JP6910436B2 - Outdoor unit and refrigeration cycle device - Google Patents

Description

The present invention relates to an outdoor unit and a refrigeration cycle device including the outdoor unit, and more particularly to an outdoor unit including an outdoor heat exchanger having a main heat exchange section and an auxiliary heat exchange section, and a refrigeration cycle device including the outdoor unit. It is a thing.

An air conditioner as a refrigeration cycle device includes a refrigerant circuit including an indoor unit and an outdoor unit. In such an air conditioner, it is possible to perform a cooling operation and a heating operation by switching the flow path of the refrigerant circuit using a four-way valve or the like.

The indoor unit is provided with an indoor heat exchanger. In the indoor heat exchanger, heat is exchanged between the refrigerant flowing through the refrigerant circuit and the indoor air sent by the indoor fan. The outdoor unit is provided with an outdoor heat exchanger. In the outdoor heat exchanger, heat is exchanged between the refrigerant flowing through the refrigerant circuit and the outside air sent by the outdoor fan.

The outdoor heat exchanger used in the air conditioner includes an outdoor heat exchanger in which heat transfer tubes are arranged so as to penetrate a plurality of plate-shaped fins. Such an outdoor heat exchanger is called a fin-and-tube heat exchanger. In this fin-and-tube heat exchanger, a heat transfer tube having a reduced diameter may be used in order to efficiently exchange heat.

Further, there is a type of this type of outdoor heat exchanger provided with a main heat exchanger for condensation and an auxiliary heat exchanger for supercooling. Generally, the main heat exchange section is arranged above the auxiliary heat exchange section. When the air conditioner is operated for cooling, the outdoor heat exchanger functions as a condenser. The refrigerant sent to the outdoor heat exchanger exchanges heat with the air while flowing through the main heat exchange section and condenses into a liquid refrigerant. After flowing through the main heat exchange section, the liquid refrigerant flows through the auxiliary heat exchange section to be further cooled.

On the other hand, when the air conditioner is operated for heating, the outdoor heat exchanger functions as an evaporator. The refrigerant sent to the outdoor heat exchanger exchanges heat with the air while flowing from the auxiliary heat exchange section to the main heat exchange section and evaporates to become a gas refrigerant. Patent Document 1 is an example of a patent document that discloses an air conditioner provided with this type of outdoor heat exchanger.

Japanese Unexamined Patent Publication No. 2013-83419

When the air conditioner is operated for heating or cooling, the outside air sent by the outdoor fan passes through the outdoor heat exchanger. At this time, depending on the arrangement relationship between the outdoor heat exchanger and the outdoor fan, a region where the wind speed of the outside air passing through the outdoor heat exchanger is high and a region where the wind speed of the outside air is low may occur. Therefore, in the outdoor heat exchanger, the heat exchange between the refrigerant and the outside air may vary, and the heat exchange may not be performed efficiently.

As described above, in the outdoor unit, the heat exchanger performance may be deteriorated due to the distribution of the wind speed of the outside air passing through the outdoor heat exchanger. Therefore, there is a demand for an outdoor unit having higher heat exchanger performance.

The present invention has been made in view of the above problems, one object is to provide an outdoor unit capable of improving heat exchanger performance, and another object is to provide such an outdoor unit. To provide a refrigeration cycle device.

The outdoor unit according to the present invention includes a heat exchanger and a blower for sending a fluid to the heat exchanger. The heat exchanger includes a first heat exchange unit and a second heat exchange unit. The first heat exchange unit includes a first heat exchange region having a plurality of first refrigerant paths and a second heat exchange region having a plurality of second refrigerant paths. The second heat exchange unit includes a third heat exchange region having at least one third refrigerant path connected to the plurality of first refrigerant paths, and at least one fourth refrigerant path connected to the plurality of second refrigerant paths. Includes a fourth heat exchange region with. The flow velocity of the fluid passing through the first heat exchange region is larger than the flow velocity of the fluid passing through the second heat exchange region. The length of the third refrigerant path in the third heat exchange region is shorter than the length of the fourth refrigerant path in the fourth heat exchange region. The first heat exchange region and the third heat exchange region are arranged so as to be adjacent to each other, and the second heat exchange region and the fourth heat exchange region sandwich the first heat exchange region and the third heat exchange region. Is located in.

The refrigeration cycle device according to the present invention is a refrigeration cycle device provided with the above-mentioned outdoor unit.

According to the outdoor unit according to the present invention, the flow velocity of the fluid passing through the first heat exchange region is larger than the flow velocity of the fluid passing through the second heat exchange region, so that the amount of heat exchange in the first heat exchange region is the second heat. It is larger than the amount of heat exchange in the exchange area. Further, since the total length of the third refrigerant path is shorter than the total length of the fourth refrigerant path, when the heat exchanger operates as a condenser, the pressure loss in the third refrigerant path is relative to the pressure loss in the fourth refrigerant path. Becomes smaller. Therefore, a relatively large amount of refrigerant circulation flows through the third refrigerant path with respect to the fourth refrigerant path. Since the third refrigerant path is connected to the first refrigerant path and the fourth refrigerant path is connected to the second refrigerant path, a relatively large amount of refrigerant circulation flows through the first refrigerant path with respect to the second refrigerant path. .. Thereby, the heat exchanger performance of the heat exchanger of the outdoor unit can be improved.

According to the refrigeration cycle apparatus according to the present invention, the heat exchanger performance of the refrigeration cycle apparatus can be improved by providing the above-mentioned outdoor unit.

