JP2008138917A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent degradation of a heat exchanging capacity caused by the presence of an area of low heat flow rate in a heat exchanger disposed in an air conditioner, in the air conditioner where a refrigerant, of which a temperature is changed in a radiating process, flows. <P>SOLUTION: An outlet side 14 of a refrigerant flow channel formed in the heat exchanger 12 is disposed in an area of a wind velocity higher than an average wind velocity of the air passing through the heat exchanger 12, thus the an air-side heat transfer at the outlet side 14 can be accelerated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air conditioner provided with a refrigerant circuit in which a refrigerant changes its temperature during a heat release stroke.

  Conventionally, an air conditioner including a refrigerant circuit is known. The air conditioner is configured as a so-called separate type including, for example, an outdoor unit and an indoor unit. The outdoor unit is provided with an outdoor heat exchanger and an outdoor fan, and the indoor unit is provided with an indoor heat exchanger and an indoor fan.

  The outdoor heat exchanger and the indoor heat exchanger include, for example, a so-called cross fin type including a heat transfer tube group in which a plurality of heat transfer tubes are arranged and a plurality of heat transfer fin groups fixed to the heat transfer tube group. (For example, refer patent document 1). In this heat exchanger, the refrigerant flows inside the heat transfer tube group, and the air flows between the heat transfer fins outside the tube of the heat transfer tube group. The outdoor blower and the indoor blower are for sending air to the outside of the heat transfer tube group of each of the heat exchangers, and include, for example, a fan and driving means for rotating the fan. Here, for example, the fan of the outdoor blower is constituted by a propeller fan, and the fan of the indoor blower is constituted by a cross flow fan. Then, when the propeller fan rotates, the air around the outdoor unit is sent to the outdoor heat exchanger. Further, the air around the indoor unit is sent to the indoor heat exchanger by the rotation of the cross flow fan.

  By the way, the refrigerant circuit of the air conditioner performs a vapor compression refrigeration cycle, and when carbon dioxide is used as the refrigerant, as shown by a thick line in FIG. a supercritical refrigeration cycle (abcd) having an endothermic process (between da) at a temperature lower than the critical temperature (e) is performed. As can be seen from FIG. 6, in the case of the endothermic process, carbon dioxide absorbs heat while undergoing phase change, so the temperature of carbon dioxide during endotherm is constant. On the other hand, in the case of the heat dissipation process, since the carbon dioxide includes a portion exceeding the critical temperature (e), the carbon dioxide dissipates heat without causing a phase change. For this reason, the temperature of the refrigerant during heat dissipation greatly decreases (in the example of FIG. 6, the temperature difference ΔT≈50 ° C.).

And it is possible to make the said outdoor heat exchanger and an indoor heat exchanger perform the thermal radiation process or thermal absorption process of a supercritical refrigerating cycle. If the refrigerant circuit includes switching means for reversing the refrigerant circulation direction, for example, a four-way switching valve, the air conditioner selects the cooling operation or the heating operation by the switching operation of the four-way switching valve. Is possible. When the air conditioner performs a cooling operation, the outdoor heat exchanger performs a heat radiation process, and the indoor heat exchanger performs a heat absorption process. When performing a heating operation, the outdoor heat exchanger performs a heat radiation process. The apparatus performs an endothermic process, and the indoor heat exchanger is configured to perform a heat dissipation process.
JP-A-10-227589

  However, when the supercritical refrigeration cycle (abcd) is performed in the outdoor heat exchanger and the indoor heat exchanger, a heat exchanger that performs a heat radiation process (outdoor heat exchange in the case of cooling). In the case of a heater and an indoor heat exchanger), a region where the heat flux is high and a region where the heat flux is low are configured, and this configuration has a problem that the amount of heat exchange in the region where the heat flux is low is reduced. (Here, the heat flux is the heat transfer area per unit time and unit time).

  That is, the temperature of the carbon dioxide flowing inside the pipe of the heat exchanger decreases with heat dissipation. For this reason, a large temperature difference (ΔT≈50 ° C. in FIG. 6) occurs between the inlet side and the outlet side of the refrigerant flow path formed in the heat exchanger. On the other hand, the air flowing outside the pipe of the heat exchanger is warmed by the heat dissipation of the carbon dioxide, but the temperature difference (temperature difference is 5 to 10 ° C.) of the air before and after passing through the heat exchanger is the heat exchange. This is considered to be smaller than the temperature drop of carbon dioxide before and after passing through the vessel. From this, in the heat exchanger, when the temperature difference between carbon dioxide and air is compared, it is considered that the outlet side is smaller than the inlet side of the heat exchanger. Due to the temperature difference between carbon dioxide and air, as described above, a region with a high heat flux is formed on the inlet side of the heat exchanger, and a region with a low heat flux is formed on the outlet side. It can be considered.

