Indoor unit and air conditioning system

Abstract

To provide an indoor unit that can suppress frost formation. [Solution] The indoor unit is an indoor unit of an air conditioning system. The indoor unit uses a non-azeotropic refrigerant. The indoor unit comprises a main heat exchanger, a flow divider, and a sensor. The main heat exchanger includes multiple paths through which the refrigerant flows. The flow divider divides the refrigerant before it enters the paths. The sensor detects the temperature of the refrigerant. The sensor is positioned near the flow divider, between the flow divider and the main heat exchanger, or on the flow divider side of the midpoint of the total length of the path portion formed by the heat transfer tubes of the main heat exchanger.

Description

Technical Field

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[0001] It relates to an indoor unit and an air conditioner.

Background Art

[0002] Recently, in order to suppress global warming, a refrigerant with a low GWP (Global Warming Potential) is used in air conditioners. Refrigerants with a global warming potential of 150 or less, good cooling efficiency, and low cost have been variously studied and proposed. As a refrigerant that can meet such requirements, there is azeotropic refrigerant in which a plurality of types of refrigerants are mixed. Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2022-115320) describes an indoor unit for an air conditioner using an azeotropic refrigerant.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In the indoor unit for an air conditioner of Patent Document 1, frosting may occur.

Means for Solving the Problems

[0004] The indoor unit of the first aspect is an indoor unit of an air conditioner. The indoor unit uses an azeotropic refrigerant as the refrigerant. The indoor unit includes a main heat exchanger, a diverter, and a sensor. The main heat exchanger includes a plurality of paths through which the refrigerant flows. The diverter diverts the refrigerant before it enters the path. The sensor detects the temperature of the refrigerant. The sensor is disposed on the diverter side from the middle of the total length of the path portion formed by the vicinity in the refrigerant flow of the diverter, the pipe on the refrigerant flow path connecting the diverter and the main heat exchanger, or the heat transfer pipe of the main heat exchanger.

[0005] According to this indoor unit, frosting can be suppressed.

[0006] The indoor unit in the second view is the indoor unit in the first view, and the main heat exchanger includes the front upper section, the front lower section, and the rear section. The sensor is located near the flow divider that divides the refrigerant before it enters the front upper section path, in the piping on the refrigerant flow path connecting the flow divider and the front upper section of the path, or in the front upper section of the path.

[0007] The indoor unit in the third perspective is the indoor unit in the second perspective, and the sensor is located on the upper front side of the airflow side, on the shunter side, from the middle of the total length of the path portion formed by the heat transfer tubes of the exchanger.

[0008] The indoor unit in the fourth perspective is an indoor unit in either the first or third perspective, where, during evaporation operation, the refrigerant temperature at the part where the sensor is attached is lower than the refrigerant temperature at the inlet of the main heat exchanger.

[0009] The indoor unit in the fifth perspective is an indoor unit from either the first or fourth perspective, and during evaporation operation, the refrigerant temperature at the part where the sensor is attached is lower than the refrigerant temperature at the junction of the main heat exchanger's paths.

[0010] The indoor unit according to the sixth perspective is an indoor unit according to the first or second perspective, further comprising an exchanger. During evaporation operation, the refrigerant flows in the order of the auxiliary heat exchanger, the diverter, and the main heat exchanger. The sensor is placed in the piping on the refrigerant flow path connecting the diverter and the main heat exchanger.

[0011] The indoor unit of the seventh aspect is the indoor unit of the first or second aspect, further comprising a secondary heat exchanger. During evaporation operation, the refrigerant flows in the order of secondary heat exchanger, flow divider, and main heat exchanger. The sensor is located near the refrigerant flow in the flow divider and is positioned in the piping on the refrigerant flow path connecting the secondary heat exchanger and the flow divider.

[0012] The indoor unit of the eighth perspective is the indoor unit of the first or second perspective, further comprising a secondary heat exchanger. During evaporation operation, the refrigerant flows in the order of secondary heat exchanger, flow divider, and main heat exchanger. The sensor is positioned on the flow divider side from the middle of the total length of the path portion formed by the heat transfer tubes of the main heat exchanger.

[0013] The indoor unit in the ninth perspective is the indoor unit in the first or second perspective, and the sensor is placed in a path other than the path with the longest path length.

[0014] The indoor unit in the tenth perspective is the indoor unit in the ninth perspective, and the sensor is placed in the path with the shortest path length among the paths.

[0015] The indoor unit in the 11th perspective is the indoor unit in the 1st or 2nd perspective, and the sensor is located in the path with the highest refrigerant circulation rate of the main heat exchanger.

[0016] The indoor unit of the 12th perspective is an indoor unit of any of the 1st to 11th perspectives, further comprising a blower. During evaporation operation, the direction of refrigerant flow and the direction of airflow generated by the blower are opposite.

[0017] The indoor unit of the 13th perspective is an indoor unit of any of the 1st to 12th perspectives, further comprising a blower. During evaporation and condensation operations, the direction of refrigerant flow and the direction of airflow generated by the blower are opposite.

[0018] The indoor unit in the 14th perspective is an indoor unit in either the 1st perspective or the 13th perspective, and the non-azeotropic refrigerant is mainly composed of hydrofluoroolefin refrigerant. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram of an air conditioning system 10 having an indoor unit 30. [Figure 2] This is a front view of the indoor unit 30 with the front of the casing 33 removed. [Figure 3] This is a cross-sectional view of the indoor unit 30 cut along line AA in Figure 2. [Figure 4] This figure shows the refrigerant temperature distribution within the heat exchanger 31. [Figure 5] This is a cross-sectional view of the indoor unit 30 of modified example A. [Figure 6]It is a cross-sectional view of the indoor unit 30 of Modification B. [Figure 7] It is a cross-sectional view of the indoor unit 30 of Modifications C and D. [Figure 8] It is a cross-sectional view of the indoor unit 30 of Modification E. [Figure 9] It is a cross-sectional view of the indoor unit 30 of Modification E. [Figure 10] It is a cross-sectional view of the indoor unit 30 of Modification F. [Figure 11] It is a cross-sectional view of the indoor unit 30 of Modification F. [Figure 12] It is a cross-sectional view of the indoor unit 30 of Modification G. [Figure 13] It is a cross-sectional view of the indoor unit 30 of Modification G. [Figure 14] It is a schematic view of the air conditioner 10 having the indoor unit 30 of Modification I. [Figure 15] It is a cross-sectional view of the indoor unit 30 of Modification I. [Figure 16] It is a cross-sectional view of the indoor unit 30 of Modification I.

Embodiments for Carrying Out the Invention

[0020] <0000!05>Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or its uses. Also, the components of each of the following embodiments, modifications, and other examples can be combined or partially replaced within the scope where the present invention can be implemented. The upper, lower, left, right, front, and rear directions mentioned in the following description correspond to the directions indicated by the arrows in each figure.