It is a figure which shows an example of the refrigerant circuit of the air conditioner which concerns on each embodiment. It is a perspective view which shows the outdoor heat exchanger which concerns on Embodiment 1. FIG. It is a schematic diagram which shows the outdoor heat exchanger which concerns on Embodiment 1. FIG. It is sectional drawing which shows an example of the refrigerant passage of a heat transfer tube in the same embodiment. It is sectional drawing which shows another example of the refrigerant passage of a heat transfer tube in the same embodiment. In the same embodiment, it is a schematic side view which shows the 1st main heat exchange region. In the same embodiment, it is a schematic front view which shows the 1st main heat exchange region. In the same embodiment, it is a schematic side view which shows the 2nd main heat exchange region. In the same embodiment, it is a schematic front view which shows the 2nd main heat exchange region. It is a schematic side view which shows the auxiliary heat exchange part in the same embodiment. It is a schematic front view which shows the auxiliary heat exchange part in the same embodiment. It is a figure which shows the flow of the refrigerant in the refrigerant circuit for demonstrating the operation of the air conditioner in the same embodiment. It is a perspective view which shows the flow of the refrigerant in the outdoor heat exchanger when the outdoor heat exchanger is operated as a condenser in the same embodiment. In the same embodiment, it is a figure which shows the flow of the refrigerant in the outdoor heat exchanger, and the wind speed distribution of the outside air passing through the outdoor heat exchanger. In the same embodiment, it is a schematic side view which shows the flow of the refrigerant in the main heat exchange part when the outdoor heat exchanger is operated as a condenser. It is a schematic front view which shows the flow of the refrigerant in the main heat exchange part when the outdoor heat exchanger is operated as a condenser in the same embodiment. In the same embodiment, it is a schematic side view which shows the flow of the refrigerant in the auxiliary heat exchange part when the outdoor heat exchanger is operated as a condenser. In the same embodiment, it is a schematic front view which shows the flow of the refrigerant in the auxiliary heat exchange part when the outdoor heat exchanger is operated as a condenser. In the same embodiment, it is a graph which shows the relationship between the heat transfer coefficient in a heat transfer tube and the degree of dryness, and the relationship between the heat exchanger condensation performance and the degree of dryness, respectively. In the same embodiment, it is a graph which shows the relationship between the friction pressure loss ratio of a two-phase refrigerant with respect to a liquid refrigerant, and the degree of dryness. In the same embodiment, it is a graph which shows the relationship between the ratio of the refrigerant circulation amount and the friction pressure loss ratio of a refrigerant in the same refrigerant state. It is a perspective view which shows the flow of the refrigerant in the outdoor heat exchanger when the outdoor heat exchanger is operated as an evaporator in the same embodiment. In the same embodiment, it is a figure which shows the flow of the refrigerant in the outdoor heat exchanger, and the wind speed distribution of the outside air passing through the outdoor heat exchanger. In the same embodiment, it is a schematic side view which shows the flow of the refrigerant in the auxiliary heat exchange part when the outdoor heat exchanger is operated as an evaporator. In the same embodiment, it is a schematic front view which shows the flow of the refrigerant in the auxiliary heat exchange part when the outdoor heat exchanger is operated as an evaporator. In the same embodiment, it is a schematic side view which shows the flow of the refrigerant in the main heat exchange part when the outdoor heat exchanger is operated as an evaporator. In the same embodiment, it is a schematic front view which shows the flow of the refrigerant in the main heat exchange part when the outdoor heat exchanger is operated as an evaporator. In the same embodiment, it is a graph which shows the relationship between the heat transfer coefficient of heat transfer in a heat transfer tube and the degree of dryness, and the relationship between the evaporation performance of a heat exchanger and the degree of dryness, respectively. In the same embodiment, it is a figure which shows the flow of the refrigerant in the outdoor heat exchanger, and the wind speed distribution of the outside air passing through the outdoor heat exchanger. It is a figure which shows typically the distribution of the refrigerant and the distribution of the wind speed in the outdoor heat exchanger which concerns on the comparative example of the same embodiment. In the same embodiment, it is a figure which shows typically the distribution of the refrigerant and the distribution of the wind speed in the outdoor heat exchanger. In the same embodiment, the ratio of the frictional pressure loss in the auxiliary heat exchange part to the representative value of the frictional pressure loss in the main heat exchange part and the mass velocity of the refrigerant flowing through the refrigerant path of the main heat exchange part of the auxiliary heat exchange part. It is a graph which shows the relationship with the ratio of the mass velocity of the refrigerant flowing through a refrigerant path. It is a schematic diagram which shows the outdoor heat exchanger which concerns on the modification of the said embodiment. It is a schematic side view which shows the auxiliary heat exchange part of the outdoor heat exchanger which concerns on Embodiment 2. FIG. It is a schematic front view which shows the auxiliary heat exchange part of the outdoor heat exchanger which concerns on the same embodiment. It is a schematic side view which shows the auxiliary heat exchange part of the outdoor heat exchanger which concerns on the comparative example of the same embodiment. It is a schematic front view which shows the auxiliary heat exchange part of the outdoor heat exchanger which concerns on the comparative example of the same embodiment.

Embodiment 1.
First, the overall configuration (refrigerant circuit) of the air conditioner as a refrigeration cycle device will be described. As shown in FIG. 1, the air conditioner 1 includes a compressor 3, an indoor heat exchanger 5, an indoor fan 7, a throttle device 9, an outdoor heat exchanger (heat exchanger) 11, and an outdoor fan (blower) 21. It includes a four-way valve 23 and a control unit 51. The compressor 3, the indoor heat exchanger 5, the throttle device 9, the outdoor heat exchanger 11 and the four-way valve 23 are connected by a refrigerant pipe.

The indoor heat exchanger 5 and the indoor fan 7 are arranged in the indoor unit 4. The outdoor heat exchanger 11 and the outdoor fan 21 are arranged in the outdoor unit 10. A series of operations of the air conditioner 1 is controlled by the control unit 51.

Next, the outdoor heat exchanger 11 will be described. As shown in FIGS. 2 and 3, the outdoor heat exchanger 11 includes a main heat exchange unit (first heat exchange unit) 101 and an auxiliary heat exchange unit (second heat exchange unit) 201. The main heat exchange unit 101 is arranged on the auxiliary heat exchange unit 201. The auxiliary heat exchange unit 201 is arranged below the main heat exchange unit 101. In the main heat exchange unit 101, the main heat exchange unit 101a is arranged in the first row, and the main heat exchange unit 101b is arranged in the second row. In the auxiliary heat exchange unit 201, the auxiliary heat exchange unit 201a is arranged in the first row, and the auxiliary heat exchange unit 201b is arranged in the second row.

In the main heat exchange section 101 and the auxiliary heat exchange section 201, a plurality of heat transfer tubes 33 are arranged so as to penetrate the plurality of plate-shaped fins 31.

As the heat transfer tube 33, for example, a flat tube having a major axis and a minor axis and having a flat cross-sectional shape is used. As an example of the flat pipe, FIG. 4 shows a flat pipe in which one refrigerant passage 34 is formed. As another example of the flat pipe, FIG. 5 shows a flat pipe in which a plurality of refrigerant passages 34 are formed. The heat transfer tube 33 is not limited to a flat tube, and may be, for example, a heat transfer tube having a circular or elliptical cross section.

The main heat exchange unit 101 is further divided into a first main heat exchange region (first heat exchange region) 111 and a second main heat exchange region (second heat exchange region) 121. Here, FIGS. 6 and 7 show the detailed configuration of the first main heat exchange region 111, and FIGS. 8 and 9 show the detailed configuration of the second main heat exchange region 121, respectively. In the outdoor heat exchanger 11, a refrigerant path is formed by the heat transfer tube 33. In the main heat exchange section 101, the first main refrigerant path (first refrigerant path) 113 located in the first main heat exchange region 111 and the second main refrigerant path (second refrigerant path) located in the second main heat exchange region 121. ) 123 is formed. In the first main refrigerant path 113, a plurality of refrigerant paths including one refrigerant path formed by the first main heat transfer tube 119 are formed. In the second main refrigerant path 123, a plurality of refrigerant paths including one refrigerant path formed by the second main heat transfer tube 129 are formed.

In the first embodiment, for example, eight refrigerant paths are formed in both the first main refrigerant path 113 and the second main refrigerant path 123, and each refrigerant path is composed of four heat transfer tubes. There is. Therefore, both the first main heat exchange region 111 and the second main heat exchange region 121 are composed of 32 heat transfer tubes.

The auxiliary heat exchange unit 201 is further divided into a first auxiliary heat exchange region (third heat exchange region) 211 and a second auxiliary heat exchange region (fourth heat exchange region) 221. Here, FIGS. 10 and 11 show the detailed configuration of the auxiliary heat exchange unit 201, respectively. In the auxiliary heat exchange unit 201, a refrigerant path is formed by the heat transfer tube 33. In the auxiliary heat exchange unit 201, the first auxiliary refrigerant path (third refrigerant path) 213 located in the first auxiliary heat exchange region 211 and the second auxiliary refrigerant path (fourth refrigerant path) located in the second auxiliary heat exchange region 221 ) 223 is formed. The first auxiliary refrigerant path 213 has at least one refrigerant path formed by the first auxiliary heat transfer tube 219. The second auxiliary refrigerant path 223 has at least one refrigerant path formed by the second auxiliary heat transfer tube 229. Further, the total length of the first auxiliary refrigerant path 213 is shorter than the total length of the second auxiliary refrigerant path 223. That is, the first auxiliary heat transfer tube 219 has a shorter overall length than the second auxiliary heat transfer tube 229. In the first embodiment, since the length of each heat transfer tube is the same, a short overall length of the heat transfer tube is synonymous with a small number of heat transfer tubes. In the first embodiment, the number of heat transfer tubes in the first auxiliary refrigerant path 213 is smaller than the number of heat transfer tubes in the second auxiliary refrigerant path 223. Specifically, the first auxiliary refrigerant path 213 is composed of four heat transfer tubes. The second auxiliary refrigerant path 223 is composed of 12 heat transfer tubes.