  On the other hand, the air passing through the outside of the pipe of the heat exchanger may have a region where the wind speed is partially different depending on the position of the heat exchanger with respect to the blower. That is, in the heat exchanger, the wind speed is higher in a region closer to the blower, and the wind speed is slower as the distance from the blower is longer. Due to the difference in wind speed, the heat exchanger has a region where the convective heat transfer coefficient with air is high (a region where the wind speed is fast) and a region where the convective heat transfer rate is low (a region where the wind speed is slow). Can be configured.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a heat exchanger having a low heat flux in a heat exchanger provided in the air-conditioning apparatus in an air-conditioning apparatus in which a refrigerant that changes in temperature in a heat dissipation process flows. It is in suppressing the fall of the heat exchange capability by the area | region being comprised.

  A first invention includes a heat exchanger (12, 22) in which a plurality of heat transfer tubes are arranged, and a blower (15, 25) that sends air so as to pass through the heat exchanger (12, 22). An air conditioner in which a refrigerant whose temperature changes from the inlet side (13, 23) to the outlet side (14, 24) of the refrigerant flow path with respect to the heat exchanger (12, 22) flows and exchanges heat with the air. Is assumed.

  The air velocity of the air passing through the heat exchanger (12, 22) varies depending on the position of the heat exchanger (12, 22) of the air conditioner, and the refrigerant flow in the heat exchanger (12, 22). The exit side (14, 24) of the road is arranged in a region where the wind speed is higher than the average wind speed of the air passing through the heat exchanger (12, 22). Here, since the temperature of the refrigerant changes from the inlet side (13, 23) to the outlet side (14, 24) of the refrigerant flow path, the temperature of the refrigerant and air approaches the outlet side (14, 24). The difference is smaller.

  In the first invention, the outlet side (14, 24) of the refrigerant flow path is arranged in a region faster than the average wind speed of the air passing through the heat exchanger (12, 22). 14,24) can promote the heat transfer on the air side. As a result, the heat transfer coefficient on the air side on the outlet side (14, 24) is improved, so that the decrease in the heat flux on the outlet side (14, 24) of the refrigerant flow path due to the temperature change of the refrigerant is suppressed. be able to.

  According to a second aspect of the present invention, in the first aspect of the invention, among the plurality of small regions configured by dividing the region having a higher wind speed than the average wind speed, the region having the fastest average wind speed is arranged on the outlet side ( 14,24) is arranged.

  In the second invention, an area faster than the average wind speed is divided into a plurality of small areas, and among the divided small areas, the outlet side (14,24 ) Can reliably improve the heat transfer coefficient on the air side, so that it is possible to reliably reduce the heat flux on the outlet side (14, 24) of the refrigerant flow path due to the temperature change of the refrigerant. Can be suppressed.

  According to a third invention, in the first or second invention, the heat exchanger (12, 22) is provided on a suction side of the blower (15, 25), and the heat exchanger (12, 22) The outlet side (14, 24) is closer to the inlet of the blower (15, 25) than the inlet side (13, 23) of the refrigerant flow path. Here, the suction port of the blower (15, 25) is, for example, a portion into which air flows when the blower (15, 25) includes a propeller (15a) formed with a plurality of blades, that is, It is the part between the wings. And the closer to the inlet, the faster the air flow.

  In 3rd invention, when the said heat exchanger (12,22) is provided in the suction side of the said air blower (15,25), the exit side (14,24) of the said refrigerant | coolant flow path is made into a wind speed. Of the air side on the outlet side (14, 24) can be promoted by disposing in the region near the suction port of the blower (15, 25). As a result, the heat transfer coefficient on the air side on the outlet side (14, 24) is improved, so that the reduction of the heat flux on the outlet side (14, 24) of the refrigerant flow path due to the temperature change of the refrigerant is suppressed. Can do.

  According to a fourth invention, in the first or second invention, the heat exchanger (12, 22) is provided on a blow-out side of the blower (15, 25), and the heat exchanger (12, 22) The outlet side (14, 24) is closer to the blower outlet of the blower (15, 25) than the inlet side (13, 23) of the refrigerant flow path. Here, the blower outlet of the blower (15, 25) is, for example, a portion where air flows out when the blower (15, 25) includes a propeller (15a) having a plurality of blades formed, that is, It is the part between the wings. And the closer to this air outlet, the faster the air flow.

  In 4th invention, when the said heat exchanger (12,22) is provided in the blowing side of the said air blower (15,25), the exit side (14,24) of the said refrigerant | coolant flow path is made into a wind speed. By arranging in a region where the air is fast, that is, in a region close to the blower outlet of the blower (15, 25), heat transfer on the air side on the outlet side (14, 24) can be promoted. As a result, the heat transfer coefficient on the air side on the outlet side (14, 24) is improved, so that the decrease in the heat flux on the outlet side (14, 24) of the refrigerant flow path due to the temperature change of the refrigerant is suppressed. be able to.

