WO2016103437A1

WO2016103437A1 - Refrigeration cycle apparatus

Info

Publication number: WO2016103437A1
Application number: PCT/JP2014/084466
Authority: WO
Inventors: 中村　伸; 英明前山; 石橋　晃; 真哉東井上; 伊東　大輔; 繁佳松井; 拓未西山; 裕樹宇賀神
Original assignee: 三菱電機株式会社
Priority date: 2014-12-26
Filing date: 2014-12-26
Publication date: 2016-06-30
Also published as: JP6415600B2; EP3239640A1; EP3239640A4; JPWO2016103437A1

Abstract

This refrigeration cycle apparatus is configured such that a mixed refrigerant including HFO-1123 or HFO-1123 is used as a refrigerant, and at least one of a first heat exchanger and a second heat exchanger has a plurality of fins and a plurality of flat tubes in which a plurality of channels through which the refrigerant flows are formed, wherein the plurality of flat tubes satisfy the relationship in which 0.9 mm ≤ DA ≤ 3.0 mm, where DA is the width of the flat tube.

Description

Refrigeration cycle equipment

The present invention relates to a refrigeration cycle apparatus equipped with a heat exchanger.

A conventional refrigeration cycle apparatus has been proposed that uses HFO-1123 as a working fluid (see, for example, Patent Document 1).

JP 2014-98166 A

A refrigerant containing an HFO refrigerant such as HFO-1123 described in Patent Document 1 generally has a short atmospheric life because it has a low global warming potential (hereinafter referred to as “GWP”). That is, since the stability is poor, the refrigerant is easily decomposed even when it exists in the refrigerant circuit including the heat exchanger. Therefore, it becomes a factor of the performance fall and reliability fall of a refrigerating cycle device.

The present invention has been made in the background of the above-described problems, and in the case of using HFO-1123 or a mixed refrigerant containing HFO-1123 as the refrigerant circulating in the refrigerant circuit, the heat transfer performance of the heat exchanger It aims at providing the refrigerating cycle device which can improve.

The refrigeration cycle apparatus according to the present invention includes a refrigerant circuit in which a compressor, a first heat exchanger, an expansion unit, and a second heat exchanger are sequentially connected by piping to circulate the refrigerant, and the refrigerant is HFO-1123. Or at least one of the first heat exchanger and the second heat exchanger has a plurality of fins and a plurality of flow paths through which the refrigerant flows formed therein. The plurality of flat tubes satisfy the relationship of 0.9 mm ≦ DA ≦ 3.0 mm when the width is DA.

The present invention satisfies the relationship of 0.9 mm ≦ DA ≦ 3.0 mm when the width of the flat tube is DA. For this reason, in the case where HFO-1123 or a mixed refrigerant containing HFO-1123 is used as the refrigerant circulating in the refrigerant circuit, the heat transfer performance of the heat exchanger can be improved.

It is a circuit diagram which shows an example of the refrigerant circuit of the refrigerating-cycle apparatus in Embodiment 1 of this invention. It is a perspective view which shows an example of the heat exchanger of the refrigeration cycle apparatus in Embodiment 1 of this invention. It is sectional drawing which shows an example of the flat tube of the refrigerating-cycle apparatus in Embodiment 1 of this invention. It is sectional drawing which shows an example of the heat exchanger of the refrigerating-cycle apparatus in Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the short axis diameter DA of a flat tube, and a coefficient of performance (COP) of the refrigerating-cycle apparatus in Embodiment 1 of this invention. It is sectional drawing which shows an example of the flat tube of the refrigerating-cycle apparatus in Embodiment 2 of this invention. It is a cross-sectional enlarged view which shows an example of the flat tube of the refrigerating-cycle apparatus in Embodiment 2 of this invention. It is sectional drawing which shows an example when sludge accumulates between protrusions when multiple protrusions are provided in a flat tube. It is sectional drawing which shows an example of the flat tube of the refrigerating-cycle apparatus in Embodiment 2 of this invention. It is a cross-sectional enlarged view which shows an example of the flat tube of the refrigerating-cycle apparatus in Embodiment 2 of this invention. It is a characteristic view which shows the relationship between the ratio of the thickness to of the flat tube and the short axis diameter DA, and pressure | voltage resistance performance of the refrigerating-cycle apparatus in Embodiment 3 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate.
In the following drawings, the size relationship between the constituent members may be different from the actual one. In the following drawings, the same reference numerals denote the same or corresponding parts, and this is common throughout the entire specification. Furthermore, the forms of the constituent elements shown in the entire specification are merely examples, and are not limited to these descriptions.
In the following embodiments, an air conditioner will be described as an example of the refrigeration cycle apparatus of the present invention. The refrigeration cycle apparatus of the present invention can also be applied to the apparatus.

