JP2008008541A - Heat exchanger, and indoor unit of air conditioner comprising heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger which prevents drainage from stagnating among heat transfer fins and allows air to easily pass, and also to provide an indoor unit of an air conditioner comprising the heat exchanger. <P>SOLUTION: The heat exchanger 6, 6b, 6c is a heat exchanger exchanging heat between a refrigerant and air by utilizing a supercritical refrigerant as the refrigerant, and comprises groups of heat transfer fins 71-74, 71c-78c, and a plurality of heat transfer tubes 12. The group of heat transfer fins are disposed in parallel with the vertical direction at prescribed intervals and composed of a plurality of plate-shaped heat transfer fins 11. The plurality of heat transfer tubes penetrate the groups of heat transfer fins. The plurality of groups of heat transfer fins are disposed in the vertical direction, and a fin pitch of the heat transfer fins belonging to the upper group of heat transfer fins is larger than a fin pitch of the heat transfer fins belonging to the lower group of heat transfer fins. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat exchanger that has taken measures against drainage during cooling, and an indoor unit of an air conditioner that includes the heat exchanger.

2. Description of the Related Art Conventionally, there is a heat exchanger provided in an indoor unit of an air conditioner that exchanges heat between refrigerant and air using a cross fin type. This cross fin type heat exchanger arranges a plurality of fins substantially parallel to the air flow direction at predetermined intervals, and a multi-row heat transfer tube group that penetrates each fin in the plate thickness direction. (Refer to Patent Document 1).
By the way, in the heat exchanger, drainage may occur during cooling. The drain is transferred from the upper part to the lower part through the heat transfer fins, but the stagnation between the heat transfer fins and the heat transfer fins may cause clogging. In such a case, it becomes a large air resistance and causes a decrease in cooling capacity.

  An object of the present invention is to provide a heat exchanger that suppresses the stagnation of a drain between heat transfer fins and allows air to easily pass through, and an indoor unit of an air conditioner including the heat exchanger. .

  A heat exchanger according to a first aspect of the present invention is a heat exchanger that performs heat exchange between the refrigerant and air using a supercritical refrigerant as a refrigerant, and includes a heat transfer fin group and a plurality of heat transfer tubes. The heat transfer fin group is formed by a plurality of plate-like heat transfer fins arranged in parallel to the vertical direction with a predetermined interval. The plurality of heat transfer tubes penetrate through the heat transfer fin group. A plurality of heat transfer fin groups are arranged in the vertical direction, and the fin pitch of the heat transfer fins belonging to the lower heat transfer fin group is larger than the fin pitch of the heat transfer fins belonging to the upper heat transfer fin group. .

  In the present invention, drainage is generated during cooling by making the fin pitch of the heat transfer fins belonging to the lower heat transfer fin group of the heat exchanger larger than the fin pitch of the heat transfer fins belonging to the upper heat transfer fin group. In this case, the drain is easily dropped. Therefore, it is possible to suppress the stagnation of the drain between the plurality of heat transfer fins, and the air can be easily passed. For this reason, the fall of the cooling capability can be suppressed.

  The heat exchanger according to the second invention is the heat exchanger according to the first invention, and the plurality of heat transfer tubes are arranged in a direction intersecting with the air flow to form a heat transfer tube array. The heat transfer tube rows are arranged in a plurality of rows from the upstream to the downstream of the air flow.

  In a heat exchanger using a supercritical refrigerant, for example, when used as an indoor heat exchanger during heating operation, the heat exchanger is used as a gas cooler. When used as this gas cooler, the heat exchanger of the present invention uses a multi-row heat exchanger in order to increase the amount of heat transfer between the refrigerant and the air. In such a heat exchanger, when drain is generated during cooling, the distance until the drain falls outside (down) the heat exchanger becomes long. As a result, the drain is likely to stagnate between the plurality of heat transfer fins, and the heat transfer fins are likely to be clogged by the drain.

  In the present invention, even in such a heat exchanger, the fin pitch of the heat transfer fins belonging to the lower heat transfer fin group of the heat exchanger is made larger than the fin pitch of the heat transfer fins belonging to the upper heat transfer fin group. This makes it easier to drop the drain. Therefore, it is possible to suppress the stagnation of the drain between the plurality of heat transfer fins, and the air can be easily passed.

  A heat exchanger according to a third aspect of the present invention is the heat exchanger according to the second aspect of the present invention, wherein four or more heat transfer tube rows are formed.