  According to the present invention, the outlet side (14) due to the flow of the refrigerant whose temperature changes from the inlet side (13, 23) to the outlet side (14, 24) of the refrigerant flow path with respect to the heat exchanger (12, 22). , 24) can be suppressed. That is, by promoting the heat transfer on the air side on the outlet side (14, 24), it is possible to suppress a decrease in the amount of heat exchange caused by a decrease in heat flux. As described above, in the above air conditioner, it is possible to suppress a decrease in heat exchange capability due to the flow of the refrigerant whose temperature changes from the inlet side (13, 23) to the outlet side (14, 24) of the refrigerant flow path. .

  According to the second aspect of the invention, by arranging the outlet side (14, 24) of the refrigerant flow path in the small region where the average wind speed is the fastest, the heat flux on the outlet side (14, 24) can be ensured. Can be suppressed. Thereby, the fall of the heat exchange capability in the said air conditioning apparatus can be suppressed reliably.

  Further, according to the third aspect of the invention, when the heat exchanger (12, 22) is on the suction side of the blower (15, 25), the region where the wind speed is fast is that of the blower (15, 25). Since it is considered to be an area close to the intake port, the outlet side (14, 24) of the heat exchanger (12, 22) is arranged in the area close to the intake port of this blower (15, 25), so that the outlet The decrease in the heat flux on the side (14, 24) can be suppressed. Thereby, in the said air conditioning apparatus, the fall of the heat exchange capability by the refrigerant | coolant which temperature changes from the inlet side (13,23) of a refrigerant flow path toward an outlet side (14,24) can be suppressed. .

  Further, according to the fourth aspect of the invention, when the heat exchanger (12, 22) is on the outlet side of the blower (15, 25), the region where the wind speed is fast is that of the blower (15, 25). Since it is considered to be an area close to the air outlet, the outlet side (14, 24) of the heat exchanger (12, 22) is arranged in the area close to the air outlet of this blower (15, 25). The decrease in the heat flux on the side (14, 24) can be suppressed. Thereby, in the said air conditioning apparatus, the fall of the heat exchange capability by the refrigerant | coolant which temperature changes from the inlet side (13,23) of a refrigerant flow path toward an outlet side (14,24) can be suppressed. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a circuit diagram of a refrigerant circuit including the air conditioner (1, 2) of the present embodiment. The refrigerant circuit includes an outdoor unit (air conditioner) (1) and an indoor unit (air conditioner) (2). The indoor unit (2) is in an indoor space, and the outdoor unit (1) is outdoors. While being installed, the indoor unit (2) and the outdoor unit (1) are connected by the first connecting pipe (7) and the second connecting pipe (8), so that the refrigerant circuit as shown in FIG. (10) is configured.

<Refrigerant circuit>
The refrigerant circuit (10) includes a compressor (5), a four-way switching valve (9), an outdoor heat exchanger (heat exchanger) (12), an expansion valve (6), and an indoor heat exchanger (heat exchanger). ) (22) are connected by refrigerant piping. Carbon dioxide is enclosed in the refrigerant circuit (10), and the carbon dioxide circulates through the refrigerant circuit (10), so that the heat release process in the supercritical state (b-c in FIG. 6) as described above. A supercritical refrigeration cycle (abcd in FIG. 6) is performed.

  The refrigerant circuit (10) can be switched from the cooling operation state to the heating operation state or from the heating operation state to the cooling operation state by the switching operation of the four-way switching valve (9). Here, the cooling operation state means that the four-way switching valve (9) communicates with the first port (9a) and the fourth port (9d) and at the same time the second port (9b) and the third port (9c). Is the operation state when switched to the first state (solid line in FIG. 1) in which the first port (9a) and the third port (9c) communicate with each other. This is an operation state when the port (9b) and the fourth port (9d) are switched to the second state (broken line in FIG. 1).

  In the refrigerant circuit (10), when the four-way switching valve (9) is in a cooling operation state, the heat release stroke of the supercritical refrigeration cycle is performed by the outdoor heat exchanger (12), and the four-way switching valve When (9) is in the heating operation state, the heat release process of the supercritical refrigeration cycle is configured to be performed by the indoor heat exchanger (22). And the outdoor unit (1) provided with the said outdoor heat exchanger (12) and the indoor unit (2) provided with the said indoor heat exchanger (22) are the air conditioning apparatuses (1, 2) in this embodiment. It is composed. In the supercritical refrigeration cycle, the compression stroke (between a and b in FIG. 6) is performed by the compressor (5), and the expansion stroke (between cd and FIG. 6) is performed by the expansion valve (6). Done. Further, the endothermic process (between da in FIG. 6) is performed by the indoor heat exchanger (22) in the cooling operation, and is performed by the outdoor heat exchanger (12) in the heating operation.