Embodiment 1 FIG.
1 is a circuit diagram illustrating an example of a refrigerant circuit of a refrigeration cycle apparatus according to Embodiment 1 of the present invention.
As shown in FIG. 1, a refrigeration cycle apparatus 10 includes a compressor 11, a first heat exchanger 12, an expansion means 13, and a second heat exchanger 14 that are sequentially connected by a pipe, and circulate the refrigerant. It has a circuit. The first heat exchanger 12 is provided with a fan 15a that blows air, and the second heat exchanger 14 is provided with a fan 15b that blows air.
In the following description, when the first heat exchanger 12 and the second heat exchanger 14 are not distinguished, they are referred to as the heat exchanger 1.

As the refrigerant circulating in the refrigerant circuit, 1,1,2-trifluoroethylene (HFO-1123) having one double bond in the molecular structure or a mixed refrigerant containing HFO-1123 is used.

Here, in a conventional refrigeration cycle apparatus, a hydrofluorocarbon (HFC) refrigerant such as HFC-410A is used as a working fluid. Unlike hydrochlorofluorocarbon (HCFC) refrigerants such as HCFC22, this HFC-410A has an ozone depletion coefficient (ODP) that is an index of the impact on the ozone layer in the stratosphere, and destroys the ozone layer. There is no. However, the HFC refrigerant has a possibility of causing global warming, and its index, GWP, shows a high value.

As a refrigerant having a low GWP, HFC-32 having a GWP lower than that of HFC-410A exists among HFC refrigerants having no carbon double bond in the composition. However, when this refrigerant is used as the working fluid of the refrigeration cycle apparatus 10, the discharge temperature at the outlet of the compressor 11 is higher than that of a conventional refrigerant, and therefore it is necessary to use a material that can withstand high temperatures.

Further, as a refrigerant having a low GWP, there is hydrofluoroolefin (HFO) having a carbon double bond in its composition, which is easily decomposed by OH radicals in the atmosphere. Examples of such HFO refrigerants include HFO-1234yf and HFO-1234ze. However, since these refrigerants are refrigerants having a high standard boiling point, the pressure is lower than that at the same saturation temperature as that of conventional refrigerants. That is, the refrigerant density becomes smaller than that of the conventional HFC refrigerant, and the frequency of the compressor 11 needs to be increased in order to keep the refrigerant circulation amount in the refrigeration cycle apparatus 10 equal to that of the conventional refrigerant. Therefore, the power consumption increases, which causes a reduction in energy saving performance.

As described above, the refrigerant circulating in the refrigerant circuit in the first embodiment is HFO-1123.
HFO-1123 or a mixed refrigerant containing HFO-1123 is used. Unlike HFO-1234yf and HFO-1234ze described above, HFO-1123 is a refrigerant having a low standard boiling point, and therefore has a higher pressure than at the same saturation temperature as that of a conventional HFC refrigerant. That is, the refrigerant density is larger than that of the conventional refrigerant, and even if the frequency of the compressor 11 is lowered, the refrigerant circulation amount in the refrigeration cycle apparatus 10 can be kept equal to that of the conventional refrigerant. Therefore, HFO-1123 is superior in energy saving performance among other HFO refrigerants. In addition, HFO-1123 has a larger latent heat than HFC-410A that has been used in the past, so that it is possible to reduce the refrigerant circulation amount in the refrigeration cycle apparatus 10. That is, the refrigeration cycle apparatus 10 using HFO-1123 as a working fluid reduces heat loss in the flat tube 2 (heat transfer tube) in the heat exchanger 1 and radiates heat equivalent to the case where a conventional refrigerant is used ( It is possible to demonstrate (cooling) capability.