One end side of the first main refrigerant path 113 and the second main refrigerant path 123 of the main heat exchange unit 101 and one end side of the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 of the auxiliary heat exchange unit 201 are first. It is connected by a connecting pipe 35 via a distributor 112 and a second distributor 122. More specifically, the first main refrigerant path 113 is connected to the first auxiliary refrigerant path 213 via the first distributor 112. The second main refrigerant path 123 is connected to the second auxiliary refrigerant path 223 via the second distributor 122.

The other ends of the first main refrigerant path 113 and the second main refrigerant path 123 of the main heat exchange section 101 are connected to the header 27. The other ends of the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 of the auxiliary heat exchange unit 201 are connected to the distributor 25 by the connecting pipe 36. The outdoor heat exchanger 11 is configured as described above.

Next, as an operation of the air conditioner including the outdoor unit 10 (see FIG. 1) having the outdoor heat exchanger 11 described above, first, a case of cooling operation will be described.

As shown in FIG. 12, by driving the compressor 3, the refrigerant in a high-temperature and high-pressure gas state is discharged from the compressor 3. Hereinafter, the refrigerant flows according to the dotted arrow. The discharged high-temperature and high-pressure gas refrigerant (single-phase) flows into the outdoor heat exchanger 11 of the outdoor unit 10 via the four-way valve 23. In the outdoor heat exchanger 11, heat exchange is performed between the flowing refrigerant and the outside air (air) as a fluid supplied by the outdoor fan 21. The high-temperature and high-pressure gas refrigerant condenses into a high-pressure liquid refrigerant (single-phase).

The high-pressure liquid refrigerant sent out from the outdoor heat exchanger 11 becomes a two-phase refrigerant of a low-pressure gas refrigerant and a liquid refrigerant by the throttle device 9. The two-phase refrigerant flows into the indoor heat exchanger 5 of the indoor unit 4. In the indoor heat exchanger 5, heat exchange is performed between the flowing two-phase refrigerant and the air supplied by the indoor fan 7. In the two-phase state refrigerant, the liquid refrigerant evaporates to become a low-pressure gas refrigerant (single-phase). This heat exchange cools the room. The low-pressure gas refrigerant sent out from the indoor heat exchanger 5 flows into the compressor 3 via the four-way valve 23, is compressed, becomes a high-temperature and high-pressure gas refrigerant, and is discharged from the compressor 3 again. Hereinafter, this cycle is repeated.

Next, the flow of the refrigerant in the outdoor heat exchanger 11 during the cooling operation will be described in detail. When the cooling operation is performed, the outdoor heat exchanger 11 operates as a condenser. As shown in FIGS. 13 and 14, in the outdoor heat exchanger 11, the refrigerant sent from the compressor 3 flows through the main heat exchange section 101, and then flows through the auxiliary heat exchange section 201. The air sent by the outdoor fan 21 to the main heat exchange unit 101 and the auxiliary heat exchange unit 201 is sent from the main heat exchange unit 101a and the auxiliary heat exchange unit 201a in the first row (upwind side) to the second. It flows toward the main heat exchange section 101b and the auxiliary heat exchange section 201b in the row (downwind row).

The flow of the refrigerant in the main heat exchange section 101 will be described in detail with reference to FIGS. 15 and 16. The high-temperature and high-pressure gas refrigerant sent from the compressor 3 first flows into the header 27. The refrigerant that has flowed into the header 27 is gas-distributed in the header 27, and flows through the first main refrigerant path 113 and the second main refrigerant path 123 in the directions indicated by the arrows. The refrigerant that has flowed through the first main refrigerant path 113 of the first main heat exchange region 111 flows into the first distributor 112 and joins in the distributor. The refrigerant that has flowed through the second main refrigerant path 123 of the second main heat exchange region 121 flows into the second distributor 122 and joins in the distributor.

Next, the flow of the refrigerant in the auxiliary heat exchange section 201 will be described in detail in FIGS. 17 and 18. The combined refrigerant flows from each of the first distributor 112 and the second distributor 122 into the auxiliary heat exchange unit 201 via the connecting pipe 35. The refrigerant that has flowed into the auxiliary heat exchange unit 201 flows through the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 in the direction indicated by the arrow. The refrigerant sent from the first distributor 112 flows through the first auxiliary refrigerant path 213. The refrigerant sent from the second distributor 122 flows through the second auxiliary refrigerant path 223.

The refrigerant that has flowed through each of the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 flows into the distributor 25 via the connecting pipe 36. In the distributor 25, the flowing refrigerant merges, flows through the connecting pipe 37, and is sent out of the outdoor heat exchanger 11.

When the outdoor heat exchanger 11 operates as a condenser, the refrigerant generally flows into the outdoor heat exchanger 11 as a gas refrigerant (single-phase) with a degree of superheat. In the outdoor heat exchanger 11, the refrigerant exchanges heat with the outside air (air) under a two-phase state of a liquid refrigerant and a gas refrigerant, which are said to have good heat transfer characteristics. The heat-exchanged refrigerant becomes a liquid refrigerant (single-phase) having a degree of supercooling and is sent out from the outdoor heat exchanger 11.

As described above, when the outdoor heat exchanger 11 functions as a condenser, the refrigerant flowing in the two-phase state of the liquid refrigerant and the gas refrigerant condenses into the liquid refrigerant while flowing through the outdoor heat exchanger 11. .. Here, the relationship (relationship A) between the dryness x of the two-phase refrigerant and the heat transfer coefficient αi in the heat transfer tube, the dryness x of the two-phase refrigerant and the heat exchanger performance AK value as a condenser The relationship with (relationship B) will be described. FIG. 19 shows a graph of relationship A (dotted line graph) and a graph of relationship B (solid line graph), respectively. The degree of dryness refers to the ratio (ratio) of the mass of the gas refrigerant to the mass of the wet vapor (liquid refrigerant + gas refrigerant).

Further, assuming that the thermal resistance outside the heat transfer tube is Ro, the thermal resistance inside the heat transfer tube is Ri, and the thermal resistance inside the heat transfer tube wall is Rd, the AK value is expressed by the following equation.

AK value = 1 / (Ro + Ri + Rd)

As the value of thermal resistance decreases, the AK value increases and the heat exchanger performance improves. For example, to reduce the thermal resistance Ro outside the heat transfer tube, increase the heat transfer area outside the heat transfer tube, increase the flow velocity of the fluid outside the heat transfer tube, or improve the heat transfer coefficient outside the heat transfer tube. Must have a mechanism. Further, in order to reduce the thermal resistance Ri in the heat transfer tube, it is necessary to increase the condensed heat transfer coefficient αi in the heat transfer tube or increase the heat transfer area in the heat transfer tube.

