WO2021039302A1

WO2021039302A1 - Heat exchanger

Info

Publication number: WO2021039302A1
Application number: PCT/JP2020/029707
Authority: WO
Inventors: 遼平杉村; 真一郎滝瀬
Original assignee: 株式会社デンソー
Priority date: 2019-08-29
Filing date: 2020-08-03
Publication date: 2021-03-04
Also published as: JP7383935B2; JP2021032546A; CN114341573B; CN114341573A

Abstract

A heat exchanger (10) comprises a plurality of tubes (300), a first tank (100), and a second tank (200). The internal space of the first tank is divided into upper and lower parts by a separator (130). This heat exchanger is configured so as to satisfy A_tank/A_tube ≤ 0.00000378 × L1_tank ² − 0.00305 × L1_tank + 0.78510, where: A_tube is the sum of all cross-sectional areas of flow paths (FP) formed inside the tubes above the separator, in the cross section perpendicular to the longitudinal direction thereof; A_tank is the cross-sectional area of internal space (SP) formed inside the second tank, in the cross section perpendicular to the vertical direction; and L1_tank is the length in millimeters of the portion of the second tank above the separator, along the vertical direction.

Description

Heat exchanger

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2019-156578 filed on August 29, 2019 and claims the benefit of its priority, and the entire contents of the patent application are Incorporated herein by reference.

The present disclosure relates to a heat exchanger that is used as an outdoor unit of a heat pump system, functions as an evaporator during heating, and functions as a condenser during cooling.

For example, the heat pump system that constitutes the vehicle air conditioner is equipped with an outdoor unit for heat exchange between the outdoor air and the refrigerant. Some outdoor units of heat pump systems function as an evaporator for recovering heat from the outdoor air during heating and as a condenser for releasing heat to the outdoor air during cooling. The outdoor unit is often configured as a heat exchanger including a plurality of tubes through which the refrigerant passes and a tank for distributing the refrigerant to each tube.

For the heat exchanger having the above configuration, the shape of the flow path of the refrigerant formed inside the tube so that the heat exchange between the air and the refrigerant can be performed as efficiently as possible, etc. Studies are underway to optimize the dimensions of each part of the. For example, Patent Document 1 below describes that the height of the passage in the tube of the condenser is set within a specific range in order to enhance the heat dissipation performance of the condenser.

Japanese Patent No. 3922288

When the heat exchanger is functioning as an evaporator, it is preferable that the liquid phase refrigerant before evaporation is present in the flow path in each tube as widely as possible. In such a state, heat is recovered from the air due to evaporation of the refrigerant in a wide range, and heat exchange in the evaporator is efficiently performed.

Therefore, in order for heat exchange in the evaporator to be performed efficiently, it is preferable that the liquid phase refrigerant is evenly distributed to a plurality of tubes. However, in a heat exchanger having a configuration in which a plurality of tubes are stacked and arranged in the vertical direction, the distribution of the liquid phase refrigerant to each tube tends to be uneven due to the influence of gravity.

In addition, some heat exchangers have a structure in which the internal space of the tank is divided into upper and lower parts by a separator. In the heat exchanger having such a configuration, the refrigerant flows through each tube below the separator, then is folded back and distributed to each tube above the separator. At the time of turning back, the amount of the liquid phase refrigerant has decreased due to the evaporation up to that point. For this reason, it is particularly difficult to evenly distribute the liquid phase refrigerant to each tube above the separator.

According to the experiments conducted by the present inventors, when the pressure loss of the liquid phase refrigerant flowing upward inside the tank becomes too small, most of the liquid phase refrigerant reaches the upper end of the tank and is upward. It has been found that the tubes are distributed unevenly to the tubes arranged on the side. Further, in general, when the liquid phase refrigerant is biased, if the pressure loss in the flow path in the tube is increased, it becomes difficult for the liquid phase refrigerant to enter the tube, so that the liquid phase refrigerant can spread throughout the tank. .. However, in the configuration in which the tank extends in the vertical direction, if the pressure loss of the liquid phase refrigerant in the flow path in each tube becomes large, the bias of the liquid phase refrigerant as described above becomes further large. The present inventors have obtained.

Furthermore, even when the flow velocity of the liquid phase refrigerant flowing upward inside the tank is small, it is difficult for the liquid phase refrigerant to reach the upper end of the tank. Since the flow velocity of the liquid phase refrigerant is affected by the cross-sectional area of the flow path in the tank, it is necessary to consider the shape of the tank in consideration of the flow velocity.

In view of the above findings, in order for the liquid phase refrigerant to be evenly distributed to each tube, the pressure of the liquid phase refrigerant in the space inside the tank is taken into consideration while considering the shape of the tank, which affects the flow velocity of the liquid phase refrigerant. It is necessary to properly set the balance between the loss and the pressure loss of the liquid phase refrigerant in the flow path in the tube. However, a concrete study has not been made on the configuration of the heat exchanger to realize this.

An object of the present disclosure is to provide a heat exchanger capable of evenly distributing a liquid phase refrigerant to each tube and performing heat exchange with high efficiency.

