CN111527356A - 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 exchangers and refrigeration cycle devices

technical field

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

Background technique

A heat exchanger for exchanging heat between refrigerant and outside air is used. When 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 refrigeration cycle apparatus suspends the normal operation and performs the defrosting operation. A heat exchanger capable of defrosting in a short defrosting operation is required.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2012-163319

SUMMARY OF THE INVENTION

The problem to be solved by the invention

The problem to be solved by the present invention is to provide a heat exchanger and a refrigeration cycle apparatus that can complete defrosting in a short-time defrosting operation.

means to solve the problem

The heat exchanger of the embodiment has a first header, a second header, and a plurality of heat exchange tubes. The first head and the second head are formed in a cylindrical shape, and are arranged to be spaced apart from each other. A plurality of heat exchange tubes are arranged at intervals in the direction of the central axis of the first head and the second head, and both ends are opened inside the first head and the second head . The plurality of heat exchange tubes includes a first heat exchange tube and a second heat exchange tube. The first heat exchange tube is for the flow of the gas-liquid two-phase refrigerant with many liquid phase components. The second heat exchange tube communicates with the first heat exchange tube, and supplies the gas-liquid two-phase refrigerant with many gas-phase components to flow. 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 of drawings

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

FIG. 2 is a front view of the heat exchanger according to the first embodiment.

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

FIG. 4 is a partial cross-sectional view taken along the line F4-F4 of FIG. 2 .

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

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

FIG. 7 is a flowchart of a defrosting method.

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

Detailed ways

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

In this application, the X direction, the Y direction, and the Z direction are defined as follows. The Z direction is the central axis direction (extending direction) of the first head and the second head. For example, the Z direction is the vertical direction, and the +Z direction is the upward direction. The X direction is the central axis direction (extending direction) of the heat exchange tube. For example, the X direction is the horizontal direction, and the +X direction is the 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 control unit 9 . The components of the refrigeration cycle apparatus 1 are sequentially connected by pipes 7 . In each figure, the flow direction of the refrigerant during the heating operation is indicated by the broken line arrows, and the flow direction of the refrigerant during the defrosting (cooling) operation is indicated by the solid line arrows.

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

The four-way valve 3 reverses the flow direction of the refrigerant, and switches the heating operation and the 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 causes the indoor heat exchanger 6 to function as a condenser and the outdoor heat exchanger 4 to function as an evaporator to heat the room. 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 and the indoor heat exchanger 6 to function as an evaporator to defrost the outdoor heat exchanger 4 .

The condenser radiates heat and condenses the high-temperature and high-pressure gas refrigerant discharged from the compressor 2 to the outside air, thereby forming a high-pressure liquid refrigerant. The evaporator absorbs heat from the outside air and vaporizes the low-temperature and low-pressure liquid refrigerant sent from the expansion device 5 to form a low-pressure gas refrigerant. A blower fan 4a is provided in the vicinity of the outdoor heat exchanger 4 . The blower fan 4 a 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, and forms a low-temperature and 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 way, 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, dissipates heat in the process of changing the phase from the gas refrigerant to the liquid refrigerant, and dissipates heat during the phase change from the gas refrigerant to the liquid refrigerant. Heat is absorbed during the phase change of the refrigerant to a gaseous refrigerant. Furthermore, heating, defrosting, and the like can be performed by utilizing these heat radiation and heat absorption.

(first embodiment)

FIG. 2 is a front view of the heat exchanger according to the first embodiment. 3 is a partial perspective view of the heat exchanger according to 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 can also 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 includes a first head 10 , a second head 20 , a heat exchange tube 30 , and fins 40 .

The first head 10 is formed of a material with 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, in a cylindrical shape with a circular cross section. Both ends of the first header 10 in the Z direction are blocked. A plurality of through holes into which the heat exchange tubes 30 are inserted are formed on the outer peripheral surface of the first head 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 to be spaced apart from each other in the X direction.

