JP2020003171A - Heat exchanger and vehicle air conditioner - Google Patents

Abstract

To inhibit unevenness in split flow at a path in which a heat medium flows upward and improve heat exchange performance.SOLUTION: A passage is formed narrower at a path, in which a heat medium flows upward, than other paths.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a heat exchanger and an air conditioner for a vehicle.

  In the heat exchanger, the flow from one header to the other header is defined as one pass. As shown in Patent Literature 1, a heat exchanger is generally provided with a plurality of paths, and is configured so that the flow of each path is substantially equal.

JP 2009-115342 A

In the heat exchanger, a downward path that flows downward and an upward path that flows upward are provided alternately, and in the upward path, the liquid-phase heat medium is less likely to rise than the gas-phase heat medium. . Therefore, the liquid phase heat medium is less likely to flow toward the upstream side of the ascending path, and is more likely to flow toward the downstream side. Therefore, the partial flow in the ascending path is biased, which affects the heat exchange performance.
An object of the present invention is to suppress the occurrence of bias in branch flow in a path flowing upward and improve heat exchange performance.

The heat exchanger according to one embodiment of the present invention,
A pair of headers extending in the horizontal direction and provided at intervals in the vertical direction,
A plurality of tubes extending in the vertical direction, each of the upper end and the lower end being connected to the header, and provided at intervals in the horizontal direction,
The flow of the heat medium flowing from one header to the other header through a plurality of tubes is defined as one path, and a path flowing downward and a path flowing upward are alternately provided,
The flow of the heat medium in each pass is common during heating and cooling,
The first path is the path that flows down,
The number of passes is an odd number of 3 or more,
The path flowing upward has a narrower flow path than the other paths.

  ADVANTAGE OF THE INVENTION According to this invention, since the path | pass which flows upward is narrower compared with another path | pass, it can suppress that a partial flow produces bias, and can improve heat exchange performance.

It is a figure showing the air conditioner for vehicles of one embodiment. It is a figure which shows a heating operation. It is a figure which shows a cooling operation. It is a figure showing a heat exchanger. It is a figure which shows a uniform path typically. It is a figure which shows the structure which narrowed the ascent path | pass (3-2-3) typically. FIG. 4 is a diagram schematically illustrating a configuration in which an ascending path is narrowed (2-1-3). It is a figure which shows typically the structure which narrowed the ascent path (3-1-2).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. Further, the following embodiment is an example of an apparatus and a method for embodying the technical idea of the present invention, and the configuration is not limited to the following. That is, the technical idea of the present invention can be variously modified within the technical scope described in the claims.

<< One Embodiment >>
"Constitution"
FIG. 1 is a diagram illustrating a vehicle air conditioner of one embodiment.
The vehicle air conditioner 11 includes a heat pump system mounted on an automobile, and includes an indoor heat exchange unit 12 (supply flow path) provided on the vehicle interior side and a heat exchanger 13 provided outside the vehicle interior. Prepare. The cabin side and the outside of the cabin are separated by, for example, a dash panel.
The indoor heat exchange unit 12 is disposed inside the dashboard, and is formed by a duct that introduces outside air or inside air from one end and supplies air into the vehicle interior from the other end. Inside the indoor heat exchange unit 12, a blower fan 14, an evaporator 15, a condenser 16, and an air mix damper 17 are provided.

The blower fan 14 is provided at one end of the indoor heat exchange unit 12 and, when driven by a motor, sucks outside air or inside air and discharges it to the other end.
The evaporator 15 is provided downstream of the blower fan 14 and serves as a heat absorber and a dehumidifier between the air passing around the radiation fins and the low-temperature heat medium (refrigerant) passing through the tube. Perform heat exchange. That is, by evaporating and evaporating the heat medium in the tube, the air around the radiation fins is cooled, and dehumidification is performed by causing dew condensation on the surface of the radiation fins. All the air blown out from the blower fan 14 passes through the evaporator 15.