The heat exchanger according to the present disclosure is a heat exchanger used as an outdoor unit of a heat pump system, which functions as an evaporator during heating and as a condenser during cooling. This heat exchanger is a tubular member that extends in the horizontal direction, and has a plurality of tubes stacked so as to be arranged in the vertical direction, and a first tank to which one end of each tube is connected. A second tank to which the other end of each tube is connected is provided. The internal space of the first tank is divided into upper and lower parts by a separator. A portion of the first tank below the separator is provided with an inlet portion that serves as an inlet for the refrigerant when functioning as an evaporator. The portion of the first tank above the separator is provided with an outlet portion that serves as an outlet for the refrigerant when functioning as an evaporator. The total value of all cross-sectional areas of the flow path formed inside the tube above the separator in the cross section perpendicular to the longitudinal direction is set as A _tube, and the internal space formed inside the second tank. The cross-sectional area in the cross section perpendicular to the vertical direction is A _tank, and the length of the second tank above the separator along the vertical direction is expressed in millimeters as L1 _tank . when this heat exchanger _is configured so as to satisfy the _{a tank / a tube ≦ 0.00000378 ×} L1 tank 2 -0.00305 × L1 tank +0.78510.

According to the experiments conducted by the present _inventors, in the heat exchanger configured to satisfy _{A tank / A tube ≦ 0.00000378 ×} L1 tank 2 -0.00305 × L1 tank +0.78510, when folded It has been confirmed that the amount of the liquid phase refrigerant that reaches the upper end of the second tank is suppressed more than before by increasing the pressure loss of the liquid phase refrigerant flowing in the second tank to some extent. Further, since the pressure loss of each tube above the separator is reduced to some extent, the inflow of the liquid phase refrigerant from the second tank to each tube is promoted, and the liquid phase reaches the upper end of the second tank. It has also been confirmed that the amount of refrigerant is further suppressed.

_Thus, in the heat exchanger configured to satisfy _{A tank / A tube ≦ 0.00000378 ×} L1 tank 2 -0.00305 × L1 tank +0.78510, the liquid-phase refrigerant in the interior space of the second tank The balance between the pressure loss of the liquid phase refrigerant and the pressure loss of the liquid phase refrigerant in the flow path in the tube is appropriate. As a result, the liquid phase refrigerant is evenly distributed to each tube, and heat is recovered from the air with high efficiency.

According to the present disclosure, there is provided a heat exchanger capable of evenly distributing the liquid phase refrigerant to each tube and performing heat exchange with high efficiency.

FIG. 1 is a diagram showing a configuration of a heat exchanger according to the present embodiment. FIG. 2 is a cross-sectional view showing the internal configuration of the second tank of the heat exchanger of FIG. FIG. 3 is a cross-sectional view showing the internal configuration of the tube in the heat exchanger of FIG. FIG. 4 is a diagram schematically showing an example of the distribution of the liquid phase refrigerant flowing through the heat exchanger. FIG. 5 is a diagram showing the relationship between the value of _{A tank} / A _{tube and the performance of the heat exchanger.} FIG. 6 is a diagram schematically showing the flow of the liquid phase refrigerant inside the second tank.

Hereinafter, the present embodiment will be described with reference to the attached drawings. In order to facilitate understanding of the description, the same components are designated by the same reference numerals as much as possible in each drawing, and duplicate description is omitted.

The heat exchanger 10 according to the present embodiment is used as an outdoor unit of a heat pump system constituting an air conditioner for a vehicle (not shown). The heat exchanger 10 is installed in the engine room of the vehicle. In the heat exchanger 10, heat exchange is performed between the refrigerant flowing inside the heat exchanger 10 and the air flowing in from the front grill of the vehicle. In this embodiment, a fluorocarbon-based refrigerant is used as the refrigerant.

The heat exchanger 10 functions as an evaporator during heating when the interior of the vehicle is heated. At this time, a low-temperature low-pressure liquid-phase refrigerant is supplied to the heat exchanger 10 from an expansion valve (not shown) provided in the heat pump system. In the heat exchanger 10, heat exchange is performed between the refrigerant and air, whereby heat is recovered from the air.

The heat exchanger 10 functions as a condenser during cooling when the interior of the vehicle is cooled. At this time, a high-temperature and high-pressure vapor-phase refrigerant is supplied to the heat exchanger 10 from a compressor (not shown) provided in the heat pump system. In the heat exchanger 10, heat exchange is performed between the refrigerant and the air, whereby the heat of the refrigerant is released to the air.

As a configuration of the heat pump system capable of switching the function of the heat exchanger 10 which is an outdoor unit between the evaporator and the condenser as described above, a known one can be adopted. Therefore, the description and illustration of the specific configuration of the entire heat pump system will be omitted.

The configuration of the heat exchanger 10 will be described with reference to FIG. The heat exchanger 10 includes a first tank 100, a second tank 200, a tube 300, and fins 400. In FIG. 1, the direction in which the air used for heat exchange flows is from the front side to the back side of the paper surface.