The compressor 11 compresses the refrigerant discharged from the second heat exchanger 14 and supplies the high-temperature and high-pressure refrigerant to the first heat exchanger 12. The first heat exchanger 12 functions as a condenser, performs heat exchange between the air supplied from the fan 15a and the refrigerant, and condenses and liquefies the refrigerant. The expansion means 13 includes an expansion valve, a capillary tube, a decompression device, a throttling device, and the like. The expansion means 13 expands the refrigerant discharged from the first heat exchanger 12 and supplies it to the second heat exchanger 14 as a low-temperature and low-pressure refrigerant. The second heat exchanger 14 functions as an evaporator, performs heat exchange between the air supplied from the fan 15b and the refrigerant, and evaporates the refrigerant.

In addition, by providing a flow path switching device such as a four-way valve and switching the flow direction of the refrigerant in the refrigerant circuit, the first heat exchanger 12 functions as an evaporator and the second heat exchanger 14 functions as a condenser. You may do it.

FIG. 2 is a perspective view showing an example of a heat exchanger of the refrigeration cycle apparatus according to Embodiment 1 of the present invention.
In FIG. 2, the heat exchanger 1 includes a plurality of flat tubes 2, a plurality of fins 3, and a pair of

headers

4a and 4b. The plurality of fins 3 are arranged at intervals, and are configured such that a fluid such as air flows through the intervals. The plurality of flat tubes 2 are inserted into the plurality of fins 3. In the plurality of flat tubes 2, the direction of the longitudinal dimension in the flat cross section (hereinafter referred to as the major axis direction) faces the flow direction of the air flowing between the plurality of fins 3, and the direction of the width dimension in the flat cross section ( Hereinafter, they are arranged at intervals in the short axis direction).

The

headers

4a and 4b extend vertically and are opposed to each other, and connect both ends of the plurality of flat tubes 2 respectively. The refrigerant that has flowed into the header 4 a is branched into multiple portions within the header 4 a and flows into each of the plurality of flat tubes 2. The refrigerant flowing through the refrigerant flow paths in the plurality of flat tubes 2 exchanges heat with the air flowing between the plurality of fins 3 and between the plurality of flat tubes 2 and flows into the header 4b. The refrigerant flowing into the header 4b joins inside the header 4b and then flows out from the header 4b.

The

headers

4a and 4b are written vertically in the drawing, and the refrigerant flows in the horizontal direction toward the flat tube 2. However, the orientation of the

headers

4a and 4b is not limited to this direction. For example, the

headers

4a and 4b may be installed sideways, and the refrigerant may flow in the vertical direction.
A branch pipe that branches the refrigerant may be provided instead of at least one of the

headers

4a and 4b.

The fin 3 is made of aluminum, for example. The fin 3 is produced | generated in arbitrary shapes by processing, such as a press, after cut | disconnecting an aluminum strip to a predetermined magnitude | size, for example. The material of the fin 3 is not limited to aluminum, and any material such as copper can be used. Moreover, the shape of the fin 3 can use arbitrary shapes, such as a plate-shaped plate fin or the corrugated fin formed in the wave shape, for example. Moreover, you may provide the fin 3 in the shape which improves heat exchange performance, such as cutting and raising processing or forming an uneven | corrugated | grooved part.

FIG. 3 is a cross-sectional view showing an example of a flat tube of the refrigeration cycle apparatus according to Embodiment 1 of the present invention.
As shown in FIG. 3, the flat tube 2 has a flat cross section. The flat tube 2 is configured by a flat multi-hole tube, and a plurality of flow paths 21 partitioned by the partition wall 20 are formed along the longitudinal direction of the flat tube 2. The flat tube 2 is made of, for example, aluminum.

Note that, for example, by using aluminum for the material of the fins 3 and the flat tubes 2, corrosion due to contact with different metals can be prevented. Also, brazing can be used for joining the fins 3 and the flat tubes 2. In addition, there is an adhesive in addition to brazing for joining the fin 3 and the flat tube 2, but when the fin 3 and the flat tube 2 are joined by brazing using a brazing material such as an aluminum brazing material, The adhesion between the fin 3 and the flat tube 2 is superior to that of the adhesive. Also, the joining of the fin 3 and the flat tube 2 by brazing is a heat exchanger 1 that has higher heat transfer performance and superior heat exchange performance than the pipe expansion method in which the pipe inserted into the fin 3 is expanded and joined. Can be provided.