Generally, a liquid refrigerant and a gas refrigerant are mixed in the heat transfer tube 33 of the outdoor heat exchanger 11 into which the two-phase refrigerant has flowed. The liquid refrigerant exists as a thin liquid film adhering to the inner wall surface of the heat transfer tube 33. Therefore, when the two-phase refrigerant in the heat transfer tube 33 is condensed, the condensed heat transfer coefficient in the heat transfer tube is higher than that in the case of the single-phase refrigerant (liquid refrigerant or gas refrigerant), and the heat exchanger The performance AK value also shows a high value.

However, when the amount of condensation of the liquid refrigerant increases, that is, the degree of dryness decreases, the liquid film becomes thicker, which makes it difficult to obtain the effect of promoting heat transfer, and the heat transfer performance gradually deteriorates, resulting in a liquid refrigerant (single phase) state. Transition. The liquid refrigerant (single-phase) has a smaller heat transfer coefficient in the heat transfer tube than the two-phase refrigerant. Further, since the degree of supercooling of the refrigerant in the heat transfer tube is large, the temperature difference between the temperature of the refrigerant and the temperature outside the heat transfer tube is small. Therefore, the performance as an outdoor heat exchanger is greatly deteriorated.

In particular, in small-diameter tube heat exchangers and flat multi-hole tube heat exchangers with a small inner diameter of the heat transfer tube, the heat transfer coefficient in the heat transfer tube in the liquid refrigerant (single phase) state is smaller than that in the two-phase state. The effect tends to be significant, and the heat exchanger performance in the liquid refrigerant (single phase) state deteriorates. Further, since the ratio of the liquid refrigerant occupying the entire heat exchanger also increases, the amount of the refrigerant contained in the air conditioner 1 increases.

Therefore, in the auxiliary heat exchange unit 201 of the outdoor heat exchanger 11, the number of refrigerant paths of the auxiliary heat exchange unit 201 is smaller than the number of refrigerant paths of the main heat exchange unit 101. That is, the number of the first auxiliary refrigerant paths 213 is smaller than the number of the first main refrigerant paths 113, and the number of the second auxiliary refrigerant paths 223 is smaller than the number of the second main refrigerant paths 123. As a result, the flow velocity of the refrigerant in the heat transfer tube 33 in the auxiliary heat exchange unit 201 can be increased, and the heat transfer coefficient in the heat transfer tube 33 can be improved.

Here, FIG. 20 shows the relationship between the frictional pressure loss ratio of the two-phase refrigerant and the dryness with respect to the liquid refrigerant (single phase) at a certain heat transfer tube inner diameter and heat transfer tube length. The two-phase refrigerant has a pressure loss of about 2 to 15 times that of the liquid refrigerant (single phase), about 11 times on average, and a dryness of about 0.35 is an approximate average value. Further, FIG. 21 shows the relationship between the ratio of the refrigerant circulation amount and the frictional pressure loss ratio in a certain heat transfer tube inner diameter and heat transfer tube length. In two-phase refrigerant and liquid refrigerant (single phase), the frictional pressure loss is proportional to the amount of refrigerant circulation (≈mass velocity) to the power of 1.75.

Here, it is assumed that the main heat exchange unit 101 does not change the phase of the two-phase refrigerant to the liquid refrigerant (single phase) state, and the two-phase refrigerant flows through the heat transfer tube 33 in the auxiliary heat exchange unit 201. Since the flow velocity of the refrigerant flowing through the heat transfer tube 33 in the auxiliary heat exchange section 201 is increasing and it is in a two-phase refrigerant state, it is expected that the pressure loss will increase significantly as compared with the case where it flows through the main heat exchange section 101. ..

Further, since the temperature of the two-phase refrigerant is determined as the saturation temperature depending on the pressure of the refrigerant, the temperature drops sharply inside the auxiliary heat exchange section and the degree of dryness also increases, so that the temperature of the two-phase refrigerant becomes the temperature of the refrigerant. The effect of reducing the temperature difference from the temperature outside the heat transfer tube becomes more dominant than improving the heat exchanger performance, and the performance as an outdoor heat exchanger deteriorates. Therefore, when the refrigerant flows at the outlet of the main heat exchange unit 101, in other words, at the inlet of the auxiliary heat exchange unit 201, at the boundary state between the liquid refrigerant (single phase) and the two-phase refrigerant, the refrigerant due to the pressure loss in the heat transfer tube 33. Since the temperature does not change, the effect of promoting the heat transfer of the liquid refrigerant in the heat transfer tube is greatly exerted without adversely affecting the performance of the outdoor heat exchanger 11, and the performance of the outdoor heat exchanger is improved. be able to.

Next, the case of heating operation will be described. As shown in FIG. 12, by driving the compressor 3, the refrigerant in a high-temperature and high-pressure gas state is discharged from the compressor 3. Hereinafter, the refrigerant flows according to the solid arrow. The discharged high-temperature and high-pressure gas refrigerant (single-phase) flows into the indoor heat exchanger 5 via the four-way valve 23. In the indoor heat exchanger 5, heat exchange is performed between the gas refrigerant that has flowed in and the air supplied by the indoor fan 7, and the high-temperature and high-pressure gas refrigerant is condensed to be a high-pressure liquid refrigerant (single phase). become. This heat exchange heats the room. The high-pressure liquid refrigerant sent out from the indoor heat exchanger 5 becomes a two-phase state refrigerant of a low-pressure gas refrigerant and a liquid refrigerant by the throttle device 9.

The two-phase refrigerant flows into the outdoor heat exchanger 11. In the outdoor heat exchanger 11, heat exchange is performed between the flowing two-phase state refrigerant and the outside air (air) as a fluid supplied by the outdoor fan 21, and the two-phase state refrigerant is a liquid refrigerant. Evaporates to become a low-pressure gas refrigerant (single phase). The low-pressure gas refrigerant sent out from the outdoor heat exchanger 11 flows into the compressor 3 via the four-way valve 23, is compressed, becomes a high-temperature and high-pressure gas refrigerant, and is discharged from the compressor 3 again. Hereinafter, this cycle is repeated.

Next, the flow of the refrigerant in the outdoor heat exchanger 11 during the heating operation will be described in detail. As shown in FIGS. 22 and 23, in the outdoor heat exchanger 11, the transmitted refrigerant flows through the auxiliary heat exchange section 201 and then through the main heat exchange section 101. The air sent by the outdoor fan 21 to the main heat exchange unit 101 and the auxiliary heat exchange unit 201 is sent from the main heat exchange unit 101a and the auxiliary heat exchange unit 201a in the first row (upwind side) to the second. It flows toward the main heat exchange section 101b and the auxiliary heat exchange section 201b in the row (downwind row).

The flow of the refrigerant in the auxiliary heat exchange section 201 will be described in detail with reference to FIGS. 24 and 25. The two-phase refrigerant sent from the indoor heat exchanger 5 via the throttle device 9 first flows into the distributor 25. The refrigerant that has flowed into the distributor 25 flows through the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 of the auxiliary heat exchange unit 201 in the directions indicated by the arrows. The refrigerant that has flowed through the first auxiliary refrigerant path 213 flows into the first distributor 112 via the connecting pipe 35. The refrigerant that has flowed through the second auxiliary refrigerant path 223 flows into the second distributor 122 via the connecting pipe 35.