[0021] (1) Overall Configuration The indoor unit 30 according to an embodiment of the present disclosure is used in the air conditioner 10.

[0022] As shown in Figure 1, the air conditioning unit 10 executes a vapor compression refrigeration cycle in the refrigerant circuit 11 to perform evaporation and condensation operations, which are air conditioning operations. In evaporation operation, the air conditioning unit 10 cools the air in the indoor space. In heating operation, the air conditioning unit 10 heats the air in the indoor space.

[0023] The air conditioning system 10 includes an outdoor unit 20, an indoor unit 30, and refrigerant pipes 12 and 13. The indoor unit 30 and the outdoor unit 20 are connected by the refrigerant pipes 12 and 13, forming a refrigerant circuit 11 through which the refrigerant circulates.

[0024] The refrigerant circuit 11 is filled with a non-azeotropic refrigerant mixture. The GWP of the non-azeotropic refrigerant mixture is less than 150.

[0025] A non-azeotropic refrigerant mixture is a mixture of at least two types of refrigerants. In the embodiment, the refrigerant circuit 11 of the air conditioning system 10 is filled with a non-azeotropic refrigerant mixture containing only two types of refrigerants (a first refrigerant and a second refrigerant). However, it is not limited to this, and the non-azeotropic refrigerant mixture may be a mixture of three or more types of refrigerants. For example, the second refrigerant may not be a single type of refrigerant, but an azeotropic refrigerant mixture or pseudo-azeotropic refrigerant containing two or more types of refrigerants. In short, the non-azeotropic refrigerant mixture may be a mixture of an azeotropic refrigerant mixture or pseudo-azeotropic refrigerant containing two or more types of refrigerants as the second refrigerant, and a first refrigerant which is non-azeotropic as the second refrigerant. The boiling point of the second refrigerant is higher than the boiling point of the first refrigerant.

[0026] While not limited to these, for example, the first refrigerant is difluoromethane (R32), and the second refrigerant is HFO (hydrofluoroolefin). HFO is a refrigerant with an extremely low global warming potential. While not limited to these, an example of HFO used as the second refrigerant is R1234yf (2,3,3,3-tetrafluoropropene). Difluoromethane (R32) is a refrigerant with a relatively low boiling point, while R1234yf is a refrigerant with a relatively high boiling point.

[0027] The non-azeotropic mixed refrigerant of the embodiment mainly consists of a hydrofluoroolefin refrigerant. For example, the non-azeotropic mixed refrigerant of the embodiment is R454C. R454C contains 21.5% by mass of R32 as the first refrigerant and 78.5% by mass of R1234yf as the second refrigerant.

[0028] The ratio of the total weight of the first refrigerant filled in the refrigerant circuit 11 to the total weight of all refrigerants filled in the refrigerant circuit 11 of the air conditioner 10 is preferably 15 to 30% by mass. The ratio of the total weight of the second refrigerant filled in the refrigerant circuit 11 to the total weight of all refrigerants filled in the refrigerant circuit 11 of the air conditioner 10 is preferably 70 to 85% by mass.

[0029] (2) Detailed configuration (2-1) Indoor unit 30 The indoor unit 30 is installed within the space to be air-conditioned.

[0030] As shown in Figure 2, the indoor unit 30 is a wall-mounted indoor unit 30 that is long horizontally (left to right) and has a roughly rectangular parallelepiped shape, and is used by being mounted on the wall surface of the space to be air-conditioned.

[0031] The indoor unit 30 comprises a casing 33, a heat exchanger 31, a flow divider 50, a refrigerant temperature sensor 40, a fan 32, and a control device 39.

[0032] (2-1-1) Casing 33 The casing 33 forms the outer enclosure of the indoor unit 30. Inside the casing 33, an internal space is formed to house the heat exchanger 31.

[0033] The casing 33 is formed in a horizontally elongated box shape from left to right. The casing 33 has a front plate, a rear plate, an upper plate, and a lower plate.

[0034] The casing 33 has an intake port 33a and an outlet port 33b. The casing 33 is installed in the space to be air-conditioned so that its rear panel is in contact with the wall.

[0035] The intake port 33a is an opening formed at the top of the casing 33 and is the inlet for air to flow into the interior of the casing 33. The outlet port 33b is an opening formed at the bottom of the casing 33 and is the outlet for the airflow (conditioned air). The indoor unit 30 draws air from the space to be air-conditioned into the casing 33 through the intake port 33a and blows out conditioned air through the outlet port 33b.

[0036] (2-1-2) Utilized heat exchanger 31 The heat exchanger 31 causes the refrigerant to exchange heat with the air in the space to be air-conditioned. The airflow generated by the fan 32 passes through the heat exchanger 31.

[0037] As shown in Figure 2, the heat exchanger 31 has a plurality of heat transfer tubes 31a, a plurality of heat transfer fins 31b, a plurality of U-shaped tubes 31c, and a tube sheet 31d. The heat exchanger 31 is a fin-and-tube type heat exchanger. The materials of the heat transfer tubes 31a, heat transfer fins 31b, U-shaped tubes 31c, and tube sheet 31d are not limited, but for example, the heat transfer tubes 31a, heat transfer fins 31b, U-shaped tubes 31c, and tube sheet 31d are made of aluminum or an aluminum alloy. Alternatively, for example, the heat transfer tubes 31a and U-shaped tubes 31c may be made of copper or a copper alloy, the heat transfer fins 31b may be made of aluminum or an aluminum alloy, and the tube sheet 31d may be made of steel. The heat exchanger 31 is an example of a heat exchanger. The plurality of heat transfer tubes 31a and U-shaped tubes 31c constitute a part of the refrigerant circuit 11.

[0038] Multiple heat transfer tubes 31a are arranged inside the casing 33 such that their longitudinal direction aligns with the left-right direction and they are spaced apart from one another.

[0039] Multiple heat transfer fins 31b are arranged inside the casing 33 so as to be perpendicular to each other in the left-right direction and to be spaced apart from each other in the left-right direction. Each heat transfer fin 31b has multiple holes formed through which the heat transfer tubes 31a pass. The multiple heat transfer fins 31b are arranged between two tube sheets 31d along the left-right direction.

[0040] The U-shaped pipe 31c connects the ends of two predetermined heat transfer tubes 31a. Some of the heat transfer tubes 31a have pipes connected to either the refrigerant piping 12 or the refrigerant piping 13 at their ends. This allows the refrigerant flowing into the heat transfer tubes 31a from either the refrigerant piping 12 or the refrigerant piping 13 to flow through multiple heat transfer tubes 31a while circling back in the U-shaped pipe 31c.

[0041] The tube sheet 31d supports the multiple heat transfer tubes 31a at their longitudinal ends. The tube sheet 31d is positioned inside the casing 33 perpendicular to the left-right direction. The tube sheet 31d is formed in substantially the same shape as the heat transfer fins 31b and has multiple holes through which the heat transfer tubes 31a pass.