FIG. 4 is a cross-sectional view showing an example of the heat exchanger of the refrigeration cycle apparatus in Embodiment 1 of the present invention.
In the example of FIG. 4, the flat tubes 2 are arranged in, for example, two rows in the row direction that is the air flow direction. Further, the flat tubes 2 are arranged in a plurality of stages in the step direction orthogonal to the row direction. Further, the flat tubes 2 are arranged so that adjacent rows of flat tubes 2 do not overlap in the step direction (for example, a staggered arrangement). And air flows in from the side where the fin 3 is attached upstream of the flat tube 2.

The flat tube 2 has, for example, a width dimension (hereinafter referred to as a short axis diameter DA) in a flat cross section of 2.0 mm and a long dimension (hereinafter referred to as a long axis diameter DB) in a flat cross section of 19.0 mm. In the flat tube 2, for example, the number of holes in the flow path 21 is 20, and the thickness ti of the partition wall 20 in the flow path 21 is 0.20 mm. The wall thickness to between the outer wall of the flat tube 2 and the inner wall of the flow path 21 is 0.30 mm. Further, a step pitch DP, which is a distance in the step direction connecting the centers of the adjacent flat tubes 2, is arranged at 13.6 mm.

The fin 3 has an air flow direction width L of 22 mm. The heat exchanger 1 has a height H_HEX of 600 mm and a fin product width H_W of 850 mm (see FIG. 2).

It should be noted that these dimensions are merely examples, and the present invention is not limited to this, and may be any shape that satisfies the dimensional requirements described below.

FIG. 5 is a characteristic diagram showing the relationship between the short axis diameter DA of the flat tube and the coefficient of performance (COP) in the refrigeration cycle apparatus according to Embodiment 1 of the present invention.
In FIG. 5, the case where the heat exchanger 1 is used as an evaporator is taken as an example, and the coefficient of performance (COP) at each short axis diameter DA is extracted by simulation using the short axis diameter DA of the flat tube 2 as a parameter. Show. FIG. 5 shows a comparison between the case of using HFC-410A and the case of using HFO-1123 as the refrigerant circulating in the refrigerant circuit.

Further, in the simulation result shown in FIG. 5, the ratio between the in-pipe length B of the flow channel 21 in the long axis direction of the flat tube 2 and the in-pipe length A of the flow channel 21 in the short axis direction of the flat tube 2. A certain aspect ratio B / A is constant at a preset value. For example, the aspect ratio B / A is equivalent to the dimension example described above. That is, in the dimension example described above, the in-pipe length B of the flow path 21 is 0.73 mm and the in-pipe length A is 1.4 mm, so the aspect ratio B / A is 0.52. Further, the ratio between the step pitch DP of the flat tube 2 and the short axis diameter DA is constant at a preset value. For example, it is equivalent to the dimension example described above. That is, DP / DA is 6.8, for example. Further, the ratio between the wall thickness to of the flat tube 2 and the short axis diameter DA is constant at a preset value. For example, it is equivalent to the dimension example described above. That is, to / DA is 0.15, for example. Further, the long axis diameter DB of the flat tube 2, the height H_HEX of the heat exchanger 1, and the fin product width H_W are equivalent to the above-described dimension example.

Further, in the simulation result shown in FIG. 5, the amount of heat released from the fins 3 and the flat tubes 2 to the air (the amount of heat received) is constant. In addition, the parameters of the heat transfer tubes and the heat exchanger 1 other than the above, such as the pitch of the fins 3, the number of holes, the path configuration of the heat exchanger 1, and the operating conditions of the refrigeration cycle are values at which the coefficient of performance is almost optimal. is there.

As shown in FIG. 5, when the short axis diameter DA of the flat tube 2 is reduced, the ventilation resistance between the adjacent flat tubes 2 is reduced. Further, since the step pitch DP / the short axis diameter DA is constant at a preset value, when the short axis diameter DA of the flat tube 2 is small, the flat tube 2 can be mounted with high density. Further, since the aspect ratio B / A and the wall thickness to / short axis diameter DA are constant at preset values, when the short axis diameter DA of the flat tube 2 becomes small, the flow path 21 inside the flat tube 2 is reduced. The number of holes will increase. For this reason, the area which the refrigerant | coolant in the pipe | tube of the flat tube 2 contacts with a heat-transfer surface increases, and it can heat-exchange efficiently. Therefore, the performance of the heat exchanger 1 is improved and the coefficient of performance is also improved.

