JP7383935B2 - Heat exchanger - Google Patents

Description

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

For example, a heat pump system that constitutes a vehicle air conditioner is equipped with an outdoor unit for exchanging heat between outdoor air and a refrigerant. Some outdoor units of heat pump systems function as evaporators to recover heat from outdoor air during heating, and function as condensers to release heat to outdoor air during cooling. The outdoor unit is often configured as a heat exchanger that includes a plurality of tubes through which refrigerant passes and a tank that distributes the refrigerant to each tube.

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

Patent No. 3922288

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

Therefore, in order to efficiently exchange heat in the evaporator, it is preferable that the liquid phase refrigerant is evenly distributed among the plurality of tubes. However, in a heat exchanger having a structure in which a plurality of tubes are vertically stacked, distribution of liquid phase refrigerant to each tube tends to be uneven due to the influence of gravity.

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

According to 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 top of the tank and moves upward. It has been found that the liquid is distributed unevenly to the tubes placed on the sides. Additionally, in general, if the liquid phase refrigerant is uneven, increasing the pressure loss in the flow path inside the tube will make it difficult for the liquid phase refrigerant to enter the tube, which may cause the liquid phase refrigerant to spread throughout the tank. . However, in a configuration where the tank extends in the vertical direction, as the pressure loss of the liquid phase refrigerant in the flow path in each tube increases, the above-mentioned imbalance of the liquid phase refrigerant will become even larger. The inventors have obtained.

Furthermore, even when the flow rate of the liquid phase refrigerant flowing upward inside the tank is low, it becomes difficult for the liquid phase refrigerant to reach the upper end of the tank. Since the flow rate of the liquid phase refrigerant is affected by the cross-sectional area of the flow path within the tank, it is necessary to consider the flow rate as well when considering the shape of the tank.

In view of the above knowledge, in order to distribute the liquid refrigerant evenly to each tube, the pressure of the liquid refrigerant in the space inside the tank must be It is necessary to set an appropriate balance between the loss and the pressure loss of the liquid phase refrigerant in the flow path within the tube. However, no specific study has been made regarding the configuration of a heat exchanger to achieve this.

An object of the present disclosure is to provide a heat exchanger that can evenly distribute liquid phase refrigerant to each tube and perform heat exchange with high efficiency.

The heat exchanger according to the present disclosure is a heat exchanger (10) that is used as an outdoor unit of a heat pump system, and functions as an evaporator during heating and as a condenser during cooling. This heat exchanger is a tubular member extending in the horizontal direction, and includes a plurality of tubes (300) arranged in layers in a vertical direction, and a first tube to which one end of each tube is connected. It includes a tank (100) and a second tank (200) to which the other ends of the respective tubes are connected. The internal space of the first tank is divided into upper and lower parts by a separator (130). An inlet portion (110) that serves as an inlet for refrigerant when functioning as an evaporator is provided in a portion of the first tank below the separator. An outlet section (120) that serves as an outlet for refrigerant when functioning as an evaporator is provided in a portion of the first tank above the separator. Let A _tube be the sum of all the cross-sectional areas in the cross section perpendicular to the longitudinal direction of the flow path (FP) formed inside the tube above the separator, and the flow path (FP) formed inside the second tank. A _tank is the cross-sectional area of the internal space (SP) perpendicular to the vertical direction, and the length along the vertical direction of the part above the separator in the second tank is expressed in millimeters. This heat exchanger is configured to satisfy _{A tank /} A _tube ≦0.00000378×L1 _tank ² −0.00305×L1 _tank +0.78510.

According to experiments conducted by the present inventors, in a heat exchanger configured to satisfy A _tank /A _tube ≦0.00000378×L1 _tank ² −0.00305×L1 _tank +0.78510, when turning It has been confirmed that by increasing the pressure loss of the liquid phase refrigerant flowing in the second tank to a certain extent, the amount of the liquid phase refrigerant reaching the upper end of the second tank is suppressed more than before. In addition, by reducing the pressure loss of each tube above the separator to some extent, the flow of 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.

