CN117043519A

CN117043519A - Air conditioning device

Info

Publication number: CN117043519A
Application number: CN202180096107.9A
Authority: CN
Inventors: 宫胁皓亮; 福井智哉; 迫田健一
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2021-03-26
Filing date: 2021-03-26
Publication date: 2023-11-10
Also published as: WO2022201514A1; EP4317811A1; US20240175586A1; EP4317811A4; JP7442731B2; JPWO2022201514A1

Abstract

In an air conditioning device (200) having a heat exchanger (10) that can be switched between an evaporator and a condenser, the heat exchanger (10) is provided with a first heat exchanger (21), a second heat exchanger (22), and a connection pipe (12), and the first heat exchanger (21) is provided with: a first header (213), wherein the first header (213) is divided into a plurality of chambers and connected to one end of the plurality of first heat transfer pipes (212); and a second header (214), the second header (214) extending in the horizontal direction and being connected to the other end of the plurality of first heat transfer pipes (212), the second heat exchanger (22) having: a plurality of second heat transfer pipes (222); a third header (223), wherein the third header (223) extends in the horizontal direction and is connected to one end of the plurality of second heat transfer pipes (222); and a fourth header (224), wherein the fourth header (224) extends in the horizontal direction and is connected to the other end of the plurality of second heat transfer pipes (222), wherein the connection pipe (12) connects the first heat exchanger (21) and the second heat exchanger (22), and wherein the lengths of the plurality of first heat transfer pipes (212) are longer than the lengths of the plurality of second heat transfer pipes (222).

Description

Air conditioning device

Technical Field

The present disclosure relates to an air conditioning apparatus including a heat exchanger that can function as both a condenser and an evaporator.

Background

There is known a technique of using a heat exchanger having flat tubes with flat cross sections as heat transfer tubes, in which heat is exchanged between a refrigerant flowing through the interior of the flat tubes and a fluid outside the flat tubes, for an air conditioning apparatus. For example, patent document 1 discloses a heat exchanger that functions as a condenser in an air conditioning apparatus, the heat exchanger including: the two ends of the plurality of flat tubes are connected to a pair of headers extending in the horizontal direction, and the inside of the headers is partitioned by a partition plate, so that the refrigerant flows in the flat tubes in a serpentine manner.

Patent document 1 proposes reducing the number of flat tubes from the inlet to the outlet in order, and reducing the flow path cross-sectional area of the heat exchanger downstream of the refrigerant flow to be smaller than the flow path cross-sectional area of the heat exchanger upstream of the refrigerant flow. This increases the flow rate of the refrigerant on the downstream side, suppresses the decrease in the heat transfer rate, and can maintain high heat exchange performance.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2015-230129

Disclosure of Invention

Problems to be solved by the invention

In an air conditioning apparatus that switches operation between cooling and heating, a heat exchanger that functions as a condenser also functions as an evaporator when operation is switched. A heat exchanger using flat tubes as disclosed in patent document 1 is suitable for reducing the amount of refrigerant, i.e., so-called refrigerant-saving. However, in the case where the heat exchanger of patent document 1 functions as an evaporator, the flow path cross-sectional area on the side where the refrigerant flows in is smaller than the flow path cross-sectional area on the side where the refrigerant flows out, and there is a possibility that the refrigerant pressure loss increases over the entire length of the flow path. When the pressure loss of the refrigerant increases, the saturation temperature of the refrigerant decreases, and the air conditioning performance decreases.

Accordingly, an object of the present disclosure is to realize an air conditioning apparatus including a heat exchanger capable of achieving both refrigerant saving and high performance.

Means for solving the problems

The air conditioning apparatus of the present disclosure is configured to connect a compressor, a condenser, a pressure reducing device, and an evaporator by pipes to circulate a refrigerant, and includes: a heat exchanger that switches a function of the heat exchanger between the evaporator and the condenser by switching a direction in which a refrigerant flows; and a blower that generates an air flow so as to send air to the heat exchanger, characterized in that,

The heat exchanger includes a first heat exchanger, a second heat exchanger, and a connection pipe,

the first heat exchanger has: a plurality of first heat transfer pipes; a first header extending in a horizontal direction, the internal space being partitioned into a plurality of chambers including a first chamber and a second chamber and connected to one end of the plurality of first heat transfer pipes; and a second header extending in a horizontal direction and connected to an end of the other of the plurality of first heat transfer tubes,

the second heat exchanger has: a plurality of second heat transfer pipes; a third header extending in a horizontal direction and connected to one end of the plurality of second heat transfer tubes; and a fourth header extending in a horizontal direction and connected to the other end of the plurality of second heat transfer tubes,

the connection pipe connects one of the first header and the second header of the first heat exchanger to the third header of the second heat exchanger,

in an operation of causing the heat exchanger to function as the evaporator, the plurality of first heat transfer tubes are connected to: after the refrigerant that should be evaporated from the piping flows into the first chamber of the first header, it is caused to flow from the first chamber to the second header, and is caused to flow from the second header to the second chamber of the first header; connecting the plurality of second heat transfer tubes to: flowing the refrigerant passing through the first heat exchanger from the third header to the fourth header after flowing the refrigerant into the third header of the second heat exchanger via the connection pipe; the piping is connected to: causing the refrigerant passing through the second heat exchanger to be sucked into the compressor,

In an operation of causing the heat exchanger to function as the condenser, the piping is connected to: after the refrigerant to be condensed passes through the second heat exchanger from the piping, the refrigerant is caused to flow into any one of the chambers of the first header of the first heat exchanger or the second header via the connection piping, and the refrigerant after passing through the first heat exchanger is caused to flow out of the first chamber of the first header,

the lengths of the plurality of first heat transfer tubes are longer than the lengths of the plurality of second heat transfer tubes.

Effects of the invention

According to the air conditioning apparatus of the present disclosure, the pressure loss can be reduced in the operation in which the first heat exchanger and the second heat exchanger function as evaporators, the refrigerant density can be reduced in the operation in which the first heat exchanger and the second heat exchanger function as condensers, and both the high performance and the refrigerant saving can be achieved.

Drawings

Fig. 1 is a schematic diagram showing the structure of an air conditioning apparatus according to embodiment 1.

Fig. 2 is a schematic view of an indoor heat exchanger provided in the air conditioning apparatus according to embodiment 1.

Fig. 3 is a schematic view showing an air conditioning apparatus having an indoor heat exchanger according to embodiment 1.

Fig. 4 is a graph showing the relationship between the evaporator performance and the heat transfer tube length ratio of the indoor heat exchanger according to embodiment 1.

Fig. 5 is a schematic view showing an air conditioning apparatus having an indoor heat exchanger according to embodiment 1.

Fig. 6 is a graph showing a relationship between the refrigerant amount and the heat transfer tube length ratio of the indoor heat exchanger according to embodiment 1.

Fig. 7 is a schematic diagram of a first modification of the indoor heat exchanger according to embodiment 1.

Fig. 8 is a schematic diagram of a second modification of the indoor heat exchanger according to embodiment 1.

Fig. 9 is a schematic diagram showing an indoor unit according to embodiment 2.

Fig. 10 is a schematic view showing a refrigerant flowing through a connection pipe of the indoor heat exchanger of fig. 9.

Fig. 11 is a perspective view showing the internal structure of the indoor unit according to embodiment 3.

Fig. 12 is a schematic view of A-A section of the indoor unit of fig. 11.

Fig. 13 is a schematic view of a section A-A of the indoor unit of the comparative example.

Fig. 14 is a schematic diagram illustrating a relationship between an indoor fan and a wind speed in the indoor unit according to embodiment 3.

Fig. 15 is a diagram showing a relationship between a position of the rotation axis direction of the indoor fan in fig. 14 and a wind speed and a relationship between a position of the rotation axis of the indoor fan in the circumferential direction and a wind speed.

Fig. 16 is a schematic diagram showing a refrigerant flow path structure of the heat exchanger of embodiment 3.

Fig. 17 is a characteristic diagram showing an effect of improving the refrigerant flow path structure according to embodiment 3.

Fig. 18 is a perspective view of an indoor unit according to embodiment 4.

Fig. 19 is a schematic view of a section B-B of the indoor unit of fig. 18.

Fig. 20 is a schematic view showing a wind speed distribution of an air flow flowing in the indoor unit of fig. 19.

Fig. 21 is a schematic diagram showing a schematic cross-section of the indoor unit according to embodiment 5.

Fig. 22 is a cross-sectional view schematically showing a section A-A of the indoor unit 202 according to embodiment 5.

Detailed Description

Hereinafter, embodiments of the air conditioning apparatus of the present disclosure will be described. The embodiments shown in the drawings are examples, and do not limit the present disclosure. In addition, the same reference numerals are used for the same or corresponding parts throughout the drawings, and are common throughout the specification. In the following drawings, the size relationship of each structural member may be different from the actual one.

Embodiment 1

Structure of air conditioner 200

Fig. 1 is a schematic diagram showing the structure of an air conditioning apparatus 200 according to embodiment 1. The air conditioning apparatus 200 is a heat pump apparatus including a circuit in which a refrigerant circulates, and in which heat is moved by a refrigeration cycle in which the refrigerant is compressed, condensed, expanded, and evaporated. In such a heat pump apparatus, a pressure reducing device such as a compressor, a condenser, a throttle device, and the like, and an evaporator are connected by piping to circulate a refrigerant. As shown in fig. 1, the air conditioning apparatus 200 according to embodiment 1 includes an outdoor unit 201 and an indoor unit 202. The air conditioning apparatus 200 performs a cooling operation and a heating operation by switching the flow direction of the refrigerant.

The outdoor unit 201 is provided with an outdoor fan 13a, a compressor 14, a four-way valve 15, an outdoor heat exchanger 16, and a throttle device 17. The indoor unit 202 is provided with an indoor heat exchanger 10 and an indoor fan 13b each of which is composed of a first heat exchanger 21 and a second heat exchanger 22. The indoor heat exchanger 10 is a heat exchanger that exchanges heat between indoor air and the temperature of a refrigerant. The indoor fan 13b is a fan that generates an air flow so as to send indoor air to the indoor heat exchanger 10. The outdoor unit 201 is an example of a heat source side heat exchanger. The indoor unit 202 is an example of a use side heat exchanger.

The four-way valve 15 and the outdoor heat exchanger 16 are connected by a pipe 11 a. The outdoor heat exchanger 16 and the expansion device 17 are connected by a pipe 11 b. The throttle device 17 is connected to the first heat exchanger 21 of the indoor heat exchanger 10 via a pipe 11 c. The throttle device 17 is a pressure reducing device that reduces the cross-sectional area through which the refrigerant passes so that the pressure after passing is smaller than the pressure before passing. The second heat exchanger 22 of the indoor heat exchanger 10 is connected to the four-way valve 15 via a pipe 11 d.

