JP7805162B2 - Heat exchanger plate, heat exchanger plate stack, and microchannel heat exchanger - Google Patents

Description

This disclosure relates to heat exchanger plates, heat exchanger plate stacks, and microchannel heat exchangers.

Known microchannel heat exchangers use thin plates of metals, such as stainless steel or copper, less than a few millimeters thick. These plates are etched to form minute channels, which are then stacked to allow different fluids to flow alternately across a heat transfer wall, exchanging heat. Microchannel heat exchangers achieve a large heat transfer area in a small volume by densely stacking a large number of minute channels, each with a hydraulic diameter of less than a few millimeters. Because the minute channels are composed of multiple parallel channels connected to inlet and outlet headers, they are prone to drift. This is particularly true when the fluid is a liquid or two-phase gas-liquid flow, which involves boiling or evaporation. In this regard, for example, Patent Document 1 (Patent Document 1) describes a phenomenon in which evaporation of the liquid phase of a first fluid flowing through a first channel generates bubbles, causing the first fluid to flow backward, resulting in drift of the first fluid in the first channel. Therefore, in this document, the upstream portion of the first channel is formed in a corrugated shape, and the downstream portion is formed in a straight shape. This makes it easier for air bubbles to flow downstream, preventing the first fluid from drifting.

Japanese Patent Application Laid-Open No. 2019-020068

According to the findings of the present inventors, when forming fine flow channels in heat exchanger plates using etching, there are two methods: etching from one side to form semicircular flow channels, or etching from both sides and connecting the etched surfaces to form flow channels with cross sections approaching square or rectangular. For a given flow channel hydraulic diameter, etching from both sides of the plate is preferable to achieve a compact heat exchanger with a larger heat transfer area per volume. Furthermore, square and rectangular flow channels have more corners than semicircular flow channels. Surface tension causes liquid films to collect at the corners, thinning the liquid film thickness in other areas, resulting in an enhanced evaporation heat transfer effect, resulting in a higher heat transfer coefficient. However, because this structure results in slit-shaped flow channels, it is difficult to maintain a constant spacing between the flow channel walls when the flow channel length is long. Furthermore, when the plates are stacked and assembled by diffusion bonding, the flow channel walls may deform, making it impossible to maintain the flow channel shape, resulting in poor bonding and flow drift.
Furthermore, although the above-mentioned patent documents have a certain effect in suppressing uneven flow of the first fluid, there is room for further improvement.

The objective of this disclosure is to provide a heat exchanger plate, a heat exchanger plate stack, and a microchannel heat exchanger that achieve both compactness and a high heat transfer coefficient.

A heat exchanger plate according to at least one embodiment of the present disclosure comprises:
an inlet header defined by a first opening;
an outlet header formed by the second opening;
a plurality of partition walls provided between the inlet header and the outlet header so as to divide a fluid flow path from the inlet header to the outlet header into a plurality of parallel flow paths;
a connecting portion that connects the plurality of partition walls,
one or more of the partition walls has a notch at a position of the connecting portion in the flow direction of the fluid,
The pair of parallel flow paths on both sides of the partition wall having the notch communicate with each other via the notch.

A plate stack for a heat exchanger according to at least one embodiment of the present disclosure comprises:
a plurality of first heat exchanger plates configured to allow a first fluid to flow from the inlet header to the outlet header;
a plurality of second heat exchanger plates configured to allow a second fluid to flow from the inlet header to the outlet header and arranged alternately with the plurality of first heat exchanger plates;

A microchannel heat exchanger according to at least one embodiment of the present disclosure includes the above-described heat exchanger plate stack.

This disclosure makes it possible to provide a heat exchanger plate, a heat exchanger plate stack, and a microchannel heat exchanger that achieve both compactness and a high heat transfer coefficient.

