Heat exchanger and air conditioner having the same

Abstract

A heat exchanger has a plurality of heat exchange portions that exchange heat between refrigerant and air. The heat exchange portion has a plurality of flat tubes that are arranged in parallel with each other at intervals with refrigerant flow paths formed therein flowing in the up-down direction, a plurality of fins provided between adjacent flat tubes, an upper header that connects upper end portions of the plurality of flat tubes, and a lower header that connects lower end portions of the plurality of flat tubes. For the plurality of heat exchange portions, the upper headers thereof are connected in a flowable manner, and the lower headers thereof are connected in a flowable manner via an on-off valve. In a case where the heat exchanger functions as a condenser, the on-off valve is controlled so that the flow path direction of the refrigerant of at least one of the plurality of heat exchange portions is upward, and the flow path direction of the refrigerant of the other heat exchange portions is downward.

Description

Technical Field

[0001] This disclosure relates to a heat exchanger having a plurality of flat tubes and fins disposed between adjacent flat tubes, and an air conditioner having the heat exchanger. Background Technology

[0002] Conventionally, heat exchangers used in outdoor units of air conditioners, as disclosed in Patent Document 1, are known to have the following structure: a plurality of flat tubes that form a refrigerant flow path in the vertical direction and are arranged side by side with spacing between them; a plurality of fins that are disposed between adjacent flat tubes; an upper manifold that connects to the upper ends of the plurality of flat tubes; and a lower manifold that connects to the lower ends of the plurality of flat tubes.

[0003] Patent Document 1: International Publication No. 2015 / 005352

[0004] In the heat exchanger with the above-described structure, the refrigerant flow rate needs to be increased to allow the refrigerant to rise vertically inside the flat tubes. For example, in a variable-capacity air conditioner, if the air conditioning load is small, there may be a situation where the compressor's operating frequency is reduced to operate under localized load. In this case, in the heat exchanger disclosed in Patent Document 1, the refrigerant in all the flat tubes is equally affected by gravity, thus creating regions where the refrigerant flow rate is less than that required for it to rise inside the flat tubes, potentially reducing heat exchange performance. Summary of the Invention

[0005] This disclosure was made to solve the aforementioned problems, and aims to provide a heat exchanger and an air conditioner equipped with the heat exchanger that can achieve the refrigerant flow rate required for rising inside the flat tube even when the compressor operating frequency is reduced for partial load operation, thereby suppressing the reduction of heat exchange performance.

[0006] The heat exchanger disclosed herein has multiple heat exchange sections for heat exchange between refrigerant and air. Each heat exchange section includes: multiple flat tubes forming refrigerant flow paths in a vertical direction and arranged side-by-side at intervals; multiple fins disposed between adjacent flat tubes; an upper manifold connected to the upper ends of each of the multiple flat tubes; and a lower manifold connected to the lower ends of each of the multiple flat tubes. For the multiple heat exchange sections, the upper manifolds are connected to each other in a flow-through manner, and the lower manifolds are connected to each other in a flow-through manner via on / off valves. When functioning as a condenser, the on / off valves are controlled such that the refrigerant flow path direction of at least one of the multiple heat exchange sections is upward, and the refrigerant flow path direction of the other heat exchange sections is downward.

[0007] The air conditioner disclosed herein includes a compressor and a heat exchanger for supplying refrigerant discharged from the compressor, and the opening and closing valve is controlled according to a preset operating frequency of the compressor.

[0008] According to the heat exchanger disclosed herein and the air conditioner equipped with the heat exchanger, for example, when the compressor operating frequency is reduced to perform partial load operation, the refrigerant flowing in a portion of the heat exchange section can rise only inside the flat tube, thereby obtaining the refrigerant flow rate required for rising inside the flat tube, thereby suppressing the reduction of heat exchange performance. Attached Figure Description

[0009] Figure 1 This is the refrigerant circuit diagram of the air conditioner in Embodiment 1.

[0010] Figure 2 Viewed from above Figure 1 A three-dimensional view of the cross-section of Part II shown.

[0011] Figure 3 This is a graph showing the relationship between the height of the flat tube of the heat exchanger in Embodiment 1 and the flow rate required for vertical ascent.

[0012] Figure 4 This is the heat exchanger of Embodiment 1, and it is an explanatory diagram showing the operation when the air conditioning load is low during cooling operation.

[0013] Figure 5 This is the heat exchanger of Embodiment 1, and it is an explanatory diagram showing the operation when the air conditioning load is large during cooling operation.

[0014] Figure 6 This is the heat exchanger of Embodiment 1, and is an explanatory diagram showing its operation during heating.

[0015] Figure 7 This is the heat exchanger of Embodiment 2, and it is an explanatory diagram showing the operation when the air conditioning load is small during cooling operation.

[0016] Figure 8 This is the heat exchanger of Embodiment 2, and it is an explanatory diagram showing the operation when the air conditioning load is large during cooling operation.