The first tank 100 is a container for temporarily storing the refrigerant. The first tank 100 is formed as an elongated container having a substantially cylindrical shape, and is arranged in a state in which the longitudinal direction thereof is along the vertical direction. One end of a tube 300, which will be described later, is connected to the first tank 100.

A separator 130 is arranged inside the first tank 100. The internal space of the first tank 100 is divided into upper and lower parts by a separator 130. The position where the separator 130 is arranged is a position in the internal space of the first tank 100 that is closer to the lower side than the center along the vertical direction thereof.

A first port 110 is provided in a portion of the first tank 100 below the separator 130. Further, a second port 120 is provided in a portion of the first tank 100 on the upper side of the separator 130. The first port 110 and the second port 120 are provided as inlets or outlets for the refrigerant.

When the heat exchanger 10 functions as an evaporator, the refrigerant is supplied from the first port 110 to the internal space of the first tank 100 and discharged from the second port 120 to the outside. That is, the first port 110 corresponds to an "inlet portion" that serves as an inlet for the refrigerant when the heat exchanger 10 functions as an evaporator. The second port 120 corresponds to an "outlet portion" that serves as an outlet for the refrigerant when the heat exchanger 10 functions as an evaporator.

When the heat exchanger 10 functions as a condenser, the refrigerant is supplied from the first port 110 to the internal space of the first tank 100 and discharged from the second port 120 to the outside in the same manner as described above. The Rukoto. When the heat exchanger 10 functions as a condenser instead of such a configuration, the refrigerant is supplied from the second port 120 to the internal space of the first tank 100 and discharged from the first port 110 to the outside. It may be configured as such.

In the present embodiment, the first port 110 is connected to a position in the internal space of the first tank 100 below the separator 130, which is below the center along the vertical direction thereof. Further, the second port 120 is connected to a position in the internal space of the first tank 100 above the separator 130, which is above the center along the vertical direction thereof.

The second tank 200 is a container for temporarily storing the refrigerant. Like the first tank 100 described above, the second tank 200 is formed as an elongated container having a substantially cylindrical shape, and is arranged in a state in which the longitudinal direction thereof is along the vertical direction. The other end of the tube 300 is connected to the second tank 200. The shape of the second tank 200 is substantially the same as the shape of the first tank. The second tank 200 is arranged at a position facing the first tank along the horizontal direction. No separator is arranged inside the second tank 200. Therefore, the entire internal space of the second tank 200 is a single space.

In FIG. 1, the horizontal direction from the first tank 100 to the second tank 200 is the x direction, and the x axis is set along the same direction. Further, the direction is perpendicular to the x direction, and the direction from the front side to the back side of the paper surface is the y direction, and the y axis is set along the same direction. This y direction is a horizontal direction and is a direction in which air used for heat exchange flows. Further, in FIG. 1, the direction is perpendicular to both the x direction and the y direction, and the direction from the lower side to the upper side is the z direction, and the z axis is along the same direction. It is set. In the following, the description will be given using the x-direction, y-direction, and z-direction defined as described above.

FIG. 2 shows a cross section when the second tank 200 is cut on a plane perpendicular to the z direction. The position of the cross section is on the z-direction side, that is, on the upper side of the position of the separator 130.

As shown in FIG. 2, the second tank 200 has a core plate 210 and a tank member 220. The core plate 210 is a portion to which the ends of the plurality of tubes 300 are connected. A plurality of through holes are formed in the core plate 210, and the tube 300 is inserted into each through hole. The edge of the through hole and the outer peripheral surface of the tube 300 are wax-contacted over the entire circumference.

In the internal space SP of the second tank 200, the end of the tube 300 inserted into the through hole as described above is in a state of protruding in the x direction. At the tip of the end portion, an opening serving as an end portion of the flow path FP formed in the tube 300 is formed.

The tank member 220 is a member for forming an internal space SP with the core plate 210 by covering the entire core plate 210 from the x direction side. Both the tank member 220 and the core plate 210 are made of metal and are brazed to each other.

As shown in FIG. 2, a recess 221 is formed at a position on the inner surface of the tank member 220 on the most x-direction side. The recess 221 is a groove formed so as to extend linearly along the vertical direction, that is, the z direction. The range in which the recess 221 is formed along the vertical direction is a range in which the recesses 221 can face the end faces of all the tubes 300 laminated in the same direction. The effect of forming the recess 221 will be described later.

The tube 300 is a tubular member that extends in the horizontal direction. A plurality of tubes 300 are provided in the heat exchanger 10, and these are arranged in a laminated manner so as to be arranged in the vertical direction. Fins 400, which will be described later, are arranged between the tubes 300 adjacent to each other along the vertical direction.

As shown in FIG. 3, each tube 300 has a flat cross-sectional shape perpendicular to the longitudinal direction thereof, and the longitudinal direction of the flat shape is along the air flow direction, that is, the y direction. There is. A plurality of flow paths FP through which the refrigerant passes are formed inside the tube 300, and these are arranged along the y direction. Each flow path FP is formed so as to extend along the longitudinal direction of the tube 300, that is, the x direction. The internal space of the first tank 100 and the internal space of the second tank 200 are communicated with each other by the flow path FP of each tube 300.