In this way, in a 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 internal 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 within 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, a heat exchanger is provided that can evenly distribute liquid phase refrigerant to each tube and perform heat exchange with high efficiency.

FIG. 1 is a diagram showing the configuration of a heat exchanger according to this embodiment. FIG. 2 is a sectional view showing the internal configuration of a second tank in the heat exchanger of FIG. 1. FIG. 3 is a sectional view showing the internal structure of a tube in the heat exchanger of FIG. 1. FIG. FIG. 4 is a diagram schematically showing an example of the distribution of liquid phase refrigerant flowing through a 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 liquid phase refrigerant inside the second tank.

This embodiment will be described below with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and redundant description will be omitted.

The heat exchanger 10 according to this embodiment is used as an outdoor unit of a heat pump system that constitutes a vehicle air conditioner (not shown). Heat exchanger 10 is installed in the engine room of a 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. Note that in this embodiment, a fluorocarbon-based refrigerant is used as the refrigerant.

At the time of heating the vehicle interior, the heat exchanger 10 functions as an evaporator. At this time, a low-temperature, low-pressure liquid phase refrigerant is supplied to the heat exchanger 10 from an unillustrated expansion valve included in the heat pump system. In the heat exchanger 10, heat is exchanged between the refrigerant and air, thereby recovering heat from the air.

At the time of cooling the vehicle interior, the heat exchanger 10 functions as a condenser. At this time, a high-temperature, high-pressure gaseous refrigerant is supplied to the heat exchanger 10 from a compressor (not shown) included in the heat pump system. In the heat exchanger 10, heat exchange is performed between the refrigerant and air, and thereby the heat of the refrigerant is released to the air.

Note that a publicly known structure can be adopted as a structure of a heat pump system that can switch the function of the heat exchanger 10, which is an outdoor unit, between an evaporator and a condenser as described above. Therefore, 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. 1. The heat exchanger 10 includes a first tank 100, a second tank 200, tubes 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 page.

The first tank 100 is a container for temporarily storing refrigerant. The first tank 100 is formed as an elongated container having a substantially cylindrical shape, and is arranged with its longitudinal direction aligned in the up-down 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 interior space of the first tank 100 is divided into upper and lower parts by a separator 130. The separator 130 is disposed at 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.

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 above the separator 130. The first port 110 and the second port 120 are provided as a refrigerant inlet or outlet.

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

Note that when the heat exchanger 10 functions as a condenser, the refrigerant is supplied to the internal space of the first tank 100 from the first port 110 and discharged to the outside from the second port 120, similarly to the above. The Rukoto. Instead of such a configuration, when the heat exchanger 10 functions as a condenser, the refrigerant is supplied to the internal space of the first tank 100 from the second port 120 and discharged to the outside from the first port 110. It may be configured such that

In this embodiment, the first port 110 is connected to a position below the vertical center of the internal space of the first tank 100 that is below the separator 130 . Further, the second port 120 is connected to a position above the vertical center of the internal space of the first tank 100 above the separator 130.

The second tank 200 is a container for temporarily storing refrigerant. The second tank 200, like the first tank 100 described above, is formed as an elongated container having a substantially cylindrical shape, and is arranged with its longitudinal direction aligned with the up-down direction. The other end of the tube 300 is connected to the second tank 200. The shape of the second tank 200 is generally 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. Note that no separator is arranged inside the second tank 200. Therefore, the entire interior 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 perpendicular to the x direction and going from the front side to the back side of the page 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. In FIG. 1, the z direction is a direction perpendicular to both the x direction and the y direction, going from the lower side to the upper side, and the z axis is along the same direction. It is set. The following description will be made using the x direction, y direction, and z direction defined as above.

FIG. 2 shows a cross section of the second tank 200 taken along a plane perpendicular to the z direction. Note that the position of the cross section is on the z-direction side, that is, on the upper side than the position of the separator 130.