  The condenser 16 is provided downstream of the evaporator 15 and serves as a radiator for exchanging heat between air passing around the radiation fins and a high-temperature heat medium (heat medium) passing through the tube. Perform That is, the air around the radiation fins is heated by condensing and liquefying the heat medium in the tube. The condenser 16 is disposed so as to cover substantially half of the cross section of the indoor heat exchange unit 12, so that a flow path passing through the condenser 16 and a flow path bypassing the condenser 16 are formed. ing. That is, part of the air that has passed through the evaporator 15 passes through the condenser 16, and the rest bypasses the condenser 16.

  The air mix damper 17 opens the flow path passing through the condenser 16 and closes the flow path bypassing the condenser 16, and closes the flow path passing through the condenser 16 to bypass the condenser 16. It is rotatable between a position where the flow path is opened and a position where the flow path is opened. When the air mix damper 17 is at a position where the flow path passing through the condenser 16 is opened and the flow path bypassing the condenser 16 is closed, all the air that has passed through the evaporator 15 passes through the condenser 16. When the air mix damper 17 is at a position where the flow path passing through the condenser 16 is closed and the flow path bypassing the condenser 16 is opened, all the air passing through the evaporator 15 bypasses the condenser 16. When the air mix damper 17 is in a position to open both the flow path passing through the condenser 16 and the flow path bypassing the condenser 16, a part of the air passing through the evaporator 15 passes through the condenser 16. The remainder bypasses the condenser 16. Then, on the downstream side of the condenser 16, the air passing through the condenser 16 and the air bypassing the condenser 16 are mixed.

The heat exchanger 13 is provided in the engine room or the motor room, and exchanges heat between the outside air passing around the radiation fins and the heat medium passing through the tube. The outside air is mainly a traveling wind, but when a sufficient traveling wind cannot be obtained, the outside air is blown to the radiation fins by driving a blower (not shown).
When the operation mode is heating, the heat exchanger 13 functions as an evaporator, that is, a heat absorber, and heat exchange between the outside air passing around the radiation fins and the low-temperature heat medium (refrigerant) passing through the tube. Perform That is, the heat medium in the tube is vaporized and absorbed.
When the operation mode is cooling, the heat exchanger 13 functions as a condenser, that is, a radiator, and heat is transferred between the outside air passing around the radiation fins and the high-temperature heat medium (heat medium) passing through the tube. Perform an exchange. That is, the heat medium in the tube is condensed and liquefied to release heat.

Next, the circuit configuration of the heat medium will be described.
The outlet of the condenser 16 communicates with the inlet of the heat exchanger 13 via the flow path 21. The flow path 21 is provided with an expansion valve 31 (first expansion valve).
The expansion valve 31 reduces the pressure of the high-pressure heat medium, which is a liquid phase, to a low-pressure heat medium that is easily vaporized by blowing out the mist, and the degree of opening can be adjusted from fully closed to fully open.
The outlet of the heat exchanger 13 communicates with the inlet of the condenser 16 via the flow path 22. In the flow path 22, an on-off valve 32, a check valve 33, an accumulator 34, and a compressor 35 are sequentially provided from the heat exchanger 13 side to the condenser 16 side.

The on-off valve 32 opens or closes the flow path 22.
The check valve 33 allows passage from the side of the on-off valve 32 to the side of the accumulator 34 and prevents passage in the reverse direction.
The accumulator 34 performs gas-liquid separation of the heat medium, and supplies only the heat medium in the gas phase to the compressor 35.
The compressor 35 compresses a low-pressure heat medium that is a gaseous phase to increase the pressure to a high-pressure heat medium that is easily liquefied, and is an oil supply type in which lubrication is performed by oil circulating together with the heat medium. For example, it is a rotary compressor, a swash plate type compressor, a scroll compressor, or the like. The oil concentration in the heat medium is about several percent. The drive source of the compressor 35 is an engine or an electric motor.