FIG. 1 is a conceptual illustration of a microchannel heat exchanger according to one embodiment. FIG. 2 is another conceptual illustration of a microchannel heat exchanger according to one embodiment. 3 is a conceptual cross-sectional view of the plate stack taken along the line AA in FIG. 2 . FIG. 2 is a conceptual explanatory diagram of a first heat exchanger plate according to one embodiment. FIG. 4 is a conceptual explanatory diagram of a second heat exchanger plate according to one embodiment. FIG. 10 is a conceptual enlarged view of a partition wall and a notch according to one embodiment. 7 is a conceptual cross-sectional view of the partition wall and the notch as viewed in the direction of the arrows BB in FIG. 6.

Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.
For example, expressions expressing relative or absolute arrangement such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions such as "identical,""equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained.
On the other hand, the expressions "comprise,""include," or "have" one element are not exclusive expressions that exclude the presence of other elements.
Note that the same components will be denoted by the same reference numerals and the description thereof will be omitted.

<1. Overview of Microchannel Heat Exchanger 1>
1 to 5, an overview of a microchannel heat exchanger 1 (hereinafter, sometimes simply referred to as "heat exchanger 1") according to one embodiment of the present disclosure will be illustrated. FIG. 1 is a conceptual explanatory diagram of the heat exchanger 1 according to one embodiment. FIG. 2 is another conceptual explanatory diagram of the heat exchanger 1 according to one embodiment. FIG. 3 is a conceptual cross-sectional view of a plate stack 30 as viewed in the direction of the arrows A-A in FIG. 2. FIG. 4 is a conceptual explanatory diagram of a first heat exchanger plate 31 according to one embodiment. FIG. 5 is a conceptual explanatory diagram of a second heat exchanger plate 32 according to one embodiment.

As shown in FIG. 1 , a heat exchanger 1 according to an embodiment of the present disclosure is incorporated into a refrigeration cycle including a primary refrigerant circuit 11 through which a first fluid F1 circulates and a secondary refrigerant circuit 12 through which a second fluid F2 circulates. In this embodiment, the first fluid F1 flows into the heat exchanger 1 in a gas-liquid two-phase state, and the second fluid F2 flows into the heat exchanger 1 in a gas-phase state having a higher saturation temperature than the first fluid F1. The first fluid F1 is heated and evaporated through the heat exchange, exits the heat exchanger 1, and returns to a gas-liquid two-phase state while circulating through the primary refrigerant circuit 11 as a primary refrigerant. Although not shown in detail, the primary refrigerant circuit 11 in this example includes a compressor, a condenser, an expansion valve, and the like. The first fluid F1 in a gas-liquid two-phase state expanded by the expansion valve flows into the heat exchanger 1. Meanwhile, the second fluid F2 is cooled by heat exchange and flows out of the heat exchanger 1 in a relatively low-temperature liquid phase. The second fluid F2 cools other heat transfer media while circulating through the secondary refrigerant circuit 12 as a secondary refrigerant. The secondary refrigerant circuit 12 in this example includes a receiver, a pump, a cooler, and the like. The cooler may be configured to exchange heat between the second fluid F2 and a heat transfer media such as air circulating inside the freezer. The second fluid F2, evaporated through heat exchange in the cooler, returns to the heat exchanger 1 in a gaseous phase. As an example, the first fluid F1 is _NH3 in a gaseous or liquid phase, and the second fluid F2 is _CO2 in a gaseous or liquid phase. However, the first fluid F1 and the second fluid F2 may be refrigerants other than those mentioned above, and the second fluid F2 may be a liquid that does not undergo a phase change, such as brine.

A heat exchanger 1 according to one embodiment of the present disclosure comprises a plate stack 30 including a plurality of stacked plates 35 and a pair of end plates 37, 38 sandwiching the plurality of plates 35 from both sides. The plates included in the plate stack 30 are connected to each other by, for example, diffusion bonding.