Return to Fig. 1 and continue the explanation. The fin 400 is a so-called "corrugated fin", which is formed by bending a metal plate in a wavy shape. The fins 400 are inserted between adjacent tubes 300 along the vertical direction. Therefore, in the heat exchanger 10, the tubes 300 and the fins 400 are laminated and arranged so as to be alternately arranged in the vertical direction.

Each top of the wavy fin 400 is brazing to the surface of the adjacent tube 300. When the heat exchanger 10 functions as an evaporator, the heat of the passing air is directly transferred to the tube 300, and is also transferred to the tube 300 via the fins 400. That is, the contact area with air is increased by the fins 400, whereby heat exchange between air and the refrigerant is efficiently performed. The same applies when the heat exchanger 10 functions as a condenser.

The portion of the heat exchanger 10 in which all the laminated tubes 300 and fins 400 are laminated is also referred to as "heat exchange core portion CR" below. The heat exchange core portion CR is a portion where heat exchange is performed between the external air and the internal refrigerant.

Side plates

11 and 12, which are metal plates, are provided at positions on both the upper and lower sides of the heat exchange core portion CR. The

side plates

11 and 12 are for reinforcing the heat exchange core portion CR and maintaining its shape by sandwiching the heat exchange core portion CR from both the upper and lower sides.

The flow path of the refrigerant when the heat exchanger 10 functions as an evaporator will be described. In this case, the heat exchanger 10 is supplied with the refrigerant from the first port 110, which is the inlet portion. The refrigerant is a low-temperature low-pressure refrigerant as described above. The refrigerant flows from the first port 110 into a portion of the internal space of the first tank 100 below the separator 130. After that, the refrigerant flows into the internal space SP of the second tank 200 through the flow path FP of the tube 300 located below the separator 130.

The refrigerant is heated by the air passing outside when passing through the flow path FP as described above. As a result, a part of the refrigerant evaporates and changes from the liquid phase to the gas phase. However, at the time of flowing into the internal space SP of the second tank 200, the refrigerant is in a state of containing a large amount of liquid phase refrigerant that has not yet evaporated.

The refrigerant that has flowed into the internal space SP of the second tank 200 flows upward along the longitudinal direction of the internal space SP. After that, the refrigerant flows into the internal space of the first tank 100 through the flow path FP of the tube 300 located above the separator 130.

The refrigerant is reheated by the air passing outside when passing through the flow path FP as described above. As a result, a part of the refrigerant evaporates and changes from the liquid phase to the gas phase. When the refrigerant flows into the internal space of the first tank 100, most of the refrigerant evaporates to become a vapor phase refrigerant. After flowing into the internal space of the first tank 100, the refrigerant is discharged to the outside from the second port 120, which is an outlet portion, and flows toward a compressor (not shown) provided in the heat pump system.

As described above, the heat exchanger 10 according to the present embodiment is configured so that the refrigerant flows back in the second tank 200.

When the heat exchanger 10 functions as a condenser, the path through which the refrigerant flows is in the same direction as above, but the path may be in the opposite direction to the above. .. In any case, when passing through the flow path FP, the refrigerant is deprived of heat by the air passing through the outside and condenses, and changes from the gas phase to the liquid phase.

By the way, when the heat exchanger 10 functions as an evaporator, the liquid phase refrigerant before evaporation is present in the flow path FP in the tube 300 as widely as possible, that is, the heat exchange core. It is preferable that the part CR is distributed almost entirely. In such a state, heat is recovered from the air due to evaporation of the refrigerant in a wide range of the heat exchange core portion CR, and heat exchange in the heat exchanger 10 is efficiently performed.

Therefore, in order for the heat exchange in the heat exchanger 10 as the evaporator to be performed efficiently, it is preferable that the liquid phase refrigerant is evenly distributed to the plurality of tubes 300. However, in the heat exchanger 10 having a configuration in which a plurality of tubes 300 are stacked and arranged in the vertical direction as in the present embodiment, the distribution of the liquid phase refrigerant to each tube 300 tends to be uneven due to the influence of gravity.

In particular, in the heat exchanger 10 configured such that the refrigerant flows back in the second tank 200 as in the present embodiment, the refrigerant is distributed from the second tank 200 to each tube 300 at the time of turning back. At that time, the distribution of the liquid-phase refrigerant tends to be particularly uneven. This is because the amount of the liquid phase refrigerant contained in the refrigerant is smaller than when the refrigerant is first distributed from the first tank 100 to each tube 300.

FIG. 4B schematically shows the heat exchange core portion CR in the comparative example when the heat exchanger 10 has the same configuration as the conventional one. In this comparative example, the basic configuration is the same as that of the heat exchanger 10, but it differs from the present embodiment only in the cross-sectional area of the flow path FP and the like. The alternate long and short dash line DL2 shown in FIG. 4B shows the z-coordinate of the position where the separator 130 is arranged. Also in this comparative example, the refrigerant flows in the portion below the alternate long and short dash line DL2 in the x direction, then is folded back in the second tank 200 (not shown), and the portion above the alternate long and short dash line DL2 is in the −x direction. Flow toward.