As shown in FIG. 2, the second tank 200 includes 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 circumferential surface of the tube 300 are brazed together 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 protrudes in the x direction. An opening that becomes the end of the flow path FP formed in the tube 300 is formed at the tip of the end.

The tank member 220 is a member for forming an internal space SP between the tank member 220 and 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 soldered together.

As shown in FIG. 2, a recess 221 is formed in the inner surface of the tank member 220 at a position closest to the x direction. The recess 221 is a groove formed 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 that can face the end faces of all the tubes 300 stacked along the same direction. The effect of forming the recess 221 will be explained later.

The tube 300 is a tubular member extending in the horizontal direction. The heat exchanger 10 is provided with a plurality of tubes 300, which are stacked in a vertically aligned manner. Fins 400, which will be described later, are arranged between tubes 300 that are adjacent to each other along the vertical direction.

As shown in FIG. 3, each tube 300 has a flat cross section perpendicular to its longitudinal direction, 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 flow paths FP are lined up along the y direction. Each flow path FP is formed 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 a flow path FP of each tube 300.

Returning to FIG. 1, the explanation will be continued. The fin 400 is a so-called "corrugated fin" and is formed by bending a metal plate into a wave shape. The fins 400 are inserted between tubes 300 adjacent to each other along the vertical direction. Therefore, in the heat exchanger 10, the tubes 300 and the fins 400 are arranged in a stacked manner so as to be alternately lined up along the vertical direction.

The top of each wavy fin 400 is soldered to the surface of an adjacent tube 300. When the heat exchanger 10 functions as an evaporator, the heat of the passing air is transferred not only directly to the tubes 300 but also via the fins 400. In other words, the contact area with the air is increased by the fins 400, thereby efficiently exchanging heat between the air and the refrigerant. The same applies when the heat exchanger 10 functions as a condenser.

A portion of the heat exchanger 10 in which all the stacked tubes 300 and fins 400 are arranged in a stacked manner is hereinafter also referred to as a "heat exchange core portion CR." The heat exchange core portion CR is a portion where heat exchange is performed between external air and internal refrigerant. Side plates 11 and 12, which are metal plates, are provided at the upper and lower sides of the heat exchange core CR. The side plates 11 and 12 are for reinforcing the heat exchange core CR and maintaining its shape by sandwiching the heat exchange core CR from both upper and lower sides.

The path through which the refrigerant flows when the heat exchanger 10 functions as an evaporator will be described. In this case, refrigerant is supplied to the heat exchanger 10 from the first port 110, which is an inlet. 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 that is below the separator 130 . Thereafter, 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.

When the refrigerant passes through the flow path FP as described above, it is heated by the air passing outside. As a result, a portion of the refrigerant evaporates and changes from a liquid phase to a gas phase. However, at the time when the refrigerant flows into the internal space SP of the second tank 200, the refrigerant contains 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. Thereafter, 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.

When the refrigerant passes through the flow path FP as described above, it is heated again by the air passing outside. As a result, a portion of the refrigerant evaporates and changes from a liquid phase to a gas phase. At the time when the refrigerant flows into the internal space of the first tank 100, most of the refrigerant evaporates and becomes a gaseous 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, and flows toward a compressor (not shown) included in the heat pump system.

In this way, the heat exchanger 10 according to the present embodiment is configured so that the refrigerant flows in the second tank 200 in a turned direction.

In addition, when the heat exchanger 10 functions as a condenser, the path through which the refrigerant flows is in the same direction as above, but it may be configured so that the path is in the opposite direction. . In any case, when the refrigerant passes through the flow path FP, heat is taken away by the air passing outside and the refrigerant condenses, changing from a gas phase to a liquid phase.

By the way, when the heat exchanger 10 is functioning as an evaporator, the liquid phase refrigerant before evaporation exists as widely as possible in the flow path FP within the tube 300, that is, the heat exchange core It is preferable that it be distributed over substantially the entire region CR. In such a state, heat is recovered from the air as the refrigerant evaporates over a wide range of the heat exchange core CR, and heat exchange in the heat exchanger 10 is performed efficiently.