Next, the flow of the refrigerant in the main heat exchange section 101 will be described in detail in FIGS. 26 and 27. The refrigerant that has flowed into each of the first distributor 112 and the second distributor 122 is further finely distributed in each of the distributors, and the first main refrigerant path 113 and the second main refrigerant path 123 are oriented as indicated by the arrows. Flow to. The refrigerant that has flowed into the first distributor 112 is further finely distributed and flows through the first main refrigerant path 113. The refrigerant that has flowed into the second distributor 122 is further finely distributed and flows through the second main refrigerant path 123. The refrigerant that has flowed through the first main refrigerant path 113 and the second main refrigerant path 123, respectively, flows into the header 27. The refrigerant that has flowed into the header 27 is sent out of the outdoor heat exchanger 11.

The refrigerant that has flowed through the outdoor heat exchanger 11 is sent to the compressor 3. At this time, if the refrigerant flows into the compressor 3 in the state of a liquid refrigerant, liquid compression may occur, which may cause a failure of the compressor 3. Therefore, in the heating operation in which the outdoor heat exchanger 11 functions as an evaporator, it is desirable that the refrigerant sent from the outdoor heat exchanger 11 is a gas refrigerant (single phase).

As described above, during the heating operation, heat is exchanged between the outside air sent into the outdoor unit 10 by the outdoor fan 21 and the refrigerant sent into the outdoor heat exchanger 11. When this heat exchange is performed, the moisture in the outside air (air) is condensed, and water droplets grow on the surface of the outdoor heat exchanger 11. The grown water droplets flow downward through the drainage channel of the outdoor heat exchanger 11 composed of the fins 31 and the heat transfer tube 33, and are discharged as drain water.

Further, in the case of heating operation, the condensed moisture in the air may adhere to the outdoor heat exchanger 11 as frost. Therefore, in the air conditioner 1, when the refrigerant temperature of the outdoor heat exchanger 11 becomes a constant temperature (for example, 0 ° C. (freezing point)) or less, a defrosting operation for removing frost is performed.

The defrosting operation is an operation in which a high-temperature and high-pressure gas refrigerant (hot gas) is sent from the compressor 3 to the outdoor heat exchanger 11 in order to prevent frost from adhering to the outdoor heat exchanger 11 that functions as an evaporator. That is. The defrosting operation may be performed when the duration of the heating operation reaches a predetermined value (for example, 30 minutes). Further, the defrosting operation may be performed before the heating operation when the refrigerant temperature is a constant temperature (for example, -6 ° C.) or less. The frost (and ice) adhering to the outdoor heat exchanger 11 is melted by the high temperature and high pressure refrigerant sent to the outdoor heat exchanger 11.

In the air conditioner 1, the high-temperature and high-pressure gas refrigerant discharged from the compressor 3 can be sent to the outdoor heat exchanger 11 via the four-way valve 23. In addition to this, for example, a bypass refrigerant pipe (not shown) may be provided between the compressor 3 and the outdoor heat exchanger 11.

As described above, when the outdoor heat exchanger 11 functions as an evaporator, the refrigerant flowing in the two-phase state of the liquid refrigerant and the gas refrigerant evaporates to become the gas refrigerant while flowing through the outdoor heat exchanger 11. .. Here, the relationship (relationship A) between the dryness x of the refrigerant in the two-phase state and the heat transfer coefficient αi in the heat transfer tube, the dryness x of the refrigerant in the two-phase state, and the heat exchanger performance AU value as an evaporator The relationship with (relationship B) will be described. FIG. 28 shows a graph of relationship A (dotted line graph) and a graph of relationship B (solid line graph), respectively.

Further, assuming that the thermal resistance outside the heat transfer tube is Ro, the thermal resistance inside the heat transfer tube is Ri, and the thermal resistance inside the heat transfer tube wall is Rd, the AU value is expressed by the following equation.

AU value = 1 / (Ro + Ri + Rd)

As the value of thermal resistance decreases, the AU value increases and the heat exchanger performance improves. For example, to reduce the thermal resistance Ro outside the heat transfer tube, increase the heat transfer area outside the heat transfer tube, increase the flow velocity of the fluid outside the heat transfer tube, or improve the heat transfer coefficient outside the heat transfer tube. Must have a mechanism. Further, in order to reduce the thermal resistance Ri in the heat transfer tube, it is necessary to increase the heat transfer coefficient αi in the heat transfer tube or increase the heat transfer area in the heat transfer tube.

Generally, a liquid refrigerant and a gas refrigerant are mixed in the heat transfer tube 33 of the outdoor heat exchanger 11 into which the two-phase refrigerant has flowed. The liquid refrigerant exists as a thin liquid film adhering to the inner wall surface of the heat transfer tube 33. Therefore, when the two-phase refrigerant in the heat transfer tube 33 evaporates, the evaporation heat transfer rate in the heat transfer tube is higher than that in the case of the single-phase refrigerant (liquid refrigerant or gas refrigerant), and the heat exchanger The performance AU value also shows a high value.

In the two-phase state refrigerant, as the liquid refrigerant evaporates, the proportion of the gas refrigerant increases, approaching the state of only the single-phase gas refrigerant. That is, the degree of dryness of the refrigerant is high. When the degree of dryness becomes high, a phenomenon called dryout occurs in which the liquid refrigerant (liquid film) formed on the inner wall surface of the heat transfer tube 33 dries. Therefore, as shown in FIG. 28, the heat transfer coefficient αi in the heat transfer tube 33 drops sharply. Further, the heat exchanger performance AU value also suddenly becomes a low value.

Next, the wind speed (flow velocity) distribution of the outside air (air) passing through the outdoor heat exchanger 11 will be described. Here, it is assumed that the outdoor unit 10 (see FIG. 1) accommodating the outdoor heat exchanger 11 is, for example, a side-blowing outdoor unit. In the side-blowing outdoor unit, as shown in FIG. 29, the outdoor fan 21 is arranged so as to face the outdoor heat exchanger 11. By rotating the outdoor fan 21, outside air is sent into the outdoor unit from one side surface portion of the outdoor unit (not shown). After passing through the outdoor heat exchanger 11, the sent outside air is sent out from the other side surface portion of the outdoor unit to the outside of the outdoor unit.

Here, the wind speed of the outside air passing through the outdoor heat exchanger 11 is distributed depending on the positional relationship with the outdoor fan 21. The portion of the outdoor heat exchanger 11 located closer to the outdoor fan 21 has a higher wind speed of the outside air passing through the portion of the outdoor heat exchanger 11. On the other hand, the portion of the outdoor heat exchanger 11 located farther from the outdoor fan 21 has a smaller wind speed of the outside air passing through the portion of the outdoor heat exchanger 11.

In particular, as shown in FIG. 2, the wind speed of the outside air passing through the portion of the outdoor heat exchanger 11 facing the outdoor fan 21 is the wind speed of the outside air passing through the portion of the outdoor heat exchanger 11 not facing the outdoor fan 21. It will be larger than the wind speed. That is, the wind speed of the outside air passing through the portion of the outdoor heat exchanger 11 located inside the projection surface (region of the alternate long and short dash line) of the outdoor fan is higher than the wind speed of the outside air passing through the portion located outside the projection surface.

In the present embodiment, when the outdoor heat exchanger 11 is viewed from the outdoor fan 21, the projected area where the outdoor fan 21 and the main heat exchange section 101 overlap in the first main heat exchange region 111 is the second main heat exchange region 121. It is larger than the projected area where the outdoor fan 21 and the main heat exchange unit 101 overlap. As a result, the wind speed of the outside air passing through the first main heat exchange region 111 can be made higher than the wind speed of the outside air passing through the second main heat exchange region 121.