<Outdoor unit>
−Outdoor unit configuration−
The outdoor unit (1) constitutes the air conditioner (1) of the present embodiment as described above. FIG. 2 is a diagram conceptually showing the shape and arrangement of the outdoor heat exchanger (12) and the outdoor fan (blower) (15) in the casing of the outdoor unit (1). Here, the arrow of FIG. 2 has shown the wind speed distribution of the air which flows in into the said outdoor heat exchanger (12) at the time of the driving | operation of the said outdoor fan (15). The direction of the arrow represents the wind direction, and the length of the arrow represents the wind speed.

  First, the shapes of the outdoor heat exchanger (12) and the outdoor fan (15) will be described.

  The outdoor heat exchanger (12) is a cross fin type heat exchanger, a heat transfer tube group having a plurality of straight tubular heat transfer tubes and a plurality of U-shaped tubes (12b), and a plurality of rectangular flat plate-like heat exchangers And a heat transfer fin group having heat transfer fins (12c). And the said heat exchanger tube group is arrange | positioned so that the said heat exchanger fin group may be penetrated.

  Specifically, in the heat transfer tube group, a plurality of heat transfer tubes are arranged in two rows at predetermined intervals. Here, in the heat transfer tube group, as shown in FIG. 2, the left column (the left column in FIG. 2) of the heat transfer tube group is the first tube column (12d), and the right column is the second tube column (12a). Is configured. Of the plurality of heat transfer tubes constituting the heat transfer tube group, one end (first end) (13) of the first heat transfer tube and one end (second end) of the second heat transfer tube in the first tube row (12d). ) By connecting the ends of the heat transfer tubes except for (14) with the plurality of U-shaped tubes (12b), the heat transfer tube group has the first end as the inlet end (13) and the second end as the second end. A single refrigerant channel is formed as an outlet end (14).

  The heat transfer fin group is formed such that a plurality of heat transfer fins (12c) are arranged in a line so as to be parallel to each other with a predetermined interval along the length direction of the heat transfer tube. . Each heat transfer fin (12c) is provided with a plurality of through holes penetrating the fins in the front and back direction, and each heat transfer tube is inserted into each through hole to form the heat exchanger (12, 22). Has been.

  On the other hand, the outdoor fan (15) is an axial flow type propeller fan, and includes a propeller (15a) formed with a plurality of blades, and a rotating shaft (15b) attached to the center of the propeller (15a). And a fan motor (15c) for rotating the rotating shaft (15b) in the circumferential direction. Here, the outdoor fan (15) has a suction side on the left side (fan motor (15c) side) of the propeller (15a) shown in FIG. 2, and a right side (opposite side of the fan motor (15c)). ) Is configured to be the outlet side.

  Next, the arrangement of the outdoor heat exchanger (12) and the outdoor fan (15) and the wind speed distribution will be described.

  As can be seen from FIG. 2, the outdoor heat exchanger (12) is located on the suction side of the outdoor fan (15), and the center of the outdoor heat exchanger (12) and the center of the outdoor fan (15) Are arranged so as to face each other. Then, in the outdoor unit (1) in which the outdoor heat exchanger (12) and the outdoor fan (15) are arranged in this manner, the outdoor fan (15) is activated to suck in the outdoor fan (15). On the side, a wind speed distribution as shown in FIG. 2 is formed.

-Operation of outdoor unit-
First, the flow of carbon dioxide in the outdoor heat exchanger (12) of the outdoor unit (1) will be described. In the present embodiment, the effect of the present invention can be obtained only when the outdoor heat exchanger (12) performs the heat dissipation process of the supercritical refrigeration cycle described above. Here, the refrigerant circuit (10) Only the operation of the outdoor unit (1) when the air conditioner is in the cooling state will be described, and the operation of the outdoor unit (1) when the refrigerant circuit (10) is in the heating state will be omitted.

  When the refrigerant circuit (10) is in the cooling state, the four-way switching valve (9) is switched to the first state, and carbon dioxide circulates in the direction of the solid arrow in the refrigerant circuit diagram of FIG. To do.