  In this heat exchanger, a multi-row heat exchanger having four or more rows is used. Even in such a heat exchanger, the fin pitch of the heat transfer fins belonging to the lower heat transfer fin group of the heat exchanger is made larger than the fin pitch of the heat transfer fins belonging to the upper heat transfer fin group, thereby cooling the heat exchanger. When drain is generated at times, it is easy to drop the drain. Therefore, it is possible to suppress the stagnation of the drain between the plurality of heat transfer fins, and the air can be easily passed.

  A heat exchanger according to a fourth invention is the heat exchanger according to the second invention or the third invention, wherein the heat transfer tube rows are arranged in a plurality of rows in the vertical direction, and the upper one of the plurality of heat transfer tube rows. The tube pitch of the heat transfer tubes belonging to the lower heat transfer tube row is larger than the tube pitch of the heat transfer tubes belonging to the heat transfer tube row.

  In a heat exchanger that uses a supercritical refrigerant, a multi-row heat exchanger is used in order to increase the amount of heat transfer between the refrigerant and air when performing an operation of heating air, such as during a heating operation. In such a heat exchanger, when drain is generated during cooling, a large number of heat transfer tubes are obstructed, and the drain does not easily fall from the heat exchanger. Therefore, the stagnant drain becomes a large air resistance, and the cooling capacity may be reduced.

  In the present invention, the drain pitch can be easily dropped by making the tube pitch of the heat transfer tubes belonging to the lower heat transfer tube row of the heat exchanger larger than that of the upper portion. Therefore, it is possible to prevent the drain from stagnating around the heat transfer tube, and to facilitate the passage of air.

  A heat exchanger according to a fifth aspect of the present invention is the heat exchanger according to any one of the second to fourth aspects of the present invention, wherein the heat transfer tube row penetrates in a row unit for each heat transfer fin group.

  In a heat exchanger using a supercritical refrigerant, when performing an operation of heating air, for example, during a heating operation, the heat exchanger in the indoor unit is a gas cooler that cools the refrigerant. In the gas cooler, the temperature differs between the inlet side and the outlet side of the refrigerant in the entire heat exchanger. For this reason, when adjacent heat transfer tube rows are connected by heat transfer fins, heat exchange may be performed between the heat transfer tubes via the heat transfer fins, which may cause heat loss.

  In the present invention, the heat transfer fins are divided between adjacent heat transfer tube rows so that heat exchange via the heat transfer fins is not performed. For this reason, the heat loss which arises by this heat exchange can be suppressed.

  A heat exchanger according to a sixth aspect of the present invention is the heat exchanger according to the fifth aspect of the present invention, wherein one row of heat transfer tube rows passes through one heat transfer fin group.

  In this heat exchanger, one heat transfer tube row penetrates corresponding to one heat transfer fin group. Adjacent heat transfer tube rows pass through different heat transfer fin groups. Therefore, it can reduce that more heat exchanger tubes perform heat exchange via a heat-transfer fin.

  An indoor unit of an air conditioner according to a seventh aspect includes a heat exchanger and a fan. The heat exchanger relates to any one of the first to sixth inventions. The fan generates an air flow.

  In the indoor unit of this air conditioner, the heat exchanger makes it easy to drop the drain outside (down) the heat exchanger when the drain is generated during cooling. For this reason, the heat exchanger can efficiently exchange heat, and the indoor unit of the air conditioner can be operated efficiently.

  An indoor unit of an air conditioner according to an eighth aspect of the present invention is the indoor unit of the air conditioner according to the seventh aspect of the present invention, wherein the refrigerant belongs to the heat transfer tube array on the downstream side of the air flow during the heating operation. It flows from the heat pipe to the heat transfer pipe belonging to the heat transfer pipe row on the upstream side of the air flow.

  In the indoor unit of this air conditioner, the temperature difference between the refrigerant and the air in the entire heat exchanger can be kept large by making the refrigerant flow direction and the air flow direction oppose each other during the heating operation. . For this reason, heating operation can be performed efficiently.

  An indoor unit of an air conditioner according to a ninth aspect is the indoor unit of the air conditioner according to the seventh aspect or the eighth aspect, wherein the air flows from the lower part to the upper part of the heat exchanger.

  In the lower suction upper blowout type indoor unit in which the air flow flows from the lower part to the upper part of the heat exchanger, the drain becomes difficult to fall due to the wind from the lower part of the heat exchanger. Even in such a heat exchanger, when the drain is generated during cooling, the clogging of the drain is suppressed. Therefore, it is possible to suppress the stagnation of the drain between the plurality of heat transfer fins, and the air can be easily passed.