The heat exchange tube 30 is formed of a material with high thermal conductivity and small specific gravity, such as aluminum or an aluminum alloy. As shown in FIG. 3 , the heat exchange tube 30 is formed in a flat tube 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 the line F4-F4 of FIG. 2 . The outer shape of the heat exchange tube 30 is formed in an oval shape. Inside the heat exchange tube 30, a plurality of refrigerant flow paths 34 are formed along the Y direction. Adjacent refrigerant flow paths 34 are partitioned by flow path walls 35 parallel to the XZ plane. The plurality of refrigerant flow paths 34 pass through 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 peripheral surfaces of the first head 10 and the second head 20 . Thereby, both ends of the refrigerant flow path 34 of the heat exchange tube 30 are opened to the inside of the first head 10 and the second head 20 . The first head 10 and the second head 20 and the heat exchange tube 30 are sealed and fixed by brazing or the like.

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

As shown in FIG. 4 , the width of the fins 40 in the Y direction is larger than the width of the heat exchange tubes 30 in the Y direction. Notches 43 are formed in the −Y direction from the edge of the heat sink 40 in the +Y direction. The heat exchange tube 30 is inserted into the cutout 43 . The heat exchange tubes 30 and the fins 40 are fixed by brazing or the like.

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

Outside air flow paths extending in the Y direction are formed between adjacent heat exchange tubes 30 and between adjacent fins 40 . The heat exchanger 4 circulates the outside air through the outside air flow path by the 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 . Heat exchange is performed indirectly via the heat exchange tubes 30 and the fins 40 . The heat sink 40 may be provided with unevenness. The unevenness creates a turbulent flow of the outside air circulating in the outside air flow path, and improves the heat exchange efficiency.

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

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

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

The first header 10 has a plurality of partition members. The partition member is arranged parallel to the XY plane, and partitions the inside of the first head 10 in the Z direction. The plurality of partition members divide the inside 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 15s.

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

The intermediate partition member 15s is arranged 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 and 11z. In the example of FIG. 5, the four intermediate partition members 15s divide the first chamber 11 into five first cells 11a, 11z. In the example of FIG. 5 , the heights in the Z direction of the five first cells 11a and 11z are equal.

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

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

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

The intermediate partition member 25s is arranged 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 21a. In the example of FIG. 5, three intermediate partition members 25s divide the first chamber 21 into four first small chambers 21a. In the example of FIG. 5, the height of the Z direction of the four first cells 21a is equal. The heights of the first cells 11 a and 11 z of the first head 10 are equal to the height of the first cells 21 a of the second head 20 .

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

The heat exchange pipe 30 has a first heat exchange pipe 31 and a second heat exchange pipe 32 . The first heat exchange tube 31 is arranged downward from the center in the Z direction of the heat exchanger 4 . The second heat exchange tube 32 has an upper second heat exchange tube 32u and a lower second heat exchange tube 32z. The upper second heat exchange pipe 32u is arranged above the first heat exchange pipe 31 . The lower second heat exchange tube 32 z is arranged below the first heat exchange tube 31 and is arranged at the bottom of the plurality of heat exchange tubes 30 .

The first end portion of the first heat exchange tube 31 in the −X direction is open to the first chamber 11 of the first head 10 . The plurality of first heat exchange tubes 31 are respectively opened in the plurality of first small chambers 11 a and 11 z formed in the first chamber 11 . In the example of FIG. 5 , the same number of first heat exchange tubes 31 are opened for each of the plurality of first cells 11a and 11z. Among the plurality of first cells 11a and 11z, the lowermost first cell 11z arranged at the lowermost has an opening of the lowermost first heat exchange tube 31z. The lowermost first heat exchange tube 31z is arranged at the lowermost part of the first heat exchange tube 31 . Therefore, the lowermost first heat exchange tube 31z is closest to the lower second heat exchange tube 32z.

The second end portion in the +X direction of the first heat exchange tube 31 is open to the first chamber 21 or the lowermost chamber 20z of the second head 20 . The lowermost first heat exchange tube 31z among the first heat exchange tubes 31 is opened in the lowermost chamber 20z. The upper first heat exchange tube 31u arranged above the lowermost first heat exchange tube 31z is open to 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 respectively opened. The number of the first heat exchange tubes 31u opening above the first cell 11a of the first head 10 is the same as the number of the first heat exchange tubes 31u opening above the first cell 21a of the second head 20 .