In addition, when the short axis diameter DA of the flat tube 2 becomes too small, the cross-sectional area of the flow path 21 of the flat tube 2 is also narrowed, so that the pressure loss in the tube increases. In order to suppress an increase in the pressure loss in the pipe, it is necessary to increase the number of passes of the heat exchanger 1. However, when the refrigerant is multi-branched, the

headers

4a and 4b can be used evenly in order to exhibit sufficient performance. It is necessary to distribute the refrigerant. However, if the short axis diameter DA of the flat tube 2 becomes too small, it becomes difficult to distribute the refrigerant evenly. Further, since the upper limit of the number of passes is determined depending on the size of the heat exchanger 1, if the short axis diameter DA is reduced, it becomes impossible to cope with an increase in the pressure loss in the pipe due to an increase in the number of passes. For this reason, when the short axis diameter DA of the flat tube 2 becomes too small, the performance of the heat exchanger 1 is lowered and the coefficient of performance is also lowered.

Moreover, when the short axis diameter DA of the flat tube 2 is less than 0.8 mm, it becomes difficult in manufacturing the flat tube 2 such as extrusion.

On the other hand, if the short axis diameter DA of the flat tube 2 becomes too large, the ventilation resistance between the adjacent flat tubes 2 increases. Further, the number of holes in the flow path 21 inside the flat tube 2 is reduced. For this reason, the area which the refrigerant | coolant in the pipe | tube of the flat tube 2 contacts with a heat-transfer surface reduces, and the efficiency of heat exchange worsens. Therefore, it becomes difficult to exhibit sufficient heat exchange performance, and the coefficient of performance also decreases.

As shown in FIG. 5, when compared with the type of refrigerant, when the refrigerant flowing through the flat tube 2 is HFO-1123, the pressure loss in the flat tube 2 is reduced as compared with HFC-410A. For this reason, the number of passes can be reduced even with an equivalent minor axis diameter DA, and the coefficient of performance is improved. In particular, when the minor axis diameter DA is 0.9 mm ≦ DA ≦ 3.0 mm, the coefficient of performance when the refrigerant is HFO-1123 is almost equal to the peak value of the coefficient of performance when HFC-410A is used. It becomes more than that and it becomes possible to exhibit sufficient performance.

When the short axis diameter DA of the flat tube 2 is 0.9 mm, for example, when the aspect ratio B / A is 0.52 and the wall thickness to / short axis diameter DA is 0.15 as in the above-described dimension example, The in-tube length B of the flow path 21 in the long axis direction of the flat tube 2 is 0.33 mm. Here, the size of the sludge produced by the chemical reaction of the decomposition product of HFO-1123 is about 0.15 mm. Therefore, if the in-pipe length B of the flow channel 21 is 0.33 mm, sludge is accumulated in the flow channel 21 even when HFO-1123 flowing through the flat tube 2 is decomposed and sludge is generated. It becomes possible to flow without. For this reason, it becomes possible to ensure sufficient reliability.

Therefore, the minor axis diameter DA of the flat tube 2 should satisfy the relationship of 0.9 mm ≦ DA ≦ 3.0 mm. As a result, in the case of using HFO-1123 or a mixed refrigerant containing HFO-1123 as the refrigerant circulating in the refrigerant circuit, the heat transfer performance of the heat exchanger 1 can be improved, resulting from the decomposition of the refrigerant. Even when sludge is generated, a decrease in reliability can be suppressed.

If a smaller value is selected for the aspect ratio B / A, the in-pipe length B of the flow path 21 in the long axis direction of the flat tube 2 is not sufficient, but the pressure loss in the pipe increases. In general, the aspect ratio is increased to such an extent that the pressure resistance is maintained.

In addition, as shown in FIG. 5, when the short axis diameter DA of the flat tube 2 is 1.0 mm ≦ DA ≦ 1.8 mm, the coefficient of performance when the refrigerant flowing through the flat tube 2 is HFO-1123 is Within 2% of the maximum value. For this reason, when the short axis diameter DA of the flat tube 2 satisfies the relationship of 1.0 mm ≦ DA ≦ 1.8 mm, particularly excellent performance can be exhibited.