[0042] As shown in Figure 3, the heat exchanger 31 comprises a main heat exchanger 37 and a secondary heat exchanger 38. The secondary heat exchanger 38 is positioned in front of the upper front 37a and lower front 37b of the main heat exchanger 37. The secondary heat exchanger 38 is located on the windward side, and the main heat exchanger 37 is located on the leeward side.

[0043] The main heat exchanger 37 includes multiple passes P through which the refrigerant flows. In this embodiment, there are three passes P: the first pass P1, the second pass P2, and the third pass P3.

[0044] The length of the passes P increases in the order of the first pass P1, the second pass P2, and the third pass P3. Here, in a single pass P, the heat exchange performance is substantially contributed to by the heat transfer tubes 31a inserted into the heat transfer fins 31b. Therefore, when comparing the lengths of the passes P in a simple manner, it is sufficient to use the "number of heat transfer tubes 31a inserted into the heat transfer fins 31b (hereinafter simply referred to as the number of heat transfer tubes 31a)" as a substitute for comparison. In this embodiment, the number of heat transfer tubes 31a in the first pass P1 is 10. The number of heat transfer tubes 31a in the second pass P2 is 12. The number of heat transfer tubes 31a in the third pass P3 is 14. Therefore, the first pass P1 is the longest pass P. The third pass P3 is the longest pass P.

[0045] The main heat exchanger 37 includes a front section consisting of an upper front section 37a and a lower front section 37b, and a rear section 37c. The upper front section 37a and the lower front section 37b are located on the front side of the indoor unit 30. The rear section 37c is located on the rear side of the indoor unit 30. The upper front section 37a and the lower front section 37b are arranged in an inverted V shape to surround the utilization fan 32.

[0046] During evaporation operation, the refrigerant flows in the following order: auxiliary heat exchanger 38, flow divider 50, and main heat exchanger 37. Specifically, the refrigerant enters the auxiliary heat exchanger 38 from the area indicated by the arrow in the lower left of Figure 3. After exiting the auxiliary heat exchanger 38, it is divided by the flow divider 50 and flows through the first pass P1 to the third pass P3 into the main heat exchanger 37. The refrigerant that flows out of the main heat exchanger 37 is collected again and drawn into the compressor 21 through the four-way switching valve 22 and accumulator 25.

[0047] (2-1-3) Flow divider 50 The diversion 50 connects the main pipe M to the branch pipe BP. The branch pipe BP connects the diversion 50 to the path P.

[0048] The flow divider 50 divides the refrigerant before it enters the pass P of the main heat exchanger 37. More specifically, the flow divider 50 divides the refrigerant flowing from the manifold pipe M into multiple branch pipes BP.

[0049] (2-1-4) Refrigerant temperature sensor 40 The refrigerant temperature sensor 40 is positioned in the refrigerant piping 12 near the refrigerant flow of the flow divider 50. The refrigerant temperature sensor 40 measures the temperature of the refrigerant flowing through this refrigerant piping 12. Here, "near the flow divider 50" means within 6 cm of the flow divider 50. "Near the flow divider 50" is more preferably within 5 cm of the flow divider 50. "Near the flow divider 50" is even more preferably within 4 cm of the flow divider 50. In detail, referring to Figure 3, the length B1a of the refrigerant piping 12 in the refrigerant flow connecting the refrigerant temperature sensor 40 and the flow divider 50 is 6 cm or less. The length B1a of the refrigerant piping 12 in the refrigerant flow connecting the refrigerant temperature sensor 40 and the flow divider 50 is preferably within 5 cm, and more preferably within 4 cm. The length of the refrigerant piping 12 connecting the flow divider 50 and the heat exchanger 37 is 7 to 30 cm.

[0050] More specifically, the refrigerant temperature sensor 40 is located near the flow divider 50 that divides the refrigerant before it enters the path P at the front upper part 37a. More specifically, the refrigerant temperature sensor 40 is located in the piping on the refrigerant flow path connecting the main heat exchanger 37 and the flow divider 50. The refrigerant temperature sensor 40 is located in the branch piping BP.

[0051] The refrigerant temperature sensor 40 is, for example, a resistive sensor (thermistor). The thermistor is brazed to the refrigerant piping 12. When the refrigerant temperature sensor 40 is a thermistor, the length B1a of the refrigerant piping 12 in the refrigerant flow connecting the refrigerant temperature sensor 40 and the flow divider 50 is the length of the refrigerant piping 12 in the refrigerant flow from the temperature measurement point of the thermistor to the flow divider 50.

[0052] During evaporation operation, the refrigerant temperature at the location where the refrigerant temperature sensor 40 is installed is lower than the refrigerant temperature at the inlet of the heat exchanger 31. More preferably, the refrigerant temperature at the location where the refrigerant temperature sensor 40 is installed is lower than the refrigerant temperature at the inlet 37E of the main heat exchanger 37.

[0053] During evaporation operation, the refrigerant temperature at the point where the refrigerant temperature sensor 40 is installed is lower than the junction point 37M of the pass P of the main heat exchanger 37.

[0054] (2-1-5) Fan 32 As shown in Figure 1, the utilization fan 32 generates an airflow that flows into the casing 33 from the intake port 33a, passes through the air filter 34 and the utilization heat exchanger 31, and is blown out from the outlet port 33b. The utilization fan 32 is a cross-flow fan.

[0055] The utilization fan 32 is positioned so that its axis of rotation is aligned in the left-right direction and it is surrounded by the utilization heat exchanger 31 downstream of the airflow. The utilization fan 32 is equipped with a motor, which is an actuator that rotates the body of the utilization fan 32. The motor is connected to the control device 39. The rotation speed of the motor is controlled by the control device 39.

[0056] (2-1-6) Control device 39 The control device 39 controls each actuator (the motor of the fan 32). The control device 39 is electrically connected to each actuator via wiring. The control device 39 is housed in an electrical component box and is located to the right of the motor (see Figure 2).

[0057] The control device 39 is implemented by a computer. The control device 39 comprises a control arithmetic unit and a memory device. A processor such as a CPU or GPU can be used for the control arithmetic unit. The control arithmetic unit reads a program stored in the memory device and performs predetermined arithmetic processing according to this program. Furthermore, the control arithmetic unit can write the calculation results to the memory device or read information stored in the memory device according to the program.

[0058] The control device 39 determines whether or not frost has formed based on the temperature result of the refrigerant gas detected by the refrigerant temperature sensor 40.

[0059] (2-2) Outdoor unit 20 The outdoor unit 20 is installed outside the space to be air-conditioned.