The first end in the −X direction of the upper second heat exchange tube 32u is open to the second chamber 12 of the first head 10 .

The first end in the −X direction of the lower second heat exchange tube 32 z is open to the lowermost second chamber 12 z of the first head 10 .

The second end of the upper second heat exchange tube 32u in the +X direction is opened to the second chamber 22 of the second head 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 respectively opened. In the example of FIG. 5, with respect to the four second small chambers 22a, the same number of upper second heat exchange tubes 32u are respectively opened. The number of the second heat exchange tubes 32u opened above the second small chamber 22a is greater than the number of the first heat exchange tubes 31u opened above the first small chamber 21a.

The second end in the +X direction of the lower second heat exchange tube 32 z is opened in the lowermost chamber 20 z of the second head 20 . The number of the lower second heat exchange tubes 32z is the same as the number of the lowermost first heat exchange tubes 31z, or more than the number of the lowermost first heat exchange tubes 31z.

The first header 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 respectively formed in the plurality of first cells 11a constituting the first chamber 11, and the lowermost first refrigerant port 17a The refrigerant port 17z is formed in the lowermost first cell 11z. The first refrigerant port 17a constituting the first refrigerant port 17 of the heat exchanger 4 and the lowermost first refrigerant port 17z merge with the connecting pipe 17b, and are connected to the same components 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 includes a second refrigerant port 18a formed above (upper half) of the second chamber 12, and a lowermost second refrigerant port 18z formed in the lowermost second chamber 12z. The second refrigerant port 18a constituting the second refrigerant port 18 of the heat exchanger 4 and the lowermost second refrigerant port 18z merge with the connecting pipe 18b and are connected to the same 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 the 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 apparatus 1 . The control unit 9 detects the temperature of the refrigerant flowing through the first refrigerant port 17 based on the signal input from the temperature sensor 14 .

The second head 20 has a connection flow path 26 . The connection flow path 26 connects the first chamber 21 and the second chamber 22 . Between the plurality of first cells 21a formed in the first chamber 21 and the plurality of second cells 22a formed in the second chamber 22, connection flow paths 26a are formed, respectively. In the example of FIG. 5 , the connection flow path 26 a connects the n-th (n is a natural number) first cell 21 a from above the first chamber 21 and the n-th second cell 22 a from below the second chamber 22 . Thereby, the intersection of the plurality of connection flow paths 26 can be avoided, and the layout can be simplified. The connection flow path 26a may connect the first cell 21a and the second cell 22a by 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 other than the configuration described below in the configuration of the modified example is the same as the configuration of the first embodiment.

The heat exchanger 104 does not have the intermediate partition members 15s and 25s in the first head 10 and the second head 20 . That is, the first chamber 11 of the first head 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 head 10 . The connection flow path 26 connects the upper part of the first chamber 21 and the lower part of the second chamber 22 of the second head 20 . Thereby, the gas-liquid two-phase refrigerant with many liquid-phase components flows out and flows in from below, and the gas-liquid two-phase refrigerant with many gas-phase components flows in and out from above. Therefore, it is possible to suppress the shortage of the refrigerant accompanying the retention of the refrigerant.

The heat exchanger 104 of the modified example also has the same functions and effects as the heat exchanger 4 of the first embodiment.

The flow path of the refrigerant in the heat exchanger 4 of 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 arrows, and the flow direction of the refrigerant during the defrosting operation is indicated by the solid line arrows.

The flow path of the refrigerant when the refrigeration cycle apparatus 1 performs the heating operation will be described.

When the refrigeration cycle apparatus 1 shown in FIG. 1 performs the 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 evenly distributed by a refrigerant distribution mechanism (not shown), and flows into the second refrigerant port 17 constituting the first refrigerant port 17 of the heat exchanger 4 shown in FIG. 5 via the connecting pipe 17b. A refrigerant port 17a and a lowermost first refrigerant port 17z.