  An indoor unit of an air conditioning apparatus according to a tenth aspect of the invention is an indoor unit of an air conditioning measure according to any of the seventh to ninth aspects of the invention, and the refrigerant is CO2.

  In the indoor unit of this air conditioner, CO2 refrigerant is used as the refrigerant. The CO2 refrigerant hardly destroys the ozone layer because the ozone depletion coefficient is 0 as compared with conventional refrigerants such as HFC fluorocarbon refrigerants. In addition, the CO2 refrigerant has a global warming potential of 1 and is much lower than a fluorocarbon refrigerant of several hundred to 10,000.

  For this reason, by using CO2 refrigerant | coolant, it can suppress that an environmental load is small and global environment deteriorates.

  A heat exchanger according to an eleventh aspect of the present invention is a heat exchanger that performs heat exchange between the refrigerant and air using a supercritical refrigerant as a refrigerant, and includes a heat transfer fin group and a plurality of heat transfer tubes. The heat transfer fin group is formed by a plurality of plate-like heat transfer fins arranged in parallel to the vertical direction with a predetermined interval. The plurality of heat transfer tubes penetrate through the heat transfer fin group. A plurality of heat transfer tubes are arranged in a direction crossing the air flow to form a heat transfer tube array. A plurality of heat transfer tube rows are arranged in the vertical direction, and a plurality of heat transfer tube rows belonging to a lower heat transfer tube row than a tube pitch of a plurality of heat transfer tube rows belonging to the upper heat transfer tube row among the plurality of heat transfer tube rows. The pipe pitch is larger.

  In the present invention, by making the tube pitch of the heat transfer tubes belonging to the lower heat transfer tube row of the heat exchanger larger than that of the upper portion, when drain is generated during cooling, the drain is easily dropped. Therefore, it is possible to prevent the drain from stagnating around the heat transfer tube, and to facilitate the passage of air.

  In the heat exchanger according to the first invention, the fin pitch of the heat transfer fins belonging to the lower heat transfer fin group of the heat exchanger is made larger than the fin pitch of the heat transfer fins belonging to the upper heat transfer fin group, It makes it easy to drop the drain. Therefore, it is possible to suppress the stagnation of the drain between the plurality of heat transfer fins, and the air can be easily passed. For this reason, the fall of the cooling capability can be suppressed.

  In the heat exchanger according to the second invention, the fin pitch of the heat transfer fins belonging to the lower heat transfer fin group of the heat exchanger is made larger than the fin pitch of the heat transfer fins belonging to the upper heat transfer fin group, It makes it easy to drop the drain. Therefore, it is possible to suppress the stagnation of the drain between the plurality of heat transfer fins, and the air can be easily passed.

  In the heat exchanger according to the third invention, the fin pitch of the heat transfer fins belonging to the lower heat transfer fin group of the heat exchanger is made larger than the fin pitch of the heat transfer fins belonging to the upper heat transfer fin group, It makes it easy to drop the drain. Therefore, it is possible to suppress the stagnation of the drain between the plurality of heat transfer fins, and the air can be easily passed.

  In the heat exchanger according to the fourth aspect of the invention, the drain pitch can be easily dropped by making the tube pitch of the heat transfer tubes belonging to the heat transfer tube row at the lower part of the heat exchanger larger than that at the upper part. Therefore, it is possible to prevent the drain from stagnating around the heat transfer tube, and to facilitate the passage of air.

  In the heat exchanger according to the fifth aspect of the invention, the heat transfer fins are divided between adjacent heat transfer tube rows so that heat exchange via the heat transfer fins is not performed. For this reason, the heat loss which arises by this heat exchange can be suppressed.

  In the heat exchanger according to the sixth aspect of the present invention, it can be reduced that more heat transfer tubes perform heat exchange via the heat transfer fins.

  In the indoor unit of the air conditioner according to the seventh aspect of the invention, the heat exchanger can efficiently exchange heat, and the operation of the indoor unit of the air conditioner can be performed efficiently.

  In the indoor unit of the air conditioner according to the eighth aspect of the present invention, during the heating operation, the refrigerant flow direction and the air flow direction are opposed to each other, thereby increasing the temperature difference between the refrigerant and the air in the entire heat exchanger. Can keep. For this reason, heating operation can be performed efficiently.

  In the indoor unit of the air conditioner according to the ninth aspect of the present invention, it is possible to suppress the drain from stagnating between the plurality of heat transfer fins, and to facilitate the passage of air.

  In the indoor unit of the air conditioning apparatus according to the tenth aspect, by using the CO2 refrigerant, it is possible to suppress the environmental load from being reduced and the global environment from deteriorating.