[0060] As shown in Figure 1, the outdoor unit 20 includes a compressor 21, a four-way switching valve 22, a heat source heat exchanger 23, an expansion valve 24, an accumulator 25, and a heat source fan 28. The refrigerant circuit 11 connects the compressor 21, the four-way switching valve 22, the heat source heat exchanger 23, the expansion valve 24, the accumulator 25, and the utilization heat exchanger 31 with piping. The inside of the refrigerant circuit 11 is filled with refrigerant.

[0061] In evaporation mode, the four-way switching valve 22 switches to the connection state shown by the solid line, connecting the compressor 21 to the heat source heat exchanger 23, and the utilization heat exchanger 31 to the accumulator 25. In condensation mode, the four-way switching valve 22 switches to the connection state shown by the dashed line, connecting the compressor 21 to the utilization heat exchanger 31, and the heat source heat exchanger 23 to the accumulator 25.

[0062] (3) Overall operation The basic operation of the air conditioning system 10 will be described below. The air conditioning system 10 performs evaporation and condensation operations.

[0063] (3-1) Refrigerant circulation during evaporation operation In evaporation operation, the gaseous refrigerant compressed by the compressor 21 is sent to the heat source heat exchanger 23 through the four-way switching valve 22. In the heat source heat exchanger 23, the refrigerant exchanges heat with the air outside the air-conditioned space (heat source) blown by the heat source fan 28 and condenses. The refrigerant that has exchanged heat in the heat source heat exchanger 23 expands and is depressurized in the expansion valve 24 and sent to the utilization heat exchanger 31 of the indoor unit 30 through the refrigerant piping 12. The refrigerant sent to the utilization heat exchanger 31 enters the flow divider 50 via the auxiliary heat exchanger 38, as shown in Figure 3. In the flow divider 50, the refrigerant is divided into three directions and flows into the main heat exchanger 37, flowing through the first pass P1, the second pass P2, and the third pass P3. The refrigerant flowing out of the main heat exchanger 37 merges. The low-temperature, low-pressure refrigerant sent from the expansion valve 24 to the utilization heat exchanger 31 of the indoor unit 30 exchanges heat with the air in the air-conditioned space blown by the utilization fan 32 in the utilization heat exchanger 31 and evaporates. At this time, the air that has exchanged heat with the refrigerant is cooled. The gaseous refrigerant or gas-liquid two-phase refrigerant that has exchanged heat in the utilization heat exchanger 31 is drawn into the compressor 21 through the refrigerant piping 13, the four-way switching valve 22, and the accumulator 25. The conditioned air cooled in the utilization heat exchanger 31 is blown out from the indoor unit 30 into the air-conditioned space, thereby cooling the room.

[0064] During evaporation operation, the direction of refrigerant flow (solid arrow RF in Figure 3) and the direction of airflow generated by the utilization fan 32 (dashed arrow AF in Figure 3) are parallel. That is, in a side view (longitudinal direction of the heat transfer tube), the refrigerant flows in the direction of back and front, moving from the outside (front side in Figure 3) to the inside (rear side in Figure 3), so the direction of refrigerant flow and the direction of airflow flow are in the same direction.

[0065] (3-2) Refrigerant circulation during condensation operation In condensation operation, the gaseous refrigerant compressed by the compressor 21 is sent to the utilization heat exchanger 31 through the four-way switching valve 22 and the refrigerant piping 13. In the utilization heat exchanger 31, the refrigerant condenses by exchanging heat with the air in the air-conditioned space blown by the utilization fan 32. At this time, the air that has exchanged heat with the refrigerant is heated. The refrigerant that has exchanged heat in the utilization heat exchanger 31 is sent to the expansion valve 24 through the refrigerant piping 12. The low-temperature, low-pressure refrigerant that has expanded and reduced in pressure in the expansion valve 24 is sent to the heat source heat exchanger 23, where it evaporates by exchanging heat with the air outside the air-conditioned space blown by the heat source fan 28. The gaseous refrigerant or gas-liquid two-phase refrigerant that has exchanged heat in the heat source heat exchanger 23 is drawn into the compressor 21 through the four-way switching valve 22 and the accumulator 25. The conditioned air heated in the utilization heat exchanger 31 is blown out from the indoor unit 30 into the air-conditioned space, thereby heating the room.

[0066] During condensation operation, the direction of refrigerant flow and the direction of airflow generated by the utilization fan 32 are opposite. That is, in a side view (longitudinal direction of the heat transfer tube), the refrigerant flows in the direction of back and front, moving from the inside (rear side in Figure 3) to the outside (front side in Figure 3), so the direction of refrigerant flow and the direction of airflow flow are opposite.

[0067] (4) Features (4-1) The indoor unit 30 uses a non-azeotropic refrigerant. The indoor unit 30 includes a main heat exchanger 37, a flow divider 50, and a refrigerant temperature sensor 40. The main heat exchanger 37 includes multiple paths P through which the refrigerant flows. The flow divider 50 divides the refrigerant before it enters the paths P. The refrigerant temperature sensor 40 detects the temperature of the refrigerant. The refrigerant temperature sensor 40 is positioned near the flow divider 50 in the refrigerant flow.

[0068] When using a single refrigerant such as R32, as shown by the dashed line in Figure 4, although there are some temperature changes due to some pressure loss, the refrigerant temperature remains almost constant from the upstream side where evaporation begins to the downstream side where evaporation ends.

[0069] On the other hand, non-azeotropic mixed refrigerants like R454C are refrigerants that are a mixture of two different refrigerant species, a first refrigerant and a second refrigerant. R32 in R454C has a boiling point of approximately -52°C, while R1234yf has a boiling point of approximately -29°C, resulting in a large difference in boiling points. This causes the evaporation of each component to proceed in stages within the evaporator, creating a clear temperature gradient in the refrigerant. This temperature gradient results in a characteristic where the temperature rises from the start to the end of evaporation. Therefore, in a heat exchanger that functions as an evaporator, a non-azeotropic mixed refrigerant creates a temperature gradient where the refrigerant temperature on the upstream side when evaporation begins differs from the refrigerant temperature on the downstream side when evaporation is completed. In detail, as shown by the solid line in Figure 4, the refrigerant temperature is lowest at the inlet side of the utilization heat exchanger 31 and increases towards the outlet side of the utilization heat exchanger 31.

[0070] In the indoor unit 30 of this embodiment, the refrigerant temperature sensor 40 is located near the flow divider 50 in the refrigerant flow, which is close to the position where the refrigerant temperature is lowest. With non-azeotropic refrigerants, the refrigerant temperature is not constant in the heat exchanger due to the difference in boiling points of multiple refrigerant components, and a temperature gradient is created where the temperature rises as evaporation progresses. For this reason, the lowest refrigerant temperature occurs just before the inlet of the main heat exchanger 37, that is, just before it flows into the evaporator. At this position, the refrigerant is in a liquid phase state and is in the subcooled region before evaporation begins, so the fluctuation in refrigerant temperature is small, and the stability of temperature detection by the refrigerant temperature sensor 40 is high. This makes it possible to detect the minimum value of the refrigerant temperature with high accuracy and reproducibility.