Due to the occurrence of such a wind velocity distribution, the ratio of each part of the outdoor heat exchanger 11 to the heat exchange with respect to the total amount of heat exchange changes depending on the part of the outdoor heat exchanger 11. The ratio that contributes to the heat exchange is relatively high in the part of the outdoor heat exchanger 11 located near the outdoor fan 21, and relatively high in the part of the outdoor heat exchanger 11 located away from the outdoor fan 21. It gets lower.

In the outdoor unit 10, the flow velocity (wind speed) of the fluid passing through the first main heat exchange region 111 is larger than the flow velocity (wind speed) of the fluid passing through the second main heat exchange region 121. Therefore, the wind speed (average value) of the outside air passing through the first main refrigerant path 113 is higher than the wind speed (average value) of the outside air passing through the second main refrigerant path 123. Therefore, the ratio of the first main refrigerant path 113 contributing to heat exchange is higher than the ratio of the second main refrigerant path 123 contributing to heat exchange. In this way, the amount of heat exchange in each refrigerant path (group) changes depending on the wind speed distribution.

Here, the refrigerant flowing through the refrigerant path in the outdoor heat exchanger 11 during the cooling operation and the heat exchanger performance between the refrigerant and the outside air will be described. First, as shown in FIG. 30, as a comparative example, a case where a two-phase state refrigerant of a liquid refrigerant and a gas refrigerant flows evenly into the first main refrigerant path 113 and the second main refrigerant path 123 will be described.

In this case, the refrigerant (gas refrigerant) that has evenly flowed into the first main refrigerant path 113 and the second main refrigerant path 123 is in contact with the outside air while flowing through the first main refrigerant path 113 and the second main refrigerant path 123. Heat exchange is performed between them to become a liquid refrigerant. Here, it is assumed that the refrigerant flowing through the first main refrigerant path 113 flows into the auxiliary heat exchange unit 201 at the boundary state between the two-phase refrigerant and the liquid refrigerant (single-phase), which can exert the most heat exchanger performance. The wind speed of the second main heat exchange region 121 is relatively smaller than that of the first main heat exchange region 111. Therefore, the amount of heat exchange of the refrigerant flowing through the second main refrigerant path 123 is smaller than the amount of heat exchange of the refrigerant flowing through the first main refrigerant path 113. Therefore, the refrigerant cannot flow into the auxiliary heat exchange unit 201 in the ideal refrigerant state, so that the heat exchanger performance in the second auxiliary heat exchange region 221 deteriorates. Therefore, the heat exchanger performance when viewed as one outdoor heat exchanger 11 is deteriorated. Further, even if it is assumed that the refrigerant flowing through the second main refrigerant path 123 flows into the auxiliary heat exchange unit 201 at the boundary state between the two-phase refrigerant and the liquid refrigerant (single phase), which can exhibit the heat exchanger performance most, the second main refrigerant path 123 is not included. 1 The heat exchanger performance in the main heat exchange region 111 deteriorates. Therefore, the heat exchanger performance when viewed as one outdoor heat exchanger 11 is deteriorated. Further, since the ratio of the liquid refrigerant occupying the entire heat exchanger also increases, the amount of the refrigerant contained in the air conditioner 1 increases.

In contrast to the comparative example, in the first embodiment, as shown in FIG. 31, the refrigerant distribution is adjusted according to the wind speed distribution. In this case, as will be described later, the main heat exchange unit 101 and the auxiliary heat exchange unit 201 are arranged so that the refrigerant containing a larger amount of liquid refrigerant flows into the first main refrigerant path 113 having a relatively large wind speed. There is. That is, the flow velocity of the fluid passing through the first main heat exchange region 111 is larger than the flow velocity of the fluid passing through the second main heat exchange region 121. The total length of the first auxiliary refrigerant path 213 is shorter than the total length of the second auxiliary refrigerant path 223.

During the cooling operation, the refrigerant that has flowed into the main heat exchange section 101 is distributed in the header 27, and then the first main refrigerant path 113, the second main refrigerant path 123, the first distributor 112, the second distributor 122, and the first It flows through the 1 auxiliary refrigerant path 213 and the 2nd auxiliary refrigerant path 223, and completely merges in the distributor 25. Therefore, if the frictional pressure loss of the refrigerant fluctuates in the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 of the auxiliary heat exchange unit 201, the first main refrigerant path 113 and the second main refrigerant path 123 and The flow ratio of the refrigerant flowing through the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 changes.

Here, as shown in FIG. 11, the first auxiliary refrigerant path 213 is arranged with a smaller number of heat transfer tubes than the second auxiliary refrigerant path 223 (four first auxiliary refrigerant paths and a second auxiliary refrigerant path). 12) Assuming that the refrigerant flows at the same circulation amount, the pressure loss of the first auxiliary refrigerant path 213 becomes small. Therefore, as shown in FIGS. 7 and 9, since the first main refrigerant path 113 and the second main refrigerant path 123 have the same configuration, the first main refrigerant path 113 connected to the first auxiliary refrigerant path 213 has a similar configuration. Since a relatively large amount of refrigerant flows with respect to the second main refrigerant path 123 connected to the second auxiliary refrigerant path 223, the flow rate ratio of the refrigerant is in line with the wind velocity distribution, and it is viewed as one outdoor heat exchanger 11. In this case, the heat exchanger performance will be improved. Further, since the ratio of the liquid refrigerant occupying the entire heat exchanger is also reduced, the amount of the refrigerant contained in the air conditioner 1 can be reduced.

Here, in order to compare the ratio of the frictional pressure loss between the main heat exchange unit 101 and the auxiliary heat exchange unit 201, the representative value of the frictional pressure loss of the main heat exchange unit 101 is examined. As shown in FIG. 20, the frictional pressure loss in the two-phase state is about 2 to 15 times that of the liquid refrigerant, about 11 times on average, and the dryness of about 0.35 is about the average value. Therefore, thereafter, the pressure loss at a dryness of 0.35 is compared as a representative value of the frictional pressure loss in the two-phase state, that is, the main heat exchange section 101. It is assumed that the frictional pressure loss in the auxiliary heat exchange unit 201 is in the liquid refrigerant (single phase) state.

Since the refrigerant paths are integrated in the auxiliary heat exchange unit 201, the amount of refrigerant circulation (∝ mass velocity) increases. As shown in FIG. 21, the frictional pressure loss is proportional to the amount of refrigerant circulation (≈mass velocity) to the power of 1.75. Here, in FIG. 32, the vertical axis represents the ratio of the frictional pressure loss in the auxiliary heat exchange section 201 to the representative value of the frictional pressure loss in the main heat exchange section 101, and the horizontal axis represents the refrigerant path of the main heat exchange section 101. The ratio of the mass velocity of the refrigerant flowing through the refrigerant path of the auxiliary heat exchange unit 201 to the mass velocity of the flowing refrigerant is shown. It is assumed that the heat transfer tube diameter and the number of heat transfer tubes (≈total heat transfer tube length) of each refrigerant path are the same. In the above specifications, when the heat transfer tube has a mass velocity four times that of the refrigerant path of the main heat exchange section 101, the frictional pressure loss of the refrigerant path of the auxiliary heat exchange section 201 exceeds that of the main heat exchange section 101. The frictional pressure loss of the refrigerant flowing through the auxiliary heat exchange unit 201 becomes dominant with respect to the circulation amount ratio of the refrigerant.