  In the heat exchanger according to the eleventh aspect of the invention, the drain pitch can be easily dropped by making the pipe pitch of the heat transfer tubes belonging to the heat transfer tube row at the lower part of the heat exchanger larger than that at the upper part. Therefore, it is possible to prevent the drain from stagnating around the heat transfer tube, and to facilitate the passage of air.

(First embodiment)
<Refrigeration circuit of air conditioner>
FIG. 1 is a refrigeration circuit of an air conditioner 1 using a CO2 refrigerant. The air conditioner 1 has a refrigeration circuit in which a compressor 2, a four-way switching valve 3, an outdoor heat exchanger 4, an expansion valve 5, and an indoor heat exchanger 6 are connected by a refrigerant pipe 7. In FIG. 1, solid and broken arrows indicate the flow direction of the refrigerant. The air conditioner 1 can switch between the heating operation and the cooling operation by switching the flow direction of the refrigerant with the four-way switching valve 3.

  During the cooling operation, the outdoor heat exchanger 4 serves as a gas cooler, and the indoor heat exchanger 6 serves as an evaporator. On the other hand, during the heating operation, the outdoor heat exchanger 4 serves as an evaporator and the indoor heat exchanger 6 serves as a gas cooler. The outdoor heat exchanger 4 and the indoor heat exchanger 6 each include a heat transfer fin 11 (see FIG. 3) and a heat transfer tube 12 (see FIG. 3), and the refrigerant in the heat transfer tube 12 transfers heat via an air flow. Heat exchange with the fin 11 is performed.

  In FIG. 1, point A is the suction side of the compressor 2 during the heating operation, and point B is the discharge side of the compressor 2 during the heating operation. Point C is the refrigerant outlet side of the indoor heat exchanger 6 during heating operation, and point D is the refrigerant inlet side of the outdoor heat exchanger 4 during heating operation.

  FIG. 2A is a pressure-enthalpy state diagram of the CO 2 refrigerant, in which the vertical axis represents the pressure P and the horizontal axis represents the enthalpy h. Tk is an isotherm passing through the critical point K, and Tx is an isotherm of the temperature Tx. Tx> Tk, and on the right side of the isotherm Tk, the CO2 refrigerant is neither liquefied nor two-phased. The region above the critical pressure Pk on the right side of the isotherm Tk is called a supercritical state, and the air conditioner 1 using the heat exchanger of the present embodiment is operated in a refrigeration cycle including the supercritical state. A, B, C, and D in FIG. 2A represent refrigerant states corresponding to points A, B, C, and D in FIG.

  FIG. 2B is a temperature-entropy state diagram of the CO2 refrigerant, where the vertical axis represents temperature T and the horizontal axis represents entropy s. A, B, C, and D in FIG. 2B represent refrigerant states corresponding to points A, B, C, and D in FIG. The temperature of the refrigerant decreases from the point B that is the discharge side of the compressor 2 to the point C that is the refrigerant outlet of the indoor heat exchanger 6. For this reason, the temperature of the surface of the indoor heat exchanger 6 has a temperature distribution in which the temperature on the upstream side of the refrigerant is high and the temperature on the downstream side is low. Therefore, when the air flow passes from the downstream side of the refrigerant toward the upstream side of the refrigerant, the temperature difference between the air and the indoor heat exchanger 6 is stabilized, and the heat exchange amount between the air and the indoor heat exchanger 6 is increased. Will increase.

<Structure of indoor heat exchanger>
FIG. 3 is a perspective view of the indoor heat exchanger of the air conditioner according to the embodiment of the present invention. The indoor heat exchanger 6 is a cross fin type heat exchanger. The heat transfer fin 11 is a thin flat plate made of aluminum, and a plurality of through holes 14 are formed in one heat transfer fin 11. The heat transfer tube 12 includes a straight tube 12a that is inserted into the through hole 14 of the heat transfer fin 11, and a U-shaped tube 12b that connects ends of adjacent straight tubes 12a. In the heat transfer tube 12 of this embodiment, a straight tube 12a and a U-shaped tube 12b are integrally formed. A U-shaped tube (not shown) on the back side of FIG. After being inserted into the through hole 14 of the eleventh, it is connected to the end of the straight pipe 12a by welding or the like.