[0017] Figure 9 This is the heat exchanger of Embodiment 2, and it is an explanatory diagram showing its operation during heating. Detailed Implementation

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, the same or equivalent parts will be labeled with the same reference numerals in each drawing, and their descriptions will be omitted or simplified as appropriate. Additionally, the shape, size, and arrangement of the structures depicted in the drawings can be appropriately varied.

[0019] Implementation method 1.

[0020] Figure 1 This is the refrigerant circuit diagram of the air conditioner in Embodiment 1. Figure 2 Viewed from above Figure 1 A perspective view of the cross-section of section II shown. Additionally, Figure 1 The arrows indicate the direction of refrigerant flow. Additionally, the hollow arrows on each open / closed valve indicate the valve's open state, and the black arrows indicate the valve's closed state.

[0021] like Figure 1 As shown, the air conditioner 300 of this embodiment 1 consists of an outdoor unit 100 and an indoor unit 200. Furthermore, the air conditioner 300 has a refrigerant circuit that connects a compressor 101, a first flow path switching unit 102, an indoor heat exchanger 201, an expansion mechanism 103, an outdoor heat exchanger 104, and a refrigerant container 105 via refrigerant piping 107 to circulate the refrigerant. The outdoor unit 100 includes a compressor 101, a first flow path switching unit 102, an expansion mechanism 103, an outdoor heat exchanger 104, and a refrigerant container 105. The indoor unit 200 includes an indoor heat exchanger 201. However, the air conditioner 300 is not limited to the components shown in the figures and may include other components.

[0022] The air conditioner 300 is controlled to operate by a control unit 109. The control unit 109 may consist of, for example, a computing device such as a microprocessor or CPU, and software executed thereon. Alternatively, the control unit 109 may also consist of hardware such as circuitry that implements its functions.

[0023] The compressor 101 compresses the intake refrigerant to a high temperature and high pressure state and then discharges it. As an example, the compressor 101 is a positive displacement compressor with a structure that can change its operating capacity (frequency) and is driven by a motor controlled by a frequency converter.

[0024] The first flow path switching unit 102, for example, is a four-way valve, which functions to switch the refrigerant flow path. During cooling operation, the first flow path switching unit 102 switches the refrigerant flow path by connecting the refrigerant discharge side of the compressor 101 to the gas side of the outdoor heat exchanger 104, and the refrigerant suction side of the compressor 101 to the gas side of the indoor heat exchanger 201. Conversely, during heating operation, the first flow path switching unit 102 switches the refrigerant flow path by connecting the refrigerant discharge side of the compressor 101 to the gas side of the indoor heat exchanger 201, and the refrigerant suction side of the compressor 101 to the gas side of the outdoor heat exchanger 104. Alternatively, the first flow path switching unit 102 can also be configured as a combination of a two-way valve or a three-way valve.

[0025] During cooling operation, the indoor heat exchanger 201 functions as an evaporator, exchanging heat between the refrigerant flowing from the expansion mechanism 103 and the air. During heating operation, the indoor heat exchanger 201 functions as a condenser, exchanging heat between the refrigerant discharged from the compressor 101 and the air. The indoor heat exchanger 201 draws in indoor air via an indoor fan and supplies the air, which has undergone heat exchange with the refrigerant, into the room.

[0026] The expansion mechanism 103 depressurizes the refrigerant flowing in the refrigerant circuit, causing it to expand. As an example, it is constructed from an electronic expansion valve whose opening is controlled to be variable. The refrigerant container 105 is, for example, a receiver or an energy storage device. The refrigerant container 105 stores the remaining liquid refrigerant during operation.

[0027] The outdoor heat exchanger 104 functions as a condenser during cooling operation, exchanging heat between the refrigerant discharged from the compressor 101 and the air. Additionally, during heating operation, the outdoor heat exchanger 104 functions as an evaporator, exchanging heat between the refrigerant flowing from the expansion mechanism 103 and the air. The outdoor heat exchanger 104 draws in outdoor air via an outdoor fan and discharges the air that has undergone heat exchange with the refrigerant to the outside.

[0028] The outdoor heat exchanger 104 of this embodiment 1 has a first heat exchange section 104A and a second heat exchange section 104B for heat exchange between refrigerant and air. Figure 1 as well as Figure 2 As shown, the first heat exchange section 104A and the second heat exchange section 104B have: a plurality of flat tubes 1, which form refrigerant flow paths 10 flowing in the vertical direction Y and are arranged side by side with intervals between them; a plurality of fins 2, which are disposed between adjacent flat tubes 1; an upper manifold 3, which is connected to the upper ends of the plurality of flat tubes 1; and a lower manifold 4, which is connected to the lower ends of the plurality of flat tubes 1.