  Specifically, the supercritical carbon dioxide discharged from the compressor (5) passes through the four-way switching valve (9) in the first state and enters the refrigerant flow path formed in the heat transfer tube group. From the end (13), it flows into the outdoor heat exchanger (12). The carbon dioxide that has flowed into the outdoor heat exchanger (12) flows along the refrigerant flow path while meandering below the first tube row (12d). The carbon dioxide flowing into the lowermost heat transfer tube of the first tube row (12d) flows into the lowermost heat transfer tube of the adjacent second tube row (12a) via the U-shaped tube (12b). The carbon dioxide that has flowed into the lowermost heat transfer tube of the second tube row (12a) flows while meandering along the refrigerant flow path above the second tube row (12a). The carbon dioxide flowing into the uppermost heat transfer tube of the second tube row (12a) flows into the uppermost heat transfer tube of the adjacent first tube row (12d) via the U-shaped tube (12b). To do. The carbon dioxide that has flowed into the uppermost heat transfer tube of the first tube row (12d) flows while meandering along the refrigerant flow path to the lower side of the first tube row (12d). 14)

  Here, at the inlet end (13) of the refrigerant flow path, the carbon dioxide at the temperature at point b in FIG. 6 flows through the refrigerant flow path and dissipates heat to the air outside the pipe. Decreases to the temperature at point c in FIG. 6 at the outlet end (14) of the refrigerant flow path. Thus, since the temperature of carbon dioxide itself decreases along the flow of carbon dioxide, the temperature of the carbon dioxide increases as it approaches the inlet end (13), and decreases as it approaches the outlet end (14). Become.

  Next, the flow of air in the outdoor heat exchanger (12) will be described.

  When the outdoor fan (15) is activated, air outside the casing of the outdoor unit (1) is sucked into the casing, and a plurality of heat transfer fins (12c) of the outdoor heat exchanger (12) Flows in between. The wind speed distribution of the air when flowing between the heat transfer fins (12c) is the wind speed distribution shown in FIG.

  In the wind speed distribution, except for the central portion of the outdoor heat exchanger (12), the closer to the outdoor fan (15), the higher the wind speed. Here, the central part of the outdoor heat exchanger (12) is removed because the fan motor (15c) of the outdoor fan (15) is located at a position facing the central part of the outdoor heat exchanger (12). Because is arranged. That is, the air passing through the central portion of the heat exchanger (12, 22) is not sucked into the propeller (15a) as it is, but is sucked into the propeller (15a) after colliding with the fan motor (15c). For this reason, the fan motor (15c) itself becomes an obstacle to the air flow, and as a result, the wind speed of the air flowing through the central portion of the outdoor heat exchanger (12) is reduced.

  This means that the area close to the outdoor fan (15) does not necessarily have a high air velocity. In other words, in the air flow formed by the outdoor fan (15), as described above, some object, for example, the fan motor (15c) may become an obstacle due to the configuration of the outdoor unit (1).

  The air flowing between the plurality of heat transfer fins (12c) of the outdoor heat exchanger (12) with such a wind speed distribution passes through the heat transfer fins (12c) while passing through the heat transfer fins (12c). Is heated by the carbon dioxide flowing through the heat transfer fins and flows out between the heat transfer fins (12c). Here, the temperature difference of the air before and after heating of the air, that is, before and after passing through the outdoor heat exchanger (12) is about 5 ° C. to 10 ° C., and carbon dioxide before and after passing through the outdoor heat exchanger (12). Is smaller than the temperature difference (ΔT≈50 ° C. in FIG. 6) That is, comparing the temperature difference between carbon dioxide and air near the inlet end (13) and the outlet end (14) of the refrigerant passage of the outdoor heat exchanger (12), the outlet is closer than the inlet end (13). The temperature difference between carbon dioxide and air is smaller near the end (14). For this reason, the heat flux is smaller near the outlet end (14) than near the inlet end (13). As described above, the heat flux is the amount of heat that moves per unit heat transfer area and unit time, and the magnitude of the amount of heat is proportional to the temperature difference and heat transfer rate of the portion. Therefore, the heat flux is smaller near the outlet end (14) where the temperature difference between carbon dioxide and air is small.

  In this way, the heat flux is smaller near the outlet end (14) than near the inlet end (13) because the refrigerant in the refrigerant circuit (10) is carbon dioxide in the heat release process, that is, with a phase change. This is because a refrigerant that dissipates heat is used. When a refrigerant that dissipates heat with a phase change is used instead of carbon dioxide, the temperature of the refrigerant becomes substantially constant during heat dissipation, so that the air that passes through the heat exchanger (12, 22) The temperature difference is also almost constant. That is, the heat flux near the inlet end (13) and the outlet end (14) is also substantially constant, and the heat flux is smaller near the outlet end (14) than near the inlet end (13). There is nothing.

  And in the said outdoor unit (1), the exit end (14) with a small heat flux is arrange | positioned in the area | region where wind speed is faster than average wind speed among the wind speed distribution mentioned above, for example, the area | region where wind speed is the fastest. This configuration is a feature of the present invention.

<Indoor unit>
−Configuration of indoor unit−
The indoor unit (2) constitutes the air conditioner (2) of the present embodiment as described above. FIG. 3 is a diagram conceptually showing the shape and arrangement of the indoor heat exchanger (22) and the indoor fan (blower) (25) in the casing of the indoor unit (2). FIG. 3 also shows the air velocity distribution.