As described above, in the first embodiment, the heat transfer performance of the heat exchanger 1 is improved when HFO-1123 or a mixed refrigerant containing HFO-1123 is used as the refrigerant circulating in the refrigerant circuit. Can do. Moreover, even if it is a case where the sludge resulting from decomposition | disassembly of a refrigerant | coolant generate | occur | produces, the refrigerating-cycle apparatus 10 which can suppress a reliability fall can be provided.

Embodiment 2. FIG.
FIG. 6 is a cross-sectional view showing an example of a flat tube of the refrigeration cycle apparatus according to Embodiment 2 of the present invention.
FIG. 7 is an enlarged cross-sectional view showing an example of a flat tube of the refrigeration cycle apparatus according to Embodiment 2 of the present invention.
As shown in FIGS. 6 and 7, in the flat tube 2 in the second embodiment, one or a plurality of protrusions 22 are formed on the inner wall surface of the flow channel 21 along the flow channel direction. 7 shows a case where a gas-liquid two-phase refrigerant flows, 25 indicates a two-phase liquid film, and 26 indicates a gas-liquid interface.

By forming the protrusions 22 on the inner wall surface of the flow path 21, the contact area between the inner wall surface of the flow path 21 and the refrigerant can be increased. In addition, it is possible to promote disturbance of the refrigerant flow in the flow path 21. Furthermore, as shown in FIG. 7, the liquid refrigerant concentrates on the bottom 24 of the protrusion 22 due to the surface tension of the refrigerant, so that the drainage in the tube axis direction is improved and the two phases around the bottom 24 of the protrusion 22 are improved. The thickness of the flowing liquid film 25 can be reduced. Therefore, heat exchange can be performed more efficiently than in the case where the protrusions 22 are not provided.

In the example shown in FIGS. 6 and 7, the protrusion 22 has a triangular cross-sectional shape, but the present invention is not limited to this. For example, in any projection shape such as a semicircular shape, an elliptical shape, or a rectangular shape, an effect equivalent to the above-described object can be achieved.

Here, as shown in FIG. 8, when a plurality of protrusions 22 are formed on the inner wall surface of the flow path 21 of the flat tube 2, the sludge 31 generated when the HFO-1123 is decomposed is It is easy to deposit. Of the inner wall surface of the flow channel 21 of the flat tube 2, sludge 31 is particularly easily deposited on the inner wall surface 23 facing downward in the gravitational direction. When such sludge 31 accumulates in the flow path 21, the pressure loss in the pipe increases or becomes clogged, and the pressure in the refrigerant circuit rises more than necessary, which may reduce the reliability.

Since the size of the sludge generated by the chemical reaction of the decomposition product of HFO-1123 is smaller than 0.15 mm, the distance D between the adjacent protrusions 22 satisfies 0.15 mm ≦ D. The refrigerant can flow without the sludge 31 being deposited. Moreover, although the pressure loss in a pipe | tube falls by increasing the space | interval D of the adjacent protrusion 22, when the space | interval D of the adjacent protrusion 22 becomes large too much, the increment rate of the heat-transfer area of the inner wall face of the flow path 21 will fall. . Further, the disturbance of the refrigerant flow in the flow path 21 cannot be sufficiently promoted. For this reason, the distance D between the adjacent protrusions 22 is preferably 0.50 mm or less.

Therefore, when the plurality of protrusions 22 are formed on the inner wall surface 23 on the lower side in the gravity direction among the inner wall surfaces of the flow path 21, the distance D between adjacent protrusions 22 has a relationship of 0.15 mm ≦ D ≦ 0.50 mm. Try to meet. Thereby, even when the plurality of protrusions 22 are formed on the inner wall surface of the flow path 21, the sludge 31 can flow without being deposited.