[0071] Furthermore, at this location, the refrigerant state is stable and temperature fluctuations are small, resulting in less variation in temperature measurements by the sensor and enabling highly reliable detection. This allows for accurate understanding of refrigerant temperature changes and early detection of signs of frost formation. As a result, frost formation can be suppressed.

[0072] (4-2) The main heat exchanger 37 includes a front upper section 37a, a front lower section 37b, and a rear section 37c. The refrigerant temperature sensor 40 is positioned near the flow divider 50 that divides the refrigerant before it enters the path P of the front upper section 37a.

[0073] The upper front section 37a of the main heat exchanger 37, which is closer to the intake port 33a, has a higher airflow velocity than the lower front section 37b and the rear section 37c, and is therefore more affected by frost formation and performance degradation. Here, the refrigerant temperature sensor 40 is located at the upper front section 37a, so it can preferentially detect changes in refrigerant temperature at the upper front section 37a.

[0074] (4-3) During evaporation operation, the refrigerant temperature at the location where the refrigerant temperature sensor 40 is installed is lower than the refrigerant temperature at the inlet 37E of the main heat exchanger 37.

[0075] In this configuration, the refrigerant temperature sensor 40 is positioned in a location where the refrigerant temperature is lower, thereby improving the accuracy of detecting changes in refrigerant temperature.

[0076] (4-4) During evaporation operation, the refrigerant temperature at the point where the refrigerant temperature sensor 40 is installed is lower than the refrigerant temperature at the confluence point 37M of the pass P of the main heat exchanger 37.

[0077] Here, the refrigerant temperature sensor 40 is positioned at a location where the refrigerant temperature is lower than that of the confluence section 37M of path P, thus improving the accuracy of detecting changes in refrigerant temperature.

[0078] (4-5) The indoor unit 30 is further equipped with a secondary heat exchanger 38. During evaporation operation, the refrigerant flows in the order of secondary heat exchanger 38, flow divider 50, and main heat exchanger 37. The refrigerant temperature sensor 40 is positioned in the piping on the refrigerant flow path connecting the flow divider 50 and the main heat exchanger 37.

[0079] Here, refrigerant temperature can be detected near the location where the refrigerant temperature is lowest.

[0080] (4-6) During evaporation operation, the direction of travel RF of the refrigerant and the direction of travel AF of the airflow generated by the utilization fan 32 are opposite to each other.

[0081] In this setup, during evaporation, the cooler portion of the refrigerant can be moved downwind. As a result, the cooling effect is enhanced.

[0082] (4-7) Non-azeotropic refrigerants are primarily composed of hydrofluoroolefin refrigerants.

[0083] Here, you can use refrigerants suitable for air conditioners.

[0084] (5) Variant (5-1) Variation A In the above embodiment, the refrigerant temperature sensor 40 is positioned near the refrigerant flow of the flow divider 50. However, as shown in Figure 5, the refrigerant temperature sensor 40 may be positioned anywhere in the piping on the refrigerant flow path connecting the flow divider 50 and the main heat exchanger 37. In this case, the refrigerant temperature sensor 40 is positioned in the piping on the refrigerant flow path connecting the flow divider 50 and the portion located at the upper front 37a of the path P.

[0085] If the refrigerant temperature sensor 40 is located in the refrigerant flow path connecting the diverter 50 and the main heat exchanger 37, it can measure the refrigerant temperature at a position sufficiently close to the point where the refrigerant temperature is lowest. Therefore, frost formation can be suppressed.

[0086] (5-2) Variation B In the above embodiment, the refrigerant temperature sensor 40 is positioned near the refrigerant flow in the flow divider 50. However, as shown in Figure 6, the refrigerant temperature sensor 40 may be positioned on the flow divider 50 side from the middle of the total length of the path P portion formed by the heat transfer tubes of the main heat exchanger. "On the flow divider 50 side from the middle of the total length of the path P portion formed by the heat transfer tubes of the main heat exchanger" is preferably, for example, the first U-shaped tube 31c entering the main heat exchanger 37, or the second U-shaped tube 31c entering the main heat exchanger 37.

[0087] In this case, the refrigerant temperature sensor 40 is located in the upper front part 37a of the path P. Also in this case, the refrigerant temperature sensor 40 is located on the windward side of the upper front part 37a.

[0088] If the refrigerant temperature sensor 40 is located on the side of the flow divider 50, rather than the midpoint of the entire length of the main heat exchanger section of the pass P, which is composed of the heat exchanger tubes of the main heat exchanger in the pass P, then the sensor 40 is positioned on the side of the flow divider 50, rather than the midpoint of the entire length of the main heat exchanger section of the pass P, which is composed of the heat exchanger tubes of the main heat exchanger in the pass P where the airflow velocity is high, so that it can preferentially detect refrigerant temperature changes in the first half of the pass P on the side of the flow divider 50.

[0089] In modified example B, the refrigerant temperature sensor 40 is preferably placed in all paths P except the third path P3, which has the longest path length among the paths P. Here, the refrigerant temperature sensor 40 can be placed while avoiding the third path P3, which has a higher refrigerant flow resistance compared to the first path P1 and the second path P2. Therefore, it is possible to suppress the detection of a higher refrigerant temperature due to pressure loss.

[0090] More preferably, the refrigerant temperature sensor 40 is placed in the first path P1, which has the shortest path length among the paths P. Here, the flow resistance of the refrigerant in the first path P1 is reduced, making it easier for the refrigerant to flow through the first path P1. As a result, pressure loss is less likely to occur, and detection can be performed in the first path P1, which is at a lower temperature than the second path P2 and the third path P3. Therefore, it is possible to suppress the detection of a higher refrigerant temperature due to pressure loss.

[0091] In modification B, the refrigerant temperature sensor 40 is preferably placed in the pass P of the main heat exchanger 37 with the highest refrigerant circulation rate. Passes P with a high refrigerant circulation rate are, for example, the upper front 37a, the lower front 37b, and the passes P located on the windward side of the main heat exchanger 37. The pass P with a high refrigerant circulation rate is, for example, the first pass P1. In this case, in passes P with a low refrigerant circulation rate, the refrigerant quickly evaporates and becomes a heated gas. In modification C, since the refrigerant temperature sensor 40 is placed in the pass P with a high circulation rate, the refrigerant temperature can be detected before the refrigerant becomes a heated gas.

[0092] (5-3) Modification C In the above embodiment, the refrigerant temperature sensor 40 is located near the refrigerant flow of the flow divider 50 and is positioned in the piping on the refrigerant flow path connecting the main heat exchanger 37 and the flow divider 50. However, as shown in Figure 7, the refrigerant temperature sensor 40 may also be positioned in the piping on the refrigerant flow path connecting the auxiliary heat exchanger 38 and the flow divider 50.