  First, the shapes of the indoor heat exchanger (22) and the indoor fan (25) will be described.

  The indoor heat exchanger (22) is a cross fin type heat exchanger, a heat transfer tube group having a plurality of straight tubular heat transfer tubes and a plurality of U-shaped tubes (22b), and a plurality of substantially V-shaped. And a heat transfer fin group having the heat transfer fins (22c). And the said heat exchanger tube group is arrange | positioned so that the said heat exchanger fin group may be penetrated.

  Specifically, the heat transfer tube group includes a plurality of heat transfer tubes arranged in two rows and arranged in a V shape. Here, among the plurality of heat transfer tubes arranged in two rows, as shown in FIG. 3, the indoor fan (25) side, that is, the inner row is the first tube row (22d), and the first tube row (22d ), That is, the outer row constitutes the second tube row (22a). Then, one end (first end) (23) of the first heat transfer tube of the second tube row (22a) and one end (second end) (24) of the second heat transfer tube of the first tube row (22d) are connected. By connecting the ends of the heat transfer tubes together by the plurality of U-shaped tubes (22b), the heat transfer tube group has a first end as an inlet end (23) and a second end as an outlet end (24). A single refrigerant flow path is formed.

  The heat transfer fin group is formed by arranging a plurality of heat transfer fins (22c) in a row so as to be parallel to each other with a predetermined interval along the length direction of the heat transfer tube. . Each of the heat transfer fins (22c) is provided with a plurality of through holes penetrating the fins in the front and back directions, and the heat transfer tubes are inserted into the through holes to form the indoor heat exchanger (22). ing.

  On the other hand, the indoor fan (25) is a centrifugal cross-flow fan, and has a cylindrical impeller (25a) formed with a plurality of blades and a rotation attached to the center of the impeller (25a). A shaft (25b) and a fan motor (not shown) for rotating the rotating shaft (25b) in the circumferential direction are provided. Here, the indoor fan (25) is configured such that the upper side (the indoor heat exchanger (22) side) is the suction side and the lower side is the blowing side with respect to the impeller (25a) shown in FIG. Is done.

  Next, the arrangement of the indoor heat exchanger (22) and the indoor fan (25) and the wind speed distribution will be described.

  As can be seen from FIG. 3, the indoor heat exchanger (22) and the indoor fan (25) are configured such that the indoor heat exchanger (22) is located on the suction side of the indoor fan (25) and the indoor heat The center of the indoor fan (25) is arranged from the inside of the V shape of the exchanger (22). In this way, the indoor heat exchanger (22) and the indoor fan (25) are arranged, and when the indoor fan (25) is activated, the suction side of the indoor fan (25) is shown in FIG. As shown, a wind speed distribution is formed such that the closer to the indoor fan (25), the faster the wind speed.

-Indoor unit operation-
First, the flow of carbon dioxide in the indoor heat exchanger (22) of the indoor unit (2) will be described. Here, in the present embodiment, the effect of the present invention can be obtained only when the indoor heat exchanger (22) performs the heat dissipation process of the supercritical refrigeration cycle described above. Only the operation of the indoor unit (2) when (10) is in the heating state will be described, and the operation of the indoor unit (2) when the refrigerant circuit (10) is in the cooling state will be omitted.

  When the refrigerant circuit (10) is in the heating state, the four-way switching valve (9) is switched to the second state, and carbon dioxide circulates in the direction of the broken arrow in the refrigerant circuit diagram of FIG. To do.

  Specifically, the supercritical carbon dioxide discharged from the compressor (5) passes through the four-way switching valve (9) in the second state and enters the refrigerant flow path formed in the heat transfer tube group. It flows into the indoor heat exchanger (22) from the end (23). The carbon dioxide that has flowed into the indoor heat exchanger (22) flows while meandering upward while alternately moving back and forth between the first tube row (22d) and the second tube row (22a) along the refrigerant flow path. . Then, the carbon dioxide flowing into the uppermost heat transfer tube flows while meandering downward while alternately going back and forth between the first tube row (22d) and the second tube row (22a) along the refrigerant flow path. And flows out from the outlet end (24) of the refrigerant flow path. Here, at the inlet end (23) of the refrigerant flow path, the carbon dioxide at the temperature of point b in FIG. 6 flows through the refrigerant flow path and dissipates heat to the air outside the tube, so Decreases to the temperature at point c in FIG. 6 at the outlet end (24) of the refrigerant flow path. Thus, since the temperature of carbon dioxide itself decreases along the flow of carbon dioxide, the temperature of the carbon dioxide increases as it approaches the inlet end (23), and decreases as it approaches the outlet end (24). Become.