Therefore, in order to efficiently exchange heat in the heat exchanger 10 as an evaporator, 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 vertically stacked as in the present embodiment, the distribution of 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 in the second tank 200 while turning around, as in the present embodiment, the refrigerant is distributed from the second tank 200 to each tube 300 during the turning around. In this case, the distribution of the liquid phase refrigerant is particularly likely to be uneven. This is because the amount of liquid phase refrigerant contained in the refrigerant is smaller than when the refrigerant is initially distributed from the first tank 100 to each tube 300.

FIG. 4(B) schematically shows a heat exchange core CR in a comparative example in which the heat exchanger 10 has the same configuration as the conventional one. This comparative example has the same basic configuration as the heat exchanger 10, but differs from the present embodiment only in the cross-sectional area of the flow path FP. A dashed line DL2 shown in FIG. 4(B) indicates the z-coordinate of the position where the separator 130 is arranged. In this comparative example as well, the refrigerant flows in the x direction in the portion below the dashed-dotted line DL2, turns back in the second tank 200 (not shown), and flows in the −x direction in the portion above the dashed-dotted line DL2. flowing towards.

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

On the other hand, in the portion of the heat exchange core CR that is above the dashed-dotted line DL2, the liquid phase refrigerant is supplied only to the tubes 300 located on the upper side, and the liquid phase refrigerant is supplied to the tubes 300 located on the lower side, that is, near the dashed-dotted 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 distributed in the vicinity thereof. This is thought to be because the liquid is distributed only to the connected tube 300.

When the state shown in Fig. 4(B) is reached, only the gas phase refrigerant flows in the areas not shaded, so that heat recovery from the air due to evaporation of the refrigerant is not performed efficiently. It won't happen.

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. As a result, as shown in FIG. 4(A), even in the portion of the heat exchange core CR above the dashed line DL2, it is possible to distribute the liquid phase refrigerant to each tube 300 almost equally. It becomes.

A method of setting the cross-sectional area, etc. of the flow path FP will be explained. First, two parameters consisting of A _tube and A _tank will be explained.

A _tube is the total value of all the cross-sectional areas of the flow path FP formed inside the tube 300 above the separator 130 in a cross section perpendicular to its longitudinal direction. "A cross section perpendicular to the longitudinal direction" refers to a cross section perpendicular to the x direction, as shown in FIG. As described above with reference to FIG. 3, a plurality of flow paths FP are formed in one tube 300. The above A _tube is a value obtained by summing the cross-sectional area of each flow path FP shown in FIG. 3 and then multiplying this by the number of tubes 300 located above the separator 130 be.

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 A _tank does not include the cross-sectional area of the portion where the tube 300 protrudes in FIG. That is, A _tank can be said to be the cross-sectional area of the space in the internal space SP through which the refrigerant can flow linearly along the longitudinal direction of the second tank 200. Note that if the above-mentioned cross-sectional area changes locally in the vertical direction, the shape of the portion is not considered in calculating A _tank .

The length along the vertical direction of the portion of the second tank 200 above the separator 130, that is, the length along the z direction, will be referred to as "L1 _tank " below. The unit of L1 _tank is millimeter (mm). In the heat exchanger 10 according to the present embodiment, the cross-sectional area of the flow path FP, etc. is set so that the value of A _tank /A _tube is 0.00000378 x L1 _tank ² -0.00305 x L1 _tank +0.78510. has been done. The reason for this will be explained with reference to FIG.