[0029] The flat tube 1 is, for example, made of aluminum. The flat tubes 1 are arranged side-by-side at intervals along the left-right direction X, orthogonal to the airflow direction Z. Furthermore, the flat surface of the flat tube 1 is configured to be approximately parallel to the airflow direction Z. Inside the flat tube 1, multiple refrigerant flow paths 10 for refrigerant to flow in the up-down direction Y are formed side-by-side along the airflow direction Z. The up-down direction Y includes not only the vertical direction but also a state inclined relative to the vertical direction. Similarly, the left-right direction X includes not only the horizontal direction but also a state inclined relative to the horizontal direction.

[0030] The fins 2, for example, are made of aluminum and are components that transfer heat from the refrigerant flowing in the flat tubes 1. The fins 2 are corrugated fins formed by bending a thin plate into a wave shape. The fins 2 are respectively disposed between two adjacent flat tubes 1. The bent top of the fin 2 engages with the flat surface of either of the two flat tubes 1. The space between the fins 2 and the flat tubes 1 forms a ventilation path for airflow. Alternatively, although not shown in the figure, the fins 2 can also be structures with drain holes or louvers for condensate drainage on each inclined surface. Furthermore, the fins 2 are not limited to corrugated fins; for example, they can also be plate fins.

[0031] like Figure 1 As shown, the first heat exchange unit 104A and the second heat exchange unit 104B are arranged side by side. One end of the upper manifold 3 of the first heat exchange unit 104A is connected to one end of the upper manifold 3 of the second heat exchange unit 104B in a flow-through manner via a first connecting pipe 5. One end of the lower manifold 4 of the first heat exchange unit 104A is connected to one end of the lower manifold 4 of the second heat exchange unit 104B in a flow-through manner via a second connecting pipe 6. An on / off valve 6a controlled by a control unit 109 is provided on the second connecting pipe 6. The on / off valve 6a is, for example, a solenoid valve.

[0032] Alternatively, although the diagram is omitted, it is possible to connect the upper manifold 3 of the first heat exchange unit 104A and the upper manifold 3 of the second heat exchange unit 104B without using the first connecting pipe 5, and instead use a single manifold to form the upper manifold 3 of the first heat exchange unit 104A and the upper manifold 3 of the second heat exchange unit 104B. Alternatively, it is possible to connect the lower manifold 4 of the first heat exchange unit 104A and the lower manifold 4 of the second heat exchange unit 104B without using the second connecting pipe 6, and instead use a single manifold to form the lower manifold 4 of the first heat exchange unit 104A and the lower manifold 4 of the second heat exchange unit 104B. In this case, an on / off valve for controlling the flow between the first heat exchange unit 104A and the second heat exchange unit 104B is installed inside the lower manifold.

[0033] Additionally, a first flow path pipe 7, branching from the refrigerant pipe 107 between the first flow path switching unit 102 and the outdoor heat exchanger 104, is connected to the other end of the lower manifold 4 of the first heat exchange section 104A. A second flow path switching unit 106 is provided at the branch position of the first flow path pipe 7 of the refrigerant pipe 107. The second flow path switching unit 106 is, for example, a three-way valve, and is controlled by the control unit 109.

[0034] Furthermore, the other end of the upper manifold 3 of the second heat exchange unit 104B is connected via a second flow path pipe 8 to a refrigerant pipe 107 between the second flow path switching unit 106 and the expansion mechanism 103. An on / off valve 8a controlled by the control unit 109 is provided on the second flow path pipe 8. The on / off valve 8a is, for example, a solenoid valve.

[0035] Furthermore, the other end of the lower manifold 4 of the second heat exchange section 104B is connected via a third flow path pipe 9 to a refrigerant pipe 107 between the connection point of the second flow path pipe 8 and the expansion mechanism 103. An on / off valve 9a controlled by the control unit 109 is provided on the third flow path pipe 9. The on / off valve 9a is, for example, a solenoid valve.

[0036] A valve body 108 is provided on the refrigerant pipe 107 between the connection points of the second flow path pipe 8 and the third flow path pipe 9. Through this valve body 108, the refrigerant flowing between the connection points of the second flow path pipe 8 and the third flow path pipe 9 flows in only one direction.

[0037] Next, the operation of the air conditioner 300 during cooling will be explained. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 101 flows through the first flow path switching unit 102, via the first flow path piping 7, to the outdoor heat exchanger 104, where it exchanges heat with the air to become liquid refrigerant. The liquid refrigerant flows through the second flow path piping 8 or the third flow path piping 9 to the refrigerant piping 107, where it is depressurized by the expansion mechanism 103 to become a low-pressure gas-liquid two-phase refrigerant, which flows to the indoor heat exchanger 201 and exchanges heat with the air to become gaseous refrigerant. The gaseous refrigerant passes through the first flow path switching unit 102 and is drawn into the compressor 101 via the refrigerant container 105.

