Patent Application
20240210132
The present disclosure relates to an outdoor unit heat exchanger including heat-transfer tubes extending in a vertical direction and to an air-conditioning apparatus.
There has been known a heat exchanger including a plurality of columns of heat-transfer tubes extending in a vertical direction. In such a heat exchanger, a first header into which hot-gas refrigerant flows from a refrigerant circuit during a defrosting operation is provided at the bottoms of those of the plurality of heat-transfer tubes that are situated on the furthest windward side where a large amount of frost forms. The hot-gas refrigerant flowing into the first header flows through a plurality of heat-transfer tubes arranged in a row-wise direction, is subjected to heat exchange, and is brought into a liquid-phase state or a two-phase gas-liquid state. The liquid-phase or two-phase gas-liquid refrigerant flows into a turn-back header placed at upper portions of the heat-transfer tubes. The liquid-phase or two-phase gas-liquid refrigerant flowing into the turn-back header flows through a second column of a plurality of heat-transfer tubes and flows into a second header placed parallel to the first header. The hot-gas refrigerant flowing into the second header flows out from the heat exchanger.
Patent Literature 1: International Publication No. 2019/239446
During the defrosting operation, such a heat exchanger may have an insufficient drain gap between the first header and the second header and may be shaped such that a large amount of meltwater from a corrugated fin flows through the gap between the first header and the second header. In this case, poor drainage of the meltwater between the first header and the second header becomes a factor for an ice gorge. In the worst case, freezing of the meltwater causes deformations in the first header and the second header and undesirably results in destruction of the heat exchanger.
The present disclosure has been made in view of the circumstances and has as an object to provide a heat exchanger and an air-conditioning apparatus that do not suffer from a deformation in a header even in the event of freezing of meltwater.
A heat exchanger according to an embodiment of the present disclosure includes a first header that extends in a horizontal direction and into which hot-gas refrigerant flows during a defrosting operation, a plurality of first heat-transfer tubes that extend in a vertical direction, that are provided to the first header, that are spaced from each other in a horizontal direction, and through which the hot-gas refrigerant flowing into the first header flows, a second header provided parallel to the first header, a plurality of second heat-transfer tubes that extend in a vertical direction, that are provided to the second header, that are spaced from each other in a horizontal direction, and through which refrigerant flowing into the first header flows, and a corrugated fin placed between the plurality of first heat-transfer tubes and between the plurality of second heat-transfer tubes. The corrugated fin has an inter-header region between the first header and the second header, and, in the inter-header region, a first drain slit is formed through which meltwater is drained.
According to an embodiment of the present disclosure, the corrugated fin has an inter-header region between the first header and the second header, and, in the inter-header region, a first drain slit is formed through which meltwater is drained. Accordingly, the meltwater is drained through the first drain slit. This prevents the meltwater from freezing and makes it possible to inhibit the first header and the second header from being deformed.
In the following, air-conditioning apparatuses according to embodiments are described with reference to the drawings. In the drawings, identical constituent elements are described with identical reference signs, and a repeated description is given only when needed. The present disclosure may encompass all combinations of combinable ones of components that are described in the following embodiments.
The air-conditioning apparatus 200 includes a compressor 100, a flow switching device 151, a first heat exchanger 152, an expansion device 153, and a second heat exchanger 154. The refrigerant circuit is formed by the compressor 100, the first heat exchanger 152, the expansion device 153, and the second heat exchanger 154 being connected by pipes, namely a high-pressure-side pipe 155a and a low-pressure-side pipe 155b. Further, an accumulator 300 is situated upstream of the compressor 100.
The compressor 100 is configured to suction refrigerant and compress the refrigerant into a high-temperature and high-pressure state. The refrigerant compressed by the compressor 100 is discharged from the compressor 100 and sent to the first heat exchanger 152 or the second heat exchanger 154.
The flow switching device 151 is configured to switch the flow of refrigerant between a heating operation and a cooling operation. That is, the flow switching device 151 switches between connecting the compressor 100 with the second heat exchanger 154 during the heating operation and connecting the compressor 100 with the first heat exchanger 152 during the cooling operation. It should be noted that the flow switching device 151 is preferably formed, for example, by a four-way valve. Note, however, that a combination of two-way valves or three-way valves may be employed as the flow switching device 151.