The horizontal axis in the graph of FIG. 5 indicates the value of A _tank /A _tube described above when the value of L1 _tank is 140 (mm). Further, the vertical axis in the graph indicates the value of the performance ratio. The "performance ratio" is an index indicating 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" mentioned above refers to the amount of heat recovered from the air per unit time in the heat exchanger 10. In the example of FIG. 5, when the value of A _tank /A _tube is the value shown by point P1, the recovery performance is 100%, and the ratio with 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, the value of A _tank /A _tube is calculated as 0.00000378×L1 _tank ² -0.00305×L1 _tank +0.78510 as in the present embodiment, and at that time The performance ratio is 105%. At point P3 in FIG. 5, the value of A _tank /A _tube is smaller than the value calculated by 0.00000378 x L1 _tank ² -0.00305 x L1 _tank +0.78510, and the performance ratio at that time is is 125%. In this way, the smaller the value of A _tank /A _tube , the higher the performance ratio.

In a range where the value of A _tank /A _tube is larger than that at point P2, the smaller the value of A _tank /A _tube , the smaller the pressure loss in the flow path FP of the tube 300. The performance ratio will continue to improve. This effect is due to the fact that the pressure and temperature of the refrigerant at the inlet of the flow path FP decreases, and the temperature difference between the refrigerant and the surrounding air increases.

According to what the inventors have confirmed through experiments and the like, when the value of A _tank /A _tube becomes less than the value at point P2, in addition to the above effect, the flow 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 expressed by the following equation (1).
A _tank /A _tube ≦0.00000378×L1 _tank ² -0.00305×L1 _tank +0.78510...(1)

Note that since the left side in equation (1) is dimensionless, any unit can be used as A _tank or the like. However, on the right side of equation (1), it is necessary to use the unit of millimeter as L1 _tank .

Note that, 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 smaller the pressure loss in the flow path FP and the lower the flow rate of the refrigerant, the smaller the heat transfer coefficient becomes, and the heat exchange performance as a condenser becomes lower. This is because it will decrease. It is preferable to take this point into consideration when setting the value of A _tank /A _tube .

A _tank in equation (1) is a parameter that affects the pressure loss of the refrigerant in the internal space SP formed inside the second tank 200. In addition to A _tank , examples of such parameters include, for example, the length of the second tank 200 along the z direction. Further, A _tube in the same equation is a parameter that affects the pressure loss of the refrigerant in the flow path FP of the tube 300. In addition to the A _tube , such parameters include, for example, the length of the tube 300 along the x direction.

When the heat exchanger 10 is configured as an outdoor unit of a vehicle air conditioner, a heat exchanger that satisfies the above formula (1) without considering the length of the second tank 200 along the z direction, etc. With this configuration, it is possible to obtain the effect of improving the performance ratio to some extent. However, if conditions for improving the performance ratio of the heat exchanger 10 are to be strictly determined, it is preferable to also consider parameters such as the length of the second tank 200 along the z direction. As such a strict condition, the following formula (2) can be cited.
(L1 _tube × L2 _tube / A _tube ) × (A _tank / (L1 _tank × L2 _tank )) ≦0.00000378 × L1 _tank ² -0.00305 × L1 _tank +0.78510... (2)

L1 _tube in equation (2) is the length of the tube 300 above the separator 130 along its longitudinal direction, that is, the length along the x direction.

L2 _tube is the total value of all wetted edge lengths in a cross section perpendicular to the longitudinal direction of the flow path FP formed inside the tube 300 above the separator 130. "A cross section perpendicular to the longitudinal direction" refers to a cross section perpendicular to the x direction, as shown in FIG. As described above with reference to FIG. 3, a plurality of flow paths FP are formed in one tube 300. The above L2 _tube is determined by adding up the wetted edge length of each flow path FP shown in FIG. 2, that is, the value of the circumference of the inner surface of the flow path FP in the cross section of FIG. This value is obtained by multiplying the number of tubes 300 located above the separator 130.

As described above, L1 _tank is the length of the portion of the second tank 200 above the separator 130 along the vertical direction, that is, the length along the z direction.