In the flow path 21, there is a branch point between the heat exchanger 13 and the expansion valve 31, and this branch point communicates with the inlet of the evaporator 15 via the flow path 23. An on-off valve 36 and an expansion valve 37 (second expansion valve) are sequentially provided in the flow path 23 from the branch point toward the evaporator 15.
The on-off valve 36 opens or closes the flow path 23.
The expansion valve 37 reduces the pressure of the high-pressure heat medium, which is a liquid phase, to a low-pressure heat medium that is easily vaporized by blowing out the mist, and the opening degree can be adjusted from fully closed to fully open.

In the flow path 22, there is a branch point between the heat exchanger 13 and the on-off valve 32, and in the flow path 23, there is a branch point between the on-off valve 36 and the expansion valve 37. The points communicate with each other via a flow path 24. The flow path 24 is provided with a check valve 38.
The check valve 38 allows passage from the side of the flow path 22 to the side of the flow path 23 and prevents passage in the reverse direction.
In the flow path 22, there is a branch point between the on-off valve 32 and the check valve 33, and this branch point communicates with the outlet of the evaporator 15 via the flow path 25.

Next, each operation mode will be described.
[Heating operation]
FIG. 2 is a diagram illustrating a heating operation.
In the figure, the flow path through which the low-pressure heat medium passes is indicated by a thick dotted line, the flow path through which the high-pressure heat medium passes is indicated by a thick solid line, the open on-off valve is shown in white, and the closed on-off valve is shown. Shown in black.
When the operation mode is heating, the compressor 35 is driven while the expansion valve 31 is slightly released, the on-off valve 32 is opened, the on-off valve 36 is closed, and the expansion valve 37 is closed.

Thus, the heat medium circulates through the compressor 35, the condenser 16, the expansion valve 31, the heat exchanger 13, the on-off valve 32, the check valve 33, and the accumulator 34 in this order. In this circulation path, the heat medium in the gas phase is compressed by the compressor 35 to have a high pressure, is condensed and liquefied in the condenser 16, and is cooled to a low temperature by heat radiation. The heat medium in the liquid phase is expanded by the expansion valve 31 to have a low pressure, evaporates and evaporates in the heat exchanger 13, and has a high temperature due to heat absorption.
On the other hand, in the indoor heat exchange unit 12, the blower fan 14 is driven and the flow path passing through the condenser 16 is opened by the air mix damper 17. Thereby, the introduced air is heated by the condenser 16, and warm air is supplied into the vehicle interior.

[Cooling operation]
FIG. 3 is a diagram illustrating the cooling operation.
In the figure, the flow path through which the low-pressure heat medium passes is indicated by a thick dotted line, the flow path through which the high-pressure heat medium passes is indicated by a thick solid line, the open on-off valve is shown in white, and the closed on-off valve is shown. Shown in black.
When the operation mode is the cooling mode, the compressor 35 is driven with the expansion valve 31 fully opened, the on-off valve 32 closed, the on-off valve 36 closed, and the expansion valve 37 slightly opened.

Thus, the heat medium passes through the compressor 35, the condenser 16, the expansion valve 31, the heat exchanger 13, the check valve 38, the expansion valve 37, the evaporator 15, the check valve 33, and the accumulator 34 in this order. Circulate. In this circulation path, the heat medium in the gas phase is compressed by the compressor 35 to have a high pressure, is condensed and liquefied in the condenser 16, and is cooled to a low temperature by heat radiation. The heat medium that is being liquefied is further condensed and liquefied in the heat exchanger 13, and is further cooled by heat radiation. The heat medium in the liquid phase is expanded by the expansion valve 37 to have a low pressure, evaporates and evaporates in the evaporator 15, and becomes high in temperature by heat absorption.
On the other hand, in the indoor heat exchange unit 12, the blower fan 14 is driven and the flow path passing through the condenser 16 is closed by the air mix damper 17. Thus, after the introduced air is cooled and dehumidified by the evaporator 15, the air bypasses the condenser 16 and cool dehumidified air is supplied into the vehicle interior.