[0038] Next, the operation of the air conditioner 300 during heating will be explained. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 101 flows to the indoor heat exchanger 201 through the first flow path switching unit 102, where it exchanges heat with the air to become a liquid refrigerant. The liquid refrigerant is depressurized by the expansion mechanism 103 to become a low-pressure gas-liquid two-phase refrigerant, which flows to the outdoor heat exchanger 104 through the third flow path piping 9, where it exchanges heat with the air to become a gaseous refrigerant. The gaseous refrigerant flows out to the refrigerant piping 107 through the second flow path piping 8, and after passing through the first flow path switching unit 102, it is drawn into the compressor 101 through the refrigerant container 105.

[0039] Figure 3 This is a graph showing the relationship between the height of the flat tube in the heat exchanger of Embodiment 1 and the required vertical flow rate. The horizontal axis represents the height of the flat tube. The vertical axis represents the required vertical refrigerant flow rate.

[0040] The aforementioned outdoor heat exchanger 104 causes the refrigerant to rise vertically inside the flat pipe 1. Therefore, as... Figure 3 As shown, increasing the height of the flat tube 1 increases the refrigerant flow rate required for vertical ascent. For example, in a variable-capacity air conditioner 300, if the air conditioning load is small, there may be a situation where the compressor 101 operates at a reduced frequency and operates under partial load. In this case, in the outdoor heat exchanger 104, the refrigerant inside all the flat tubes 1 is affected by gravity, thus creating a region with a refrigerant flow rate lower than that required for ascent inside the flat tube 1, which may reduce heat exchange performance.

[0041] Therefore, in the outdoor heat exchanger 104 of this embodiment 1, as Figures 4-6 As shown, the opening and closing valve 6a is controlled according to the preset operating frequency of the compressor 101, thereby changing the flow direction of the refrigerant flowing between the first heat exchange section 104A and the second heat exchange section 104B. Furthermore, Figures 4-6 The arrows indicate the direction of refrigerant flow. Additionally, the hollow arrows on each open / closed valve indicate the valve's open state, and the black arrows indicate the valve's closed state.

[0042] first, Figure 4 This is the heat exchanger of Embodiment 1, and the diagram illustrates its operation when the air conditioning load is low during cooling operation. Figure 4 As shown, the outdoor heat exchanger 104 is configured such that when the air conditioning load is low during cooling operation, the on / off valve 6a of the second connecting pipe 6 is set to the closed state, so that the refrigerant flow direction of the first heat exchange section 104A is upward and the refrigerant flow direction of the second heat exchange section 104B is downward.

[0043] The gaseous refrigerant flowing from the first flow path pipe 7 into the lower manifold 4 of the first heat exchange section 104A is distributed to each flat pipe 1 of the first heat exchange section 104A. At this time, the on / off valve 6a of the second connecting pipe 6 is closed, and the gaseous refrigerant flowing into the lower manifold 4 of the first heat exchange section 104A does not flow into the lower manifold 4 of the second heat exchange section 104B. The gaseous refrigerant rises and condenses inside the flat pipe 1 to become liquid refrigerant. The liquid refrigerant from each flat pipe 1 merges in the upper manifold 3 and flows into the upper manifold 3 of the second heat exchange section 104B via the first connecting pipe 5. The liquid refrigerant flowing into the upper manifold 3 of the second heat exchange section 104B is distributed to each flat pipe 1 of the second heat exchange section 104B and descends inside the flat pipe 1. This achieves subcooling. At this time, the on / off valve 8a of the second flow path piping 8 is closed, and the liquid refrigerant flowing into the upper manifold 3 of the second heat exchange section 104B does not flow out to the refrigerant piping 107 through the second flow path piping 8. The liquid refrigerant descending from each flat pipe 1 in the second heat exchange section 104B merges in the lower manifold 4, flows out to the refrigerant piping 107 through the third flow path piping 9, whose on / off valve 9a is open, and flows towards the expansion mechanism 103.

[0044] In this way, during localized load operation where the air conditioning load is small and the operating frequency of the compressor 101 is reduced during cooling operation, the refrigerant flowing in the first heat exchange section 104A rises only inside the flat tube 1. Therefore, the refrigerant flow rate required for rising inside the flat tube 1 can be obtained, thereby suppressing the reduction of heat exchange performance.

[0045] Next, Figure 5 This is the heat exchanger of Embodiment 1, and the diagram illustrates its operation under conditions of high air conditioning load during cooling operation. Figure 5 As shown, the outdoor heat exchanger 104 is configured such that when the air conditioning load is large during cooling operation, the on / off valve 6a of the second connecting pipe 6 is set to the open state, so that the flow direction of the refrigerant in the first heat exchange section 104A and the flow direction of the refrigerant in the second heat exchange section 104B are upward.