The shaded area in FIG. 4B indicates the range in which the liquid phase refrigerant is distributed in the heat exchange core portion CR. As shown in the figure, in the portion of the heat exchange core portion CR below the alternate long and short dash line DL2, the liquid phase refrigerant is distributed substantially evenly in each tube 300, and as a result, the liquid phase is distributed. The refrigerant is distributed throughout.

On the other hand, in the portion of the heat exchange core portion CR above the alternate long and short dash line DL2, the liquid phase refrigerant is supplied only to the tube 300 on the upper side, and is arranged on the lower side, that is, in the vicinity of the alternate long and short dash line DL2. Almost no liquid phase refrigerant is supplied to the tube 300. This is because the flow path resistance in the internal space SP of the second tank 200 is too small, so that most of the liquid phase refrigerant flowing upward in the internal space SP reaches the upper end of the second tank 200 and is in the vicinity thereof. It is considered that this is because it is distributed only to the connected tube 300.

In the state shown in FIG. 4 (B), only the vapor phase refrigerant flows in the area not shaded, so that the heat recovered from the air due to the evaporation of the refrigerant can be efficiently recovered. I can't.

Therefore, in the heat exchanger 10 according to the present embodiment, the above problem is solved by appropriately setting the cross-sectional area of the flow path FP and the like. As a result, as shown in FIG. 4A, it is possible to distribute the liquid phase refrigerant to each tube 300 substantially evenly even in the portion of the heat exchange core portion CR above the alternate long and short dash line DL2. It has become.

A method of setting the cross-sectional area of the flow path FP and the like will be described. First, two parameters consisting of _{A tube} and A _{tank will be described.}

A _tube is the total cross-sectional area of the flow path FP formed inside the tube 300 on the upper side of the separator 130 in the cross section perpendicular to the longitudinal direction thereof. The "cross section perpendicular to the longitudinal direction" is a cross section perpendicular to the x direction as shown in FIG. As described above with reference to FIG. 3, a plurality of flow path FPs are formed in one tube 300. The above A _tube is a value obtained by summing the cross-sectional area values of each flow path FP shown in FIG. 3 and multiplying this by the number of tubes 300 on the upper side of the separator 130. is there.

The A _tank is the cross-sectional area of the internal space SP formed inside the second tank 200 in a cross section perpendicular to the vertical direction. That is, A _tank is the cross-sectional area of the internal space SP in the cross section shown in FIG. This _tank does not include the cross-sectional area of the protruding portion of the tube 300 in FIG. That is, _{it can be said that the tank} is the cross-sectional area of the space SP in which the refrigerant can flow linearly along the longitudinal direction of the second tank 200. If the cross-sectional area changes locally in the vertical direction, the shape of the portion shall not be considered in the calculation of the _tank.

The length of the portion above the separator 130 of the second tank 200 along the vertical direction, that is, the length along the z direction is hereinafter referred to as _{"L1 tank".} The unit of L1 _tank is millimeter (mm). The heat exchanger 10 according to this _embodiment, as the value of _A tank _/ A _tube is _{^{_{0.00000378 × L1 tank 2 -0.00305 × L1}}} tank +0.78510, the cross-sectional area of the flow path FP and settings such as Has been done. The reason will be described with reference to FIG.

The horizontal axis in the graph of FIG. 5 shows the above-mentioned A _tank / A _tube value _{when the value of L1 tank is 140 (mm).} The vertical axis in the graph shows the value of the performance ratio. The "performance ratio" is an index showing the magnitude of the heat recovery performance from the air as a ratio to the recovery performance when the shape of the heat exchanger 10 is a specific shape. The "recovery performance" in the above is the amount of heat recovered from the air per unit time in the heat exchanger 10. In the example of FIG. 5, the _{recovery performance when the value of A tank} / _{Tube is} the value indicated by the point P1 is 100%, and the ratio to this is the performance ratio shown on the vertical axis. ..

At point P1 in FIG. 5, the performance ratio is 100% as described above. At point P2 in FIG. 5, has a value that the value of _{_A} tank _/ _A _tube is calculated by _{^{_{0.00000378 × L1 tank 2 -0.00305 × L1}}} tank +0.78510 as in this embodiment, at that time The performance ratio is 105%. At point P3 in FIG. _5, the value of _A tank _/ A _tube has a smaller value than the value calculated by _{^{_{0.00000378 × L1 tank 2 -0.00305 × L1}}} tank +0.78510, performance ratio at that time Is 125%. As described above, the _{smaller the value of A tank} / A _tube , the higher the performance ratio.