Next, the heat exchanger 13 will be described.
FIG. 4 is a diagram illustrating a heat exchanger.
The heat exchanger 13 includes a pair of upper and lower headers 41, a plurality of tubes 42, and a plurality of fins 43.
The pair of headers 41 extend in the horizontal direction and are provided at intervals in the vertical direction. The header 41 is formed by a cylindrical pipe whose both ends are closed, and the inside is partitioned by a partition 46 into sections arranged in a lateral direction. The inside of the upper header 41 is divided into a section 41A on one side in the horizontal direction and a section 41B on the other side in the horizontal direction, and an inlet 44 is provided in the section 41A on one side in the horizontal direction. The inside of the lower header 41 is divided into a section 41C on one side in the horizontal direction and a section 41D on the other side in the horizontal direction, and a discharge port 45 is provided in the section 41D on the other side in the horizontal direction.

Each tube 42 extends in the up-down direction, the upper end and the lower end are respectively connected to the header 41, and are provided at equal intervals along the horizontal direction. The tube 42 is thin and flat in the lateral direction, and both ends are connected to the inside of the header 41 and brazed to the header 41. Here, there is shown a case where there are twelve, and when each is identified, 42a to 42l are sequentially set from one end in the horizontal direction to the other end. In the upper header 41, the tube 42d and the tube 42e are partitioned by a partition 46, and in the lower header 41, the tube 42h and the tube 42i are partitioned by the partition 46.
Each fin 43 is fixed between adjacent tubes 42 by brazing.

  A flow path is formed by the header 41 and the tube 42, through which the heat medium flows. That is, first, it flows into the section 41A at one lateral side of the upper header 41 via the inflow port 44, is distributed to the tubes 42a to 42d, and then flows into the section 41C at one lateral side of the lower header 41. Next, after being distributed to the tubes 42e to 42h, it flows into the section 41B on the other side in the horizontal direction of the upper header 41, and is then distributed to the tubes 42i to 42l and then flows to the other side in the lower header 41. It flows into the section 41D and is discharged through the discharge port 45. Thus, when the heat medium flows through each tube 42, heat exchange is performed between the heat medium and air flowing around the tubes 42 and the fins 43.

In the heat exchanger 13, the flow of the heat medium flowing from one header 41 to the other header 41 through the plurality of tubes 42 is defined as one path, and a path that flows downward and a path that flows upward Are provided alternately. A path flowing downward through the tubes 42a to 42d is referred to as a first path P1, a path flowing upward through the tubes 42e to 42h is referred to as a second path P2, and is directed downward through the tubes 42i to 421. The path flowing through is referred to as a third path P3. Here, for the sake of simplicity, the first path P1, the second path P2, and the third path P3 are equal paths in which the number of tubes 42 is the same.
FIG. 5 is a diagram schematically illustrating an equal path.
The width of each pass schematically represents the number of tubes 42. In the following description, the reference number of the tubes 42 is represented by “2”, the number larger than the reference number is represented by “3”, and the number smaller than the reference number is represented by “1”. Here, all of the first path P1, the second path P2, and the third path P3 are the reference “2”.

Next, an example of setting a path in the present embodiment will be described.
FIG. 6 is a diagram schematically illustrating a configuration in which the ascending path is narrowed (3-2-3).
Here, the first path P1 is set to “3”, the second path P2 is set to “2”, and the third path P3 is set to “3”. That is, the second path P2 is narrower than the first path P1 and the third path P3.
FIG. 7 is a diagram schematically illustrating a configuration in which the ascending path is narrowed (2-1-3).
Here, the first path P1 is set to “2”, the second path P2 is set to “1”, and the third path P3 is set to “3”. That is, the second path P2 is narrower than the first path P1 and the third path P3. The third path P3 on the exit side is wider than the first path P1 on the entrance side.
FIG. 8 is a diagram schematically illustrating a configuration in which the ascending path is narrowed (3-1-2).
Here, the first path P1 is set to “3”, the second path P2 is set to “1”, and the third path P3 is set to “2”. That is, the second path P2 is narrower than the first path P1 and the third path p3. The first path P1 on the entrance side is wider than the third path P3 on the exit side.