The refrigerant flows into the compressor 14, the four-way valve 15, the outdoor heat exchanger 16, the expansion device 17, and the indoor heat exchanger 10, thereby constituting a refrigeration cycle. The four-way valve 15 is a switching valve for switching the flow direction of the refrigerant discharged from the compressor 14, and can switch the flow direction of the refrigerant to either one of the flow toward the outdoor heat exchanger 16 through the pipe 11a and the flow toward the indoor heat exchanger 10 through the pipe 11 d. The four-way valve 15 switches the direction of the flow of the refrigerant to switch the cooling operation and the heating operation of the air conditioning apparatus 200. Instead of the four-way valve 15, the switching valve may be configured by combining a plurality of two-way valves or the like and combining other valves, piping, or the like.

The indoor heat exchanger 10 functions as an evaporator during the cooling operation of the air conditioning apparatus 200, the outdoor heat exchanger 16 functions as a condenser, the indoor heat exchanger 10 functions as a condenser during the heating operation, and the outdoor heat exchanger 16 functions as an evaporator. That is, the air-conditioning apparatus 200 includes a heat exchanger that switches the function between the evaporator and the condenser by reversing the direction of the flow of the refrigerant.

Structure of indoor Heat exchanger 10

Fig. 2 is a schematic view of the indoor heat exchanger 10 provided in the air conditioning apparatus 200 according to embodiment 1. As shown in fig. 2, the indoor heat exchanger 10 is configured by a first heat exchanger 21, a second heat exchanger 22, and a connection pipe 12 connecting the first heat exchanger 21 and the second heat exchanger 22.

The first heat exchanger 21 has a plurality of first heat transfer tubes 212, a plurality of first fins 211, a first header 213, and a second header 214. The second heat exchanger 22 includes a plurality of second heat transfer tubes 222, a plurality of second fins 221, a third header 223, and a fourth header 224. The first heat exchanger 21 and the second heat exchanger 22 are connected by a connecting pipe 12. The first heat transfer pipe 212 and the second heat transfer pipe 222 are heat transfer pipes for passing the refrigerant inside and exchanging heat with the surrounding air outside thereof. The first heat transfer pipe 212 and the second heat transfer pipe 222 are each arranged with a space between adjacent heat transfer pipes, and air passes through the space. The first header 213, the second header 214, the third header 223, and the fourth header 224 distribute refrigerant to or collect refrigerant from a plurality of heat transfer tubes such as the plurality of first heat transfer tubes 212 and the plurality of second heat transfer tubes 222. The piping is connected to either one of the first header 213 and the second header 214 of the first heat exchanger 21, and either one of the third header 223 and the fourth header 224 of the second heat exchanger 22, so that the refrigerant flows in or out.

The connection pipe 12 connects the first heat exchanger 21 and the second heat exchanger 22 in series. That is, the refrigerant passing through one of the first heat exchanger 21 and the second heat exchanger 22 flows into the other through the connecting pipe 12. When both the first heat exchanger 21 and the second heat exchanger 22 function as evaporators, the refrigerant including the liquid phase flows into the second heat exchanger 22 through the first heat exchanger 21 and the connection pipe 12. When both the first heat exchanger 21 and the second heat exchanger 22 function as condensers, the refrigerant including the gas phase flows into the first heat exchanger 21 through the second heat exchanger 22 and the connection pipe 12. In addition, when functioning as an evaporator, the header to which the piping is connected so that the refrigerant containing the liquid phase flows into the first heat exchanger 21 is referred to as a first header 213, and the header to which the piping 12 is connected so as to flow into the second heat exchanger 22 is referred to as a third header 223. In this case, the following configuration is provided: the configuration is not necessarily limited to this, but the refrigerant is allowed to flow into the second heat exchanger 22 from the connection pipe 12 connected to the second header 214 of the first heat exchanger 21 and the refrigerant is allowed to flow out from the fourth header 224 of the second heat exchanger 22. The refrigerant may be introduced into the second heat exchanger 22 from the connection pipe 12 connected to the first header 213 of the first heat exchanger 21, or the refrigerant may be discharged to the outside from the third header 223 of the second heat exchanger 22.

The plurality of first heat transfer tubes 212 of the first heat exchanger 21 are flat tubes, and are stacked alternately with the plurality of first fins 211. The plurality of first fins 211 are, for example, corrugated fins. The flat tube has a cross section perpendicular to the extending direction thereof in a flat shape having a long side in one direction. In general, in an air conditioning apparatus in which a high-pressure refrigerant flows, a porous tube is used that divides an internal flow path into a plurality of portions in a longitudinal direction. Corrugated fins are formed by corrugating a metal sheet having excellent heat conductivity such as aluminum. The heat exchange area of the first heat exchanger 21 is enlarged by the first fins 211 and the second fins 221, so that heat exchange between the heat transfer tubes and the air passing around the flat tubes is improved. The plurality of first heat transfer tubes 212 are arranged in parallel in the longitudinal direction and at intervals in the short direction, and corrugated fin wave tops are bonded to flat tube surfaces facing each other with the intervals therebetween.

The first header 213 and the second header 214 of the first heat exchanger 21 extend in the horizontal direction. The first header 213 is connected to one end of the plurality of first heat transfer tubes 212, and the second header 214 is connected to the other end of the plurality of first heat transfer tubes 212. The first header 213 and the second header 214 have a tubular structure having a larger flow path cross-sectional area inside than the first heat transfer pipe 212. The plurality of first heat transfer pipes 212 are pipes extending in the up-down direction, respectively, and are juxtaposed at intervals in the horizontal direction.

The first heat exchanger 21 and the second heat exchanger 22 are not in a relationship between the upwind and the downwind with respect to the wind sent from the indoor blower 13b or the like, that is, the first heat exchanger 21 and the second heat exchanger 22 are disposed at positions offset when viewed from the upwind side of the blower or the blower path. Typically, either one of first header 213 and second header 214 is disposed in close proximity to either one of third header 223 and fourth header 224, and the other one of first header 213 and second header 214 is disposed further apart from the other one of third header 223 and fourth header 224.

The plurality of second heat transfer tubes 222 of the second heat exchanger 22 are flat tubes, and are alternately stacked with the plurality of second fins 221. The plurality of second fins 221 are, for example, corrugated fins. The second fin 221 expands the heat exchange area of the second heat exchanger 22, as in the first fin 211. Instead of the corrugated fins, plate-like fins or the like may be used for either or both of the first heat exchanger 21 and the second heat exchanger 22.

The third header 223 and the fourth header 224 of the second heat exchanger 22 extend in the horizontal direction. The third header 223 is connected to one end of the plurality of second heat transfer tubes 222, and the fourth header 224 is connected to the other end of the plurality of second heat transfer tubes 222. The third header 223 and the fourth header 224 have tubular structures each having a larger flow path cross-sectional area inside than the second heat transfer pipe 222. The second heat exchanger 22 has a substantially similar structure to the first heat exchanger 21, but differs in the length of the heat transfer tube, the inside of the header, and the like as described later. The plurality of second heat transfer pipes 222 are pipes extending in the up-down direction, respectively, and are juxtaposed at intervals in the horizontal direction. In fig. 1, the plurality of first heat transfer pipes 212 and the plurality of second heat transfer pipes 222 are each shown in a plane, but the present invention is not limited to a configuration in which the first heat transfer pipes 212 and the second heat transfer pipes 222 extend in the vertical direction. At least one of the first heat transfer pipe 212 and the second heat transfer pipe 222 may extend obliquely or in a direction having an angle with each other.

The space inside the first header 213 is partitioned by the partition member 4 into a plurality of chambers including a first chamber 213a and a second chamber 213 b. The space partitioned by the partition member 4 will be referred to as a chamber, and when the partitioned chambers of the respective headers are individually referred to, the first chamber, the second chamber, and the like will be described. In the example of the drawing, the first header 213 is partitioned into three chambers from the first chamber 213a to the third chamber 213 c. In the example of the drawing, the space inside the second header 214 is partitioned by the partition member 4 into a plurality of chambers from the first chamber 214a to the third chamber 214 c.

The space inside the third header 223 is partitioned into a first chamber 223a and a second chamber 223b by a partition member 4. Fourth header 224 is divided into a first chamber 224a and a second chamber 224b by a partition member 4. In the above, all of the manifold interiors are partitioned into a plurality of chambers by the partition member 4, but some of the manifold interior spaces may be configured as a single chamber without being partitioned. The number of divided chambers in first header 213 and second header 214 may be different, and the number of divided chambers in third header 223 and fourth header 224 may be different.

The connection pipe 12 connects one of the first header 213 and the second header 214 of the first heat exchanger 21 to the third header 223 of the second heat exchanger 22. In the example of the drawing, the connection pipe 12 connects the fourth chamber 213d of the first header 213 with the first chamber 223a of the third header 223. In the example of the drawing, the fourth chamber 213d of the first header 213 and the first chamber 223a of the third header 223, to which the connection pipe 12 is connected, are located at the same end portions in the horizontal direction of the first header 213 and the third header 223, respectively. In this way, by adopting a structure in which the connecting pipe 12 connects the chambers of the headers located at the same side ends to each other, the length of the connecting pipe 12 can be shortened. In the drawings, the following structure is shown: the first heat exchanger 21 and the second heat exchanger 22 are connected to the pipes 11c and 11d so that the refrigerant flows in and out from one side in the horizontal direction, and the connecting pipe 12 connects the chambers of the headers at the ends opposite to each other in the horizontal direction. The first chamber 213a of the first header 213 is a chamber at one end in the horizontal direction of the first header 213, and the connecting pipe 12 connects any one of the chambers of the first header 213 located at the other end in the horizontal direction or any one of the chambers of the second header 214 located at the other end in the horizontal direction to the third header 223. The above configuration makes it possible to shorten the connecting pipe 12, but it is also possible to connect the connecting pipe 12 or the pipes 11c and 11d to the chambers at the opposite ends in the horizontal direction. The connection pipe 12 may be connected to any one of the chambers of the third header 223.

In the operation of causing the indoor heat exchanger 10 to function as an evaporator, the refrigerant to be evaporated flows from the pipe 11c into the first chamber 213a of the first header 213 of the first heat exchanger 21. Then, the refrigerant flows from the first heat transfer tube 212 connected to the first chamber 213a into the first chamber 214a of the second header 214, and flows out from the second header 214 while turning the flow direction in the first chamber 214 a. Further, the refrigerant flows from the second header 214 into the second chamber 213b of the first header 213 through the first heat transfer tubes 212 connected to the second chamber 213b of the first header 213. In the first heat transfer tube 212 connected to the first chamber 214a of the second header 214, the flow direction of the refrigerant is opposite up and down in the first heat transfer tube 212 connected to the first chamber 213a of the first header 213 and the first heat transfer tube 212 connected to the second chamber 213b of the first header 213.