FIG. 9 is a cross-sectional view showing an example of a flat tube of the refrigeration cycle apparatus according to Embodiment 2 of the present invention.
FIG. 10 is an enlarged cross-sectional view showing an example of a flat tube of the refrigeration cycle apparatus according to Embodiment 2 of the present invention.
9 and 10 show a case in which one protrusion 22 is provided on the inner wall surface 23 facing downward in the gravity direction and one protrusion 22 is provided on the inner wall surface facing upward in the gravity direction among the inner wall surfaces of the flow path 21. . The number of protrusions 22 is not limited to this, and a plurality of protrusions 22 may be provided on one inner wall surface. In addition, when providing the some protrusion 22, the space | interval D is formed so that the relationship mentioned above may be satisfy | filled.

When one or a plurality of protrusions 22 are formed on the inner wall surface of the flow path 21, sludge 31 generated when the HFO-1123 is decomposed easily accumulates between the protrusion 22 and the side wall of the flow path 21. Of the inner wall surface of the flow channel 21 of the flat tube 2, sludge 31 is particularly easily deposited on the inner wall surface 23 facing downward in the gravitational direction. For this reason, when the distance C from the bottom 24 of the protrusion 22 to the side wall of the flow path 21 satisfies 0.15 mm ≦ C, the refrigerant can flow without depositing sludge 31 in the flow path 21. Moreover, when the distance C becomes too large, the increment rate of the heat transfer area of the inner wall surface of the flow path 21 will fall. Further, the disturbance of the refrigerant flow in the flow path 21 cannot be sufficiently promoted. Therefore, the distance C is preferably 0.50 mm or less.

Therefore, when one or more protrusions 22 are formed on the inner wall surface 23 on the lower side in the gravity direction of the inner wall surface of the flow path 21, the distance C from the bottom 24 of the protrusion 22 to the side wall of the flow path 21 is 0. The relationship of 15 mm ≦ D ≦ 0.50 mm is satisfied. Thus, even when one or a plurality of protrusions 22 are formed on the inner wall surface of the flow path 21, the sludge 31 can flow without being deposited.

Embodiment 3 FIG.
FIG. 11 is a characteristic diagram showing the relationship between the pressure ratio performance and the ratio between the thickness to of the flat tube and the minor axis diameter DA of the refrigeration cycle apparatus according to Embodiment 3 of the present invention.
When HFO-1123 or a mixed refrigerant containing HFO-1123 is used as the refrigerant circulating in the refrigerant circuit, HFO-1123 is a refrigerant having a lower standard boiling point than the conventionally used HFC-410A. For this reason, the pressure becomes larger than that at the saturation temperature equivalent to that of HFC-410A. For this reason, it is necessary to sufficiently ensure the pressure resistance performance of the flat tube 2.

In the example of FIG. 11, the wall thickness to of the flat tube 2 and the short axis diameter DA are used as parameters in the calculation conditions during the performance coefficient simulation shown in FIG. 5 of the first embodiment described above. In FIG. 11, the horizontal axis indicates the ratio to / DA between the wall thickness to of the flat tube 2 and the short axis diameter DA, and the vertical axis indicates the pressure resistance Pr of the flat tube 2 and the flat tube 2 required. The ratio Pr / Pn to the breakdown voltage Pn is shown.

As shown in FIG. 11, to / DA and Pr / Pn are in a proportional relationship. That is, regardless of the absolute value of the short axis diameter DA of the flat tube 2, the value of Pr / Pn decreases as to / DA decreases. When to / DA decreases, the wall thickness to with respect to the minor axis diameter DA decreases, so that the cross-sectional area of the flow path 21 and the heat transfer area of the flow path 21 increase, and the heat exchange performance also increases. Further, when to / DA decreases, the thickness to with respect to the minor axis diameter DA decreases, so that the pressure resistance performance Pr decreases and Pr / Pn decreases.

The pressure resistance performance Pr needs to exceed the required pressure resistance Pn. That is, when Pr / Pn is 1 or less, the pressure resistance performance cannot be sufficiently ensured, so it is necessary to satisfy Pr / Pn> 1. In the example shown in FIG. 11, when to / DA is less than 0.10, Pr / Pn is 1 or less. Therefore, it is necessary to satisfy the relationship of 0.10 ≦ to / DA. On the other hand, when to / DA increases too much, the pressure resistance is sufficiently ensured, but the cross-sectional area of the flow path 21 and the heat transfer area of the flow path 21 are reduced, and the heat exchange performance is also reduced. In particular, when to / DA exceeds 0.20, nearly half of the flat tube 2 in the short axis direction is filled with a thickness, and the performance cannot be sufficiently exhibited. From the above, it is desirable that to / DA is 0.10 ≦ to / DA ≦ 0.20.