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

The refrigerant flows into the upper first heat exchange tube 31u from the first cell 11a, and flows into the lowermost first heat exchange tube 31z from the lowermost first cell 11z. The refrigerant absorbs heat from the outside air while circulating through the first heat exchange tubes 31 . As a result, the liquid refrigerant becomes a gas-liquid two-phase refrigerant having a large amount of liquid phase components. That is, the gas-liquid two-phase refrigerant with many liquid phase components flows through the first heat exchange tube 31 .

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

The refrigerant flows from the first small chamber 21a through the connecting flow path 26a and flows into the second small chamber 22a.

The refrigerant flows into the upper second heat exchange tube 32u from the second small chamber 22a, and flows into the lower second heat exchange tube 32z from the lowermost chamber 20z. The refrigerant absorbs heat from the outside air while circulating through the second heat exchange tubes 32 . Thereby, the gas-liquid two-phase refrigerant having a large liquid phase component becomes a gas-liquid two-phase refrigerant having a large gas phase component. That is, the gas-liquid two-phase refrigerant with many gas-phase components flows through the second heat exchange tube 32 .

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

The refrigerant flows out of the heat exchanger 4 from the second refrigerant port 18a and the lowermost second refrigerant port 18z. 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 in the first cell 11a of the first head 10, the upper first heat exchange tube 31u, the first cell 21a of the second head, the connecting flow path 26a, and the second cell 22a of the second head , and the upper second heat exchange tube 32u circulates. In addition, the refrigerant flows in the lowermost first small chamber 11z of the first head 10 , the lowermost first heat exchange tube 31z , the lowermost chamber 20z of the second head, the lower second heat exchange tube 32z and the first head 10 . The lowermost second chamber 12z circulates. The flow paths of these refrigerants constitute modules. A plurality of modules are arranged in parallel in the heat exchanger 4 .

The flow path of the refrigerant when the refrigeration cycle apparatus 1 performs the defrosting operation will be described.

When the defrosting operation is performed, the refrigerant flows in the opposite direction to that when the heating operation is performed. 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 into the second chamber 12 of the first head 10 and the lowermost second chamber 12z from the second refrigerant ports 18a and 18z. The refrigerant flows into the second heat exchange tube 32 from the second chamber 12 and the lowermost second chamber 12z. In the process of flowing through the second heat exchange tube 32, the refrigerant radiates heat to the outside air. Thereby, the gas refrigerant becomes a gas-liquid two-phase refrigerant with many gas-phase components. That is, the gas-liquid two-phase refrigerant with many gas-phase components flows through the second heat exchange tube 32 .

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

The refrigerant flows into the first heat exchange tube 31 from the first chamber 21 and the lowermost chamber 20z of the second head 20 . In the process of flowing through the first heat exchange tube 31, the refrigerant radiates heat to the outside air. Thereby, the gas-liquid two-phase refrigerant with many gas phase components becomes the gas-liquid two-phase refrigerant with many liquid phase components. That is, the gas-liquid two-phase refrigerant with many liquid phase components flows through the first heat exchange tube 31 .

The refrigerant flows into the first chamber 11 of the first head 10 from the first heat exchange tube 31 . The refrigerant flows into the first refrigerant port 17 from the first chamber 11 . The refrigerant flows out from the first refrigerant port 17 to the outside of the heat exchanger 4 . 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 with a large liquid phase component flows through the first heat exchange tube 31 , and the gas-liquid two-phase refrigerant flows through the second heat exchange tube 32 with a large gas phase component gas-liquid two-phase refrigerant. That is, in the first heat exchange tube 31 , the gas-liquid two-phase refrigerant having more liquid phase components than the second heat exchange tube 32 flows. In the second heat exchange tube 32 , a gas-liquid two-phase refrigerant having more gas-phase components than the first heat exchange tube 31 flows.