[0093] If the refrigerant temperature sensor 40 is in the vicinity of the refrigerant flow of the diverter 50 and is located in the refrigerant flow path connecting the auxiliary heat exchanger 38 and the diverter 50, it can measure the refrigerant temperature near where the refrigerant temperature is lowest. Therefore, frost formation can be suppressed.

[0094] (5-4) Modification D In the above embodiment, the refrigerant temperature sensor 40 is located near the refrigerant flow of the flow divider 50 and is positioned in the piping on the refrigerant flow path connecting the main heat exchanger 37 and the flow divider 50. However, as shown as 40A in Figure 7, the refrigerant temperature sensor 40A may be located on the flow divider 50 side from the middle of the total length of the path P portion formed by the heat transfer tubes of the main heat exchanger, even if a secondary heat exchanger 38 is provided.

[0095] (5-5) Variation E In the above embodiment, the indoor unit 30 has a secondary heat exchanger 38, but the indoor unit 30 does not need to have a secondary heat exchanger 38.

[0096] As shown in Figure 8, if the indoor unit 30 does not have a secondary heat exchanger 38, the refrigerant temperature sensor 40 is located near the refrigerant flow of the diverter 50 and in the piping on the refrigerant flow path connecting the diverter 50 and the main heat exchanger 37.

[0097] Alternatively, as shown in Figure 9, the refrigerant temperature sensor 40 may be placed in the U-shaped pipe 31c immediately after entering the inlet 37E of the main heat exchanger 37.

[0098] (5-6) Modification F In the above embodiment, during evaporation operation, the refrigerant flows in the order of auxiliary heat exchanger 38, flow divider 50, and main heat exchanger 37. However, as shown in Figure 10, the refrigerant may flow through the auxiliary heat exchanger 38, then once through the main heat exchanger 37, then through the flow divider 50, and then back through the main heat exchanger 37. In Figure 10, the numbers enclosed in squares indicate the order in which the refrigerant passes. The same applies to the following drawings.

[0099] In this modified example F, for example, during evaporation operation, the refrigerant flowing from the heat source heat exchanger 23 flows through the route shown by squares 1 to 4 in Figure 10, through the auxiliary heat exchanger 38, and into the flow divider 50. The refrigerant flowing out of the flow divider 50 is divided into three paths: the fourth path P4, the fifth path P5, and the sixth path P6. The fourth path P4 is on the route shown by squares 11 to 16 in Figure 10. The fifth path P5 is on the route shown by squares 5 to 10 in Figure 10. The sixth path P6 is on the route shown by squares 17 to 22 in Figure 10. The refrigerant that has passed through the fourth path P4, the fifth path P5, and the sixth path P6 merge again at the merging section 37M and flows to the outdoor unit 20.

[0100] In this modified example F, the refrigerant temperature sensor 40 is located near the refrigerant flow of the flow divider 50 and is positioned in the piping on the refrigerant flow path connecting the flow divider 50 and the main heat exchanger 37 in the portion that passes through the second time.

[0101] Alternatively, as shown in Figure 11, the refrigerant temperature sensor 40 may be placed in the U-shaped pipe 31c immediately after entering the inlet 37E of the main heat exchanger 37, which is the portion that the refrigerant passes through the second time.

[0102] (5-7) Variation G The indoor unit 30 may have a solenoid valve 26. In modified example G, as shown in Figure 12, the solenoid valve 26 is located in the piping on the refrigerant flow path connecting the front upper part 37a and front lower part 37b, which are the front part of the heat exchanger 31, and the rear part 37c.

[0103] In modified example G, during evaporation operation, the high-pressure refrigerant discharged from the compressor 21 flows from the heat source heat exchanger 23 through the refrigerant piping 12 and reaches the utilization heat exchanger 31. The high-pressure refrigerant that reaches the utilization heat exchanger 31 flows into the auxiliary heat exchanger 38 from square 1 or square 13 in Figure 13.

[0104] The refrigerant flowing from square 1 into the auxiliary heat exchanger 38 exits from square 3 into the auxiliary heat exchanger 38 and is divided into three directions by the first flow divider 51. The divided refrigerant flows into the main heat exchanger 37 and travels through three routes: one through squares 4-6, one through squares 7-9, and one through squares 10-12. The high-pressure refrigerant condenses as it flows through the three paths P, becoming liquid refrigerant. The refrigerant that flows out of the three paths P after leaving the main heat exchanger 37 rejoins at the confluence section 37M and flows into the solenoid valve 26.

[0105] The refrigerant flowing from square 13 into the auxiliary heat exchanger 38 exits from square 15 and is divided into three directions by the second flow divider 52. The divided refrigerant flows into the main heat exchanger 37 and travels through three routes: one through squares 16-18, one through squares 19-21, and one through squares 22-24. The high-pressure refrigerant condenses as it flows through the three paths P, becoming liquid refrigerant. The refrigerant that flows out of the three paths P after leaving the main heat exchanger 37 rejoins at the confluence section 37M and flows into the solenoid valve 26.

[0106] The liquid refrigerant is depressurized by the solenoid valve 26 and then divided into four paths P by the third flow divider 53. The divided refrigerant reaches the rear part 37c of the heat exchanger 31. Multiple paths P are also formed in the rear part 37c. The divided refrigerant enters each path P via routes through squares 27-29, squares 30-32, squares 33-35, and squares 36-38. The refrigerant that enters the multiple paths P evaporates as it flows through the multiple paths P, becoming gaseous refrigerant and flowing out from the rear part 37c. The gaseous refrigerant that flows out from the rear part 37c rejoins at square 39 and reaches the outdoor unit 20 via the refrigerant piping 13.

[0107] By circulating the refrigerant as described above, the performance of the air conditioning system 10 can be improved.

[0108] In this modified example G, the air conditioning unit 10 has multiple flow dividers 50, but the arrangement of the refrigerant temperature sensor 40 should be considered in relation to the second flow divider 52 located near the upper front 37a of the heat exchanger 31, and the upper front 37a of the heat exchanger 31.

[0109] In detail, when the refrigerant temperature sensor 40 is placed near the refrigerant flow of the second diverter 52, the refrigerant temperature sensor 40 is placed at one of the positions shown in Figure 12 in the piping on the refrigerant flow path connecting the second diverter 52 and the upper front part 37a of the main heat exchanger 37.

[0110] When the refrigerant temperature sensor 40 is placed on the upper front 37a of the heat exchanger 31, the refrigerant temperature sensor 40 is placed near the inlet of the upper front 37a of the main heat exchanger 37, where the refrigerant flowing from the second diverter 52 first enters, as shown in Figure 13. The refrigerant temperature sensor 40 is placed in one of the positions shown in Figure 13. Note that in Figure 13, the rear section 37c and the refrigerant piping leading to it are omitted.