The refrigerant turns the flow direction in the second chamber 213b of the first header 213, flows out of the second chamber 213b, and flows into the second chamber 214b of the second header 214. Then, the refrigerant turns the flow direction in second chamber 214b, flows out from second chamber 214b of second header 214, and flows into third chamber 213c of first header 213. Then, the refrigerant turns the flow direction in the third chamber 213c, flows out from the third chamber 213c of the first header 213, and flows into the third chamber 214c of the second header 214. Thereafter, the refrigerant flows from the third chamber 213c of the first header 213 to the first chamber 223a of the third header 223 of the second heat exchanger 22 via the connection pipe 12. Then, the refrigerant flows from the second heat transfer tube 222 connected to the first chamber 223a of the third header 223 into the first chamber 224a of the fourth header 224, and flows into the second chamber 223b of the third header 223 while turning the flow direction in the first chamber 224a of the fourth header 224. Then, the flow direction of the refrigerant is reversed in second chamber 223b and the refrigerant flows into second chamber 224b of fourth header 224. Thereafter, the refrigerant flows out of pipe 11d connected to second chamber 224b of fourth header 224. The pipe 11d is connected to the refrigerant passing through the second heat exchanger 22 so as to be sucked into the compressor 14.

In the operation in which the indoor heat exchanger 10 functions as a condenser, the refrigerant flows in the opposite direction to the evaporator. That is, the refrigerant flows into the second chamber 224b of the fourth header 224 of the second heat exchanger 22 from the pipe 11d, and flows out from the first chamber 213a of the first header 213 of the first heat exchanger 21. After passing through the second heat exchanger 22 from the pipe 11d, the refrigerant discharged from the compressor 14 to be condensed flows into any one of the chambers of the first header 213 or the second header 214 of the first heat exchanger 21 via the connection pipe 12. In the drawing, the connection pipe 12 is connected from the first chamber 223a of the third header 223 of the second heat exchanger 22 to the third chamber 213c of the first header 213, but may be connected to the second header 214. The refrigerant condensed via the first heat exchanger 21 flows out of the first chamber 213a of the first header 213 and toward the throttle device 17.

As described above, the refrigerant that has entered from the chamber at one end of the header in the horizontal direction turns the flow direction between the pair of headers connected by the first heat transfer pipe 212, and advances in a serpentine manner toward the opposite side of the inflow side in the horizontal direction. After flowing into the chamber at the most opposite side, the refrigerant flows out to the other heat exchanger through the connection pipe 12 or flows out to the outside through the pipe 11c or 11 d.

The total of the number of chambers of third header 223 and the number of chambers of fourth header 224 of second heat exchanger 22 is smaller than the total of the number of chambers of first header 213 and the number of chambers of second header 214 of first heat exchanger 21. Therefore, the number of turns in the flow direction of the refrigerant in the second heat exchanger 22 is smaller than that in the first heat exchanger 21.

The number of the first heat transfer pipes 212 and the number of the second heat transfer pipes 222 are the same. The flow path cross-sectional area of each of the plurality of first heat transfer pipes 212 and the plurality of second heat transfer pipes 222 is the same. The lengths of the first header 213, the second header 214, the third header 223, and the fourth header 224 are all the same. Since the first header 213 and the second header 214 use the same thickness pipe, the internal space thereof is substantially the same volume except for the partition member 4, a minute difference in the connection portion with each pipe, and the like. Similarly, the internal spaces of third header 223 and fourth header 224 are substantially the same volume. When the internal spaces of first header 213, second header 214, third header 223 and fourth header 224 are all substantially the same volume, the structure becomes simple. The third header 223 and the fourth header 224 of the second heat exchanger may have a larger internal space than the first header 213 and the second header 214, and for this purpose, the third header 223 and the fourth header 224 may have a larger pipe diameter than the first header 213 and the second header 214.

Length L of the plurality of first heat transfer tubes 212 ₁ Length L of more than one second heat transfer pipe 222 ₂ Long. Length L of first heat transfer tube 212 ₁ Refers to the length from one end of the first heat transfer pipe 212 connected to the first header 213 to the other end of the first heat transfer pipe 212 connected to the second header 214. In addition, the length L of the second heat transfer pipe 222 ₂ Refers to the length from one end of the second heat transfer pipe 222 connected to the third header 223 to the other end of the second heat transfer pipe 222 connected to the fourth header 224.

The number of first heat transfer tubes 212 connected to the first to third chambers 213a to 213c of the first header 213 is not the same but different in the chambers (first to third chambers 213a to 213 c) of the first header 213. The number of first heat transfer tubes 212 connected to the first to third chambers 214a to 214c of the second header 214 is not the same but different in the chambers (first to third chambers 214a to 214 c) of the second header 214. That is, the number of the plurality of first heat transfer tubes 212 connected to the first to third chambers 213a to 213c of the first header 213 and the first to third chambers 214a to 214c of the second header 214 is adjusted. This results in the following structure: the flow path cross-sectional area of the refrigerant is not reduced but is the same or increased before and after the diversion of the flow direction of the refrigerant at the time of the condenser operation.

The average number of the second heat transfer tubes 222 connected to the chambers (the first chamber 223a and the chamber 223 b) of the third header 223 is larger than the average number of the first heat transfer tubes 212 connected to the plurality of chambers (the first chamber 213a to the third chamber 213 c) of the first header 213.

In addition, in the first chamber 213a of the first header 213 which is a chamber connected to the pipe 11c, the second chamber 224b of the fourth header 224 which is a chamber connected to the pipe 11d, and the third chamber 214c of the second header 214 and the first chamber 223a of the third header 223 which are chambers connected to the connection pipe 12, since no refrigerant is turned back between the connected heat transfer pipes, the length of the chamber is shorter than that of the adjacent chamber in which the turning back is generated.

Next, the operation of the indoor heat exchanger 10 will be described.

< during cooling operation >

Fig. 3 is a schematic view showing an air conditioning apparatus 200 having the indoor heat exchanger 10 according to embodiment 1. In fig. 3, arrows show the flow of the refrigerant at the time of the cooling operation. In the cooling operation of the air conditioning apparatus 200, the indoor heat exchanger 10 functions as an evaporator, and the outdoor heat exchanger 16 functions as a condenser.

The refrigerant is formed into a high-temperature and high-pressure gas in the compressor 14, flows into the outdoor heat exchanger 16 mounted in the outdoor unit 201 via the four-way valve 15, and radiates heat to the outdoor air blown by the outdoor fan 13a to form a liquid-phase refrigerant or a liquid-body refrigerant. Then, the refrigerant is depressurized by the throttle device 17, flows into the first heat exchanger 21 of the indoor heat exchanger 10 of the indoor unit 202, and absorbs heat from the indoor air blown by the indoor blower 13b in the first heat exchanger 21. The refrigerant then flows from the low-temperature low-pressure two-phase refrigerant to the low-pressure gas refrigerant from the first heat exchanger 21 of the indoor heat exchanger 10 to the second heat exchanger 22 of the indoor heat exchanger 10, flows out of the indoor heat exchanger 10, and returns to the compressor 14 again through the four-way valve 15.

Fig. 4 is a graph showing the relationship between the evaporator performance and the heat transfer tube length ratio of the indoor heat exchanger 10 according to embodiment 1. In fig. 4, the vertical axis represents evaporator performance, and the horizontal axis represents heat transfer pipe length ratio.

The heat transfer pipe length ratio is the length L of the first heat transfer pipe 212 ₁ With respect to a length L obtained by adding the first heat transfer pipe 212 and the second heat transfer pipe 222 ₁ +L ₂ Is a ratio of (c).

As shown in fig. 4, when the heat transfer pipe length ratio becomes large, the pressure loss is less likely to decrease, and the evaporator performance improves. In addition, when the heat transfer tube length ratio becomes smaller, the evaporator performance is lowered due to a decrease in pressure loss.

When the indoor heat exchanger 10 functions as an evaporator, the refrigerant decompressed by the throttle device 17 absorbs heat from the indoor air in the first heat transfer pipe 212 of the first heat exchanger 21, and flows through the second heat transfer pipe 222 of the second heat exchanger 22 while being in a state of an increased dryness.

At this time, the volume flow rate of the refrigerant flowing in the second heat exchanger 22 is larger than that of the first heat exchanger 21. Thus, at length L which is the second heat transfer pipe 222 ₂ Length L of the first heat transfer pipe 212 ₁ In the case of a long structure, that is, in the case of a structure in which the heat transfer pipe length is relatively small, the pressure loss in the second heat transfer pipe 222 increases, and the saturation temperature in the indoor heat exchanger 10 decreases, so that the evaporator performance decreases.

On the other hand, in order to make the length L of the second heat transfer pipe 222 ₂ Length L of the first heat transfer pipe 212 ₁ In the case of a short structure, that is, in the case of a structure in which the heat transfer tube has a relatively large length, the path through which the refrigerant having a relatively high dryness flows becomes short. Therefore, the pressure loss in the second heat transfer pipe 222 is reduced, and the saturation temperature in the indoor heat exchanger 10 is increased, so that the evaporator can be improved in performance.

< heating operation >)

Fig. 5 is a schematic diagram showing an air conditioning apparatus 200 having an indoor heat exchanger 10 according to embodiment 1. In fig. 5, arrows show the flow of the refrigerant during the heating operation.

In the heating operation of the air conditioning apparatus 200, the indoor heat exchanger 10 functions as a condenser, and the outdoor heat exchanger 16 functions as an evaporator.

The refrigerant is converted into a high-temperature and high-pressure gas in the compressor 14, flows into the indoor heat exchanger 10 of the indoor unit 202 through the four-way valve 15, and is discharged as a liquid-phase refrigerant or a liquid-body refrigerant by radiating heat from the indoor air blown by the indoor blower 13b in the first heat exchanger 21 and the second heat exchanger 22 of the indoor heat exchanger 10. Then, the refrigerant is depressurized by the throttle device 17, absorbs heat from the outside air blown by the outdoor blower 13a in the outdoor heat exchanger 16 of the outdoor unit 201, and turns from the low-temperature low-pressure two-phase refrigerant into a low-pressure gas refrigerant. Then, the refrigerant flows out of the outdoor heat exchanger 16 and returns to the compressor 14 again via the four-way valve 15.

Fig. 6 is a diagram showing a relationship between the amount of refrigerant and the length ratio of the heat transfer tubes in the indoor heat exchanger 10 according to embodiment 1. In fig. 6, the vertical axis represents the amount of refrigerant, and the horizontal axis represents the heat transfer pipe length ratio.

As shown in fig. 6, when the heat transfer tube length is relatively small, the refrigerant density increases, and therefore, the amount of refrigerant in the indoor heat exchanger 10 also increases. In addition, when the heat transfer tube length is relatively large, the refrigerant density decreases, and therefore, the refrigerant amount of the indoor heat exchanger 10 also decreases.

When the indoor heat exchanger 10 functions as a condenser, the refrigerant having a high quality flows into the second heat exchanger 22, and flows through the second heat exchanger 22 and the first heat exchanger 21 while radiating heat to the indoor air. Then, the refrigerant is in a state of reduced dryness and flows out of the first heat exchanger 21.