The first heat exchanger 152 serves as an evaporator during the heating operation and serves as a condenser during the cooling operation. That is, when the first heat exchanger 152 serves as an evaporator, the first heat exchanger 152 causes low-temperature and low-pressure refrigerant flowing out from the expansion device 153 and air supplied, for example, by a fan (not illustrated) to exchange heat with each other, so that low-temperature and low-pressure liquid refrigerant (or two-phase gas-liquid refrigerant) evaporates. On the other hand, when the first heat exchanger 152 serves as a condenser, the first heat exchanger 152 causes high-temperature and high-pressure refrigerant discharged from the compressor 100 and air supplied, for example, by a fan (not illustrated) to exchange heat with each other, so that high-temperature and high-pressure gas refrigerant condenses. It should be noted that the first heat exchanger 152 may be formed by a refrigerant-water heat exchanger. In this case, the first heat exchanger 152 causes refrigerant and a heat medium such as water to exchange heat with each other.
The expansion device 153 is configured to expand and decompress refrigerant flowing out from the first heat exchanger 152 or the second heat exchanger 154. The expansion device 153 is preferably formed, for example, by an electric expansion valve that is capable of adjusting the flow rate of refrigerant. As the expansion device 153, a mechanical expansion valve including a pressure sensing diaphragm, a capillary tube, or other devices, as well as an electric expansion valve, may be applied.
The second heat exchanger 154 serves as a condenser during the heating operation and serves as an evaporator during the cooling operation. That is, when the second heat exchanger 154 serves as a condenser, the second heat exchanger 154 causes high-temperature and high-pressure refrigerant discharged from the compressor 100 and air supplied, for example, by a fan (not illustrated) to exchange heat with each other, so that high-temperature and high-pressure gas refrigerant condenses. On the other hand, when the second heat exchanger 154 serves as an evaporator, the second heat exchanger 154 causes low-temperature and low-pressure refrigerant flowing out from the expansion device 153 and air supplied, for example, by a fan (not illustrated) to exchange heat with each other, so that low-temperature and low-pressure liquid refrigerant (or two-phase gas-liquid refrigerant) evaporates. It should be noted that the second heat exchanger 154 may be formed by a refrigerant-water heat exchanger. In this case, the second heat exchanger 154 causes refrigerant and a heat medium such as water to exchange heat with each other.
Further, the air-conditioning apparatus 200 is provided with a controller 160 configured to exercise overall control of the air-conditioning apparatus 200. Specifically, the controller 160 controls the driving frequency of the compressor 100 according to the required cooling capacity or heating capacity. Further, the controller 160 controls the opening degree of the expansion device 153 for each operational state and each mode. Furthermore, the controller 160 controls the flow switching device 151 according to each mode.
On the basis of an operating instruction from a user, the controller 160 controls an actuator of each of the devices such as the compressor 100, the expansion device 153, and the flow switching device 151 with reference to information sent from temperature sensors (not illustrated) and pressure sensors (not illustrated).
It should be noted that the controller 160 can be formed by hardware such as a circuit device that performs functions of the controller 160 and can be formed by an arithmetic device such as a microcomputer and a CPU and software that is run on the arithmetic device.
The controller 160 is formed by dedicated hardware or a central processing unit (CPU; also referred to as “central processor”, “processing unit”, “arithmetic device”, “microprocessor”, “microcomputer”, or “processor”) configured to execute programs that are stored in a memory. In a case in which the controller 160 is the dedicated hardware, the controller 160 corresponds to, for example, a single circuit, a complex circuit, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination of these circuits and array. Functional parts that the controller 160 includes may be formed by respective separate pieces of hardware or may be formed by one piece of hardware. In a case in which the controller 160 is the CPU, functions that the controller 160 executes may be implemented by software, firmware, or a combination of the software and the firmware. The software and the firmware are described as programs and stored in the memory. The CPU implements the functions of the controller 160 by reading out and executing the programs stored in the memory. Note here that the memory is a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, and an EEPROM. Some of the functions of the controller 160 may be implemented by the dedicated hardware, and others of the functions of the controller 160 may be implemented by the software or the firmware.