[0111] (5-8) Modification H In the above embodiment, during evaporation operation, the refrigerant was flowed so that the direction of travel RF of the refrigerant and the direction of travel AF of the airflow generated by the utilization fan 32 were parallel. However, during evaporation operation, the refrigerant may be flowed so that the direction of travel RF of the refrigerant and the direction of travel AF of the airflow generated by the utilization fan 32 are opposite to each other.

[0112] In this case, the performance of the air conditioning system 10 can be improved.

[0113] In this modified example H, the air conditioning system 10 does not have a secondary heat exchanger 38, but the other configurations are the same as in the above embodiment. Therefore, except for those related to the secondary heat exchanger 38, the arrangement of the refrigerant temperature sensor 40 is the same as in the above embodiment.

[0114] (5-9) Variation I In the above embodiment, during evaporation operation, the direction of refrigerant flow RF and the direction of airflow AF generated by the utilization fan 32 are parallel. However, during both evaporation and condensation operation, the direction of refrigerant flow RF and the direction of airflow AF generated by the utilization fan 32 may be opposite.

[0115] In modified example I, as shown in Figure 14, the indoor unit 30 has a heat exchanger 31 and a bridge circuit 80. The heat exchanger 31 has a refrigerant inlet pipe 31e and a refrigerant outlet pipe 31f. The refrigerant enters the heat exchanger 31 through the refrigerant inlet pipe 31e and exits the heat exchanger 31 through the refrigerant outlet pipe 31f. The fan 32 promotes heat exchange between the air and the refrigerant by generating an airflow that passes through the heat exchanger 31.

[0116] The bridge circuit 80 ensures that the direction of refrigerant travel RF in the heat exchanger 31 is always the same. Due to the function of the bridge circuit 80, regardless of whether the direction of refrigerant travel RF is arrow CO or arrow HO, the refrigerant always enters the heat exchanger 31 at the refrigerant inlet pipe 31e and always exits the heat exchanger 31 at the refrigerant outlet pipe 31f.

[0117] The bridge circuit 80 has a first node A', a second node B', a third node C', and a fourth node D'. The first node A' is connected to the refrigerant outlet pipe 31f. The second node B' is connected to the compressor 21 via a four-way switching valve 22. The third node C' is connected to the refrigerant inlet pipe 31e. The fourth node D' is connected to the expansion valve 24.

[0118] Furthermore, the bridge circuit 80 has a first channel A'B' extending from the first node A' to the second node B', a second channel B'C' extending from the second node B' to the third node C', a third channel D'C' extending from the fourth node D' to the third node C', and a fourth channel A'D' extending from the first node A' to the fourth node D'.

[0119] The bridge circuit 80 includes a first check valve 81, a second check valve 82, a third check valve 83, and a fourth check valve 84. These check valves maintain the same direction RF of refrigerant flow in the installed flow path and prevent backflow of refrigerant. The first check valve 81 is located in the first flow path A'B' and allows refrigerant to flow only in the direction from the first node A' to the second node B'. The second check valve 82 is located in the second flow path B'C' and allows refrigerant to flow only in the direction from the second node B' to the third node C'. The third check valve 83 is located in the third flow path D'C' and allows refrigerant to flow only in the direction from the fourth node D' to the third node C'. The fourth check valve 84 is located in the fourth flow path A'D' and allows refrigerant to flow only in the direction from the first node A' to the fourth node D'.

[0120] When performing evaporation operation, the four-way switching valve 22 is connected as shown by the solid line in Figure 1, and the refrigerant is directed in the direction indicated by the arrow CO.

[0121] The compressor 21 draws in low-pressure gaseous refrigerant through the intake pipe and discharges high-pressure gaseous refrigerant through the discharge pipe. The high-pressure gaseous refrigerant passes through the four-way switching valve 22 and enters the heat source heat exchanger 23. The heat source heat exchanger 23 generates high-pressure liquid refrigerant by condensing it using the coldness of the air. The high-pressure liquid refrigerant exits the heat source heat exchanger 23 through the refrigerant outlet pipe, is depressurized at the heat source expansion valve 15, and becomes a gas-liquid two-phase refrigerant. Subsequently, the refrigerant reaches the fourth node D'. Subsequently, the refrigerant passes through the third check valve 83 and reaches the third node C'. Subsequently, the refrigerant enters the utilization heat exchanger 31 at the refrigerant inlet pipe 31e. The utilization heat exchanger 31 provides the user with the coldness carried by the refrigerant by evaporating the gas-liquid two-phase refrigerant, and also generates low-pressure gaseous refrigerant. Subsequently, the refrigerant exits the heat exchanger 31 through the refrigerant outlet pipe 31f and then reaches the first node A'. After that, the refrigerant passes through the first check valve 81 and reaches the second node B'. After that, the refrigerant passes through the refrigerant piping 13 and reaches the outdoor unit 20.

[0122] The flow of refrigerant in the heat exchanger 31 is as follows:

[0123] The refrigerant that reaches square 1 in Figure 15 of the heat exchanger 31 is divided into two directions, square 2 and square 18, by the first flow divider 51 in Figure 15.

[0124] The refrigerant flowing into square 2 is further divided into three directions by the second diverter 52. The divided refrigerant passes through the main heat exchanger 37 and the auxiliary heat exchanger 38 via the routes of squares 3-7, squares 8-12, and squares 13-17. The refrigerant flowing out of the auxiliary heat exchanger 38 rejoins at the confluence section 37M and reaches the outdoor unit 20.

[0125] The refrigerant flowing into square 18 is further divided into three directions by the third diverter 53. The divided refrigerant passes through the main heat exchanger 37 and the auxiliary heat exchanger 38 via the routes of squares 19-23, squares 24-28, and squares 29-33. The refrigerant flowing out of the auxiliary heat exchanger 38 rejoins at the confluence section 37M. After that, the refrigerant exits the utilization heat exchanger 31 from the refrigerant outlet pipe 31f and then reaches the first node A'.

[0126] When performing condensation operation, the four-way switching valve 22 makes the connection shown by the dashed line in Figure 14, and the refrigerant is directed in the direction indicated by the arrow HO. In this case as well, the refrigerant enters the utilization heat exchanger 31 at the refrigerant inlet pipe 31e and exits the utilization heat exchanger 31 from the refrigerant outlet pipe 31f. Therefore, in both evaporation and condensation operation, the direction of refrigerant movement (solid arrow RF in Figure 15) and the direction of airflow generated by the utilization fan 32 (dashed arrow AF in Figure 15) are opposite.

[0127] In this modified example I, the air conditioning unit 10 has multiple flow dividers, but the arrangement of the refrigerant temperature sensor 40 should be considered in relation to the second flow divider 52 and the third flow divider 53 which are close to the main heat exchanger 37, and the upper front part 37a of the utilization heat exchanger 31.