[0046] The gaseous refrigerant flowing from the first flow path pipe 7 into the lower manifold 4 of the first heat exchange section 104A is distributed to each flat pipe 1 of the first heat exchange section 104A, and flows into the lower manifold 4 of the second heat exchange section 104B via the second connecting pipe 6. At this time, the on / off valve 9a of the third flow path pipe 9 is closed, and the gaseous refrigerant flowing into the lower manifold 4 of the second heat exchange section 104B does not flow out to the refrigerant pipe 107 through the third flow path pipe 9. The gaseous refrigerant rises and condenses inside each flat pipe 1 of the first heat exchange section 104A and the second heat exchange section 104B, thereby becoming liquid refrigerant. The liquid refrigerant of each flat pipe 1 merges in the upper manifold 3. The liquid refrigerant of the upper manifold 3 of the first heat exchange section 104A flows into the upper manifold 3 of the second heat exchange section 104B via the first connecting pipe 5, and merges with the liquid refrigerant of the upper manifold 3 of the second heat exchange section 104B. Then, the combined liquid refrigerant flows out of the refrigerant piping 107 through the second flow path piping 8 with the on / off valve 8a in the open state, and flows to the expansion mechanism 103 through the valve body 108.

[0047] In this way, when the air conditioning load is large during cooling operation and there is no need to reduce the operating frequency of the compressor 101, the flow direction of the refrigerant in the first heat exchange section 104A and the flow direction of the refrigerant in the second heat exchange section 104B are aligned upwards, thereby improving the heat exchange efficiency.

[0048] Next, Figure 6 This is the heat exchanger of Embodiment 1, and it is an explanatory diagram showing its operation during heating. (Example:) Figure 6 As shown, the outdoor heat exchanger 104 is configured such that, during heating operation, the on / off valve 6a of the second connecting pipe 6 is set to the open state, so that the flow direction of the refrigerant in the first heat exchange section 104A and the flow direction of the refrigerant in the second heat exchange section 104B are upward.

[0049] The gas-liquid two-phase refrigerant flowing from the third flow path pipe 9 (with the on / off valve 9a in the open state) into the lower manifold 4 of the second heat exchange section 104B is distributed to each flat pipe 1 of the second heat exchange section 104B and flows into the lower manifold 4 of the first heat exchange section 104A via the second connecting pipe 6. At this time, the flow direction of the second flow path switching unit 106 is controlled so that the gas-liquid two-phase refrigerant flowing into the lower manifold 4 of the first heat exchange section 104A does not flow out into the first flow path pipe 7. The gas-liquid two-phase refrigerant rises and evaporates inside each flat pipe 1 of the first heat exchange section 104A and the second heat exchange section 104B, thereby becoming a gaseous refrigerant. The gaseous refrigerants of each flat pipe 1 merge in the upper manifold 3. The gaseous refrigerant in the upper manifold 3 of the first heat exchange section 104A flows into the upper manifold 3 of the second heat exchange section 104B via the first connecting pipe 5, and merges with the gaseous refrigerant in the upper manifold 3 of the second heat exchange section 104B. Then, the merged gaseous refrigerant flows out through the second flow path pipe 8 (with the on / off valve 8a in the open state) to the refrigerant pipe 107, and flows towards the compressor 101. In addition, during heating operation, the pressure in the third flow path pipe 9 is higher than the pressure in the second flow path pipe 8, so the gaseous refrigerant flowing out of the second flow path pipe 8 will not flow towards the valve body 108.

[0050] In this way, when the air conditioner load is large during heating operation and there is no need to reduce the operating frequency of the compressor, the flow direction of the refrigerant in the first heat exchange section 104A and the flow direction of the refrigerant in the second heat exchange section 104B are aligned upwards, thereby improving the heat exchange efficiency.

[0051] Implementation method 2.

[0052] Next, refer to Figure 1 as well as Figure 2 And based on Figures 7-9 The heat exchanger 104 of this embodiment 2 and the air conditioner 300 equipped with the heat exchanger 104 will be described. Figure 7 This is the heat exchanger of Embodiment 2, and it is an explanatory diagram showing the operation when the air conditioning load is small during cooling operation. Figure 8 This is the heat exchanger of Embodiment 2, and it is an explanatory diagram showing the operation when the air conditioning load is large during cooling operation. Figure 9 This is the heat exchanger of Embodiment 2, and it is an explanatory diagram showing its operation during heating. Furthermore, the same reference numerals are used for the same components as those described in Embodiment 1, including the heat exchanger 104 and the air conditioner 300 equipped with the heat exchanger 104, and their descriptions are omitted as appropriate.

[0053] like Figures 7-9As shown, the outdoor heat exchanger 104 of this embodiment 2 includes a first heat exchange section 104A, a second heat exchange section 104B, and a third heat exchange section 104C for heat exchange between refrigerant and air. Figure 2 As shown, the first heat exchange section 104A, the second heat exchange section 104B, and the third heat exchange section 104C have: a plurality of flat tubes 1, which form refrigerant flow paths 10 flowing in the vertical direction Y and are arranged side by side with intervals between them; a plurality of fins 2, which are disposed between adjacent flat tubes 1; an upper manifold 3, which is connected to the upper ends of the plurality of flat tubes 1; and a lower manifold 4, which is connected to the lower ends of the plurality of flat tubes 1.

