat exchanger 4 can efficiently defrost frost adhering to the lowermost portion. Therefore, the defrosting can be completed in a short defrosting operation.

The first head 10 and the second head 20 have a plurality of chambers divided in the Z direction. The second head 20 has a first chamber 21, a second chamber 22, and a lowermost chamber 20z as a plurality of chambers. The upper first heat exchanger tube 31u as a part of the first heat exchanger tube 31 is opened to the first chamber 21. The second chamber 22 communicates with the first chamber 21, and the upper second heat exchange tubes 32u open to the second chamber 22. The lower second heat exchanger tube 32z and the lowermost first heat exchanger tube 31z open to the lowermost chamber 20z, with the lowermost first heat exchanger tube 31z being the first heat exchanger tube 31 closest to the lower second heat exchanger tube 32 z.

Both the lower second heat exchanger tube 32z and the lowermost first heat exchanger tube 31z open to the lowermost chamber 20 z. Therefore, a connection flow path for connecting the lower second heat exchange tube 32z and the lowermost first heat exchange tube 31z is not required. This can suppress the manufacturing cost of the heat exchanger 4.

The number of second heat exchange tubes 32u opening above the second chamber 22 of the second head 20 is greater than the number of first heat exchange tubes 31u opening above the first chamber 21 of the second head 20.

The gas-liquid two-phase refrigerant having a large phase component flows through the upper second heat exchange tubes 32 u. Since the number of the upper second heat exchange tubes 32u is larger than that of the upper first heat exchange tubes 31u, the pressure loss during the circulation of the refrigerant can be suppressed. On the other hand, a two-phase gas-liquid refrigerant having a large liquid component flows through the upper first heat exchange tube 31 u. In this case, only the gas-phase component of the gas-liquid two-phase refrigerant may flow through the upper portion of the heat exchange tube (gas discharge) and the liquid-phase component may be retained in the lower portion of the heat exchange tube (liquid accumulation). Since the number of the upper first heat exchange tubes 31u is smaller than the number of the upper second heat exchange tubes 32u, the flow path sectional area of the upper first heat exchange tubes 31u is small. Therefore, the two-phase gas-liquid refrigerant flows through the upper first heat exchange tube 31u as a single body. This suppresses the refrigerant circulation by suppressing liquid accumulation, and thus can suppress the refrigerant shortage.

The refrigeration cycle apparatus 1 includes a heat exchanger 4, a temperature sensor 14, and a controller 9. The temperature sensor 14 is connected to the lowermost first refrigerant port 17z below the first chamber 11 opened by the first heat exchange tube 31 in the first header 10, and outputs a signal corresponding to the refrigerant temperature. The control unit 9 controls the defrosting operation based on the output signal of the temperature sensor 14.

When defrosting of frost adhering to the lowermost portion of the heat exchanger 4 is completed, the temperature of the refrigerant flowing out of the first refrigerant port 17 below the first chamber 11 of the first header 10 rises. The temperature sensor 14 is connected to the lowermost first refrigerant port 17z of the first chamber 11. Therefore, the control unit 9 can accurately determine the completion of defrosting of the lowermost portion of the heat exchanger 4 based on the output signal of the temperature sensor 14. Therefore, the defrosting can be completed in a short defrosting operation.

In the heat exchanger 4 of the first embodiment, the temperature sensor 14 is connected to the lowermost first refrigerant port 17 z. During the defrosting operation, high-temperature gas refrigerant flows into the lowermost second refrigerant port 18z adjacent to the lowermost first refrigerant port 17 z. Therefore, the temperature sensor 14 connected to the lowermost first refrigerant port 17z may be affected by the refrigerant temperature of the lowermost second refrigerant port 18 z. In this case, the temperature sensor 14 may be connected to the first refrigerant port 17a below (lower half) the first chamber 11 of the first header 10 except for the lowermost first refrigerant port 17 z. For example, the temperature sensor 14 may be connected to the first refrigerant port 17a of the first small chamber 11a adjacent to the lowermost first small chamber 11 z. Thereby, the temperature sensor 14 becomes less susceptible to the influence of the refrigerant temperature of the lowermost second refrigerant port 18 z.

(second embodiment)

Fig. 8 is a schematic configuration diagram of a heat exchanger 204 according to a second embodiment. The heat exchanger 204 of the second embodiment shown in fig. 8 is different from the heat exchanger 4 of the first embodiment shown in fig. 5 in that it has a connection flow path 19. The configuration of the second embodiment other than the configuration described below is the same as that of the first embodiment.

The connecting channel 19 communicates the lowermost second chamber 12z of the first head 10 with the second chamber 12. The connection channel 19 is connected to the lower side of the second chamber 12.

The lubricating oil (compressor oil) of the compressor 2 is mixed into the refrigerant flowing through the refrigeration cycle apparatus 1. During the heating operation, the gas-phase component of the two-phase gas-liquid refrigerant increases while flowing through the upper second heat exchange tube 32 u. When the gas refrigerant flows into the second chamber 12 from the upper second heat exchange tubes 32u, the liquid compressor oil mixed in the refrigerant falls downward of the second chamber 12 and is retained below the second chamber 12. Therefore, there is a possibility that the compressor oil in the compressor 2 is insufficient.