At this time, when the dryness of the refrigerant in third header 223 and fourth header 224 of second heat exchanger 22 is low, the average refrigerant density in third header 223 and fourth header 224 increases. Thus, the amount of refrigerant in the third header 223 and the fourth header 224 increases, and therefore, the amount of refrigerant in the indoor heat exchanger 10 also increases.

On the other hand, the length L of the first heat transfer pipe 212 is set to ₁ Length L of the second heat transfer pipe 222 ₂ The long structure promotes heat transfer in the first heat exchanger 21, and the dryness in the third header 223 and the fourth header 224 of the second heat exchanger 22 increases. This reduces the average refrigerant density of the indoor heat exchanger 10, and reduces the amount of refrigerant.

In this way, when the indoor heat exchanger 10 is caused to function as an evaporator, the saturation temperature in the indoor heat exchanger 10 increases, and when the indoor heat exchanger 10 is caused to function as a condenser, the average refrigerant density in the indoor heat exchanger 10 decreases.

This makes it possible to achieve both high performance and refrigerant saving of the air conditioning apparatus 200.

Further, the number of partition members 4 partitioning the internal spaces of first header 213, second header 214, third header 223, and fourth header 224 and the number of chambers partitioned by partition members 4 can be appropriately changed. The third header 223 and the fourth header 224 may have a structure having only one chamber without the partition member 4.

However, the total of the number of chambers of third header 223 and the number of chambers of fourth header 224 of second heat exchanger 22 is smaller than the total of the number of chambers of first header 213 and the number of chambers of second header 214 of first heat exchanger 21. Alternatively, the number of chambers in the first header 213 or the second header 214 of the first heat exchanger 21 connected by the connection pipe 12 is larger than the number of chambers in the third header 223 of the second heat exchanger 22 connected by the connection pipe 12. Accordingly, the number of times of turning the flow direction of the refrigerant in the second heat exchanger 22 is smaller than the number of times of turning the flow direction of the refrigerant in the first heat exchanger 21, and the pressure loss due to collision or friction between the wall surfaces inside the third header 223 and the fourth header 224 and the refrigerant is reduced.

When the evaporator is operated, the number of heat transfer pipes 212 connected to the chamber of the first heat exchanger 21 to which the liquid refrigerant is supplied and which is connected to the pipe 11c < the number of first heat transfer pipes 212 connected to the chamber of the first heat exchanger 21 to which the refrigerant flows out of the connection pipe 12 is equal to or less than the number of second heat transfer pipes 222 connected to the chamber of the second heat exchanger 22 to which the refrigerant flows in from the connection pipe 12 and the number of second heat transfer pipes 222 connected to the chamber of the second heat exchanger 22 to which the supplied refrigerant flows out of the pipe 11 d.

In addition, even if expansion or contraction of the flow occurs due to the second heat transfer pipe 222 protruding toward the third header 223 and the fourth header 224, the pressure loss caused by the flow resistance of the refrigerant can be reduced.

Unlike the first heat exchanger 21, the second heat exchanger 22 may be configured such that the flow path cross-sectional area does not vary throughout the entire path of the refrigerant. The first chamber 223a of the third header 223 and the second chamber 224b of the fourth header 224, in which the refrigerant is introduced and discharged to and from the outside and there is no turn-back of the refrigerant, may be the same in size, and the second chamber 223b of the third header 223 and the first chamber 224a of the fourth header 224, in which the refrigerant is turned-back, may be the same in size. Desirably, the number of second heat transfer tubes 222 connected to first chamber 223a of third header 223 and second chamber 224b of fourth header 224 is the same as the number of second heat transfer tubes 222 connected to second chamber 223b of third header 223 and first chamber 224a of fourth header 224, respectively. That is, the number of second heat transfer tubes 222 in which the refrigerant flows from one of the chambers of third header 223 and fourth header 224 toward the opposite chamber of fourth header 224 and third header 223 is the same. Therefore, the second heat exchanger 22 having a short heat transfer pipe length can maintain a large flow path cross-sectional area over the entire length of the heat transfer pipe. In addition, the quotient of dividing the number of the second heat transfer tubes 222 connected to the third header 223 by the number of chambers of the third header 223 is sometimes not an integer. In this case, the number of chambers connected to the third header 223 may be increased or decreased by 1 with respect to the quotient thereof to be an integer, and the difference between the numbers may be 1 or less. The number of the chambers is not exactly the same, but the effects described in the above description can be obtained because the number is almost the same. For example, in the case where the second heat transfer tubes 222 connected to the third header 223 are 21 and the number of chambers of the third header 223 is 2, the number of connections to each chamber is 10 and 11. In addition, the size of each chamber of the third header 223 may vary by about 10% with this, but in this case, in the present disclosure, the plurality of chambers are also equal in size, and the number of connected second heat transfer tubes 222 is also the same.

The refrigerant having a higher dryness than the refrigerant flowing through the first header 213 flows through the third header 223 and the fourth header 224. By maintaining a large flow path cross-sectional area throughout the entire path of the refrigerant flowing through the second heat exchanger 22, the pressure loss in the second heat exchanger 22 can be reduced when the indoor heat exchanger 10 operates as an evaporator.

The chambers (first chamber 213a to third chamber 213 c) of the first manifold 213 are partitioned so that the average size of the chambers (first chamber 223a and second chamber 223 b) of the third manifold 223 is smaller than the average size of the chambers. That is, during the condenser operation of the indoor heat exchanger 10, the chambers (the first chamber 213a to the third chamber 213 c) of the first heat exchanger 21 disposed downstream of the refrigerant are partitioned so that the average size of the chambers (the first chamber 223a and the second chamber 223 b) of the second heat exchanger 22 is smaller. As a result, the area in which the supercooled state refrigerant having a high refrigerant density exists can be reduced in the indoor heat exchanger 10, and the refrigerant amount can be reduced.

In the above description, the example in which the indoor heat exchanger 10 is constituted by the first heat exchanger 21 and the second heat exchanger 22 has been shown, but the outdoor heat exchanger 16 may be constituted by the first heat exchanger 21 and the second heat exchanger 22 instead of the indoor heat exchanger 10.

The indoor heat exchanger 10 may be constituted by the first heat exchanger 21 and the second heat exchanger 22, and the outdoor heat exchanger 16 may be constituted by the first heat exchanger 21 and the second heat exchanger 22.

The pipe 11c through which the two-phase refrigerant flows when the indoor heat exchanger 10 is in the condenser operation is longer than the pipe 11b through which the two-phase refrigerant flows when the outdoor heat exchanger 16 is in the condenser operation. Therefore, from the standpoint of reducing the amount of refrigerant during the condenser operation, the effect of reducing the amount of refrigerant is increased by configuring the indoor heat exchanger 10 with the first heat exchanger 21 and the second heat exchanger 22.

According to the air conditioning apparatus 200 of embodiment 1 described above, the length L of the first heat transfer pipe 212 of the first heat exchanger 21 constituting the indoor heat exchanger 10 ₁ Length L of second heat transfer pipe 222 of second heat exchanger 22 ₂ Long. Therefore, in the case where the indoor heat exchanger 10 is caused to function as an evaporator, the refrigerant having a relatively high quality is longer than the length L of the first heat transfer pipe 212 of the first heat exchanger 21 ₁ The second heat transfer pipe 222 of the short second heat exchanger 22 circulates. This reduces the pressure loss, and can improve the performance of the indoor heat exchanger 10. In addition, when the indoor heat exchanger 10 is made to function as a condenser, it is possible to promote The heat exchange in the first heat exchanger 21 can promote the circulation of the refrigerant having a high quality. Thus, the average refrigerant density of first header 213, second header 214, third header 223, and fourth header 224 is reduced, and refrigerant saving can be achieved.

In addition, when the indoor heat exchanger 10 functions as a condenser, the refrigerant pipe through which the refrigerant having a high quality flows is longer than when the outdoor heat exchanger 16 functions as a condenser. Therefore, the indoor heat exchanger 10 is constituted by the first heat exchanger 21 and the second heat exchanger 22, whereby the refrigerant-saving effect can be obtained more greatly.

Further, since the number of the plurality of chambers (first chamber 213a to third chamber 213 c) in the first header 213 is larger than the number of chambers (first chamber 223a, second chamber 223 b) in the third header 223, when the indoor heat exchanger 10 functions as an evaporator, the pressure loss in the third header 223 is reduced. This can realize a higher performance of the indoor heat exchanger 10.

Among the plurality of chambers 213a to 213c of the first header 213, when the indoor heat exchanger 10 functions as a condenser, the first chamber 213a located downstream in the flow direction of the refrigerant is smaller than the second and third chambers 213b and 213c located upstream. Therefore, the refrigerant in the supercooled state having a low dryness can be reduced from being retained in the first header 213.

In addition, the first chamber 223a and the second chamber 223b of the third header 223 are partitioned into the same size. By dividing the indoor heat exchanger 10 into equal pieces in this way, when functioning as an evaporator, the cross-sectional area of the flow path through which the refrigerant having a high dryness fraction flows can be increased, and therefore, the pressure loss can be reduced, and high performance can be achieved.

In addition, when a refrigerant having a smaller gas density than the R32 refrigerant or the R410A refrigerant is used as the refrigerant, the refrigerant flow rate per unit capacity increases, and therefore, the performance improvement effect due to the reduction of the pressure loss is large. Examples of such refrigerants include olefin refrigerants having a double bond in the molecule, such as HFO1234yf and HFP1234ze (E), propane, DME (dimethyl ether), and the like.

Further, the first heat exchanger 21 and the second heat exchanger 22 may be integrally formed as long as the limitation of the lengths of the first heat transfer pipe 212 and the second heat transfer pipe 222 can be ensured.

< first modification >)

Fig. 7 is a schematic diagram of a first modification of the indoor heat exchanger 10 according to embodiment 1.

As shown in fig. 7, the connection positions of the pipes 11c and 11d of the indoor heat exchanger 10 according to the first modification are different from those of fig. 2. In fig. 2, in the first heat exchanger 21, the pipe 11c is connected to the first header 213, and the connection pipe 12 is connected to the second header 214. That is, the piping 11c and the connection piping 12 are connected to different headers. In fig. 2, in the second heat exchanger 22, the pipe 11d is connected to the fourth header 224, and the connecting pipe 12 is connected to the third header 223. That is, the piping 11d and the connection piping 12 are connected to different headers. In contrast, in the first modification of fig. 7, in the first heat exchanger 21, the piping 11c and the connection piping 12 are connected to the same first header 213. In the first modification, in the second heat exchanger 22, the piping 11d and the connection piping 12 are connected to the same third header 223. In fig. 7, the space inside the third header 223 is partitioned so that the plurality of chambers (the first chamber 223a and the second chamber 223 b) are equal in size.