In the first embodiment, the number of passes of the main heat exchange unit 101 is eight times the number of passes of the auxiliary heat exchange unit 201, so that the average mass velocity of the refrigerant flowing through the auxiliary heat exchange unit 201 is the main heat exchange unit 101. Since it is eight times the average mass velocity of the refrigerant flowing through the main heat exchange unit 101, the auxiliary heat exchange unit is in a two-phase state and the refrigerant flowing in the auxiliary heat exchange unit 201 is in a liquid refrigerant (single phase) state. It can be said that the frictional pressure loss of the refrigerant flowing through 201 is dominant.

Further, the pressure loss increases in proportion to the length of the flow path (total heat transfer tube), but the relationship between the total heat transfer tube lengths of the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 in the auxiliary heat exchange section 201 is related. , Total heat transfer tube length of the first auxiliary refrigerant path 213 <total heat transfer tube length of the second auxiliary refrigerant path 223. Therefore, from the above, it is considered that the frictional pressure loss of the refrigerant of the auxiliary heat exchange unit 201 is sufficiently dominant even when the main heat exchange unit 101 is included, so that the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 are considered to be sufficiently dominant. The mass velocity changes so that the pressure loss in is balanced. The relationship between the mass velocities is that the mass velocity of the first auxiliary refrigerant path 213> the mass velocity of the second auxiliary refrigerant path 223.

As a result, the refrigerant circulation amount of the first auxiliary refrigerant path 213 and the first main refrigerant path 113 becomes larger than the refrigerant circulation amount of the second auxiliary refrigerant path 223 and the second main refrigerant path 123, and the wind speed is relatively high. 1 A relatively large amount of refrigerant circulation can flow through the main refrigerant path 113. Therefore, it is possible to make the outlet sides of the first main heat exchange region 111 and the second main heat exchange region 121 close to the ideal refrigerant state (the boundary state between the two-phase refrigerant and the liquid refrigerant (single phase)). Become. As a result, the performance of the outdoor heat exchanger 11 can be improved.

Subsequently, a modified example of the present embodiment will be described with reference to FIG. 33. In the above embodiment, the second auxiliary refrigerant path 223 is arranged at the bottom of the auxiliary heat exchange unit 201. On the other hand, in the modified example of the present embodiment, the first auxiliary refrigerant path 213 is arranged at the lowermost stage of the auxiliary heat exchange unit 201.

In the outdoor heat exchanger 11 during the heating operation, the condensed moisture in the air may adhere to the outdoor heat exchanger 11 as frost. Therefore, in the air conditioner 1, when the refrigerant temperature of the outdoor heat exchanger 11 becomes a constant temperature (for example, 0 ° C. (freezing point)) or less, a defrosting operation for removing frost is performed. The defrosting operation often operates in the same manner as the cooling operation, that is, the outdoor heat exchanger 11 functions as a condenser.

Here, the water melted by defrosting tends to stay at the bottom of the outdoor heat exchanger due to the influence of surface tension. Therefore, in the frost formation operation, the water at the bottom of the outdoor heat exchanger may also solidify, and it is necessary not only to melt the frost but also to melt (heat the temperature) the retained water.

Therefore, the refrigerant path located at the bottom of the outdoor heat exchanger requires a large amount of heat required for melting. Here, since the first auxiliary refrigerant path 213 has a relatively larger amount of refrigerant circulation than the second auxiliary refrigerant path 223, the first auxiliary heat exchange region 211 including the first auxiliary refrigerant path 213 is subjected to outdoor heat. By arranging it at the bottom of the exchanger 11, a larger amount of heat is input to the bottom of the outdoor heat exchanger 11 than when the second auxiliary heat exchange area 221 is arranged at the bottom of the outdoor heat exchanger 11. By applying the amount of heat required for defrosting according to the load, it is possible to reduce the time required for defrosting.

Embodiment 2.
The outdoor heat exchanger of the outdoor unit according to the second embodiment will be described. 34 and 35 show the detailed configuration of the auxiliary heat exchange section 201 of the outdoor heat exchanger 11. As shown in FIGS. 34 and 35, in the outdoor heat exchanger 11 according to the second embodiment, the arrangement relationship of the heat transfer tubes constituting the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 is the same as that of the first embodiment. It is different from the arrangement relationship of the outdoor heat exchanger 11. Further, since the other configurations are the same as the configurations of the outdoor heat exchanger 11 shown in FIGS. 2 and 3, the same members are designated by the same reference numerals, and the description thereof shall not be repeated unless necessary. do.

Here, regarding the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 in the auxiliary heat exchange section 201 of the outdoor heat exchanger 11, the refrigerant flowing through the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 and the refrigerant thereof. The performance of the heat exchanger with the outside air will be described. First, as a comparative example, the auxiliary heat exchange unit 201 having the configuration shown in FIGS. 36 and 37 will be described.

The auxiliary heat exchange unit 201 shown in FIGS. 36 and 37 has four heat transfer tubes 33 of the first auxiliary refrigerant path 213 with respect to the number of heat transfer tubes occupying the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223. It is composed of the first auxiliary heat transfer tube 219 on the leeward side. The second auxiliary heat transfer tube 229 of the second auxiliary refrigerant path 223 is composed of twelve, of which eight are the second auxiliary heat transfer tubes 229 on the windward side and four are the second auxiliary heat transfer tubes 229 on the leeward side. It is composed of.

Here, the relationship between the outside air temperature and the upwind and leeward will be described. The fluid (air) passing through the outdoor heat exchanger 11 is the same as the outside air temperature on the upwind, but is used as a condenser because it exchanges heat with the refrigerant in the heat exchange region on the upwind. If so, the temperature rises above the outside air temperature. Therefore, from the viewpoint of the refrigerant, it is possible to secure a large temperature difference by exchanging heat on the windward side, so that a large amount of heat exchange can be secured even in the same heat exchange area.

Further, here, the refrigerant circulation amount of the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 will be described. Since the first auxiliary heat transfer tube 219 of the first auxiliary refrigerant path 213 is composed of four, and the second auxiliary heat transfer tube 229 of the second auxiliary refrigerant path 223 is composed of twelve, frictional pressure loss. The refrigerant circulation amount of the first auxiliary refrigerant path 213 will flow more than that of the second auxiliary refrigerant path 223 so as to be balanced with each other. Therefore, even if the first auxiliary refrigerant path 213 has the same amount of heat exchange, the temperature change of the refrigerant is relatively small. On the other hand, even if the second auxiliary refrigerant path 223 has the same amount of heat exchange, the temperature change of the refrigerant is relatively large.

Further, since the number of heat transfer tubes in the first auxiliary refrigerant path 213 is smaller than that in the second auxiliary refrigerant path 223, the heat exchange area is also small. Therefore, the temperature change of the refrigerant becomes smaller. On the other hand, since the heat exchange area of the second auxiliary refrigerant path 223 is larger than that of the first auxiliary refrigerant path 213, the temperature change of the refrigerant becomes larger, and the outlets of the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 There is a big difference in the refrigerant temperature state.

As a heat exchanger, the smaller the temperature difference, the more heat exchange area is required to secure the same amount of heat exchange. Therefore, if the refrigerant temperature state at the outlet of each refrigerant path varies, heat exchange will occur in a region where the temperature difference is small, and a large heat exchange area is required. As a result, the performance of the heat exchanger as the auxiliary heat exchange unit 201 is deteriorated. That is, in order to exhibit the heat exchanger performance, it is necessary to make the refrigerant temperature at the outlet of each refrigerant path uniform in the liquid refrigerant (single-phase) region.