As shown in Figures 1 and 2, a first supply pipe 51 that supplies a first fluid F1 in a two-phase gas-liquid state via an expansion valve to the plate stack 30 and a first discharge pipe 59 that discharges the first fluid F1 are joined to the end plate 37. The first supply pipe 51 and the first discharge pipe 59 are respectively connected to a first communication port 41 and a second communication port 42 provided in each of the stacked plates 35.

Furthermore, the end plate 37 is provided with a second supply pipe 52 that supplies the second fluid F2 in a relatively high-temperature gas phase supplied from the cooler to the plate stack 30, and a second discharge pipe 57 that discharges the second fluid F2 in a relatively low-temperature liquid phase toward the receiver. The second supply pipe 52 and second discharge pipe 57 are respectively connected to the third communication port 43 and the fourth communication port 44 provided in each of the stacked plates 35.

The description of the configuration of the multiple plates 35 of this embodiment will continue with reference to Figures 2 and 3. Inside the multiple plates 35, multiple parallel flow paths 318 through which the first fluid F1 supplied from the first communication port 41 flows, and multiple parallel flow paths 328 through which the second fluid F2 supplied from the third communication port 43 flows are formed. The multiple parallel flow paths 318 and the multiple parallel flow paths 328 are separated from each other.

Specifically, the multiple plates 35 sandwiched between a pair of end plates 37, 38 include multiple first heat exchanger plates 31 and multiple second heat exchanger plates 32 arranged alternately along the stacking direction, and multiple partition plates 33. The first heat exchanger plates 31 and second heat exchanger plates 32 are each sandwiched between a pair of partition plates 33 on both sides of the stacking direction. In other words, the multiple plates 35 are configured such that, starting from one side of the stacking direction, the first heat exchanger plates 31, partition plates 33, second heat exchanger plates 32, and partition plates 33 are arranged in this order. Hereinafter, these three types of plates will be collectively referred to simply as "plates 35," and the thickness direction of the plates 35 will sometimes be referred to as the "plate thickness direction." The plate thickness direction coincides with the stacking direction of the plate stack 30.

As shown in FIG. 4 , the first heat exchanger plate 31 includes an inlet header 311 formed by first openings 111 including first communication ports 41, an outlet header 312 formed by second openings 122 including second communication ports 42, and multiple partition walls 315 provided between the inlet header 311 and the outlet header 312. The multiple partition walls 315 are provided so as to separate the flow path of the first fluid F1 toward the inlet header 311 and the outlet header 312 into multiple parallel flow paths 318. In this example, each partition wall 315 extends linearly between the inlet header 311 and the outlet header 312. In the following description, the extension direction of the partition walls 315 will sometimes be referred to as the "flow direction of the first fluid F1," and the direction in which the multiple partition walls 315 are arranged will sometimes be referred to as the "width direction of the parallel flow paths 318." As described above, in this embodiment, the first heat exchanger plate 31 is sandwiched between a pair of partition plates 33 (see Figure 3). Therefore, the parallel flow paths 318 are defined by multiple partition walls 315 and a pair of partition plates 33. Furthermore, although the inlet header 311 in this embodiment is configured so that the flow path width narrows toward the downstream side, inlet headers 311 in other embodiments may be configured so that the flow path width on the upstream side is the same as the flow path width on the downstream side.

As shown in FIG. 5 , the second heat exchanger plate 32 includes an inlet header 321 formed by the first openings 221 including the third communication port 43, an outlet header 322 formed by the second openings 222 including the fourth communication port 44, and a plurality of partition walls 325 provided between the inlet header 321 and the outlet header 322. The plurality of partition walls 325 are provided so as to separate the flow path of the second fluid F2 toward the inlet header 321 and the outlet header 322 into a plurality of parallel flow paths 328. In this example, each partition wall 325 extends linearly and bends between the inlet header 321 and the outlet header 322. In the following description, the extension direction of the partition wall 325 will sometimes be referred to as the "flow direction of the second fluid F2," and the direction in which the plurality of partition walls 325 are arranged will sometimes be referred to as the "width direction of the parallel flow paths 328." As described above, in this embodiment, the second heat exchanger plate 32 is sandwiched between a pair of partition plates 33 (see Figure 3). Therefore, the parallel flow paths 328 are defined by multiple partition walls 315 and the pair of partition plates 33.