In indoor heat exchanger 10, second header 214 and fourth header 224 are located at the farthest positions from each other, and first header 213 and third header 223 are located at the closest positions to each other. In the first modification, the connecting pipe 12 is configured to connect the chambers at one end of the first header 213 and the third header 223 in the vicinity of each other, as in fig. 2. As described above, the connection of one end portions of the headers in the horizontal direction, which are close to each other, is effective in shortening the connection pipe 12. The pipes 11c and 11d through which the refrigerant flows in and out are connected to chambers at the other ends in the horizontal direction of the first header 213 and the third header 223 in the vicinity thereof. The second header 214 and the fourth header 224 are not connected to piping. Therefore, this configuration can simplify the piping process, and is advantageous in the case of miniaturizing the indoor heat exchanger 10, and is also effective in reducing the amount of refrigerant.

Further, since the connection of the pipes 11c and 11d and the connection pipe 12 is different from that of fig. 2, the number of chambers and the number of partition members 4 in the header of a part of fig. 7 are also different from that of fig. 2. The first header 213 connected to the pipe 11c and the connecting pipe 12 is divided into four chambers 213a to 213d by three partition members 4. The number of partition members 4 and the number of chambers in the first header are larger than those in the second header 214 which is not connected to the piping. Similarly, the third header 223 connected to the pipe 11d and the connecting pipe 12 is divided into two chambers 213a and 213b by one partition member 4. Fourth header 224 does not have partition member 4 and is formed of one chamber. The number of partition members 4 and the number of chambers in the third header are larger than those in the fourth header 224 which is not connected to the piping.

The first heat transfer pipe 212 of the first heat exchanger 21 is longer than the second heat transfer pipe 222 of the second heat exchanger 22, as in fig. 2. The same applies to fig. 2, in which the number of partition members 4 of the first header 213 is larger than the number of partition members 4 of the third header 223, the number of chambers of the first header 213 is larger than the number of chambers of the third header 223, and the average size of the chambers of the first header 213 is smaller than the average size of the chambers of the third header 223. Therefore, the first modification can achieve both the reduction in the refrigerant and the pressure loss, and can reduce the size of the heat exchanger, as in the configuration of fig. 2.

< second modification >)

Fig. 8 is a schematic diagram of a second modification of the indoor heat exchanger 10 according to embodiment 1. As shown in fig. 8, the indoor heat exchanger 10 of the second modification is constituted by a first heat exchanger 21, a second heat exchanger 22, and a third heat exchanger 23.

The first header 213 of the first heat exchanger 21 is partitioned into a plurality of chambers 213a to 213c by a plurality of partition members 4, and the second header 214 is partitioned into a plurality of chambers 214a to 214c by a plurality of partition members 4.

The third header 223 of the second heat exchanger 22 is partitioned into a first chamber 223a and a second chamber 223b.

The third heat exchanger 23 is a serpentine type heat exchanger in which one third heat transfer pipe 6 is turned a plurality of times.

One end 8 of the third heat transfer tube 6 of the third heat exchanger 23 is connected to the pipe 11c, and the other end 7 is connected to the first chamber 213a of the first header 213.

Length L from one turning position to the next turning position in the third heat transfer pipe 6 ₃ Length L of the first heat transfer pipe 212 of the first heat exchanger 21 ₁ Short. In addition, the length of the piping of the third heat transfer pipe 6 is longer than the length L of the first heat transfer pipe 212 ₁ Long.

In the indoor heat exchanger 10 of the second modification, during the operation of the evaporator of the indoor heat exchanger 10, the refrigerant flows from the pipe 11c toward the one end 8 of the third heat transfer pipe 6 and flows toward the other end 7 of the third heat transfer pipe 6. Then, the refrigerant flows into the first chamber 213a of the first header 213 from the other end 7.

The refrigerant flows from the first chamber 213a of the first header 213 into the third chamber 213c of the first header 213 via the first chamber 214a of the second header 214, the second chamber 213b of the first header 213, and the second chamber 214b of the second header 214.

The refrigerant flows from the third chamber 213c of the first header 213 to the first chamber 223a of the third header 223 through the third chamber 214c of the second header 214 and through the connecting pipe 12. Then, the refrigerant passes through fourth header 224, reaches second chamber 223b of third header 223, and flows out of pipe 11 d.

At this time, the length L from one turning position of the third heat transfer pipe 6 to its next turning position ₃ Length L of the first heat transfer pipe 212 ₁ Short, but the length of the piping of the third heat transfer pipe 6 is shorter than the length L of the first heat transfer pipe 212 ₁ Long. The second modification is considered to be a structure in which the third heat exchanger 23 is provided between the piping 11c of the structure of fig. 2 and 7 and the first chamber 213a of the first header 213 to which the piping 11c is connected. The third heat exchanger 23 is longer and fewer in number than the first heat transfer tubes 212 connected to the first chamber 213a of the first header 213 chamber, becauseThe flow path has a small cross-sectional area. Therefore, the density of the refrigerant flowing into second header 214 decreases, and the average amount of refrigerant in the whole of first header 213, second header 214, third header 223, and fourth header 224 can be reduced.

Embodiment 2

Fig. 9 is a schematic diagram illustrating an indoor unit 202 according to embodiment 2. The indoor unit 202 of embodiment 2 is an example of the indoor unit 202 of the air-conditioning apparatus 200 of embodiment 1.

As shown in fig. 9, the indoor unit 202 according to embodiment 2 is arranged such that the height position of the second header 214 of the first heat exchanger 21 is lower than the height position of the fourth header 224 of the second heat exchanger 22 in the vertical direction 31. The first header 213 of the first heat exchanger 21 and the third header 223 of the second heat exchanger 22 are at the same height. The first heat transfer pipe 212 of the first heat exchanger 21 and the second heat transfer pipe 222 of the second heat exchanger 22 are inclined in the vertical direction, and are arranged so that the first header 213 and the third header 223 at the respective upper ends are horizontally adjacent to each other, and the second header 214 and the fourth header 224 at the respective lower ends are horizontally separated from each other.

That is, in the indoor unit 202 according to embodiment 2, the lowermost portion 41 of the first heat exchanger 21 is located below the lowermost portion 42 of the second heat exchanger 22 in the vertical direction 31.

Fig. 10 is a schematic view showing the refrigerant flowing through the connection pipe 12 of the indoor heat exchanger 10 of fig. 9. Fig. 10 shows a case when the condenser of the indoor heat exchanger 10 is operated. The liquid-phase refrigerant 61 and the gas-phase refrigerant 62 are mixed together, and these flow through the connecting pipe 12. The connection pipe 12 in this figure shows a structure in which the U-shaped connection pipe 12 is connected between the upper surface of the first header 213 and the upper surface of the third header 223. The connecting pipe 12 may be configured to connect the horizontal ends of the first header 213 and the third header 223 to each other, that is, the connecting pipe 12 may be configured to draw a U-shape in the depth direction of the drawing.

As shown in fig. 10, during the condenser operation of the indoor heat exchanger 10, the refrigerant flows from the second heat exchanger 22 to the first heat exchanger 21 in the refrigerant flow direction 30 via the connection pipe 12. The refrigerant flowing through the first heat exchanger 21 is a refrigerant having a lower dryness than the refrigerant flowing through the second heat exchanger 22. The refrigerant having dryness between the refrigerant flowing through the first heat exchanger 21 and the refrigerant flowing through the second heat exchanger 22 flows through the connection pipe 12.

Inertial force 52 and gravity 51 acting in the flow direction of the refrigerant act on liquid-phase refrigerant 61 moving through connection pipe 12. Since the flow path cross-sectional area of the inside of each header is larger than the flow path cross-sectional area of each heat transfer pipe and the flow velocity is reduced, the inertial force 52 is reduced and the influence of the gravity 51 is increased.

When the flow rate of the refrigerant is large, the inertia force 52 acting on the liquid-phase refrigerant 61 is large as compared with the gravity 51, and therefore the liquid-phase refrigerant 61 of the connection pipe 12 can flow from the second heat exchanger 22 in the direction of the first heat exchanger 21, that is, in the refrigerant flow direction 30.

In the low-capacity operation, the inertial force 52 decreases and the influence of the gravity 51 increases due to the decrease in the refrigerant flow rate.

At this time, when the first heat transfer pipe 212 of the first heat exchanger 21 is shorter than the second heat transfer pipe 222 of the second heat exchanger 22, the influence of the gravity 51 acting in the direction of the second heat exchanger 22 increases. In this way, the influence of the gravity 51 acting in the direction of the second heat exchanger 22 becomes larger with respect to the inertia force 52 acting on the liquid-phase refrigerant 61 of the connection pipe 12, and the liquid-phase refrigerant 61 is less likely to flow in the refrigerant flow direction 30. As a result, the liquid-phase refrigerant 61 is particularly likely to be retained in the header pipe or the connection pipe 12 having the small inertial force 52. Thereby, the refrigerant density in the second heat exchanger 22 increases, and the refrigerant amount increases.

In embodiment 2, since the first heat transfer pipe 212 of the first heat exchanger 21 is made longer than the second heat transfer pipe 222 of the second heat exchanger 22, the influence of the gravity 51 acting in the direction of the first heat exchanger 21 is greater than the influence of the gravity 51 acting in the direction of the second heat exchanger 22. Accordingly, even when the inertia force 52 acting on the liquid-phase refrigerant 61 decreases during the low-capacity operation, the refrigerant can be driven in the refrigerant flow direction 30, and therefore, an increase in the refrigerant density during the low-capacity operation can be suppressed, and the refrigerant can be saved.

In the air conditioning apparatus 200 according to embodiment 2 described above, the indoor heat exchanger 10 is disposed such that the lowermost portion 41 of the first heat exchanger 21 is positioned below the lowermost portion 42 of the second heat exchanger 22 in the vertical direction 31. In this way, when the indoor heat exchanger 10 is caused to function as a condenser, the increase in the refrigerant density of the second heat exchanger 22 due to the difficulty in flowing the liquid-phase refrigerant 61 flowing through the first heat exchanger 21 in the refrigerant flow direction 30 can be reduced, and the refrigerant can be saved.

Further, since the second heat transfer pipe 222 is made shorter than the first heat transfer pipe 212, the heat exchange amount of the second heat exchanger 22 is smaller than that in the case where the same length is used. Therefore, the dryness of the second heat exchanger 22 is relatively high, and even when the liquid-phase refrigerant 61 is retained in the header pipe or the connection pipe 12, the amount thereof is small. On the other hand, the dryness of the first heat exchanger 21 decreases, and the first header 213 and the second header 214 have a portion where the dryness is slightly decreased, but when the refrigerant originally functions as a condenser, the refrigerant is generally in a supercooled state, and the amount of the refrigerant does not change only in the portion where the liquid-phase refrigerant 61 flows. As a result, in the heat exchanger of the structure of embodiment 2, the amount of the liquid-phase refrigerant 61 is reduced as a whole.

Embodiment 3

Embodiment 3 refers to the relationship between the indoor heat exchanger 10 and the indoor fan 13b in the indoor unit 202 in the air conditioning apparatus 200 according to embodiment 1, and as the indoor fan 13b, a fan in which the rotation axis such as a cross flow fan extends in the horizontal direction is used. Since the configuration of the air conditioning apparatus 200 and the indoor heat exchanger 10 is the same as that of embodiment 1, the description thereof is omitted, and the same or corresponding parts are denoted by the same reference numerals.