[0054] like Figure 7 As shown, the first heat exchange unit 104A, the second heat exchange unit 104B, and the third heat exchange unit 104C are arranged side by side. One end of the upper manifold 3 of the first heat exchange unit 104A is connected to one end of the upper manifold 3 of the second heat exchange unit 104B by a first connecting pipe 5 in a flow-through manner. Furthermore, the other end of the upper manifold 3 of the second heat exchange unit 104B is connected to one end of the upper manifold 3 of the third heat exchange unit 104C by a third connecting pipe 50 in a flow-through manner.

[0055] One end of the lower manifold 4 of the first heat exchange unit 104A is connected to one end of the lower manifold 4 of the second heat exchange unit 104B in a flow-through manner via a second connecting pipe 6. An on / off valve 6a, controlled by a control unit 109, is provided on the second connecting pipe 6. The on / off valve 6a is, for example, a solenoid valve. The other end of the lower manifold 4 of the second heat exchange unit 104B is connected to one end of the lower manifold 4 of the third heat exchange unit 104C in a flow-through manner via a fourth connecting pipe 60. An on / off valve 60a, controlled by a control unit 109, is provided on the fourth connecting pipe 60. The on / off valve 60a is, for example, a solenoid valve.

[0056] Alternatively, although the diagram is omitted, the upper manifold 3 of the first heat exchange unit 104A, the upper manifold 3 of the second heat exchange unit 104B, and the upper manifold 3 of the third heat exchange unit 104C can be connected by a single manifold instead of using the first connecting pipe 5 and the third connecting pipe 50. Similarly, the lower manifold 4 of the first heat exchange unit 104A, the lower manifold 4 of the second heat exchange unit 104B, and the lower manifold 4 of the third heat exchange unit 104C can be connected by a single manifold instead of using the second connecting pipe 6 and the fourth connecting pipe 60. In this case, an on / off valve for controlling the flow between the first heat exchange section 104A and the second heat exchange section 104B, and an on / off valve for controlling the flow between the second heat exchange section 104B and the third heat exchange section 104C are respectively installed inside a lower manifold.

[0057] Furthermore, the other end of the lower manifold 4 of the first heat exchange unit 104A is connected to a first flow path pipe 7, which branches off from the refrigerant pipe 107 between the first flow path switching unit 102 and the outdoor heat exchanger 104. Additionally, the other end of the upper manifold 3 of the third heat exchange unit 104C is connected via a second flow path pipe 8 to the refrigerant pipe 107 between the second flow path switching unit 106 and the expansion mechanism 103. An on / off valve 8a, controlled by the control unit 109, is provided on the second flow path pipe 8. The on / off valve 8a is, for example, a solenoid valve.

[0058] Furthermore, the other end of the lower manifold 4 of the third heat exchange unit 104C is connected via the third flow path pipe 9 to the refrigerant pipe 107 between the connection point of the second flow path pipe 8 and the expansion mechanism 103. An on / off valve 9a controlled by the control unit 109 is provided on the third flow path pipe 9. The on / off valve 9a is, for example, a solenoid valve.

[0059] like Figures 7-9 As shown, in this embodiment 2, the outdoor heat exchanger 104 controls the opening and closing valves 6a and 60a according to the preset operating frequency of the compressor 101, thereby changing the flow direction of the refrigerant flowing in the first heat exchange section 104A, the second heat exchange section 104B, and the third heat exchange section 104C. Furthermore, Figures 7-9 The arrows indicate the direction of refrigerant flow. The hollow arrows on each open / closed valve indicate the valve's open state, and the black arrows indicate the valve's closed state.

[0060] First, such as Figure 7As shown, when the air conditioning load is low during cooling operation, the outdoor heat exchanger 104 sets the on / off valve 6a of the second connecting pipe 6 to the open state and the on / off valve 60a of the fourth connecting pipe 60 to the closed state. That is, it is configured such that the refrigerant flow direction of the first heat exchange section 104A and the refrigerant flow direction of the second heat exchange section 104B are upward, and only the refrigerant flow direction of the third heat exchange section 104C is downward.