  Eight heat transfer tube rows 61 to 68 of the heat transfer tubes 12 arranged in a direction intersecting the air flow are arranged from the upstream of the air flow toward the downstream of the air flow. During heating, the refrigerant flows from the heat transfer tube 12 belonging to the heat transfer tube row 68 on the downstream side of the air flow to the heat transfer tube 12 belonging to the heat transfer tube row 61 on the upstream side of the air flow. This refrigerant distribution path is called a path 81 (see FIG. 5). By this path 81, the air flow and the refrigerant flow are opposed to each other, and the amount of heat exchange is increased as compared with the non-opposed one. However, experiments have shown that in heat exchangers with three or less heat transfer tube rows, there is no significant difference in effect whether the air flow and the refrigerant flow are opposed or not. Further, during cooling, the refrigerant flows from the heat transfer tube 12 belonging to the heat transfer tube row 61 on the upstream side of the air flow to the heat transfer tube 12 belonging to the heat transfer tube row 68 on the downstream side of the air flow. During cooling, the air flow and the refrigerant flow flow in parallel. During cooling, the indoor heat exchanger 6 serves as an evaporator, and there is no temperature difference between the upstream side of the refrigerant in the indoor heat exchanger 6 and the downstream side of the refrigerant. For this reason, there is almost no difference in the effect with the case of a counterflow.

  3 is the path 81 (see FIG. 5) through which the refrigerant flows, and the connection tube 12d and the connection tube 12e (see FIG. 5) are adjacent to each other. The heat transfer tubes 12 positioned at the ends in the opposite directions of 61 to 68 are connected.

  The heat transfer fins 11 are divided between the heat transfer tube row 62 and the heat transfer tube row 63. This division is also performed between the heat transfer tube row 64 and the heat transfer tube row 65 and between the heat transfer tube row 66 and the heat transfer tube row 67. The heat transfer fins 11 include a heat transfer fin group 71 into which the heat transfer tube row 61 and the heat transfer tube row 62 are inserted, a heat transfer fin group 72 into which the heat transfer tube row 63 and the heat transfer tube row 64 are inserted, and a heat transfer tube. The heat transfer fin group 73 into which the row 65 and the heat transfer tube row 66 are inserted is divided into the heat transfer fin group 74 into which the heat transfer tube row 67 and the heat transfer tube row 68 are inserted. As a result, the heat on the surface of the heat transfer fins 11 can hardly move beyond the dividing portion 13.

  FIG. 4 shows a side view of the indoor heat exchanger 6 as seen from the vertical direction of the straight pipe 12a of the heat transfer pipe 12. FIG. The fin pitch PF1 of the heat transfer fin group 71, the fin pitch PF2 of the heat transfer fin group 72, the fin pitch PF3 of the heat transfer fin group 73, and the fin pitch PF4 of the heat transfer fin group 74 are PF4 <PF3 <PF2. <PF1. The indoor heat exchanger 6 becomes an evaporator when the indoor unit 51 performs a cooling operation. For this reason, drainage is generated. By making the fin pitch of the heat transfer fin group at the lower part of the indoor heat exchanger 6 larger than that at the upper part, the drain can be easily dropped. Thereby, the clogging by the drain is reduced, and the air easily passes through the indoor heat exchanger 6.

<Configuration of air conditioner>
FIG. 5 is a longitudinal sectional view of the indoor unit of the air conditioner according to the embodiment of the present invention. The indoor unit 51 has the indoor heat exchanger 6 mounted inside the casing 52. A fan 53 that generates an air flow is disposed above the indoor heat exchanger 6, and an air outlet 52 a is provided above the fan 53. An air suction port 52b is provided below the indoor heat exchanger 6. Note that the fan 53 used in the present embodiment is a sirocco fan.

  The line connecting the centers of the heat transfer tubes 12 indicates the path 81 through which the refrigerant flows during heating operation, the solid line indicates the U-shaped tube 12b on the near side of the figure, and the broken line indicates the U-shaped tube on the opposite side ( A not shown) and a connecting pipe (not shown) are shown. During the heating operation, the refrigerant flows from the upper side to the lower side in the path 81 of the indoor heat exchanger 6, and the air flow flows from the lower side to the upper side of the indoor heat exchanger 6. For this reason, since an air flow heat-exchanges with a refrigerant | coolant of a higher temperature, and temperature rises as it approaches the air blower outlet 52a, refrigerant | coolant temperature and air are passed through the whole heat dissipation process when the indoor heat exchanger 6 functions as a gas cooler. The temperature difference from the temperature is properly maintained.