Fig. 11 is a perspective view of an indoor unit 202 according to embodiment 3. As shown in fig. 11, a cross-flow fan such as a cross-flow fan operating at a low pressure and a high air volume is mounted as the indoor fan 13b in the indoor unit 202. The indoor blower 13b generates an air flow in the circumferential direction of the rotary shaft 18.

In the indoor heat exchanger 10, the first heat transfer pipe 212 and the second heat transfer pipe 222 are arranged along the circumferential direction of the rotation shaft 18, which is the tangential direction of a circle centering on the rotation shaft 18 of the indoor fan 13b, and the refrigerant flows along the circumferential direction of the rotation shaft 18 of the indoor fan 13 b.

The first heat exchanger 21 is disposed such that the extending directions of the first header 213 and the second header 214 are parallel to the axial direction of the rotation shaft 18 of the indoor fan 13 b. The second heat exchanger 22 is disposed such that the extending direction of the third header 223 and the fourth header 224 is parallel to the axial direction of the rotation shaft 18 of the indoor fan 13 b.

Fig. 12 is a schematic view of a section A-A of the indoor unit 202 of fig. 11. As shown in fig. 12, the first heat exchanger 21 and the second heat exchanger 22 are disposed at different positions in the circumferential direction of the rotation shaft 18 of the indoor fan 13 b. That is, first header 213, second header 214, third header 223, and fourth header 224 do not overlap with each other in the radial direction of rotary shaft 18. The first heat exchanger 21 and the second heat exchanger 22 are arranged in parallel with respect to the air flow flowing into the indoor fan 13 b.

By arranging the first heat exchanger 21 and the second heat exchanger 22 in parallel with each other with respect to the airflow in this manner, the static pressure of the airflow is reduced, and the air volume is increased. This improves heat transfer performance, and reduces the supercooling zone of the refrigerant formed during the condenser operation of the indoor heat exchanger 10, thereby reducing the refrigerant density and saving the refrigerant.

Fig. 13 is a schematic view of a section A-A of the indoor unit 202 of the comparative example. As shown in fig. 13, in the indoor unit 202 of the comparative example, the first heat exchanger 21 and the second heat exchanger 22 are disposed at the same position in the circumferential direction with respect to the rotation shaft 18 of the indoor fan 13 b. That is, the first heat exchanger 21 and the second heat exchanger 22 are arranged in series with respect to the air flow of the indoor blower 13 b.

If the first heat exchanger 21 and the second heat exchanger 22 are arranged like the indoor unit 202 of the comparative example, the airflow flowing through the indoor heat exchanger 10 is likely to be blocked. This is because the height positions of the first header 213, the second header 214, the third header 223, and the fourth header 224 are different due to the difference in the lengths of the first heat transfer tubes 212 of the first heat exchanger 21 and the second heat transfer tubes 222 of the second heat exchanger 22.

As in the indoor unit 202 according to embodiment 3, the first heat exchanger 21 and the second heat exchanger 22 are arranged in parallel with each other with respect to the airflow, whereby the static pressure of the airflow is reduced, the air volume is increased, and the heat transfer performance can be improved. This reduces the supercooling region of the refrigerant formed when the indoor heat exchanger 10 is operated as a condenser, reduces the density of the refrigerant, and saves the refrigerant.

Fig. 14 is a schematic diagram illustrating a relationship between the air speed and the indoor fan 13b of the indoor unit 202 according to embodiment 3. In fig. 14, the corner C at one end of the second header 214 is set to be 0%, and the corner D at the other end of the second header 214 after the movement from the corner C in the rotation axis direction 33 is set to be 100%. In fig. 14, a corner E at one end of the fourth header 224 is set to be 100% of the position after the corner C has moved along the first heat transfer pipe 212 and the second heat transfer pipe 222 in the circumferential direction 34 of the rotary shaft 18.

Fig. 15 is a diagram showing a relationship between the position of the rotation axis direction 33 of the indoor fan 13b and the wind speed and a relationship between the position of the rotation axis 18 of the indoor fan 13b in the circumferential direction 34 and the wind speed in fig. 14. In fig. 15, a solid line shows a relationship between a position of the rotation shaft direction 33 of the indoor fan 13b and a wind speed, and a broken line shows a relationship between a position of the rotation shaft 18 of the indoor fan 13b in the circumferential direction 34 and a wind speed.

As shown in fig. 14 and 15, when the indoor fan 13b is configured to include the first heat exchanger 21 and the second heat exchanger 22 upstream thereof, the indoor fan 13b mixes the low-temperature air having passed through the first heat exchanger 21 with the high-temperature air having passed through the second heat exchanger 22.

Therefore, the saturation temperature of the refrigerant required to blow out the air temperature equal to or higher than a predetermined value becomes smaller during the operation of the condenser. Thereby, the performance per unit air temperature provided to the user is improved.

When the structure is such that the refrigerant flow is provided in the direction parallel to the rotation shaft 18 of the indoor fan 13b, the variation in the wind speed in the circumferential direction of the rotation shaft 18 of the indoor fan 13b is greatly different. Therefore, the heat exchange capacity of the heat transfer tubes greatly fluctuates, and a region in which the degree of supercooling of the refrigerant increases is generated during the condenser operation, and the refrigerant saving effect is reduced.

In contrast, in embodiment 3, the first heat transfer pipe 212 and the second heat transfer pipe 222 are arranged in the tangential direction of a circle centered on the rotation shaft 18 in the circumferential direction of the rotation shaft 18 of the indoor fan 13 b. Therefore, the variation in the wind speed in the rotation axis direction 33 is small, and the refrigerant flows in the circumferential direction of the rotation axis 18 of the indoor fan 13b, so that the variation in the heat exchange capacity of the first heat transfer pipe 212 and the second heat transfer pipe 222 is small. Thus, the difference in supercooling degree is reduced during the condensing operation, and the refrigerant can be saved, and the heat load is unevenly reduced during the condenser operation and the evaporator operation, thereby achieving the high performance, and the refrigerant saving and the high performance can be simultaneously achieved.

The air conditioning apparatus 200 according to embodiment 3 described above employs a cross-flow fan as the indoor fan 13b, and the first heat exchanger 21 and the second heat exchanger 22 are arranged in parallel in the circumferential direction with respect to the rotation shaft 18 of the indoor fan 13 b. As a result, the static pressure of the airflow is reduced and the air volume is increased, so that the heat transfer of the first heat exchanger 21 and the second heat exchanger 22 is improved, and the supercooling region during the condenser operation is reduced.

Fig. 16 is a schematic diagram showing the refrigerant flow path structure of the indoor heat exchanger 10 according to embodiment 3. Fig. 17 is a characteristic diagram showing the effect of improving the refrigerant-saving and heat exchange performance with respect to the refrigerant flow path structure. As shown in fig. 16, in the indoor heat exchanger 10, the refrigerant flows in a serpentine manner between the two headers facing each other as indicated by the outline arrows by the first heat transfer pipe 212 connecting the first header 213 to the second header 214 and the second heat transfer pipe 222 connecting the third header 223 to the fourth header 224. In the drawings 16, the refrigerant flows from the pipe 11c of the first heat exchanger 21 to the second heat exchanger 22 through the first chamber 213a of the first header 213, 2 first heat transfer pipes 212, the first chamber 214a of the second header 214, 3 first heat transfer pipes 212, the second chamber 213b of the first header 213, 3 first heat transfer pipes 212, the second chamber 214b of the second header 214, 3 first heat transfer pipes 212, the third chamber 213c of the first header 213, 5 first heat transfer pipes 212, the third chamber 214c of the second header 214, 5 first heat transfer pipes 212, and the fourth chamber 213d of the first header 213. The total number of the first heat transfer tubes 212 connecting the first header 213 and the second header 214 is 21. The first heat transfer tubes 212 connecting the chambers of the opposed headers are divided into six groups that change orientation and flow as indicated by the open arrows. As such, the plurality of first heat transfer pipes 212 are grouped in the following manner: when the chambers of the first header 213 to which one end of the plurality of first heat transfer tubes 212 is connected and the chambers of the second header 214 to which the other end is connected are the same, the chambers are included in the same group, and when the chambers are different, the chambers are included in different groups. In addition, the case where the direction of the flow of the refrigerant of the heat transfer tube is turned back in the chamber of the header in this way is referred to as turning, and the number of times of turning in one heat exchanger is referred to as turning times. In fig. 16, the number of first heat transfer tubes 212 divided into groups from the piping 11c to the connection piping 12 is denoted by n _1，1 、n _1，2 、n _1，3 、n _1，4 、n _1，5 、n _1，6 . In the first heat transfer pipes 212 of the respective groups, the refrigerant flows in the same direction without being turned. In addition, in the first heat transfer tubes 212 of the adjacent groups, the refrigerant flows in the opposite directions. The number of groups whose flow directions are opposite due to the turning is the number obtained by adding 1 to the number of turns.

Here, the average branch number N1 of the first heat exchanger 21 is a value obtained by summing up the values of the squares of the numbers of the first heat transfer tubes 212 of the respective groups for all the groups and dividing the sum by the numbers of the first heat transfer tubes 212 of all the groups. Expressed by a mathematical expression, n1=Σ (N _1，k ×n _1，k )/Σn _1，k . In the example of fig. 16, the number of turns is 5, the number of groups is 6, the sum of squares of the numbers of the groups is 81, and the average number of branches N1 is about 3.9 for the total of 21 first heat transfer pipes 212 with respect to the first heat exchanger 21.

Similarly, in the second heat exchanger 22, the refrigerant flows out of the connection pipe 12 through the first chamber 223a of the third header 223, 10 second heat transfer pipes 222, the first chamber 224a of the fourth header 224, 11 second heat transfer pipes 222, and the second chamber 223b of the third header 223, and then flows out of the pipe 11 d. The total number of the second heat transfer tubes 222 connecting the first header 213 and the second header 214 is 21 as in the case of the first heat exchanger 21. The second heat transfer tubes 222 connecting the chambers of the opposite headers are divided into two groups that change orientation and flow as indicated by the open arrows. The plurality of second heat transfer pipes 222 are grouped as follows: when the chambers of the third header 223 to which one end portion of the plurality of second heat transfer tubes 222 is connected and the chambers of the fourth header 224 to which the other end portion is connected are the same, the chambers are included in the same group, and when the chambers are different, the chambers are included in different groups. In fig. 16, the number of the second heat transfer pipes 222 that are grouped is denoted by n _2，1 、n _2，2 . The sum of squares of the numbers of the second heat transfer pipes 222 in the respective groups divided by the number of the groups is set as the average number N2 of the second heat exchanger 22. Expressed by a mathematical expression, n2=Σ (N _2，k ×n _2，k )/Σn _2，k . In the example of fig. 16, the number of turns is 1 and the number of groups is 2 for the total of 21 second heat transfer pipes 222 with respect to the second heat exchanger 22. The sum of squares of the numbers of each group was 221, and the average number of branches N2 was about 10.5.