  Next, the air flow in the indoor heat exchanger (22) will be described.

  When the indoor fan (25) is activated, the air outside the casing of the indoor unit (2) flows between the heat transfer fins (22c) of the indoor heat exchanger (22). The wind speed distribution of the air at this time is the wind speed distribution shown in FIG. Here, the outlet end (24) of the refrigerant flow path is arranged in a region where the wind speed is fastest in the wind speed distribution.

  The air flowing between the plurality of heat transfer fins (22c) of the indoor heat exchanger (22) flows in the heat transfer tube while passing between the heat transfer fins (22c) with such a wind speed distribution. Heated by carbon dioxide, it flows out between the heat transfer fins (22c). Here, as in the outdoor unit (1) described above, the temperature difference of the air before and after heating of the air, that is, before and after passing through the indoor heat exchanger (22) is about 5 ° C. to 10 ° C. It is smaller than the temperature difference of carbon dioxide before and after passing through the exchanger (22) (ΔT≈50 ° C. in FIG. 6). That is, when the temperature difference between carbon dioxide and air is compared near the inlet end (23) and the outlet end (24) of the refrigerant passage of the indoor heat exchanger (22), the outlet is closer than the vicinity of the inlet end (23). The temperature difference between carbon dioxide and air is smaller near the end (24). For this reason, the heat flux is smaller near the outlet end (24) than near the inlet end (23). Therefore, the heat flux is smaller near the outlet end (24) where the temperature difference between carbon dioxide and air is small.

  And in the said indoor unit (2), the exit end (24) with a small heat flux is arrange | positioned among the said wind speed distribution in the area | region where a wind speed is faster than an average wind speed, for example, the area | region where the wind speed is the fastest. This configuration is a feature of the present invention.

-Effect of the embodiment-
According to this embodiment, in the outdoor heat exchanger (12) and the indoor heat exchanger (22), the outlet ends (14, 24) of the refrigerant flow paths formed in both heat exchangers (12, 22). ) Is arranged in a region where the wind speed is fastest among the wind speed distributions of the air formed in the respective heat exchangers (12, 22). Here, the region with the highest wind speed is considered to be the region with the highest air-side heat transfer coefficient. That is, the outlet end (14, 24) of the refrigerant flow path is arranged in a region where the heat transfer coefficient on the air side is the highest.

  On the other hand, when the refrigerant circuit (10) that performs the supercritical refrigeration cycle performs cooling operation, in the outdoor heat exchanger (12) that performs the heat dissipation process, as described above, the refrigerant circuit (10) near the outlet end (14) of the refrigerant flow path The heat flux is lower than the heat flux near the inlet end (13). Further, when the refrigerant circuit (10) performs a heating operation, in the indoor heat exchanger (22) performing the heat radiation process, the heat flux near the outlet end (24) of the refrigerant flow path is near the inlet end (23). It is lower than the heat flux. That is, by disposing the outlet end (14, 24) of each refrigerant flow path in a region where the heat transfer coefficient on the air side is the highest, it is possible to suppress a decrease in the heat flux. Thereby, the fall of the heat exchange capability of the outdoor unit (1) in air_conditionaing | cooling operation and the indoor unit (2) in heating operation can be suppressed.

-Modification 1 of embodiment-
In the modification 1 of the embodiment, as shown in FIG. 4, the shape of the outdoor heat exchanger (32), the outdoor heat exchanger (32), and the outdoor fan are compared with the outdoor unit (1) of the above embodiment. The positional relationship with (35) has been changed. In addition, the shape of the outdoor heat exchanger (32) of the modification 1 is a cross fin type heat exchanger having a substantially U-shape in plan view, and the outdoor heat exchanger (32) is an outdoor fan (35). It is arranged below. Thereby, as shown in FIG. 4, the wind speed distribution with respect to the outdoor heat exchanger (32) is a distribution in which the wind speed increases toward the top of the outdoor heat exchanger (32). Even for such a wind speed distribution, the outlet end (34) of the refrigerant flow path of the outdoor heat exchanger (32) is arranged at the uppermost part, so that the heat flux at the outlet end (34) is reduced. The decrease can be suppressed. Thereby, the fall of the heat exchange capability of the outdoor unit (31) in the cooling operation can be suppressed.