During the defrosting operation, a gas-liquid two-phase refrigerant having many gas-phase components flows into the second heat exchange pipe 32 . In the process of flowing through the second heat exchange tube 32, the refrigerant radiates heat to the outside air, so that the liquid phase component of the gas-liquid two-phase refrigerant increases. The upper second heat exchange pipe 32u occupying most of the second heat exchange pipe 32 is arranged above the first heat exchange pipe 31 . Therefore, the liquid phase component of the refrigerant flows through the first heat exchange tube 31 from the upper second heat exchange tube 32u due to gravity. Thereby, the shortage of the refrigerant accompanying the retention of the refrigerant can be suppressed.

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

FIG. 7 is a flowchart of a defrosting method. The control part 9 of the refrigeration cycle apparatus 1 performs a heating operation (S02). The control unit 9 switches the four-way valve 3 so that 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.

When the refrigeration cycle apparatus 1 performs the 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 that constitute the external air flow path. The dew condensation water flows downward along the plate-shaped fins 40 and stays at the bottom of the heat exchanger 4 . When the outside air temperature is low, the dew condensation water freezes and frost adheres. Therefore, frost tends to adhere to the lowermost part of the heat exchanger 4 .

When frost forms on the outside air flow path of the heat exchanger 4 , it becomes difficult for the refrigerant to absorb heat from the outside air, and the heat exchange efficiency decreases. When the temperature of the refrigerant is lower than that of the outside air, the refrigerant tends to absorb heat from the outside air, and the heat exchange efficiency improves. Therefore, the control unit 9 reduces the temperature of the refrigerant by throttling the expansion device 5 . When frost forms on the external air flow path of the heat exchanger 4, the refrigerant temperature is lowered to less than 0°C.

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

When the determination of S04 is YES, the control part 9 substitutes Te into Te0 (S06). The control unit 9 determines whether or not the difference ΔTe between the previously detected refrigerant temperature Te0 and the newly detected refrigerant temperature Te exceeds a predetermined value α ( S08 ). The predetermined value α is set at, for example, 3°C to 10°C. When the difference ΔTe exceeds the predetermined value α, the refrigerant temperature drops sharply. When frost forms on the outside air flow path of the heat exchanger 4, the control unit 9 rapidly lowers the temperature of the refrigerant.

When the determination of S08 is YES, the control part 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 4 a of the heat exchanger 4 .

The control part 9 performs a defrosting operation (S12). The control unit 9 switches the four-way valve so that 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. The control unit 9 starts the operation of the compressor 2 . The control unit 9 does not operate the blower fan 4a.

During the defrosting operation, the high-temperature gas refrigerant flowing out of the compressor 2 flows into the second heat exchange tube 32 of the heat exchanger 4 . The gas refrigerant dissipates heat in the process of circulating in the second heat exchange pipe 32 . The heat exchanger 4 of the embodiment has, as the second heat exchange pipe 32 , in addition to the upper second heat exchange pipe 32u, the lower second heat exchange pipe 32z. The frost adhering to the lowermost part of the heat exchanger 4 is melted while the high-temperature gas refrigerant flows through the lower second heat exchange tube 32z. Even when a large amount of frost adheres to the lowermost part of the heat exchanger 4, since the lower second heat exchange tube 32z is arranged below the heat exchanger 4, efficient defrosting can be performed. Thereby, defrosting can be completed in a short defrosting operation. The water after the frost has melted falls below the heat exchanger 4, so that the re-adhesion of the frost can be prevented.

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

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

The control unit 9 restarts the heating operation (S18). At this time, the control unit 9 switches the four-way valve 3 so that 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.

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

As described in detail above, the heat exchanger 4 of the embodiment includes the first head 10 , the second head 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 are arranged to be spaced apart 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 ends are opened at the first head 10 and the second head 20 . internal. The plurality of heat exchange tubes 30 have first heat exchange tubes 31 and second heat exchange tubes 32 . The first heat exchange tube 31 flows a gas-liquid two-phase refrigerant with many liquid phase components. The second heat exchange pipe 32 communicates with the first heat exchange pipe 31, and supplies the gas-liquid two-phase refrigerant with many gas-phase components to flow. The second heat exchange tube 32 has an upper second heat exchange tube 32u and a lower second heat exchange tube 32z. The upper second heat exchange pipe 32u is arranged above the first heat exchange pipe 31 . The lower second heat exchange pipe 32z is arranged below the first heat exchange pipe 31 .