In _{the range where the value of A tank} / A _tube is larger than that at the point P2, the _{smaller the value of A tank} / A _tube is, the smaller the pressure loss in the flow path FP of the tube 300 is mainly due to the effect. The performance ratio will improve. This effect is due to the fact that the pressure and temperature of the refrigerant at the inlet portion of the flow path FP are reduced and the temperature difference from the surrounding air is increased.

According to the results confirmed by the present inventors by experiments and the like _{, when the value of A tank} / A _tube becomes equal to or less than the value at the point P2, in addition to the above effect, from the second tank 200 to each tube 300. It has been confirmed that the performance ratio is significantly improved by adding the effect of evenly distributing the liquid phase refrigerant. Therefore, it is preferable that the cross-sectional area of the flow path FP is set so as to satisfy the condition represented by the following formula (1).
_{_{A tank / A tube ≦ 0.00000378 ×}} L1 tank 2 -0.00305 × L1 tank +0.78510 ···· (1)

Since the left side in the equation (1) is dimensionless, any unit can be used as the _{tank or the like.} However, on the right side of the equation (1), it is necessary to use the unit of millimeter as _{the L1 tank.}

As _{the value of A tank} / A _tube becomes smaller, the performance ratio when the heat exchanger 10 functions as an evaporator improves as described above. However, _{if the value of A tank} / A _tube is made too small, the heat exchange performance when the heat exchanger 10 functions as a condenser may deteriorate. This is because when the heat exchanger 10 functions as a condenser, the heat transfer coefficient becomes smaller as the pressure loss of the flow path FP becomes smaller and the flow velocity of the refrigerant becomes smaller, and the heat exchange performance as a condenser becomes lower. This is because it will decrease. It is preferable to consider this point when setting the value of A _tank / A _tube.

_{The tank} of the formula (1) is a parameter that affects the pressure loss of the refrigerant in the internal space SP formed inside the second tank 200. As such a parameter _{, in addition to the tank} , for example, the length of the second tank 200 along the z direction and the like can be mentioned. Further, A _tube of the same formula is a parameter that affects the pressure loss of the refrigerant in the flow path FP of the tube 300. As such a parameter _{, in addition to A tube} , for example, the length of the tube 300 along the x direction can be mentioned.

When the heat exchanger 10 is configured as the outdoor unit of the vehicle air conditioner, the above equation (1) is satisfied without considering the length of the second tank 200 along the z direction and the like. If it is configured, the effect of improving the performance ratio can be obtained to some extent. However, if the conditions for improving the performance ratio of the heat exchanger 10 are strictly determined, it is preferable to consider parameters such as the length of the second tank 200 along the z direction. As such a strict condition, the following equation (2) can be mentioned.
_{_{_{(L1 tube × L2 tube / A}}} tube) × (A tank / (L1 tank × L2 tank)) ≦ 0.00000378 × L1 tank 2 -0.00305 × L1 tank +0.78510 ···· (2)

_{The L1 tube} in the formula (2) is the length of the tube 300 above the separator 130 along the longitudinal direction, that is, the length along the x direction.

L2 _tube is the total value of all wet edge lengths of the flow path FP formed inside the tube 300 on the upper side of the separator 130 in the cross section perpendicular to the longitudinal direction thereof. The "cross section perpendicular to the longitudinal direction" is a cross section perpendicular to the x direction as shown in FIG. As described above with reference to FIG. 3, a plurality of flow path FPs are formed in one tube 300. The above L2 _tube is obtained by summing the values of the wet edge length of each flow path FP shown in FIG. 2, that is, the value of the peripheral length of the inner surface of the flow path FP in the cross section of FIG. It is a value obtained by multiplying the number of tubes 300 on the upper side of the separator 130.

As _{described above, the L1 tank} is the length of the portion of the second tank 200 above the separator 130 in the vertical direction, that is, the length in the z direction.

L2 _tank is the wet edge length of the internal space SP formed inside the second tank 200 in the cross section perpendicular to the vertical direction, that is, the peripheral length of the inner surface of the internal space SP in the cross section of FIG. is there. The internal space SP in this case does not include the portion where the tube 300 protrudes in FIG. That is, it _{can be said that the L2 tank} is the wet edge length of the portion of the internal space SP where the refrigerant can flow linearly along the longitudinal direction of the second tank 200.

On the right side of the equation (2), it is necessary to use the unit of millimeter as _{the L1 tank.} In equation (2), since the L1 _tank also exists on the left side, it is necessary to use the unit of millimeters for each element on the left side as well.

According to the experiments conducted by the present inventors, if the configuration of the heat exchanger 10 satisfies the above-mentioned equation (1) and also satisfies the equation (2), the first is more reliable. It has been confirmed that the liquid phase refrigerant is distributed from the two tanks 200 to each tube 300, and the heat exchanger 10 performs heat exchange with high efficiency. Even when the parameter shown on the left side of the equation (2) is set to the horizontal axis of FIG. 5, a graph substantially similar to that of FIG. 5 is drawn.

In the heat exchanger 10, some further measures have been taken to improve its performance. The device will be described below.