<Features of First Embodiment>
(1)
In the present invention, the heat transfer fin groups 71 to 74 of the indoor heat exchanger 6 are arranged in the vertical direction, and the heat transfer fin group 74, the heat transfer fin group 73, the heat transfer fin group 72, and the heat transfer fin group 71 are arranged from the top. They are arranged in the order. By setting these fin pitches to PF4 <PF3 <PF2 <PF1, the fin pitch of the heat transfer fins 11 belonging to the lower heat transfer fin group is made larger than the upper portion, and the drain is easily dropped. Therefore, it is possible to prevent the drain from stagnating between the plurality of heat transfer fins 11, and to facilitate the passage of air. For this reason, the fall of the cooling capability can be suppressed.

(2)
In the air conditioner 1 using a supercritical refrigerant, in order to increase the amount of heat transfer between the refrigerant and air during heating operation, the straight pipe 12a of the heat transfer pipe 12 serves as the indoor heat exchanger 6 in eight rows of heat transfer tube rows 61 to 68. A multi-row heat exchanger is used. In such an indoor heat exchanger 6, the distance until the drain falls outside (below) the indoor heat exchanger 6 is increased. As a result, the drain is likely to stagnate between the heat transfer fins 11 and the like, and the drain is likely to be clogged.

  In the present invention, even in such a heat exchanger, the fin pitch of the heat transfer fins 11 belonging to the lower heat transfer fin group than the upper portion is increased to make it easier to drop the drain. Therefore, it is possible to prevent the drain from stagnating between the plurality of heat transfer fins 11, and to facilitate the passage of air.

(3)
In the air conditioner 1 using a supercritical refrigerant, the indoor heat exchanger 6 in the indoor unit 51 is a gas cooler that cools the refrigerant during heating operation. In the gas cooler, the temperature differs between the inlet side and the outlet side of the refrigerant in the entire heat exchanger. For this reason, when adjacent heat transfer tube rows are connected by heat transfer fins, heat exchange may be performed between the heat transfer tubes via the heat transfer fins, which may cause heat loss.

  In the present invention, the heat transfer fins 11 are arranged between the heat transfer tube row 62 and the heat transfer tube row 63, between the heat transfer tube row 64 and the heat transfer tube row 65, and between the heat transfer tube row 66 and the heat transfer tube row 67. It is divided. For this reason, heat exchange via the heat transfer fins 11 can be suppressed, and heat loss can be suppressed.

(4)
In the indoor unit 51 of the air conditioner 1, the temperature difference between the refrigerant and the air in the entire indoor heat exchanger 6 is increased by making the refrigerant flow direction and the air flow direction oppose each other during the heating operation. Can keep. For this reason, heating operation can be performed efficiently.

(5)
The indoor unit 51 of the air conditioner 1 is a lower suction upper blowout type indoor unit in which the air flow flows from the lower part to the upper part of the indoor heat exchanger 6. For this reason, it is difficult for the drain to fall due to the wind from the lower part of the heat exchanger. Also in such an indoor heat exchanger 6, the clogging of the drain is suppressed. Therefore, it is possible to prevent the drain from stagnating between the plurality of heat transfer fins 11, and to facilitate the passage of air.

(6)
The indoor unit 51 of the air conditioner 1 uses CO2 as a refrigerant. CO2 hardly destroys the ozone layer because its ozone depletion coefficient is 0, as compared with conventional refrigerants such as HFC-based fluorocarbon refrigerants. Moreover, CO2 has a global warming potential of 1, which is much lower than that of CFC refrigerant of several hundred to 10,000.

  For this reason, CO2 has a small environmental load. By using this CO2 as a refrigerant, deterioration of the global environment can be suppressed.

(Second Embodiment)
Regarding the heat exchanger according to the second embodiment, differences from the indoor unit 51 of the air conditioner 1 of the first embodiment will be mainly described below.

<Structure of indoor heat exchanger>
FIG. 6 is a longitudinal sectional view of an air conditioner 1a according to the second embodiment of the present invention. The indoor heat exchanger 6a is a cross-fin type heat exchanger, and mainly includes heat transfer fins 11a and heat transfer tubes 12.

  The heat transfer tubes 12 are arranged in a direction intersecting with the air flow, and eight heat transfer tube rows 61a to 68a are arranged from the upstream of the air flow toward the downstream of the air flow. The refrigerant flows from the heat transfer tubes 12 belonging to the heat transfer tube row 68a on the downstream side of the air flow to the heat transfer tubes 12 belonging to the heat transfer tube row 61a on the upstream side of the air flow. This refrigerant distribution path is called a path 81a (see FIG. 6). By this path 81a, the air flow and the refrigerant flow are opposed to each other, and the amount of heat exchange is increased as compared with those not opposed to each other.