The heat exchanger 204 of the second embodiment has a connection channel 19 that connects the lowermost second chamber 12z of the first header 10 and the lower side of the second chamber 12. Thereby, the gas refrigerant flowing out of the lowermost second chamber 12z flows through the connecting passage 19 and flows into the lower portion of the second chamber 12. At this time, the gas refrigerant blows up the compressor oil retained below the second chamber 12 and flows out from the second refrigerant port 18. Thus, the compressor oil is returned to the compressor, and therefore, the shortage of the compressor oil in the compressor 2 can be suppressed.

The heat exchanger 4 of the above embodiment is configured as follows: the refrigerant flows into the first head 10, turns back at the second head 20, and flows out of the first head 10. In contrast, the heat exchanger may be configured such that the refrigerant is turned back at each header a plurality of times.

The heat exchanger 4 of the embodiment is configured such that the same number of upper second heat exchange tube openings are provided for the plurality of second cells 22a formed in the second header 20, respectively. In contrast, the heat exchanger may have a different number of upper second heat exchange tube openings for each of the plurality of second cells 22 a.

According to at least one embodiment described above, the heat exchanger 4 has the second heat exchange tubes 32 through which the gas-liquid two-phase refrigerant having a large gas-phase component flows. The second heat exchange tube 32 has a lower second heat exchange tube 32z disposed below the first heat exchange tube 31. This enables defrosting to be completed in a short defrosting operation.

Several embodiments of the present invention have been described, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Description of the reference numerals

1 … refrigeration cycle device, 4 … heat exchanger, 9 … control part, 10 … first head, 11 … first chamber, 12 … second chamber, 12z … second chamber, 14 … temperature sensor, 17 … first refrigerant port (refrigerant inlet/outlet), 20 … second head, 20z … lowest chamber, 21 … first chamber, 22 … second chamber, 30 …, 31 … first heat exchange tube, 31u … upper first heat exchange tube (part of first heat exchange tube), 31z … lowest first heat exchange tube, 32 … second heat exchange tube, 32u … upper second heat exchange tube, 32z … lower second heat exchange tube.

Claims (4)

1. A heat exchanger, having:

a first end enclosure and a second end enclosure which are formed in a cylindrical shape and arranged to be separated from each other; and

a plurality of heat exchange tubes which are arranged at intervals in the central axis direction of the first seal head and the second seal head, two end parts of the heat exchange tubes are opened in the first seal head and the second seal head,

the plurality of heat exchange tubes have a first heat exchange tube through which a gas-liquid two-phase refrigerant having a large liquid phase component flows, and a second heat exchange tube communicating with the first heat exchange tube through which a gas-liquid two-phase refrigerant having a large gas phase component flows,

the second heat exchange tube is provided with an upper second heat exchange tube and a lower second heat exchange tube, the upper second heat exchange tube is arranged above the first heat exchange tube, the lower second heat exchange tube is arranged below the first heat exchange tube,

the first seal head and the second seal head are provided with a plurality of chambers divided along the direction of the central shaft,

as the plurality of chambers, the second head has a first chamber, a second chamber, and a lowermost chamber, a portion of the first heat exchange tubes opens into the first chamber, the second chamber communicates with the first chamber and the upper second heat exchange tubes open into the second chamber, both the lower second heat exchange tubes and the first heat exchange tubes closest to the lower second heat exchange tubes open into the lowermost chamber,

the first chamber is formed with a plurality of first small chambers, the heights of the second seal heads of the plurality of first small chambers in the central axis direction are equal,

a plurality of second small chambers, the number of which is the same as that of the first small chambers, are formed in the second chamber, the height of the second head of the plurality of second small chambers in the central axis direction is equal to the height of the second head of the plurality of second small chambers in the central axis direction, and the height of the second head is larger than that of the first small chambers,

the second head has a plurality of connection flow paths that connect the plurality of first small chambers and the plurality of second small chambers, and each connection flow path connects the nth (n is a natural number) first small chamber from the top of the first chamber and the nth second small chamber from the bottom of the second chamber.

2. The heat exchanger of claim 1,

the number of the second heat exchange tubes opening to the upper part of the second chamber of the second head is more than that of the first heat exchange tubes opening to the first chamber of the second head.

3. The heat exchanger of claim 1 or 2,

as the plurality of chambers, the first head has a first chamber, a second chamber, and a lowermost second chamber, the first heat exchange tube opens into the first chamber, the upper second heat exchange tube opens into the second chamber, the lower second heat exchange tube opens into the lowermost second chamber,

the second chamber at the bottom of the first seal head is communicated with the lower part of the second chamber of the first seal head.

4. A refrigeration cycle apparatus includes:

the heat exchanger of any one of claims 1 to 3;

a temperature sensor that is disposed at a refrigerant inlet and outlet below a first chamber in which the first heat exchange tube in the first header opens, and that outputs a signal corresponding to a refrigerant temperature; and

and a control unit for controlling the defrosting operation based on the output signal of the temperature sensor.

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