Next, actions of the air-conditioning apparatus 200 are described with reference to the flow of refrigerant. Actions of the air-conditioning apparatus 200 during the cooling operation are described here by taking as an example a case in which air serves as a heat exchange fluid at the first heat exchanger 152 and the second heat exchanger 154. In
Driving the compressor 100 causes high-temperature and high-pressure gaseous refrigerant to be discharged from the compressor 100. The high-temperature and high-pressure gas refrigerant (single-phase) discharged from the compressor 100 flows into the first heat exchanger 152. In the first heat exchanger 152, the high-temperature and high-pressure gas refrigerant flowing into the first heat exchanger 152 and air supplied by a fan (not illustrated) exchange heat with each other, so that the high-temperature and high-pressure gas refrigerant condenses into high-pressure liquid refrigerant (single-phase).
The high-pressure liquid refrigerant sent out from the first heat exchanger 152 is turned by the expansion device 153 into two-phase refrigerant including low-pressure gas refrigerant and liquid refrigerant. The two-phase refrigerant flows into the second heat exchanger 154. In the second heat exchanger 154, the two-phase refrigerant flowing into the second heat exchanger 154 and air supplied by a fan (not illustrated) exchange heat with each other, so that the liquid refrigerant included in the two-phase refrigerant evaporates into low-pressure gas refrigerant (single-phase). The low-pressure gas refrigerant sent out from the second heat exchanger 154 flows into the compressor 100 via the accumulator 300, is compressed into high-temperature and high-pressure gas refrigerant, and is discharged again from the compressor 100. Then, this cycle is repeated.
It should be noted that the actions of the air-conditioning apparatus 200 during the heating operation are executed by using the flow switching device 151 to cause refrigerant to flow as indicated by the solid arrows in
It should be noted that the flow switching device 151, which is provided on a discharge side of the compressor 100, may be omitted so that refrigerant flows in a given single direction.
As shown in
The first header 1 has a hot-gas refrigerant inlet 1_1 through which hot-gas refrigerant flows in during a defrosting operation. The first header 1 has the shape of a cuboid that extends in a horizontal direction.
The plurality of first heat-transfer tubes 4 are provided in an upper surface of the first header 1 such that the plurality of first heat-transfer tubes 4 are spaced from each other in a horizontal direction and extend in a vertical direction. The hot-gas refrigerant flowing into the first header 1 flows through the plurality of first heat-transfer tubes 4. The plurality of first heat-transfer tubes 4 are flat tubes.
The second header 2 has the shape of a cuboid that extends in a horizontal direction, and is provided parallel to the first header 1. The second header 2 has a hot-gas refrigerant outlet 2_1. During the defrosting operation, the hot-gas refrigerant flows in through the hot-gas refrigerant inlet 1_1 and is condensed into liquid refrigerant or two-phase gas-liquid refrigerant and is caused to flow out from the hot-gas refrigerant outlet 2_1.
An inter-header distance between the first header 1 and the second header 2 is δ [mm].
The plurality of second heat-transfer tubes 5 are provided in an upper surface of the second header 2 such that the plurality of second heat-transfer tubes 5 are spaced from each other in a horizontal direction and extend in a vertical direction. During the defrosting operation, the hot-gas refrigerant flows into the first header 1 and is condensed into the liquid refrigerant or two-phase gas-liquid refrigerant and flows through the plurality of second heat-transfer tubes 5. The plurality of second heat-transfer tubes 5 are flat tubes.
The third header 3 has the shape of a cuboid and is provided at upper portions of the plurality of first heat-transfer tubes 4 and at upper portions of the plurality of second heat-transfer tubes 5. The liquid refrigerant or two-phase gas-liquid refrigerant into which the hot-gas refrigerant has been condensed by flowing through the plurality of first heat-transfer tubes 4 flows from the plurality of first heat-transfer tubes 4 into the third header 3. Further, the third header 3 causes the liquid refrigerant or two-phase gas-liquid refrigerant flowing in from the first heat-transfer tubes 4 to flow through the plurality of second heat-transfer tubes 5.
Note here that δ×W is an inter-header gap area. It should be noted that the drain slit area A1 is a value obtained by combining all of the areas of a first drain slit 23, a second drain slit 24a, a second drain slit 24b, and a second drain slit 24c in one surface of the corrugated fin 20. The term “one surface of the corrugated fin 20” refers to one surface bridging between adjacent first heat-transfer tubes 4, that is, the surface shown in
As shown in
In the inter-header region S1 of the corrugated fin 20, a first drain slit 23 is formed through which meltwater is drained. The first drain slit 23 has the shape of a rectangle and is formed parallel to a direction along long sides of the first header 1 and the second header 2.