  In these heat transfer tube rows 61a to 68a, the tube pitch of the heat transfer tube rows in the lower portion is larger than the upper portion every two rows. That is, tube pitch PP1 of heat transfer tube row 61a and heat transfer tube row 62a, tube pitch PP2 of heat transfer tube row 63a and heat transfer tube row 64a, tube pitch PP3 of heat transfer tube row 65a and heat transfer tube row 66a, and heat transfer tube row The pipe pitch PP4 of 67a and the heat transfer pipe row 68a is PP4 <PP3 <PP2 <PP1. The indoor heat exchanger 6a is an evaporator when the indoor unit 51a performs a cooling operation. For this reason, drainage is generated. By making the pipe pitch of the heat transfer tube row at the lower part of the indoor heat exchanger 6a larger than that at the upper part, the drain can be easily dropped. Thereby, clogging due to drain is reduced, and air easily passes through the interior of the indoor heat exchanger 6a.

  The heat transfer fins 11 are divided between the heat transfer tube row 61 and the heat transfer tube row 62. This is also performed between the heat transfer tube row 63 and the heat transfer tube row 64, between the heat transfer tube row 65 and the heat transfer tube row 66, and between the heat transfer tube row 67 and the heat transfer tube row 68. As a result, the heat on the surface of the heat transfer fins 11 cannot move beyond the dividing portion 13.

<Features of Second Embodiment>
In the indoor unit 51a of the air conditioner 1a that uses a supercritical refrigerant, the straight pipe 12a of the heat transfer pipe 12 is used as the indoor heat exchanger 6a in order to increase the heat transfer amount between the refrigerant and air during the heating operation. A multi-row heat exchanger of 68a arranged in 8 rows is used. In such an indoor heat exchanger 6a, a large number of the heat transfer tubes 12 are obstructed, and the drain does not easily fall from the indoor heat exchanger 6a. Therefore, the stagnant drain becomes a large air resistance, and the cooling capacity may be reduced.

  In the present invention, the heat transfer tube rows 61a to 68a of the indoor heat exchanger 6a are arranged in the vertical direction. The heat transfer tube row 63a, the heat transfer tube row 62a, and the heat transfer tube row 61a are arranged in this order. By setting these tube pitches to PP4 <PP3 <PP2 <PP1, the tube pitch of the heat transfer tubes 12 belonging to the lower heat transfer tube row than the upper portion is increased, and the drain is easily dropped. Therefore, it is possible to prevent the drain from stagnating around the heat transfer tube, and to facilitate the passage of air.

<Modification>
(1)
The first embodiment and the second embodiment may be combined (combination of FIGS. 5 and 6). That is, the fin pitches PF1 to PF4 of the heat transfer fin group of the indoor heat exchanger 6b are larger as they go to the lower part than the upper part, and the pipe pitches PP1 to PP4 of the heat transfer tube row of the indoor heat exchanger 6b are lower than the upper part. It can be as big as you go.

  In this modification, in the indoor heat exchanger 6b mounted on the indoor unit 51b of the air conditioner 1b, the fin pitch of the heat transfer fins belonging to the lower heat transfer fin group is made larger than the upper fin pitch, and By making the tube pitch of the heat transfer tubes belonging to the lower heat transfer tube row larger than the upper tube pitch, the drain is easily dropped. Therefore, it is possible to suppress the stagnation of the drain around the heat transfer tube 12 and to facilitate the passage of air.

  Here, the size of the pipe pitch is increased every time it goes to the lower part of the two rows. However, the present invention is not limited to this.

(2)
In the indoor unit 51 of the air-conditioning apparatus 1 according to the above embodiment, two heat transfer tube rows pass through one heat transfer fin group, but not limited to this, one heat transfer fin group. You may make it the structure which 1 row of heat exchanger tube rows penetrates.

  In the indoor unit 51c of the air conditioner 1c, one row of heat transfer tube rows 61 to 68 penetrates corresponding to one heat transfer fin group 71c to 78c. Adjacent heat transfer tube rows pass through different heat transfer fin groups. Therefore, it can reduce that more heat exchanger tubes perform heat exchange via a heat-transfer fin.

(3)
The indoor unit 51 of the air conditioner 1 according to the above embodiment is a floor-standing type air conditioner, but is not limited thereto, and may be a wall-hanging type, a ceiling embedded type, a wall embedded type, or the like.

(4)
In the indoor unit 51 of the air-conditioning apparatus 1 according to the above embodiment, CO2 is used as a refrigerant. However, the present invention is not limited to this, and an HFC-based fluorocarbon refrigerant may be used.