L2 _tank is the wetted edge length of the internal space SP formed inside the second tank 200 in a cross section perpendicular to the vertical direction, that is, the circumferential length of the inner surface of the internal space SP in the cross section of FIG. be. Note that the internal space SP in this case does not include the portion from which the tube 300 protrudes in FIG. 3 . In other words, L2 _tank can be said to be the length of the wetted edge of the portion of the internal space SP where the refrigerant can flow linearly along the longitudinal direction of the second tank 200.

Note that on the right side of equation (2), it is necessary to use the unit of millimeter as L1 _tank . In equation (2), since L1 _tank also exists on the left side, it is necessary to use millimeter units for each element on the left side.

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

Several further improvements have been made to the heat exchanger 10 to improve its performance. The invention will be explained below.

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

In this 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 in the vertical direction. go. That is, compared to the case where the recess 221 is not formed, more liquid phase refrigerant flows through 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, it is preferable that the recess 221 be located at a position on the inner surface of the second tank 200 that faces the end of the tube 300. A dotted line DL1 shown in FIG. 2 indicates the x-coordinate of the position of the end of the tube 300. "The position facing the end of the tube 300" is a position on the x-direction side of such dotted line DL1. More preferably, the recess 221 is formed at a position that overlaps the end of the tube 300 when viewed along the x-axis.

The recess 221 may be formed over the entire range from the lower end to the upper end of the second tank 200 as in the present embodiment, but the recess 221 may be formed over the entire range from the lower end to the upper end of the second tank 200. It may be formed only in the upper part.

As shown in FIG. 2, a protrusion 211 is formed around a portion of the inner surface of the second tank 200 to which the tube 300 is connected so as to protrude toward the inside of the second tank 200. There is. The protruding portion 211 becomes a surface that protrudes from other parts as it approaches the tube 300, the further it is located inside the second tank 200 and toward the distal end of the tube 300.

As mentioned above, the liquid phase refrigerant tends to flow along the inner surface of the second tank 200. In this 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 flows along the protrusion 211 into the tube. 300 is guided to the tip side. This makes it easier for the liquid phase refrigerant to flow into the flow path FP of the tube 300 compared to the case where the protrusion 211 is not formed.

As described above, in this embodiment, a protrusion is provided around the part of the inner surface of the second tank 200 to which the tube 300 is connected, for guiding the refrigerant flowing along the inner surface to the end of the tube 300. 211 is formed. This allows the liquid phase refrigerant to be distributed more evenly to each tube 300.

As shown in FIG. 1, the first port 110, which is an inlet portion, is formed to protrude from the first tank 100 in the −x direction. 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 that flows into the internal space of the first tank 100 while flowing through the first port 110 in the x direction flows into the flow path FP of each tube 300 without generally changing its flow direction. It flows in and continues to flow in the x direction. Therefore, it is possible to reduce flow path resistance due to a change in the flow direction of the refrigerant.

Further, the second port 120, which is the outlet portion, is also formed to protrude from the first tank 100 in the −x direction. 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 flows into the second port 120 without generally changing its flow direction. It will flow in and be discharged from the second port 120 in the −x direction. Therefore, it is possible to reduce flow path resistance due to a change in the flow direction of the refrigerant.

As mentioned above, the position where the separator 130 is arranged in the first tank 100 is a position closer to the lower side than the center along the vertical direction of the internal space of the first tank 100. There is. Therefore, the number of tubes 300 located above the separator 130 is greater than the number of tubes 300 located below the separator 130. The effect of having such a configuration of the heat exchanger 10 will be explained with reference to FIG. 6.

In FIG. 6, a heat exchange core CR and a first tank 100 and a second tank 200 on both sides thereof are schematically shown. A dashed-dotted 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 refrigerant in the tube 300 located below the separator 130 is indicated by an arrow AR1. In this embodiment, as described above, the number of tubes 300 located below the separator 130 is smaller than the number of tubes 300 located above. Therefore, compared to the case where the separator 130 is arranged at the center in the vertical direction, the flow velocity of the refrigerant indicated by the arrow AR1 is higher.