[0061] The gaseous refrigerant flowing from the first flow path pipe 7 into the lower manifold 4 of the first heat exchange section 104A is distributed to each flat pipe 1 of the first heat exchange section 104A, and flows into the lower manifold 4 of the second heat exchange section 104B through the second connecting pipe 6, and is also distributed to each flat pipe 1 of the second heat exchange section 104B. At this time, the on / off valve 60a of the fourth connecting pipe 60 is closed, and the gaseous refrigerant flowing into the lower manifold 4 of the second heat exchange section 104B will not flow into the lower manifold 4 of the third heat exchange section 104C. The gaseous refrigerant rises and condenses inside the flat pipe 1, thus becoming liquid refrigerant. The liquid refrigerant in each flat pipe 1 merges in the upper manifold 3. The liquid refrigerant in the upper manifold 3 of the first heat exchange section 104A flows into the upper manifold 3 of the second heat exchange section 104B through the first connecting pipe 5, and merges with the liquid refrigerant in the upper manifold 3 of the second heat exchange section 104B. Then, the combined liquid refrigerant flows into the upper manifold 3 of the third heat exchange section 104C via the third connecting pipe 50. The liquid refrigerant flowing into the upper manifold 3 of the third heat exchange section 104C is distributed to each flat pipe 1 of the third heat exchange section 104C and descends inside the flat pipe 1. This achieves subcooling. At this time, the on / off valve 8a of the second flow path pipe 8 is closed, and the liquid refrigerant flowing into the upper manifold 3 of the third heat exchange section 104C does not flow out to the refrigerant pipe 107 through the second flow path pipe 8. The liquid refrigerant descending in each flat pipe 1 of the third heat exchange section 104C merges in the lower manifold 4, flows out to the refrigerant pipe 107 via the third flow path pipe 9 with the on / off valve 9a in the open state, and flows towards the expansion mechanism 103.

[0062] In this way, during localized load operation where the air conditioning load is small and the operating frequency of the compressor 101 is reduced during cooling operation, the refrigerant flowing in the first heat exchange section 104A and the second heat exchange section 104B rises only inside the flat pipe 1. Therefore, the refrigerant flow rate required for rising inside the flat pipe 1 can be obtained, thereby suppressing the reduction of heat exchange performance.

[0063] In addition, although the illustration is omitted, the outdoor heat exchanger 104 can also be configured such that the on / off valve 6a of the second connecting pipe 6 and the on / off valve 60a of the fourth connecting pipe 60 are in the closed state, so that the refrigerant flowing in the first heat exchange section 104A rises inside the flat pipe 1.

[0064] Next, as Figure 8 As shown, the outdoor heat exchanger 104 is configured such that when the air conditioning load is large during cooling operation, the on / off valve 6a of the second connecting pipe 6 and the on / off valve 60a of the fourth connecting pipe 60 are set to the open state, so that the refrigerant flow direction of the first heat exchange section 104A, the second heat exchange section 104B and the third heat exchange section 104C is all upward.

[0065] The gaseous refrigerant flowing from the first flow path pipe 7 into the lower manifold 4 of the first heat exchange section 104A is distributed to each flat pipe 1 of the first heat exchange section 104A, and flows into the lower manifold 4 of the second heat exchange section 104B via the second connecting pipe 6, and further flows into the lower manifold 4 of the third heat exchange section 104C via the fourth connecting pipe 60. At this time, the on / off valve 9a of the third flow path pipe 9 is closed, and the gaseous refrigerant flowing into the lower manifold 4 of the third heat exchange section 104C does not flow out to the refrigerant pipe 107 through the third flow path pipe 9. The gaseous refrigerant rises and condenses inside each flat pipe 1 of the first heat exchange section 104A, the second heat exchange section 104B, and the third heat exchange section 104C, thereby becoming liquid refrigerant. The liquid refrigerant of each flat pipe 1 merges in the upper manifold 3. The liquid refrigerant in the upper manifold 3 of the first heat exchange section 104A flows into the upper manifold 3 of the second heat exchange section 104B via the first connecting pipe 5, and merges with the liquid refrigerant in the upper manifold 3 of the second heat exchange section 104B. Furthermore, this merged liquid refrigerant flows into the upper manifold 3 of the third heat exchange section 104C via the third connecting pipe 50, and merges with the liquid refrigerant in the upper manifold 3 of the third heat exchange section 104C. Then, this merged liquid refrigerant flows out through the second flow path pipe 8 (with the on / off valve 8a in the open state) to the refrigerant pipe 107, and flows through the valve body 108 to the expansion mechanism 103.

[0066] In this way, when the air conditioning load is large during cooling operation and there is no need to reduce the operating frequency of the compressor 101, the refrigerant flow direction of the first heat exchange section 104A, the second heat exchange section 104B, and the third heat exchange section 104C is all upward, thereby improving the heat exchange efficiency.

[0067] Next, as Figure 9 As shown, the outdoor heat exchanger 104 is configured such that, during heating operation, the on / off valve 6a of the second connecting pipe 6 and the on / off valve 60a of the fourth connecting pipe 60 are set to the open state, so that the refrigerant flow direction of the first heat exchange section 104A, the second heat exchange section 104B and the third heat exchange section 104C is all upward.