Here, the first auxiliary refrigerant path 213, which has a large amount of refrigerant circulation and requires a large amount of heat exchange in Comparative Example 2 shown in FIGS. 36 and 37, is composed of only the first auxiliary heat transfer tube 219 on the leeward side. Therefore, the amount of heat exchange is small and the temperature change of the refrigerant is small. On the other hand, for the second auxiliary refrigerant path 223, which has a small refrigerant circulation amount and does not require a relatively large amount of heat exchange with respect to the first auxiliary refrigerant path 213, there are eight second auxiliary heat transfer tubes 229 on the wind side. Since all the heat transfer tubes 33 on the wind side of the auxiliary heat exchange section 201 are formed, and the second auxiliary heat transfer tubes 229 on the leeward side are composed of four, the amount of heat exchange is large and the refrigerant can be used. The temperature change is large. Therefore, as described above, the refrigerant temperature states at the outlets of the first auxiliary refrigerant paths 213 and the second auxiliary refrigerant paths 223 differ greatly, and the heat exchanger performance of the auxiliary heat exchange unit 201 deteriorates.

On the other hand, in the auxiliary heat exchange unit 201 of the second embodiment shown in FIGS. 34 and 35, the auxiliary heat exchange units 201 are arranged side by side along the flow of the fluid sent by the outdoor fan 21. It has a section (first row section) 201a and an auxiliary heat exchange section (second row section) 201b. The auxiliary heat exchange unit 201a is arranged upstream of the fluid flow from the auxiliary heat exchange unit 201b. All the first auxiliary refrigerant paths 213 are arranged in the auxiliary heat exchange section 201a. The first auxiliary refrigerant path 213, which has a large amount of refrigerant circulation and requires a large amount of heat exchange, is composed of only the first auxiliary heat transfer tube 219 on the windward side. Therefore, the amount of heat exchange is large and the temperature change of the refrigerant is large with respect to the first auxiliary refrigerant path 213 of Comparative Example 2. On the other hand, the second auxiliary refrigerant path 223, which has a small amount of refrigerant circulation and does not require a relatively large amount of heat exchange with respect to the first auxiliary refrigerant path 213, has four second auxiliary heat transfer tubes 229 on the windward side. In addition, the second auxiliary heat transfer tube 229 on the leeward side is composed of eight tubes. Therefore, the amount of heat exchange is small and the temperature change of the refrigerant is small with respect to the second auxiliary refrigerant path 223 of Comparative Example 2. Therefore, as described above, it is possible to reduce the difference (variation) with respect to the refrigerant temperature states at the outlets of the first auxiliary refrigerant path 213 and the second auxiliary refrigerant path 223 of Comparative Example 2. That is, it is possible to make the refrigerant temperature state in the liquid phase state uniform. Therefore, the heat exchanger performance as the auxiliary heat exchange unit 201 is improved. As a result, the heat exchanger performance of the outdoor heat exchanger 11 can be improved.

As the refrigerant used in the air conditioner 1 described in each of the above-described embodiments, any refrigerant such as refrigerant R410A, refrigerant R407C, refrigerant R32, refrigerant R507A, and refrigerant HFO1234yf may be used when operating as a condenser. It is possible to improve the performance of the heat exchanger.

Further, as the refrigerating machine oil used for the air conditioner 1, a refrigerating machine oil having compatibility is used in consideration of mutual solubility with the applicable refrigerant. For example, in the fluorocarbon-based refrigerant such as the refrigerant R410A, an alkylbenzene oil-based, ester oil-based or ether oil-based refrigerating machine oil is used. In addition to these, refrigerating machine oils such as mineral oil-based or fluorine oil-based may be used.

The air conditioner provided with the outdoor heat exchanger described in each embodiment can be combined in various ways as needed.

The embodiments disclosed this time are examples and are not limited thereto. The present invention is shown by the claims, not the scope described above, and is intended to include all modifications in the sense and scope equivalent to the claims.

INDUSTRIAL APPLICABILITY The present invention is effectively used in an air conditioner having an outdoor heat exchanger provided with a main heat exchange unit and an auxiliary heat exchange unit.

1 air conditioner, 3 compressor, 4 indoor unit, 5 indoor heat exchanger, 7 indoor fan, 9 throttle device, 10 outdoor unit, 11 outdoor heat exchanger, 21 outdoor fan, 23 four-way valve, 25 distributor, 27 Header, 31 fins, 33 heat transfer tube, 34 refrigerant passage, 35, 36, 37 connection pipe, 51 control unit, 101, 101a, 101b main heat exchange unit, 111 first main heat exchange area, 112 first distributor, 113 1st main refrigerant path, 119 1st main heat transfer tube, 121 2nd main heat exchange area, 122 2nd distributor, 123 2nd main refrigerant path, 129 2nd main heat transfer tube, 201, 201a, 201b Auxiliary heat exchange section , 211 1st auxiliary heat exchange area, 213 1st auxiliary refrigerant path, 219 1st auxiliary heat transfer tube, 221 2nd auxiliary heat exchange area, 223 2nd auxiliary refrigerant path, 229 2nd auxiliary heat transfer tube.

Claims (7)

With a heat exchanger
It is equipped with a blower that sends fluid to the heat exchanger.
The heat exchanger includes a first heat exchange unit and a second heat exchange unit.
The first heat exchange unit includes a first heat exchange region having a plurality of first refrigerant paths and a second heat exchange region having a plurality of second refrigerant paths.
The second heat exchange unit includes a third heat exchange region having at least one third refrigerant path connected to the plurality of first refrigerant paths, and at least one first heat exchange region connected to the plurality of second refrigerant paths. Includes a fourth heat exchange region with 4 refrigerant paths
The flow velocity of the fluid passing through the first heat exchange region is larger than the flow velocity of the fluid passing through the second heat exchange region.
The total length of the third refrigerant path in the third heat exchange region is shorter than the total length of the fourth refrigerant path in the fourth heat exchange region.
The first heat exchange region and the third heat exchange region are arranged so as to be adjacent to each other, and the second heat exchange region and the fourth heat exchange region are the first heat exchange region and the third heat exchange region. An outdoor unit that is placed so as to sandwich the heat exchange area. The third refrigerant path and the fourth refrigerant path each include a heat transfer tube.
The outdoor unit according to claim 1, wherein the number of the heat transfer tubes in the third refrigerant path is smaller than the number of the heat transfer tubes in the fourth refrigerant path. Looking at the heat exchanger from the blower portion, the projected area where the blower portion and the first heat exchange portion overlap in the first heat exchange region is the projected area where the blower portion and the first heat exchange portion overlap in the second heat exchange region. The outdoor unit according to claim 1 or 2, which is larger than the projected area where the heat exchange unit overlaps. The heat exchanger includes a first distributor and a second distributor.
The first refrigerant path is connected to the third refrigerant path via the first distributor.
The outdoor unit according to any one of claims 1 to 3, wherein the second refrigerant path is connected to the fourth refrigerant path via the second distributor. The number of the third refrigerant paths is smaller than the number of the first refrigerant paths.
The outdoor unit according to any one of claims 1 to 4, wherein the number of the fourth refrigerant paths is smaller than the number of the second refrigerant paths. The heat exchanger includes a first row portion and a second row portion arranged side by side along the flow of the fluid sent by the blower portion.
The first row portion is arranged upstream of the flow of the fluid from the second row portion.
The outdoor unit according to any one of claims 1 to 5, wherein all the third refrigerant paths are arranged in the first row portion. The outdoor unit according to any one of claims 1 to 6 is provided.
A refrigeration cycle device in which a refrigerant flows from the first heat exchange unit to the second heat exchange unit when the heat exchanger operates as a condenser.

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