When the refrigerant having such a high flow rate flows into the internal space SP of the second tank 200, the refrigerant immediately collides with the inner wall of the second tank 200, causing turbulence in the flow. In FIG. 6, such a flow of refrigerant is indicated by an arrow AR2.

When turbulence occurs in the flow of the refrigerant, the gaseous refrigerant and the liquid refrigerant are mixed, and the liquid 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 distributed in this manner is indicated by an arrow AR3.

In this way, in the heat exchanger 10 according to the present embodiment, the number of tubes 300 located above the separator 130 is greater than the number of tubes 300 located below the separator 130, so that the This makes it possible to more evenly distribute the refrigerant to each tube 300.

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

In such a configuration, since turbulence is more likely to occur in the flow of the refrigerant after turning, the mixing of the gaseous refrigerant and the liquid refrigerant as described above is further promoted.

Note that the position where the constricted portion 230 is formed may be any position that is part of a predetermined range that includes the height corresponding to the separator 130. The size of this "predetermined range" is preferably the size of the range where the three tubes 300 are connected along the vertical direction. Furthermore, if the gas phase refrigerant and the liquid phase refrigerant are sufficiently mixed even if the throttle section 230 is not formed, the throttle section 230 may be omitted.

The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design changes made by those skilled in the art as appropriate to these specific examples are also included within the scope of the present disclosure as long as they have the characteristics of the present disclosure. The elements included in each of the specific examples described above, their arrangement, conditions, shapes, etc. are not limited to those illustrated, and can be changed as appropriate. The elements included in each of the specific examples described above can be appropriately combined as long as no technical contradiction occurs.

10: Heat exchanger 100: First tank 110: First port 120: Second port 130: Separator 200: Second tank 300: Tube FP: Flow path SP: Internal space

Claims (7)

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 arranged in a stacked manner along the vertical direction;
a 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;
The internal space of the first tank is divided into upper and lower parts by a separator (130),
An inlet portion (110) that serves as an inlet for the refrigerant when functioning as an evaporator is provided in a portion of the first tank below the separator;
An outlet portion (120) that serves as an outlet for the refrigerant when functioning as an evaporator is provided in a portion of the first tank above the separator;
Let A _tube be the sum of all cross-sectional areas in a cross section perpendicular to the longitudinal direction of the flow path (FP) formed inside the tube above the separator,
Let A _tank be the cross-sectional area of the internal space (SP) formed inside the second tank in a cross section perpendicular to the vertical direction;
When L1 _tank is the length along the vertical direction of the portion above the separator in the second tank, expressed in millimeters,
A _tank /A _tube ≦0.00000378×L1 _tank 2-0.00305×L1 _tank +0.78510
and L1 _tank =140
A heat exchanger configured to meet A protrusion (211) for guiding the refrigerant flowing along the inner surface to the end of the tube is formed around a portion of the inner surface of the second tank to which the tube is connected. , The heat exchanger according to claim 1. The length along the longitudinal direction of the tube located above the separator is L1tube,
The total value of all wetted edge lengths in a cross section perpendicular to the longitudinal direction of the flow path formed inside the tube above the separator is defined as L2tube,
When the length of the wetted edge in a cross section perpendicular to the vertical direction of the internal space formed inside the second tank is L2tan,
(L1tube×L2tube/Atube)×(Atank/(L1tank×L2tank))≦0.00000378×L1tank2-0.00305×L1tank+0.78510
The heat exchanger according to claim 1 or 2, configured to satisfy the following. In a part of the second tank within a predetermined range including a position at a height corresponding to the separator,
Any one of claims 1 to 3, wherein a cross-sectional area of the internal space formed inside the second tank in a cross section perpendicular to the vertical direction is locally smaller than the cross-sectional area of other parts. 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 to 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 are both in the longitudinal direction of the tube. The heat exchanger according to any one of claims 1 to 5, wherein the heat exchanger is in a direction along. The heat exchanger according to any one of claims 1 to 6, wherein the number of tubes located above the separator is greater than the number of tubes located below the separator.

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