As described above with reference to FIG. 2, a recess 221 extending linearly along the vertical direction is formed on the inner surface of the second tank 200, specifically, the inner surface of the tank member 220.
When the gas-liquid mixed refrigerant flows inside a tubular member such as the second tank 200, the liquid-phase refrigerant flows along the pipe wall, and the gas-liquid refrigerant flows through the space inside the pipe wall. Tends to flow. Therefore, when the refrigerant flows upward through the internal space SP of the second tank 200, the liquid phase refrigerant also tends to flow along the inner surface of the second tank 200.

In the present embodiment, a part of the liquid phase refrigerant flowing in this way is distributed to the flow path FP of each tube 300 facing the recess 221 while being guided by the recess 221 extending linearly along the vertical direction. I will go. That is, as compared with the case where the recess 221 is not formed, a larger amount of the liquid phase refrigerant flows through the position of the recess 221 and is distributed to each tube 300. This makes it possible to more evenly distribute the liquid phase refrigerant to each tube 300.

In order to realize such a function, the position of the recess 221 is preferably a position of the inner surface of the second tank 200 facing the end of the tube 300. The dotted line DL1 shown in FIG. 2 indicates the x-coordinate of the position of the end portion of the tube 300. The "position facing the end of the tube 300" is a position on the x-direction side of the dotted line DL1. More preferably, the recess 221 may be formed at a position overlapping the end of the tube 300 when viewed along the x-axis.

The recess 221 may be formed so as to cover the entire range from the lower end to the upper end of the second tank 200 as in the present embodiment, but is larger than the separator 130 of the second tank 200. It may be formed only in the portion on the upper side.

As shown in FIG. 2, a protruding portion 211 is formed around the portion of the inner surface of the second tank 200 to which the tube 300 is connected so as to project toward the inside of the second tank 200. There is. The protruding portion 211 is a surface that protrudes from other portions so as to be closer to the tube 300, the inside of the second tank 200, and toward the tip end side of the tube 300.

As mentioned earlier, the liquid phase refrigerant tends to flow along the inner surface of the second tank 200. In the present embodiment, since the protrusion 211 as described above is formed around the tube 300, a part of the liquid-phase refrigerant flowing along the inner surface of the second tank 200 is sewn along the protrusion 211. It is guided to the tip side of 300. As a result, the liquid phase refrigerant is more likely to flow into the flow path FP of the tube 300 as compared with the case where the protruding portion 211 is not formed.

As described above, in the present embodiment, the protrusion for guiding the refrigerant flowing along the inner surface to the end of the tube 300 around the portion of the inner surface of the second tank 200 to which the tube 300 is connected. 211 is formed. This makes it possible to more evenly distribute the liquid phase refrigerant to each tube 300.

As shown in FIG. 1, the first port 110, which is an inlet portion, is formed so as to project from the first tank 100 toward the −x direction side. Therefore, the direction in which the refrigerant flows from the first port 110 into the internal space of the first tank 100 is the x direction, that is, the direction along the longitudinal direction of the tube 300. In such a configuration, the refrigerant flowing into the internal space of the first tank 100 while flowing in the x direction through the first port 110 goes to the flow path FP of each tube 300 without substantially changing the flow direction. It flows in and flows in the x direction as it is. Therefore, it is possible to reduce the flow path resistance due to the change in the flow direction of the refrigerant.

Further, the second port 120, which is an outlet portion, is also formed so as to protrude from the first tank 100 toward the −x direction side. Therefore, the direction in which the refrigerant flows out from the internal space of the first tank 100 to the second port 120 is the −x direction, that is, the direction along the longitudinal direction of the tube 300. In such a configuration, the refrigerant flowing into the internal space of the first tank 100 while flowing in the −x direction through the flow path FP of the tube 300 goes to the second port 120 without substantially changing the flow direction. It flows in and is discharged from the second port 120 as it is in the −x direction. Therefore, it is possible to reduce the flow path resistance due to the change in the flow direction of the refrigerant.

As described above, the position where the separator 130 is arranged in the first tank 100 is a position in the internal space of the first tank 100 that is closer to the lower side than the center along the vertical direction thereof. There is. Therefore, the number of tubes 300 above the separator 130 is larger than the number of tubes 300 below the separator 130. The effect of having such a configuration of the heat exchanger 10 will be described with reference to FIG.

In FIG. 6, the heat exchange core portion CR and the first tank 100 and the second tank 200 on both sides thereof are schematically shown. The alternate long and short dash line DL3 shown in FIG. 6 indicates the z coordinate of the position where the separator 130 is arranged.

In FIG. 6, the flow of the refrigerant in the tube 300 below the separator 130 is indicated by the arrow AR1. In the present embodiment, as described above, the number of tubes 300 below the separator 130 is smaller than the number of tubes 300 above the separator 130. Therefore, the flow velocity of the refrigerant indicated by the arrow AR1 is higher than that in the case where the separator 130 is arranged at the center in the vertical direction.

When the refrigerant having such a high flow velocity flows into the internal space SP of the second tank 200, the refrigerant collides with the inner wall of the second tank 200 immediately after that, and the flow is disturbed. In FIG. 6, such a flow of refrigerant is indicated by arrow AR2.