Next, it is studied that the first heat transfer pipe length L1 of the first heat exchanger 21 and the second heat transfer pipe length L2 of the second heat exchanger 22 can reduce the effect of the refrigerant and the influence on the performance as a heat exchanger. The refrigerant-saving effect of the heat exchanger in 50% load operation of the condenser with respect to the case where the first heat transfer pipe length L1 and the second heat transfer pipe length L2 are equal is Δmg. The performance of the heat exchanger in which the evaporator was operated at 50% load was Ga epsilon. The product of Δmg and Ga epsilon is set as the performance index FM. A heat exchanger having a large performance index FM is excellent from the viewpoints of refrigerant-saving effect and performance index.

Fig. 17 is a characteristic diagram showing the performance index FM of the refrigerant flow path structure of the heat exchanger 2 according to embodiment 3. The vertical axis of fig. 17 shows the performance index FM. In the test, the first heat exchanger 21 and the second heat exchanger 22 were disposed around the rotation axis of the indoor fan 13b, and R32 was used as the refrigerant. Fig. 17 shows the following case: the ratio of the first heat transfer pipe length L1 to the average branch number N1 is L1/N1, the ratio of the second heat transfer pipe length L2 to the average branch number N2 is L2/N2, and how the performance index FM changes with respect to their ratio (L1/N1)/(L2/N2), that is, (L1/N1) × (N2/L2), where L1 > L2. As can be seen from the figure: the performance index FM has a maximum value when (L1/N1) x (N2/L2) is between 2 and 3. In fig. 17, the maximum value of the performance index FM is represented as 100% of the reference. In the configuration in which the number and length of the heat transfer tubes of the first heat exchanger 21 and the second heat exchanger 22 are the same, (L1/N1) × (N2/L2) =1, however, compared with this case, the following case is shown: by adjusting the average number of branches and the length, a performance index FM of 1.5 times or more can be obtained. In addition, it is known that: even when (L1/N1) × (N2/L2) is in the range of 1.3 to 5.2, performance of 80% or more of the maximum value can be obtained, and the improvement in performance index FM is large. More preferably, the ratio of (L1/N1) × (N2/L2) is 1.4 to 4.5, and the performance of 90% or more of the maximum value can be obtained. If L1/N1 is increased relative to L2/N2, that is, if L1 is increased or N1 is decreased, the refrigerant-saving effect is improved, but if it is too large, the heat exchange performance is lowered. Further, it is considered that if the first heat exchanger 21 and the second heat exchanger 22 have the same structure and (L1/N1) × (N2/L2) is close to 1, the refrigerant-saving effect is reduced.

When the refrigerant type is changed, the performance index FM slightly changes depending on the operating refrigerant pressure P and the latent heat change amount Δh according to the influence received from N1 and N2, but if the ratio of N1 to N2 is the same, the influence is small. For example, the following can be confirmed: even if the refrigerant type is changed from R32 to R410A, and even if the refrigerant type is changed to an olefin refrigerant, propane, dimethyl ether, or the like, which is a refrigerant having a lower gas density than the refrigerant type, the relative change of N2 to N1, which is the peak of the performance index FM, is small and 8% or less. Therefore, it can be expected that: in the range of (L1/N1) × (N2/L2) where the effect is seen in the refrigerant R32, the effect of improving the performance index FM can be similarly obtained even when the type of refrigerant is changed.

In addition, even if the temperature of the air passing through the first heat exchanger 21 is different from the temperature of the air passing through the second heat exchanger 22, the performance per unit air temperature supplied to the room can be improved by mixing the air by the indoor blower 13 b.

Embodiment 4

Embodiment 4 refers to the relationship between the indoor heat exchanger 10 and the indoor fan 13b in the indoor unit 202 in the air conditioning apparatus 200 according to embodiment 1, and an axial flow fan is used as the indoor fan 13 b. Since the configuration of the air conditioning apparatus 200 and the indoor heat exchanger 10 is the same as that of embodiment 1, the description thereof is omitted, and the same or corresponding parts are denoted by the same reference numerals.

Fig. 18 is a perspective view of an indoor unit 202 according to embodiment 3. As shown in fig. 18, as the indoor fan 13b, a fan such as a propeller fan operating at a low pressure and a high air volume is mounted on the indoor unit 202. An air flow is generated from the suction port 35 toward the discharge port 36 in the direction of the rotation shaft 18 by the indoor fan 13 b.

The indoor heat exchanger 10 is arranged such that the extending directions of the first header 213 and the second header 214 of the first heat exchanger 21 are parallel to the direction orthogonal to the rotation axis 18 of the indoor blower 13 b. The second heat exchanger 22 is disposed such that the extending directions of the third header 223 and the fourth header 224 are parallel to the direction orthogonal to the rotation axis 18 of the indoor fan 13 b. That is, the extending directions of the first header 213, the second header 214, the third header 223, and the fourth header 224 extend in the tangential direction of a circle centered on the rotation axis 18 of the indoor blower 13 b. The first heat exchanger 21 and the second heat exchanger 22 are disposed at positions not overlapping each other around the rotation shaft 18 when viewed in the axial direction of the rotation shaft 18. The angular range in which the first heat exchanger 21 is located around the rotation shaft 18 is different from the angular range in which the second heat exchanger 22 is located around the rotation shaft 18.

Fig. 19 is a schematic view of a section B-B of the indoor unit 202 of fig. 18. In fig. 19, a straight line F is a straight line connecting the second header 214 of the first heat exchanger 21 and the fourth header 224 of the second heat exchanger 22. The lowermost portion G shows the height positions of the first heat exchanger 21 and the second heat exchanger 22 in the vertical direction 31. In fig. 19, the straight line F is set to 100% of the height position, and the lowermost portion G is set to 0% of the height position.

As shown in fig. 19, the first heat exchanger 21 and the second heat exchanger 22 are disposed at different positions in the circumferential direction about an intersection 45 of the straight line F and the rotation shaft 18 in a cross section passing through the rotation shaft 18 of the indoor fan 13b and perpendicular to the extending direction.

By arranging the first heat exchanger 21 and the second heat exchanger 22 in parallel with the airflow in this way, the static pressure of the airflow is reduced, the air volume is increased, and heat transfer is improved, as compared with the case where the heat exchangers are arranged in series with the airflow. Thus, during the condenser operation of the indoor heat exchanger 10, the refrigerant supercooling region is reduced, the refrigerant density is reduced, and refrigerant saving can be achieved.

Fig. 20 is a schematic diagram showing a wind speed distribution of the airflow flowing in the indoor unit 202 of fig. 19. In fig. 20, the vertical axis indicates the height position in the vertical direction 31 from the lowermost portion G to the straight line F in the indoor unit 202, and the horizontal axis indicates the wind speed.

As shown in fig. 20, when the indoor fan 13b is an axial flow fan, the distance between the indoor fan 13b and the indoor heat exchanger 10 increases, and the variation in the wind speed in the vertical direction 31 increases.

In the indoor heat exchanger 10, the extending directions of the first header 213, the second header 214, the third header 223, and the fourth header 224 are set along the tangential direction of a circle centered on the rotation axis 18. One end of the first heat transfer pipe 212 of the first heat exchanger 21 and one end of the second heat transfer pipe 222 of the second heat exchanger 22 are positioned at the level of the straight line F, and the other end is positioned at the level of the lowermost portion G.

Therefore, the difference in the air volume of the air flow around the first heat transfer pipe 212 is not generated between the first heat transfer pipes 212, and the difference in the air volume of the air flow around the second heat transfer pipe 222 is not generated between the second heat transfer pipes 222. Therefore, the difference in heat exchange amount between the first heat transfer pipes 212 and the second heat transfer pipes 222 is reduced, and the supercooling region during the condenser operation and the performance during the condenser operation or the evaporator operation can be reduced, and both the refrigerant saving and the performance improvement can be achieved.

In the above description, the case where the air flow flows from the suction port 35 to the blowout port 36 has been described, but even if the flow from the suction port 35 to the blowout port 36 is reversed, the effect is not affected.

The air conditioning apparatus 200 according to embodiment 4 described above employs an axial-flow fan as the indoor fan 13b, and the first heat exchanger 21 and the second heat exchanger 22 are arranged in parallel with respect to the airflow. Therefore, by reducing the static pressure of the air flow and increasing the air volume, the heat transfer is improved, and the supercooling region during the operation of the condenser can be reduced. In addition, the variation in heat exchange capacity between the first heat transfer pipes 212 and the second heat transfer pipes 222 is reduced, and refrigerant saving during the condenser operation and performance improvement during the evaporator operation can be achieved.

Embodiment 5

Embodiment 5 refers to the relationship between the indoor heat exchanger 10 and the indoor fan 13b in the indoor unit 202 in the air conditioning apparatus 200 according to embodiment 1, and a centrifugal fan having a scroll casing 5 is used as the indoor fan 13b. Since the configuration of the air conditioning apparatus 200 and the indoor heat exchanger 10 is the same as that of embodiment 1, the description thereof is omitted, and the same or corresponding parts are denoted by the same reference numerals.

Fig. 21 is a schematic diagram showing a schematic view of a cross section of the indoor unit 202 according to embodiment 5. As shown in fig. 21, an indoor fan 13b including a centrifugal fan such as a sirocco fan and a scroll casing 5 (hereinafter referred to as a casing) that accommodates the centrifugal fan is mounted as the indoor fan 13b in the indoor unit 202. As such centrifugal blowers, there are sirocco fans and the like. A typical centrifugal blower has a structure in which a plurality of blades are arranged in a cylindrical shape. In the rotation angle around the rotation axis of the centrifugal blower, the housing 5 has a rotation angle position where the distance between the housing 5 and the blade is closest, and the distance from the blade becomes gradually longer from this position in the rotation direction of the blade. In the case 5, a position closest to the blade is set as a winding start position 19. That is, the outer shape of the scroll housing 5 as viewed from the rotation axis direction is as follows: at the winding start position 19, the position closest to the rotation outer periphery of the inner blade is gradually away from the rotation outer periphery of the blade as the movement proceeds in the rotation direction of the blade. The indoor fan 13b sucks in the wind from the direction of the rotation axis, and the housing 5 has a blowout port that blows out the wind in the tangential direction of the rotation of the blade before rotating one turn in the rotation direction of the blade from the winding start position 19. Hereinafter, the case where the housing 5 is viewed in the direction of rotation of the blade will be described as being viewed in the winding direction 32. A winding start position 19 is present in the winding direction 32 immediately adjacent to the outlet opening. Therefore, the winding start position 19 is a shape that contracts at an acute angle when viewed in the rotation axis direction, also referred to as a tongue. In fig. 21, the position H is the position where the first heat exchanger 21 is closest to the housing 5. Position I is the position of the second heat exchanger 22 closest to the housing 5. Fig. 22 is a schematic cross-sectional view showing a schematic case of the section A-A of the indoor unit 202 according to embodiment 5.