[0068] The gas-liquid two-phase refrigerant flowing from the third flow path pipe 9 into the lower manifold 4 of the third heat exchange section 104C is distributed to each flat pipe 1 of the third heat exchange section 104C, and flows into the lower manifold 4 of the second heat exchange section 104B via the fourth connecting pipe 60, and further into the lower manifold 4 of the first heat exchange section 104A via the second connecting pipe 6. At this time, the flow direction of the second flow path switching unit 106 is controlled so that the gas-liquid two-phase refrigerant flowing into the lower manifold 4 of the first heat exchange section 104A does not flow out of the first flow path pipe 7. The gas-liquid two-phase refrigerant rises and evaporates inside each flat pipe 1 of the first heat exchange section 104A, the second heat exchange section 104B, and the third heat exchange section 104C, thereby becoming a gaseous refrigerant. The gaseous refrigerants of each flat pipe 1 merge in the upper manifold 3. The refrigerant gas from the upper manifold 3 of the first heat exchange section 104A flows into the upper manifold 3 of the second heat exchange section 104B via the first connecting pipe 5, and merges with the refrigerant gas from the upper manifold 3 of the second heat exchange section 104B. This merged refrigerant gas then flows into the upper manifold 3 of the third heat exchange section 104C via the third connecting pipe 50, and merges with the refrigerant gas from the upper manifold 3 of the third heat exchange section 104C. Then, this merged refrigerant gas flows out through the second flow path pipe 8 (with the on / off valve 8a in the open state) to the refrigerant pipe 107, and flows towards the compressor 101. Furthermore, during heating operation, the pressure in the third flow path pipe 9 is higher than the pressure in the second flow path pipe 8, therefore the refrigerant gas flowing out of the second flow path pipe 8 does not flow towards the valve body 108.

[0069] In this way, when the air conditioning load is large during heating operation and there is no need to reduce the operating frequency of the compressor 101, the refrigerant flow direction of the first heat exchange section 104A, the second heat exchange section 104B, and the third heat exchange section 104C is all upward, thereby improving the heat exchange efficiency.

[0070] The heat exchanger 104 and the air conditioner 300 equipped with the heat exchanger 104 have been described above based on embodiments. However, the heat exchanger 104 and the air conditioner 300 are not limited to the structures of the embodiments described above. For example, although the heat exchanger 104 is shown to be composed of two or three heat exchange sections, it may also be composed of four or more heat exchange sections. In addition, the heat exchanger 104 and the air conditioner 300 are not limited to the above-described constituent elements and may include other constituent elements. In summary, the heat exchanger 104 and the air conditioner 300 are described within the scope of their technical concept, including design changes and application changes commonly made by those skilled in the art.

[0071] Explanation of reference numerals in the attached figures

[0072] 1…Flat pipe; 2…Fin; 3…Upper manifold; 4…Lower manifold; 5…First connecting pipe; 6…Second connecting pipe; 6a…On / off valve; 7…First flow path pipe; 8…Second flow path pipe; 8a…On / off valve; 9…Third flow path pipe; 9a…On / off valve; 10…Refrigerant flow path; 50…Third connecting pipe; 60…Fourth connecting pipe; 60a…On / off valve; 100…Outdoor unit; 101…Compressor; 102…First flow path switching unit; 103…Expansion mechanism; 104…Outdoor heat exchanger; 104A…First heat exchange section; 104B…Second heat exchange section; 104C…Third heat exchange section; 105…Refrigerant container; 106…Second flow path switching unit; 107…Refrigerant piping; 108…Valve body; 109…Control section; 200…Indoor unit; 201…Indoor heat exchanger; 300…Air conditioner.

Claims

1. A heat exchanger having a plurality of heat exchange sections for heat exchange between a refrigerant and air, characterized in that, The heat exchange section has: Multiple flat tubes, which form refrigerant flow paths in the vertical direction and are arranged side by side with gaps between them; Multiple fins are disposed between adjacent flat tubes; The upper manifold is connected to the upper ends of each of the multiple flat pipes; as well as The lower manifold is connected to the lower ends of each of the aforementioned flat pipes. For the plurality of heat exchange units, their upper manifolds are connected in a flow-through manner, and their lower manifolds are connected in a flow-through manner via on / off valves. The heat exchanger comprises the following components: When functioning as an evaporator, the on / off valve is controlled to ensure that the refrigerant flow direction in all heat exchange sections is upward. When functioning as a condenser, the on / off valve is controlled such that the refrigerant flow direction in at least one of the multiple heat exchange sections is upward, while the refrigerant flow direction in the other heat exchange sections is downward. The refrigerant enters the heat exchanger from the lower manifold and then flows in the following order: upward in at least one of the plurality of heat exchange sections, downward through the upper manifold and through another or several of the plurality of heat exchange sections, and then exits the heat exchanger.

2. The heat exchanger according to claim 1, characterized in that, It includes the following components: when functioning as a condenser, the on / off valve is controlled so that the refrigerant flow direction of all the heat exchange sections is upward.

3. An air conditioner, characterized in that, have: compressor; and The heat exchanger according to claim 1 or 2 is supplied with refrigerant discharged from the compressor. The opening and closing valves are controlled according to the preset operating frequency of the compressor.

Images