In addition, when the absolute value of the wall thickness to itself is small, there is a possibility that a hole is opened in the tube due to corrosion of the flat tube 2 or the like. For this reason, it is desirable to satisfy the relationship of to ≧ 0.10 mm in addition to the above-mentioned range of to / DA.

In this way, by satisfying the relationship of 0.10 ≦ to / DA ≦ 0.20 and to ≧ 0.10 mm, the pressure resistance performance is improved in the case of using HFO-1123 or a mixed refrigerant containing HFO-1123. Sufficiently can be secured and the heat exchange performance can be improved.

In the first to third embodiments, the heat exchanger 1 has been described as an example when used as an evaporator in an outdoor unit of an air conditioner. For example, the heat exchanger 1 is used as a condenser in an indoor unit of an air conditioner. Thus, the same effect can be achieved when used as another heat exchanger 1.

In addition to the air conditioner, in the refrigerant circuit configured by sequentially connecting at least the compressor 11, the first heat exchanger 12, the expansion means 13, and the second heat exchanger 14 by piping, The same effect can be achieved also when it is applied to at least one of the first heat exchanger 12 and the second heat exchanger 14 in the refrigeration cycle apparatus 10 using the heat exchanger 1 described above.

1 heat exchanger, 2 flat tube, 3 fins, 4a header, 4b header, 10 refrigeration cycle device, 11 compressor, 12 1st heat exchanger, 13 expansion means, 14 2nd heat exchanger, 15a fan, 15b fan 20 partition walls, 21 flow paths, 22 protrusions, 23 inner wall surfaces, 24 bottom parts, 25 two-phase liquid film, 31 sludge.

Claims

A compressor, a first heat exchanger, an expansion means, and a second heat exchanger are sequentially connected by piping, and a refrigerant circuit for circulating the refrigerant is provided.
The refrigerant is HFO-1123 or a mixed refrigerant containing HFO-1123,
At least one of the first heat exchanger and the second heat exchanger is
Multiple fins,
A plurality of flow paths through which the refrigerant flows have a plurality of flat tubes formed therein;
The plurality of flat tubes, when the width is DA,
0.9mm ≦ DA ≦ 3.0mm
A refrigeration cycle device that satisfies the relationship
The plurality of flat tubes are
0.9mm ≦ DA ≦ 3.0mm
Satisfy the relationship, and
The refrigeration cycle apparatus according to claim 1, wherein a ratio between a step pitch, which is a distance connecting the centers of adjacent flat tubes, and the width becomes a preset value.
The plurality of flat tubes are
0.9mm ≦ DA ≦ 3.0mm
Satisfy the relationship, and
The ratio between the length in the other direction of the flow path and the length in the one direction, and the ratio between the thickness of the flat tube and the width are set to predetermined values. Or the refrigeration cycle apparatus of 2.
The plurality of flat tubes are
1.0mm ≦ DA ≦ 1.8mm
The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the refrigeration cycle apparatus is configured to satisfy the following relationship.
The flat tube is
The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein one or more protrusions are formed along the flow path direction on an inner wall surface of the flow path.
The flat tube is
At least one protrusion is formed along the flow path direction on the inner wall surface on the lower side in the gravity direction among the inner wall surfaces of the flow path,
When the distance from the bottom of the projection to the side wall of the flow path is C,
0.15mm ≦ C ≦ 0.50mm
The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the refrigeration cycle apparatus is configured to satisfy the following relationship.
The flat tube is
A plurality of protrusions are formed along the flow path direction on the inner wall surface of the flow path,
When the interval between adjacent protrusions is D,
0.15mm ≦ D ≦ 0.50mm
The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the refrigeration cycle apparatus is configured to satisfy the following relationship.
The flat tube is
When the wall thickness between the outer wall of the flat tube and the inner wall of the flow path is to,
0.10 ≦ to / DA ≦ 0.20, and
to ≧ 0.10mm
The refrigeration cycle apparatus according to any one of claims 1 to 7, wherein the refrigeration cycle apparatus is configured to satisfy the following relationship.