When the flow of the refrigerant is disturbed, the vapor-phase refrigerant and the liquid-phase refrigerant are mixed, so that the liquid-phase refrigerant is distributed throughout the second tank 200. Therefore, the liquid phase refrigerant is evenly distributed from the second tank 200 to each tube 300 and flows into each flow path FP. In FIG. 6, the flow of the refrigerant thus distributed is indicated by the arrow AR3.

As described above, in the heat exchanger 10 according to the present embodiment, the number of tubes 300 on the upper side of the separator 130 is larger than the number of tubes 300 on the lower side of the separator 130, so that after folding back. It is possible to more evenly distribute the refrigerant of the above to each tube 300.

In the present embodiment, the throttle portion 230 is formed in a portion of the inside of the second tank 200 that has a height corresponding to the separator 130. In the throttle portion 230, the cross-sectional area of the internal space SP formed inside the second tank 200 in the cross section perpendicular to the vertical direction is locally smaller than the cross-sectional area of the other portion. That is, the cross-sectional area of the inside of the second tank 200, which is the height corresponding to the separator 130, is locally smaller than that of the _tank.

In such a configuration, the flow of the refrigerant after turning back is more likely to be disturbed, so that the mixing of the gas phase refrigerant and the liquid phase refrigerant as described above is further promoted.

The position where the throttle portion 230 is formed may be a position that is a part of a predetermined range including the height corresponding to the separator 130. The size of this "predetermined range" is preferably the size of the range in which the three tubes 300 are connected along the vertical direction. Further, even if the throttle portion 230 is not formed, the throttle portion 230 may be omitted if the vapor phase refrigerant and the liquid phase refrigerant are sufficiently mixed.

The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Those skilled in the art with appropriate design changes to these specific examples are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each of the above-mentioned specific examples, its arrangement, conditions, shape, etc. is not limited to the illustrated one, and can be appropriately changed. The combinations of the elements included in each of the above-mentioned specific examples can be appropriately changed as long as there is no technical contradiction.

Claims

A heat exchanger (10) used as an outdoor unit of a heat pump system, which functions as an evaporator during heating and as a condenser during cooling.
A plurality of tubes (300) which are tubular members extending in the horizontal direction and are arranged in a stack so as to be arranged in the vertical direction.
The first tank (100) to which one end of each of the tubes is connected,
A second tank (200) to which the other end of each of the tubes is connected is provided.
The internal space of the first tank is divided into upper and lower parts by a separator (130).
A portion of the first tank below the separator is provided with an inlet portion (110) that serves as an inlet for the refrigerant when functioning as an evaporator.
The portion of the first tank above the separator is provided with an outlet portion (120) that serves as an outlet for the refrigerant when functioning as an evaporator.
The total value of all cross-sectional areas of the flow path (FP) formed inside the tube on the upper side of the separator in the cross section perpendicular to the longitudinal direction thereof is defined as A tube .
The cross-sectional area of the internal space (SP) formed inside the second tank in the cross section perpendicular to the vertical direction is defined as A tank .
When the length of the second tank above the separator along the vertical direction is expressed in millimeters as L1 tank ,
A tank / A tube ≦ 0.00000378 × L1 tank 2 -0.00305 × L1 tank +0.78510
A heat exchanger that is configured to meet.
A protrusion (211) for guiding the refrigerant flowing along the inner surface to the end of the tube is formed around the portion of the inner surface of the second tank to which the tube is connected. , The heat exchanger according to claim 1.
The length of the tube on the upper side of the separator along the longitudinal direction thereof is defined as L1 tube.
The total value of all wet edge lengths in the cross section perpendicular to the longitudinal direction of the flow path formed inside the tube on the upper side of the separator is defined as L2 tube .
When the wet edge length of the internal space formed inside the second tank in the cross section perpendicular to the vertical direction is L2 tank ,
(L1 tube × L2 tube / A tube) × (A tank / (L1 tank × L2 tank)) ≦ 0.00000378 × L1 tank 2 -0.00305 × L1 tank +0.78510
The heat exchanger according to claim 1 or 2, which is configured to satisfy the above conditions.
In a part of the second tank within a predetermined range including a position corresponding to the separator,
Any of claims 1 to 3, wherein the cross-sectional area of the internal space formed inside the second tank in the cross section perpendicular to the vertical direction is locally smaller than the cross-sectional area of the other portion. The heat exchanger according to item 1.
The heat exchanger according to any one of claims 1 to 4, wherein a recess (221) extending in the vertical direction is formed on the inner surface of the second tank.
The direction in which the refrigerant flows from the inlet portion into the internal space of the first tank and the direction in which the refrigerant flows out from the internal space of the first tank to the outlet portion are both in the longitudinal direction of the tube. The heat exchanger according to any one of claims 1 to 5, which is in the direction along the line.
The heat exchanger according to any one of claims 1 to 6, wherein the number of the tubes above the separator is larger than the number of tubes below the separator.