Frost tends to adhere to the lowermost part of the heat exchanger 4 . A gas-liquid two-phase refrigerant with many gas-phase components flows through the second heat exchange tube 32 . The second heat exchange pipe 32 has a lower second heat exchange pipe 32z. Therefore, the heat exchanger 4 can efficiently defrost the frost adhering to the bottom. Therefore, 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 exchange pipe 31u which is a part of the first heat exchange pipe 31 is opened to the first chamber 21 . The second chamber 22 communicates with the first chamber 21 , and the upper second heat exchange tube 32u is opened in the second chamber 22 . Both the lower second heat exchange tube 32z and the lowermost first heat exchange tube 31z are opened in the lowermost chamber 20z, and the lowermost first heat exchange tube 31z is the first heat exchange tube closest to the lower second heat exchange tube 32z 31.

Both the lower second heat exchange tube 32z and the lowermost first heat exchange tube 31z are opened in the lowermost chamber 20z. Therefore, a connection flow path connecting the lower second heat exchange tube 32z and the lowermost first heat exchange tube 31z is not required. Thereby, the manufacturing cost of the heat exchanger 4 can be suppressed.

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

The gas-liquid two-phase refrigerant with many gas-phase components flows through the upper second heat exchange tube 32u. Since the number of the upper second heat exchange tubes 32u is larger than the number of the upper first heat exchange tubes 31u, the pressure loss during the flow of the refrigerant can be suppressed. On the other hand, a gas-liquid two-phase refrigerant having many liquid-phase components flows through the upper first heat exchange tube 31u. At this time, only the gas-phase component of the gas-liquid two-phase refrigerant circulates in the upper part of the heat exchange tube (gas discharge), and the liquid phase component may stay in the lower part 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 passage cross-sectional area of the upper first heat exchange tubes 31u is small. Therefore, in the upper first heat exchange tube 31u, the gas-liquid two-phase refrigerant flows integrally. Thereby, the liquid accumulation is suppressed and the refrigerant circulates, so that the shortage of the refrigerant can be suppressed.

The refrigeration cycle apparatus 1 includes a heat exchanger 4 , a temperature sensor 14 , and a control unit 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 head 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 the defrosting of the frost adhering to the lowermost part of the heat exchanger 4 is completed, the temperature of the refrigerant flowing out from the first refrigerant port 17 below the first chamber 11 of the first head 10 increases. The temperature sensor 14 is connected to the lowermost first refrigerant port 17z in the lowermost part of the first chamber 11 . Therefore, based on the output signal of the temperature sensor 14, the control part 9 can judge correctly that the defrosting of the lowermost part of the heat exchanger 4 is complete. Therefore, 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 17z. During the defrosting operation, a high-temperature gas refrigerant flows into the lowermost second refrigerant port 18z adjacent to the lowermost first refrigerant port 17z. Therefore, the temperature sensor 14 connected to the lowermost first refrigerant port 17z may be influenced by the refrigerant temperature of the lowermost second refrigerant port 18z. In this case, the temperature sensor 14 may be connected to the first refrigerant port 17a below (lower half) of the first chamber 11 of the first head 10 except for the lowermost first refrigerant port 17z. For example, the temperature sensor 14 may be connected to the first refrigerant port 17a of the adjacent first cell 11a above the lowermost first cell 11z. Thereby, the temperature sensor 14 becomes less susceptible to the influence of the refrigerant temperature of the lowermost second refrigerant port 18z.

(Second Embodiment)

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

The connection flow path 19 communicates the lowermost second chamber 12z of the first head 10 with the second chamber 12 . The connection flow path 19 is connected to the lower part of the second chamber 12 .

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

The heat exchanger 204 according to the second embodiment has the connection flow path 19 that communicates the lowermost second chamber 12z of the first head 10 and the lower side of the second chamber 12 . Thereby, the gas refrigerant flowing out of the lowermost second chamber 12 z flows through the connecting flow path 19 and flows into the lower part of the second chamber 12 . At this time, the gas refrigerant ejects the compressor oil stagnant under the second chamber 12 and flows out from the second refrigerant port 18 . Thereby, since the compressor oil is returned to the compressor, the shortage of the compressor oil in the compressor 2 can be suppressed.