In
In the first heat-transfer tube region S2, the second drain slit 24a is formed. As with the first drain slits 23, the second drain slit 24a formed in the first heat-transfer tube region S2 has the shape of a rectangle and is formed parallel to a direction along the long sides of the first header 1 and the second header 2.
In the second heat-transfer tube region S3, a plurality of louvers 22a are formed parallel to a direction along the long sides of the first header 1. The plurality of louvers 22a connect the first heat-transfer tubes 4 with each other. The plurality of louver 22a include a pair of louvers 22a, which face each other across the second drain slit 24a.
In the second heat-transfer tube region S3, the second drain slit 24b is formed. As with the first drain slits 23, the second drain slit 24b formed in the second heat-transfer tube region S3 has the shape of a rectangle and is formed parallel to a direction along the long sides of the first header 1 and the second header 2.
In the second heat-transfer tube region S3, a plurality of louvers 22b are formed parallel to a direction along the long sides of the second header 2. The plurality of louvers 22b connect the second heat-transfer tubes 5 with each other. The plurality of louver 22b include a pair of louvers 22b, which face each other across the second drain slit 24b.
As shown in
As shown in
As shown in
As shown in
Ls denotes the distance between the left louvers 22b_1 and 22b_2 along a louver direction, the distance between the louvers 22b_2 and 22b_3 along the louver direction, and the distance between the louvers 22b_3 and 22b_4 along the louver direction. Ls is a space in which frost grows.
Rp is the distance between the center of the right louver 22a_1 and the center of the louver 22a_2 in a horizontal direction, the distance between the center of the louver 22a_2 and the center of the louver 22a_3 in a horizontal direction, and the distance between the center of the louver 22a_3 and the center of the louver 22a_4 in a horizontal direction.
Lp is the distance between the center of the left louver 22b_1 and the center of the louver 22b_2 in a horizontal direction, the distance between the center of the louver 22b_2 and the center of the louver 22b_3 in a horizontal direction, and the distance between the center of the louver 22b_3 and the center of the louver 22b_4 in a horizontal direction.
θ is an angle that the right lovers 22a_1 to 22a_4 and the left louvers 22b_1 to 22b_4 form with a horizontal direction. In
Further, the louver 22a_1 and the louver 22b_1 make a pair. The louver 22a_2 and the louver 22b_2 make a pair. The louver 22a_4 and the louver 22b_4 make a pair.
Ss denotes the width of the first drain slit 23 in a horizontal direction. Line DD-DD is an auxiliary line passing through the center of the width Ss of the first drain slit 23 in a horizontal direction from an upper surface to a lower surface of the corrugated fin 20.
As shown in
Similarly, virtual auxiliary lines drawn to lines extending along surfaces of the pair of louvers 22a_1 and 22b_1 intersect each other on the lower surface side of the corrugated fin 20. Virtual auxiliary lines drawn to lines extending along surfaces of the pair of louvers 22a_2 and 22b_2 intersect each other on the lower surface side of the corrugated fin 20. Virtual auxiliary lines drawn to lines extending along surfaces of the pair of louvers 22a_4 and 22b_4 intersect each other on the lower surface side of the corrugated fin 20.
Accordingly, the heat exchanger 10 according to Embodiment 1 causes meltwater to be drained through the first drain slit 23, thus making it possible to inhibit the first header 1 and the second header 2 from being deformed by the meltwater freezing.
Further, even in a case in which the inter-header area is smaller than the opening area of the first drain slit 23, meltwater that is retained between the first header 1 and the second header 2 can be reduced. This results in making it possible to inhibit the first header 1 and the second header 2 from being deformed. Embodiment 2.
A heat exchanger 10 of Embodiment 2 is one in which the inter-header distance δ between the first header 1 and the second header 2 is kept by forming protrusions on the first header 1 and the second header 2.
As shown in
The first protrusion 1_2 and the second protrusion 2_2 are provided in positions corresponding to each other. In a case in which the first header 1 and the second header 2 are placed, the first protrusion 1_2 and the second protrusion 2_2 are in contact with each other, and the length of the first protrusion 1_2 and the second protrusion 2_2 in contact with each other in a horizontal direction is the inter-header distance δ. This causes the inter-header distance, which is the distance between the first header 1 and the second header 2, to be δ.