-Modification 2 of embodiment-
In the second modification of the embodiment, as shown in FIG. 5, the shape of the outdoor heat exchanger (42), the indoor heat exchanger (42), and the outdoor fan are compared with the indoor unit (2) of the above embodiment. The positional relationship with (45) has been changed. In addition, the shape of the indoor heat exchanger (42) of the modified example 2 is a substantially rectangular cross fin type heat exchanger (12, 22), and the indoor heat exchanger (22) is shown in FIG. As shown in FIG. 4, it is arranged around the outdoor fan (15). The indoor fan (45) is a turbo fan. Thereby, the wind speed distribution with respect to the indoor heat exchanger (42) becomes a distribution in which the wind speed increases as it goes to the upper part of the indoor heat exchanger (42), as shown in FIG. 5B. Even for such a wind speed distribution, by arranging the outlet end (44) of the refrigerant flow path of the outdoor heat exchanger (42) at the top, the heat flux at the outlet end (44) is reduced. The decrease can be suppressed. Thereby, the fall of the heat exchange capability of the indoor unit (42) in heating operation can be suppressed.

<< Other Embodiments >>
About the said embodiment, it is good also as the following structures.

  In the above embodiment, the outdoor unit (1) and the indoor unit (2) have been described. However, an integrated air conditioner in which the outdoor unit (1) and the indoor unit (2) are integrated may be used. . In this case, in the two heat exchangers mounted on the integrated air conditioner, the outlet end of each heat exchanger is located in the region where the wind speed is the fastest in the wind speed distribution of the air formed in each heat exchanger. May be arranged.

  Moreover, although only one outlet end (14, 24) is formed in the heat exchanger (12, 22) of the embodiment, it is not necessary to be one, and there are a plurality of outlet ends (14, 24). It may be formed. That is, a plurality of refrigerant flow paths may be formed in the heat exchanger. In this case, what is necessary is just to arrange | position the several exit end in a refrigerant | coolant flow path in the area | region where the wind speed is the fastest among the wind speed distribution of the air formed in a heat exchanger.

  Further, in the above embodiment, carbon dioxide is used as the refrigerant, but it is not necessary to be carbon dioxide. From the inlet end (13, 23) of the refrigerant flow path to the heat exchanger (12, 22) to the outlet end (14, It may be a refrigerant whose temperature changes toward 24).

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for the shape of a cross-fin type heat exchanger suitable for an air conditioner provided with a refrigerant circuit in which the refrigerant changes its temperature during the heat release stroke.

It is a circuit diagram of the refrigerant circuit to which the air conditioning apparatus which is embodiment of this invention was connected. It is the figure which showed notionally the shape and arrangement | positioning of the outdoor heat exchanger of the outdoor unit which is embodiment of this invention, and an outdoor fan. It is the figure which showed notionally the shape and arrangement | positioning of the indoor heat exchanger and indoor fan of the indoor unit which is embodiment of this invention. It is the figure which showed notionally the shape and arrangement | positioning of the outdoor heat exchanger of the outdoor unit which is the modification 1 of embodiment of this invention, and an outdoor fan. It is the figure which showed notionally the shape and arrangement | positioning of the indoor heat exchanger of an indoor unit which is the modification 2 of embodiment of this invention, and an indoor fan, (A) is a top view, (B) is a side view. . It is the figure which represented the supercritical refrigerating cycle on the TS diagram of a carbon dioxide.

Explanation of symbols

1 Outdoor unit (air conditioner)
2 Indoor unit (air conditioner)
10 Refrigerant circuit
12 Outdoor heat exchanger (heat exchanger)
13 Entrance end
14 Exit end
15 Outdoor fan (blower)
22 Indoor heat exchanger (heat exchanger)
23 Entrance end
24 Exit end
25 Indoor fan (blower)

Claims (4)

A heat exchanger (12, 22) in which a plurality of heat transfer tubes are arranged; and a blower (15, 25) for sending air so as to pass through the heat exchanger (12, 22). 12, 22) is an air conditioner in which a refrigerant whose temperature changes from the inlet side (13, 23) to the outlet side (14, 24) of the refrigerant flow path and exchanges heat with the air,
Depending on the position of the heat exchanger (12, 22), the wind speed of the air passing through the heat exchanger (12, 22) is different,
The outlet side (14, 24) of the refrigerant flow path in the heat exchanger (12, 22) is disposed in a region where the wind speed is higher than the average wind speed of the air passing through the heat exchanger (12, 22). An air conditioner characterized by that. In claim 1,
The outlet side (14, 24) of the refrigerant channel is arranged in a region where the average wind speed is the fastest among a plurality of small regions configured by dividing a region where the wind speed is higher than the average wind speed. Air conditioner. In claim 1 or 2,
The heat exchanger (12, 22) is provided on the suction side of the blower (15, 25),
In the heat exchanger (12, 22), the outlet side (14, 24) is closer to the suction port of the blower (15, 25) than the inlet side (13, 23) of the refrigerant flow path. Air conditioner. In claim 1 or 2,
The heat exchanger (12, 22) is provided on the outlet side of the blower (15, 25);
In the heat exchanger (12, 22), the outlet side (14, 24) is closer to the blower outlet of the blower (15, 25) than the inlet side (13, 23) of the refrigerant flow path. Air conditioner.

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