  The heat exchanger according to the present invention can suppress a decrease in cooling capacity, and is useful as a heat exchanger including a heat exchanger that has taken measures against drainage during cooling.

A refrigeration circuit for an air conditioner using a CO2 refrigerant. (A) Pressure-enthalpy state diagram of CO2 refrigerant. (B) Temperature-entropy state diagram of CO2 refrigerant. The perspective view of the indoor heat exchanger of the air conditioning apparatus which concerns on 1st Embodiment. The side view of the indoor heat exchanger seen from the perpendicular | vertical direction with respect to the straight pipe of a heat exchanger tube. The longitudinal cross-sectional view of an air conditioning apparatus. The longitudinal cross-sectional view of the air conditioning apparatus which concerns on 2nd Embodiment. The longitudinal cross-sectional view of the air conditioning apparatus which concerns on a modification (2).

Explanation of symbols

1-1c Air conditioner 6-6c Indoor heat exchanger (heat exchanger)
11, 11a Heat transfer fins 12 Heat transfer tubes 51-51c Indoor unit 53 Fans 61-68, 61a-68a Heat transfer tube rows 71-74, 71a-74a, 71c-78c Heat transfer fin groups PF1-PF4 Fin pitch PP1-PP8 Tubes pitch

Claims (11)

A heat exchanger that performs heat exchange between the refrigerant and air using a supercritical refrigerant as the refrigerant,
A heat transfer fin group (71-74, 71c-78c) formed by a plurality of plate-like heat transfer fins (11) arranged parallel to the vertical direction at a predetermined interval;
A plurality of heat transfer tubes (12) penetrating the heat transfer fin group;
With
The plurality of heat transfer fin groups are arranged in the vertical direction, and the fins of the heat transfer fins belonging to the lower heat transfer fin group than the fin pitch of the heat transfer fins belonging to the upper heat transfer fin group. The pitch is bigger,
Heat exchanger (6, 6b, 6c). The plurality of heat transfer tubes are arranged in a direction crossing the air flow to form a heat transfer tube row (61-68),
The heat transfer tube rows are arranged in a plurality of rows from the upstream of the air flow toward the downstream of the air flow.
The heat exchanger (6, 6b, 6c) according to claim 1. The heat transfer tube rows are formed in four or more rows,
The heat exchanger (6, 6b, 6c) according to claim 2. The heat transfer tube rows are arranged in a plurality of rows in the vertical direction,
Among the plurality of heat transfer tube rows, the tube pitch of the heat transfer tubes belonging to the lower heat transfer tube row is larger than the tube pitch of the heat transfer tube belonging to the upper heat transfer tube row,
The heat exchanger (6, 6b, 6c) according to claim 2 or 3. The heat transfer tube row passes through the heat transfer fin group per row.
The heat exchanger (6, 6b, 6c) according to any one of claims 2 to 4. In the heat transfer tube row, one row penetrates one heat transfer fin group.
The heat exchanger (6, 6b, 6c) according to claim 5. The heat exchanger (6-6c) according to any one of claims 1 to 6,
A fan (53) for generating the air flow;
The indoor unit (51, 51b, 51c) of the air conditioner (1, 1b, 1c) provided with In the heating operation, the refrigerant flows from the heat transfer tube belonging to the heat transfer tube row on the downstream side of the air flow to the heat transfer tube belonging to the heat transfer tube row on the upstream side of the air flow.
The indoor unit (51, 51b, 51c) of the air conditioner (1, 1b, 1c) according to claim 7. The flow of air flows from the bottom to the top of the heat exchanger;
The indoor unit (51, 51b, 51c) of the air conditioner (1, 1b, 1c) according to claim 7 or 8. The refrigerant is CO2.
The indoor unit (51, 51b, 51c) of the air conditioner (1, 1b, 1c) according to any one of claims 7 to 9. A heat exchanger that performs heat exchange between the refrigerant and air using a supercritical refrigerant as the refrigerant,
A group of heat transfer fins (71a to 74a) formed by a plurality of plate-like heat transfer fins (11a) arranged parallel to the vertical direction at a predetermined interval;
A plurality of heat transfer tubes (12) penetrating the heat transfer fin group;
With
The plurality of heat transfer tubes are arranged in a direction intersecting the air flow to form a heat transfer tube array (61a to 68a),
The heat transfer tube rows are arranged in a plurality in the vertical direction, and belong to the heat transfer tube row below the tube pitch of the plurality of heat transfer tubes belonging to the upper heat transfer tube row among the plurality of heat transfer tube rows. The pipe pitch of the plurality of heat transfer tubes is larger,
Heat exchanger (6a).

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