The number of first protrusions 1_2 and the number of second protrusions 2_2 may be plural, although a case has been described in which one first protrusion 1_2 is formed on the first header 1 and one second protrusion 2_2 is formed on the second header 2.
Accordingly, the heat exchanger 10 according to Embodiment 2 has the first protrusion 1_2 formed on the first header 1 and the second protrusion 2_2 formed on the second header 2. This makes it possible to secure the inter-header distance o between the first header 1 and the second header 2. This results in making it possible to inhibit the first header 1 and the second header 2 from being damaged by an ice gorge.
A heat exchanger 10 of Embodiment 3 is one in which the inter-header distance δ between the first header 1 and the second header 2 is kept by providing a positioning element between the first header 1 and the second header 2.
As shown in
It should be noted that a plurality of the positioning elements 31 may be provided between the first header 1 and the second header 2.
Accordingly, the heat exchanger 10 according to Embodiment 3 has the positioning element 31 provided between the first header 1 and the second header 2. This makes it possible to secure the inter-header distance δ between the first header 1 and the second header 2. This results in making it possible to inhibit the first header 1 and the second header 2 from being damaged by an ice gorge.
A heat exchanger 10 according to Embodiment 4 has a plurality of headers integrally formed and a drain slit provided between a flow passage of each header and a flow passage of an adjacent header.
As shown in
The first header 1a has a hot-gas refrigerant inlet through which hot-gas refrigerant flows in during a defrosting operation. The first header 1a has the shape of a cuboid that extends in a horizontal direction. The first header 1b is provided parallel to the first header 1a and has a hot-gas refrigerant inlet through which hot-gas refrigerant flows in during a defrosting operation. The first header 1b has the shape of a cuboid that extends in a horizontal direction.
A plurality of first heat-transfer tubes 4a are provided in an upper surface of the first header 1a such that the plurality of first heat-transfer tubes 4a are spaced from each other in a horizontal direction and extend in a vertical direction. The hot-gas refrigerant flowing into the first header 1a flows through the plurality of first heat-transfer tubes 4a. The plurality of first heat-transfer tubes 4a are flat tubes. A plurality of first heat-transfer tubes 4b are provided in an upper surface of the first header 1b such that the plurality of first heat-transfer tubes 4b are spaced from each other in a horizontal direction and extend in a vertical direction. The hot-gas refrigerant flowing into the first header 1b flows through the plurality of first heat-transfer tubes 4b. The plurality of first heat-transfer tubes 4b are flat tubes.
A third drain slit 25 is provided between the first header 1a and the first header 1b. The third drain slit 25 allows drainage of meltwater from the first heat-transfer tubes 4a and the first heat-transfer tubes 4b. The third drain slit 25 has the shape of a rectangle whose long sides extend in a direction orthogonal to a horizontal direction and a direction of extension of the first heat-transfer tubes 4a. As shown in
It should be noted that also in a case in which the second header 2 includes a plurality of headers, a configuration that is similar to that in which the first header 1 includes a plurality of headers can be employed. Further, although Embodiment 4 has shown a case in which the first header 1 includes the first header 1a and the first header 1b, the number of first headers is not limited to two but may be larger than or equal to three.
Further, the first header 1a is also referred to as “third header”, and the first header 1b is also referred to as “fourth header”.
Accordingly, the heat exchanger 10 according to Embodiment 4 makes it possible to form a heat exchanger at low cost, as the first header 1a and the first header 1b can be integrally formed. Further, providing the third drain slit 25 makes it possible to insulate heat of a flow passage of the first header 1a and heat of a flow passage of the first header 1b from each other. This makes it possible to thermally reduce heat leakage between the first header 1a and the first header 1b. At this time, making the gap of the third drain slit 25 greater than or equal to 1 mm more preferably makes it possible to reduce residual meltwater.
The embodiments have been presented as examples and are not intended to limit the scope of the claims. The embodiments may be carried out in other various forms, and various omissions, substitutions, and changes can be made without departing from the gist of the embodiments. These embodiments and modifications of these embodiments are encompassed in the scope and gist of the embodiments.
This application is a U.S. National Stage Application of International Application No. PCT/JP2021/019807 filed May 25, 2021, the contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/019807 | 5/25/2021 | WO |