《Action》
Next, main functions and effects of the embodiment will be described.
In the heat exchanger 13, the flow of the heat medium in each path is common for heating and cooling. Thereby, even if the operation mode is switched, the inlet and the outlet of the heat medium can always be kept constant. The first first pass P1 is a descending pass that flows from top to bottom, that is, follows gravity. Thereby, the heat medium easily flows. The number of passes is three, that is, an odd number. Thereby, the last third pass P3 is also a descending pass that flows downward, and the heat medium easily flows. If the last third pass P3 flows upward from the bottom, that is, if it is a rising pass against gravity, the oil circulating together with the heat medium will not be easily discharged. Therefore, by using the last third pass P3 as a descending pass, the accumulation of oil can be suppressed. Further, as the number of passes increases, the pressure loss increases, and therefore, the number of passes is preferably three.

On the other hand, in the second pass P2, which is the ascending pass, the liquid phase heat medium is less likely to rise than the gas phase heat medium. Therefore, the heat medium in the liquid phase hardly flows into the tube 42 closer to the first path P1 of the second path P2, and easily flows to the tube 42 closer to the third path P3. That is, a bias occurs in the branch flow in the second path P2, which affects the heat exchange performance.
Therefore, in the second path P2 which is the ascending path, the flow path is narrower than the other paths. That is, the number of tubes 42 is reduced in the second pass P2 which is the ascending pass, as compared with the other passes. Thereby, it is possible to suppress the occurrence of bias in the branch flow in the second path P2, and to improve the heat exchange performance. Furthermore, the first path P1 and the third path P3 can be widened by the amount of the narrowing of the second path P2, so that the space can be effectively used and the heat exchange performance can be improved.

According to the configuration of FIG. 6, the first path P1 is set to “3” wider than the reference, the second path P2 is set to “2” of the reference, and the third path P3 is “3” wider than the reference. Is set to The second path P2, which is an ascending path, tends to have a bias in the branch flow. Therefore, by making the second path P2 relatively narrowest, it is possible to suppress the bias in the branch flow.
According to the configuration of FIG. 7, the first path P1 is set to the reference “2”, the second path P2 is set to “1” narrower than the reference, and the third path P3 is set to “3” wider than the reference. Is set to Since the outdoor heat exchanger 13 functions as an evaporator during heating, the heat medium evaporates closer to the outlet of the heat exchanger 13. Since the gas phase has a lower density of the heat medium and a higher flow velocity than the liquid phase, the pressure loss is large. That is, at the time of heating, the pressure loss increases in the outlet side path where the heat medium evaporates. Therefore, the third path P3 on the exit side is wider than the first path P1 on the entrance side. That is, the number of tubes 42 in the third path P3 on the outlet side is larger than that in the first path P1 on the inlet side. Thereby, pressure loss at the time of heating can be reduced, and heat exchange performance can be improved. Therefore, it is suitable for a vehicle in which heating is prioritized. Further, since frost starts to be formed from the outlet side during heating, the flow path on the outlet side is widened, so that the blockage of the ventilation path due to the frost can be suppressed.