The indoor heat exchanger 10 is arranged such that the extending directions of the first header 213 and the second header 214 of the first heat exchanger 21 are parallel to the axial direction of the rotation shaft 18 of the indoor fan 13 b. The second heat exchanger 22 is disposed such that the extending direction of the third header 223 and the fourth header 224 is parallel to the axial direction of the rotary shaft 18 of the indoor fan 13 b. The first heat transfer pipe 212 and the second heat transfer pipe 222 extend in a direction orthogonal to the rotation axis of the indoor blower 13 b.

In the second heat exchanger 22, the distance from the winding start position 19 of the casing 5 to the position I is shorter than the distance from the winding start position 19 of the casing 5 to the position H when viewed in the winding direction 32 of the casing 5. That is, the second heat exchanger 22 is disposed at a position close to the winding start position 19 of the housing 5, and the first heat exchanger 21 is disposed at a position distant from the winding start position 19 of the housing 5 when viewed in the winding direction 32 of the housing 5.

In the indoor fan 13b having the casing 5, the airflow is relatively small in the vicinity of the winding start position 19 of the casing 5, and is larger as it is farther. In the condenser operation of the indoor heat exchanger 10, since the air volume flowing through the first heat exchanger 21 increases, the heat transfer of the first heat exchanger 21 can be promoted, and the refrigerant supercooling region of the first heat exchanger 21 decreases. Thus, the refrigerant density is reduced, and refrigerant can be saved.

Since the refrigerant pressure of the second heat exchanger 22 is on the low pressure side during the evaporator operation of the indoor heat exchanger 10, dew condensation water is generated due to a refrigerant temperature difference from the air temperature, and when the airflow passing through the second heat exchanger 22 is large, dew condensation water is blown out from the surfaces of the second fins 221 into the indoor space. By disposing the second heat exchanger 22 on the upstream side of the airflow near the winding start position 19 of the housing 5, the inertial force of blowing dew condensation water from the surface of the second fin 221 is reduced. This makes it possible to increase the air volume without deteriorating the quality of the indoor heat exchanger 10, and to increase the performance of the air conditioning apparatus 200.

In the air-conditioning apparatus 200 according to embodiment 5 described above, the second heat exchanger 22 is disposed such that the distance from the winding start position 19 of the case 5 to the second heat exchanger 22 is shorter than the distance from the winding start position 19 of the case 5 to the first heat exchanger 21. Therefore, when the condenser is operated, the air volume of the first heat exchanger 21 is increased, so that the supercooling region is reduced and the refrigerant density is reduced, thereby saving the refrigerant. Further, since the second heat exchanger 22 is disposed on the upstream side of the airflow during the operation of the evaporator, the inertial force of the airflow for blowing out the dew condensation water into the indoor space is reduced, and the quality of the indoor heat exchanger 10 is not reduced, thereby achieving a high wind level.

As shown in fig. 22, the length of the casing 5 of the blower in the direction of the rotation shaft 18 is shorter than the length of the first heat exchanger 21 in the direction of the rotation shaft 18. The housing 5 is formed with an air inlet 5a for sucking air in the direction of the rotation shaft 18. At least a part, preferably all, of the area of the first chamber 213a of the second heat exchanger 22 that is the most downstream side when operating as a condenser is located at a position offset from the housing 5 in the direction of the rotation axis 18. Since the first chamber 213a is located at a position where the housing 5 is not provided in the rotation circumferential direction of the rotary shaft 18 of the blower, the air volume passing through the first heat transfer pipe 212 and the first fin 211 connected to the first chamber 213a is larger than the air volume in the region overlapping the housing 5 in the direction of the rotary shaft 18. Therefore, in the heat exchanger according to embodiment 5, heat transfer of the liquid refrigerant can be promoted, and both refrigerant saving and high performance can be achieved. The indoor fan 13b can have the same effect even if it includes a centrifugal fan such as a sirocco fan and a scroll casing accommodating the centrifugal fan, and a cross-flow fan is provided at a part thereof.

The first heat exchanger 21 and the second heat exchanger 22 are disposed at positions not overlapping each other around the rotation shaft 18 when viewed in the axial direction of the rotation shaft 18 of the centrifugal fan 13 b. The angular range in which the first heat exchanger 21 is located around the rotation shaft 18 is different from the angular range in which the second heat exchanger 22 is located around the rotation shaft 18. Therefore, as described in embodiment 4, by arranging the first heat exchanger 21 and the second heat exchanger 22 in parallel with the airflow, the static pressure of the airflow is reduced, the air volume is increased, and the heat transfer is improved, as compared with the case where the heat exchangers are arranged in series with the airflow. Thus, during the condenser operation of the indoor heat exchanger 10, the refrigerant supercooling region is reduced, the refrigerant density is reduced, and refrigerant saving can be achieved.

Further, since the first heat exchanger 21 and the second heat exchanger 22 are arranged in parallel with the air flow, the static pressure of the air flow is reduced, and the air volume is increased, so that the heat transfer is improved, and the supercooling zone during the condenser operation is reduced.

Industrial applicability

The present disclosure can be used in an air conditioning apparatus including a heat exchanger that can function as both a condenser and an evaporator.

Description of the reference numerals

4 partition member, 5 case, 6 third heat transfer tube, 7 other end, 8 one end, 10 indoor heat exchanger, 11a piping, 11b piping, 11C piping, 11D piping, 12 connection piping, 13a outdoor blower, 13b indoor blower, 14 compressor, 15 four-way valve, 16 outdoor heat exchanger, 17 throttle device (pressure reducing device), 18 rotation shaft, 19 case winding start position, 20 impeller, 21 first heat exchanger, 22 second heat exchanger, 23 third heat exchanger, 30 refrigerant direction, 31 vertical direction, 32 case winding direction, 33 rotation shaft direction, 35 suction inlet, 36 blow-out port, 41 lowermost portion, 42 lowermost portion, 45 intersection point, 51 gravity, 52 inertia force, 61 liquid phase refrigerant, 62 vapor phase refrigerant, 71 flat tube section, 200 air conditioning device, 201 outdoor unit, 202 indoor unit, 211 first fin, 212 first heat transfer tube, 213 first header, 213a chamber, 213b chamber, 213C chamber, 213D chamber, 214 second header 214a chamber, 214b chamber, 214C chamber, 222C chamber, 221 second fin, 222 third header 223a, 223b, 223 fourth header portion, 223G, fourth header portion E.

Claims

1. An air conditioning apparatus for connecting a compressor, a condenser, a pressure reducing device, and an evaporator by pipes to circulate a refrigerant, comprising: a heat exchanger that switches a function of the heat exchanger between the evaporator and the condenser by switching a direction in which a refrigerant flows; and a blower that generates an air flow so as to send air to the heat exchanger, characterized in that,

2. The air-conditioning apparatus according to claim 1, wherein,

the space inside the second header and the third header is partitioned into a plurality of chambers, and the connecting pipe connects any one of the plurality of chambers of the first header or any one of the plurality of chambers of the second header with any one of the plurality of chambers of the third header.

3. The air-conditioning apparatus according to claim 2, wherein,

the number of chambers in the first header or the second header connected to the connection pipe is larger than the number of chambers in the third header connected to the connection pipe.

4. An air conditioning unit according to any of claims 1 to 3, wherein,

the first chamber of the first header is smaller than the second chamber.

5. The air-conditioning device according to any one of claims 1 to 4, wherein,

the space inside the third header is partitioned so that the plurality of chambers are equal in size.

6. The air-conditioning device according to any one of claims 1 to 5, wherein,

The lowermost portion of the first heat exchanger is located below the lowermost portion of the second heat exchanger in the vertical direction.

7. The air conditioning device according to any one of claims 1 to 6, wherein,

the first chamber of the first header is a chamber at one end in a horizontal direction of the first header,

the connection pipe connects any one of the chambers of the first header positioned at the other end in the horizontal direction or any one of the chambers of the second header positioned at the other end in the horizontal direction to the third header.

8. The air conditioning device according to any of claims 1 to 7, wherein,

grouping the plurality of first heat transfer tubes in the following manner: when the chambers of the first header to which one end of the plurality of first heat transfer tubes is connected and the chambers of the second header to which the other end of the plurality of first heat transfer tubes is connected are the same, the chambers are included in the same group, and when the chambers are included in different groups, the square value of the number of the first heat transfer tubes in each group is summed up in all groups, the sum of the sum is divided by the number of the first heat transfer tubes in all groups to obtain a value N1 of average branches of the first heat transfer tubes,

Grouping the plurality of second heat transfer tubes in the following manner: when the chamber of the third header to which one end of the plurality of second heat transfer tubes is connected and the chamber of the fourth header to which the other end of the plurality of second heat transfer tubes is connected are the same, the chambers are included in the same group, and when the chambers are different, the chambers are included in different groups, and at this time, the sum of the square values of the numbers of the second heat transfer tubes in each group is summed up in all groups, the sum of the square values divided by the numbers of the second heat transfer tubes in all groups is set as the average branch number N2 of the second heat transfer tubes,

when the length of the first heat transfer pipe is L1 and the length of the second heat transfer pipe is L2, (L1/N1) × (N2/L2) is in the range of 1.3 to 5.2.

9. The air conditioning device according to any of claims 1 to 8, wherein,

the fan is configured such that a blade rotates around a rotation axis, and the first heat exchanger and the second heat exchanger are arranged at non-overlapping positions around the rotation axis when viewed in an axial direction of the rotation axis.

10. The air conditioning device according to any of claims 1 to 9, wherein,

The air blower is an axial flow air blower,

the extending directions of the first header, the second header, the third header, and the fourth header extend in a tangential direction of a circle centered on a rotation axis of the blower,

the first heat exchanger and the second heat exchanger are positioned at a position not overlapping each other when viewed in plan on a plane orthogonal to the rotation axis.

11. The air conditioning device according to any of claims 1 to 9, wherein,

the blower is a centrifugal blower with a vortex shell,

the first heat transfer pipe and the second heat transfer pipe extend in a direction orthogonal to a rotation axis of the blower,

the extending directions of the first header, the second header, the third header, and the fourth header extend in a direction parallel to the axial direction of the rotary shaft,

in a plane orthogonal to the rotation axis, the second heat exchanger is located closer to a winding start side of the scroll case than the first heat exchanger when viewed in a winding direction of the scroll case.

12. The air conditioning device according to any of claims 1 to 11, wherein,

the first heat exchanger and the second heat exchanger are mounted on the indoor unit.

13. The air conditioning device according to any of claims 1 to 12, wherein,

the refrigerant is an olefin refrigerant, propane or dimethyl ether refrigerant, and has a gas density smaller than that of the R32 refrigerant or the R410A refrigerant.

14. The air conditioning device according to any of claims 1 to 13, wherein,

the air conditioning device is composed of at least one compressor, a utilization side heat exchanger, a throttling device and a heat source side heat exchanger,

at least one of the use side heat exchanger and the heat source side heat exchanger is configured by the first heat exchanger and the second heat exchanger.