The heat exchanger 4 of the above-described embodiment is configured such that the refrigerant flows into the first head 10 , turns back at the second head 20 , and flows out from the first head 10 . On the other hand, the heat exchanger may have a configuration in which the refrigerant is folded back multiple times at each head.

The heat exchanger 4 of the embodiment is configured to have the same number of openings for the upper second heat exchange tubes in each of the plurality of second cells 22 a formed in the second head 20 . On the other hand, the heat exchanger may be configured to have a different number of upper second heat exchange tube openings with respect to each of the plurality of second cells 22a.

According to at least one embodiment described above, the heat exchanger 4 includes the second heat exchange tubes 32 through which the gas-liquid two-phase refrigerant having many gas-phase components flows. The second heat exchange pipe 32 has a lower second heat exchange pipe 32z arranged below the first heat exchange pipe 31 . Thereby, defrosting can be completed in a short defrosting operation.

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

Description of reference numerals

1...refrigeration cycle device, 4...heat exchanger, 9...control unit, 10...first head, 11...first chamber, 12...second chamber, 12z...lowermost second chamber, 14...temperature sensor, 17 ...first refrigerant port (refrigerant inlet and outlet), 20...second head, 20z...lowermost chamber, 21...first chamber, 22...second chamber, 30...heat exchange tube, 31...first heat exchange tube , 31u...the first heat exchange pipe above (a part of the first heat exchange pipe), 31z...the first heat exchange pipe at the bottom, 32...the second heat exchange pipe, 32u...the second heat exchange pipe above, 32z...the bottom one Two heat exchange tubes.

Claims (5)

1. A heat exchanger having: The first head and the second head are formed in a cylindrical shape, and are arranged to be separated from each other; and A plurality of heat exchange tubes are arranged at intervals in the direction of the central axis of the first head and the second head, and both ends are opened at the first head and the second head. internal, The plurality of heat exchange tubes include a first heat exchange tube and a second heat exchange tube, the first heat exchange tube is for the flow of a gas-liquid two-phase refrigerant with many liquid phase components, and the second heat exchange tube is connected to the second heat exchange tube. A heat exchange tube is connected to supply the gas-liquid two-phase refrigerant with many gas-phase components to flow, 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, and the lower second heat exchange tube is arranged at the top of the first heat exchange tube. below the first heat exchange tube. 2. The heat exchanger of claim 1 wherein, The first head and the second head have a plurality of chambers divided along the direction of the central axis, As the plurality of chambers, the second head includes a first chamber, a second chamber, and a lowermost chamber, a part of the first heat exchange tubes are opened in the first chamber, and the second chamber is connected to the lowermost chamber. The first chamber is communicated and the upper second heat exchange tube is open to the second chamber, the lower second heat exchange tube and the first heat exchange tube closest to the lower second heat exchange tube are Both sides are opened in the lowermost chamber. 3. The heat exchanger of claim 2, wherein: The number of the upper second heat exchange tubes opening in the second chamber of the second head is greater than the number of the first heat exchange tubes opening in the first chamber of the second head many. 4. The heat exchanger of claim 2 or 3, wherein, As the plurality of chambers, the first head includes a first chamber, a second chamber, and a lowermost second chamber, the first heat exchange pipe is opened in the first chamber, and the upper second heat exchange The tube is opened in the second chamber, the lower second heat exchange tube is opened in the lowermost second chamber, The lowermost second chamber of the first head communicates with the lower part of the second chamber of the first head. 5. A refrigeration cycle device comprising: The heat exchanger of any one of claims 1 to 4; a temperature sensor arranged at a refrigerant inlet and outlet in the first head below the first chamber where the first heat exchange tube opens, and outputs a signal corresponding to the temperature of the refrigerant; and The control unit controls the defrosting operation based on the output signal of the temperature sensor.

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