[0128] In detail, when the refrigerant temperature sensor 40 is placed near the refrigerant flow of the second diverter 52 or the third diverter 53, the refrigerant temperature sensor 40 is placed at one of the positions shown in Figure 15 in the piping on the refrigerant flow path connecting the second diverter 52 or the third diverter 53 and the upper front part 37a of the main heat exchanger 37.

[0129] When the refrigerant temperature sensor 40 is placed on the upper front 37a of the heat exchanger 31, the refrigerant temperature sensor 40 is placed near the inlet of the upper front 37a of the main heat exchanger 37, through which the refrigerant flowing from the second diverter 52 or the third diverter 53 first passes, as shown in Figure 16. The refrigerant temperature sensor 40 is placed in one of the positions shown in Figure 16.

[0130] Each of the above modifications can be combined and adopted where relevant.

[0131] While embodiments of this disclosure have been described above, it will be understood that various modifications to the form and details are possible without departing from the spirit and scope of this disclosure as described in the claims. Furthermore, these embodiments and modifications may be combined or substituted as appropriate, as long as they do not impair the function of the subject matter of this disclosure. The terms “First,” “Second,” etc., described above are used to distinguish the phrases to which these terms are attached, and do not limit the number or order of such phrases. [Industrial applicability]

[0132] As described above, this disclosure is useful for indoor units 30 and air conditioning systems. [Explanation of symbols]

[0133] 10: Air conditioning system 11: Refrigerant Circuit 12: Refrigerant piping 13: Refrigerant piping 20:Outdoor unit 26: Solenoid valve 30: Indoor unit 31: Heat exchanger used (an example of a heat exchanger) 31a: Heat transfer tube 31b: Heat transfer fins 31c: U-shaped tube 32: Fans used (an example of a blower) 33: Casing 37: Main heat exchanger 37E: Entrance 37M: Confluence 37a: Upper front 37b: lower front 37c: Back part 38: Sub-heat exchanger 40: Refrigerant temperature sensor (an example of a sensor) 50: Flow divider 80: Bridge Circuit AF: Direction of airflow BP: Branch piping M: Collective piping P: Pass P1: First pass (an example of the shortest pass) P2: Second Pass P3: Third pass (an example of the longest pass) RF: Direction of refrigerant travel [Prior art documents] [Patent Documents]

[0134] [Patent Document 1] Japanese Patent Publication No. 2022-115320

Claims

1. An indoor unit (30) of an air conditioning system (10) that uses a non-azeotropic refrigerant as the refrigerant, A main heat exchanger (37) including multiple paths (P) through which the refrigerant flows, A flow divider (50) that divides the refrigerant before it enters the aforementioned path, A sensor (40) for detecting the temperature of the refrigerant, Auxiliary heat exchanger (38), Equipped with, During evaporation operation, the refrigerant flows in the following order: the auxiliary heat exchanger, the diverter, and the main heat exchanger. The sensor is positioned in the piping on the refrigerant flow path connecting the flow divider and the main heat exchanger. Indoor unit.

2. An indoor unit (30) of an air conditioning system (10) using a non-azeotropic refrigerant as the refrigerant, A main heat exchanger (37) including multiple paths (P) through which the refrigerant flows, A flow divider (50) that divides the refrigerant before it enters the aforementioned path, A sensor (40) for detecting the temperature of the refrigerant, Blower (32) and Equipped with, The sensor is positioned near the flow divider in the refrigerant flow, in the piping on the refrigerant flow path connecting the flow divider and the main heat exchanger, or on the flow divider side of the midpoint of the total length of the path portion formed by the heat transfer tube (31a) of the main heat exchanger. During evaporation operation, the direction of travel RF of the refrigerant and the direction of travel AF of the airflow generated by the blower are opposite to each other. Indoor unit.

3. An indoor unit (30) of an air conditioning system (10) using a non-azeotropic refrigerant as the refrigerant, A main heat exchanger (37) including multiple paths (P) through which the refrigerant flows, A flow divider (50) that divides the refrigerant before it enters the aforementioned path, A sensor (40) for detecting the temperature of the refrigerant, Blower (32) and Equipped with, The sensor is positioned near the flow divider in the refrigerant flow, in the piping on the refrigerant flow path connecting the flow divider and the main heat exchanger, or on the flow divider side of the midpoint of the total length of the path portion formed by the heat transfer tube (31a) of the main heat exchanger. During evaporation and condensation, the direction of travel RF of the refrigerant and the direction of travel AF of the airflow generated by the blower are opposite to each other. Indoor unit.

4. The main heat exchanger includes a front upper section (37a), a front lower section (37b), and a rear section (37c). The sensor is located near the flow divider that divides the refrigerant before it enters the upper front pass, in the piping on the refrigerant flow path connecting the flow divider and the upper front portion of the pass, or in the upper front portion of the pass. The indoor unit according to claim 2 or 3.

5. The sensor is positioned on the windward side of the upper front surface, closer to the flow divider than the midpoint of the entire length of the path portion formed by the heat transfer tubes of the main heat exchanger. The indoor unit according to claim 4.

6. During evaporation operation, the refrigerant temperature at the part where the sensor is attached is lower than the refrigerant temperature at the inlet (37E) of the main heat exchanger. The indoor unit according to any one of claims 1 to 3.

7. During evaporation operation, the refrigerant temperature at the portion where the sensor is attached is lower than the refrigerant temperature at the confluence (37M) of the paths of the main heat exchanger. The indoor unit according to any one of claims 1 to 3.

8. It is further equipped with a secondary heat exchanger, During evaporation operation, the refrigerant flows in the following order: the auxiliary heat exchanger, the diverter, and the main heat exchanger. The sensor is located near the refrigerant flow of the flow divider and is positioned in the piping on the refrigerant flow path connecting the auxiliary heat exchanger and the flow divider. The indoor unit according to claim 2 or 3.

9. It is further equipped with a secondary heat exchanger, During evaporation operation, the refrigerant flows in the following order: the auxiliary heat exchanger, the diverter, and the main heat exchanger. The sensor is positioned on the side of the flow divider from the middle of the entire length of the path portion formed by the heat transfer tubes of the main heat exchanger. The indoor unit according to claim 2 or 3.

10. The sensor is placed in all paths except the one with the longest path length (P3). The indoor unit according to claim 2 or 3.

11. The sensor is placed in the path with the shortest path length (P1) among the paths. The indoor unit according to claim 10.

12. The sensor is positioned in the path of the main heat exchanger where the refrigerant circulation rate is highest. The indoor unit according to claim 2 or 3.

13. The aforementioned non-azeotropic refrigerant mainly consists of a hydrofluoroolefin refrigerant. The indoor unit according to any one of claims 1 to 3.

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