  According to the configuration of FIG. 8, the first path P1 is set to “3” wider than the reference, the second path P2 is set to “1” narrower than the reference, and the third path P3 is set to “2” of the reference. Is set to Since the outdoor heat exchanger 13 functions as a condenser during cooling, the heat medium is liquefied closer to the outlet of the heat exchanger 13. That is, the heat medium is in a gas phase on the inlet side. Since the gas phase has a lower density of the heat medium and a higher flow velocity than the liquid phase, the pressure loss is large. That is, at the time of cooling, the pressure loss increases in the path on the inlet side where the heat medium becomes a gas phase. Therefore, the first path P1 on the entrance side is wider than the third path P3 on the exit side. That is, the number of tubes 42 in the first path P1 on the inlet side is larger than that in the third path P3 on the outlet side. Thereby, pressure loss during cooling can be reduced, and heat exchange performance can be improved. Therefore, it is suitable for a vehicle in which cooling is prioritized.

《Modification》
In the present embodiment, the number of paths is three, but is not limited to this. Since the number of passes may be an odd number of three or more, the number of passes may be set to, for example, five.
In the present embodiment, the width of the flow path in each path is adjusted by the number of tubes 42, but is not limited to this. For example, the adjustment may be made according to the flow path cross-sectional area of the tube 42.
In the present embodiment, in the indoor heat exchange unit 12, only the condenser 16 is provided as a heat source for heating, but the present invention is not limited to this, and another heat source may be separately added. For example, a PTC heater (PTC: Positive Temperature Coefficient) whose resistance changes with temperature may be provided. According to this, the heating effect is improved.

  Although the above has been described with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of the embodiments based on the above disclosure will be obvious to those skilled in the art.

DESCRIPTION OF SYMBOLS 11 ... Vehicle air conditioner, 12 ... Indoor heat exchange unit, 13 ... Heat exchanger, 14 ... Blower fan, 15 ... Evaporator, 16 ... Condenser, 17 ... Air mix damper, 21 ... Flow path, 22 ... Flow 23, flow path, 24, flow path, 25, flow path, 31, expansion valve, 32, on-off valve, 33, check valve, 34, accumulator, 35, compressor, 36, on-off valve, 37, expansion Valve 38, check valve, 41 header, 41A section, 41B section, 41C section, 41D section, 42 tube, 43 fin, 44 inlet, 45 outlet, 46 partition P1 first pass, P2 second pass, P3 third pass

Claims (6)

A pair of headers extending in the horizontal direction and provided at intervals in the vertical direction,
A plurality of tubes extending in the vertical direction, each of an upper end and a lower end connected to the header, and provided at intervals in the horizontal direction;
The flow of the heat medium flowing from one header to the other header through a plurality of tubes is defined as one path, and a path flowing downward and a path flowing upward are alternately provided. Yes,
The flow of the heat medium in each pass is common during heating and cooling,
The first path is the path that flows down,
The number of passes is an odd number of 3 or more,
A heat exchanger characterized in that a path flowing upward has a narrower flow path than other paths.   The heat exchanger according to claim 1, wherein a flow path of the outlet side path is wider than other paths.   2. The heat exchanger according to claim 1, wherein a flow path of the inlet-side path is wider than other paths.   The heat exchanger according to any one of claims 1 to 3, wherein the width of the flow path is adjusted by the number of the tubes.   The number of passes is three, The heat exchanger as described in any one of Claims 1-4. A supply channel for supplying air to the vehicle interior;
A condenser provided in the supply flow path, performs heat exchange between the air passing through the surroundings and the heat medium passing through the inside, and radiates heat to the heat medium,
An evaporator that is provided upstream of the condenser in the supply flow path, performs heat exchange between air passing around and the heat medium passing through the inside, and absorbs heat by the heat medium,
The heat exchanger according to any one of claims 1 to 5, wherein the heat exchanger is provided outside the vehicle compartment, and performs heat exchange between outside air passing around and the heat medium passing inside.
A compressor for compressing the heat medium,
A first expansion valve and a second expansion valve for expanding the heat medium,
During heating, the compressor, the condenser, the first expansion valve, in order of the heat exchanger, circulate the heat medium,
During cooling, the heat medium is circulated in the order of the second expansion valve, the evaporator, the compressor, the condenser, and the heat exchanger in this order.

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