Heat exchange between the first fluid F1 and the second fluid F2 in the heat exchanger 1 having the structure described above with reference to Figures 1 to 5 is carried out as follows. The first fluid F1, which flows from the inlet header 311 into the multiple parallel flow paths 318, exchanges heat with the second fluid F2, which flows from the inlet header 321 into the multiple parallel flow paths 328, via the partition plate 33. The first fluid F1, which flows in in a gas-liquid two-phase state, is heated as it moves downstream in the flow direction of the first fluid F1 and is discharged from the heat exchanger 1 in a vaporized state from the outlet header 312 via the first discharge pipe 59. On the other hand, the second fluid F2, which flows in in a relatively high-temperature gas phase, is cooled and condensed as it moves downstream in the flow direction of the second fluid F2 and is discharged from the heat exchanger 1 in a relatively low-temperature liquid phase from the outlet header 322 via the second discharge pipe 57.

<2. Details of the configuration of the first heat exchanger plate 31>
4, 6, and 7, details of the first heat exchanger plate 31 according to one embodiment of the present disclosure are illustrated. Fig. 6 is a conceptual enlarged view of the partition wall 315 and the notch 314 according to one embodiment. Fig. 7 is a conceptual cross-sectional view of the partition wall 315 and the notch 314 as viewed in the direction of the arrows B-B in Fig. 6.

<2-1. Structure of the connecting portion 317 and the notch 314>
6, the first heat exchanger plate 31 of this embodiment includes at least one connecting portion 317 that connects the plurality of partition walls 315. In this embodiment, all of the partition walls 315 are connected to any of the connecting portions 317, but two or more partition walls 315 without any connecting portion 317 may be provided.

In this embodiment, one or more of the multiple partition walls 315 have a notch 314 at the position of the connecting portion 317 in the flow direction of the first fluid F1. The notch 314 is aligned with the connecting portion 317 in the width direction of the parallel flow path 318. In this example, a notch 314 is provided in each of all of the partition walls 315. Furthermore, in this embodiment, a pair of parallel flow paths 318 on either side of a partition wall 315 having a notch 314 communicate with each other via the notch 314. In other words, a communication path 316 communicating with the pair of parallel flow paths 318 is defined by the notch 314.

Therefore, as illustrated in the enlarged view of FIG. 4 , the first fluid F1 can move between the multiple parallel flow paths 318 via the communication paths 316 defined by the notches 314. Mixing and branching of the first fluid F1 flowing through each of the multiple parallel flow paths 318 occurs, thereby equalizing the flow pattern of the first fluid F1 in the multiple parallel flow paths 318. This can prevent localized dryout, in which the liquid-phase first fluid F1 disappears, for example, downstream of the parallel flow paths 318. Therefore, the first heat exchanger plate 31 can achieve a high heat transfer coefficient. Furthermore, the provision of the connecting portions 317 can prevent deformation and misalignment of the partition walls 315 before and during assembly of the first heat exchanger plate 31. In particular, when diffusion bonding is performed on plates constituting the plate stack 30, such as the first heat exchanger plate 31, uniform heating is not possible immediately after heating begins, resulting in a temperature gradient in the plates. As a result, there is a risk that the partition wall 315 may be deformed due to differential expansion caused by the temperature gradient, but in this embodiment, the provision of the connecting portion 317 makes it possible to suppress such deformation.

A processing method for fabricating the connecting portion 317 according to one embodiment of the present disclosure is, for example, as follows (see Figures 6 and 7). First, a plate-shaped substrate for fabricating the first heat exchanger plate 31 is subjected to double-sided etching so as to form the parallel flow path 318. Then, instead of double-sided etching, a half-etching process is performed only at the location where the connecting portion 317 is to be installed, thereby forming the connecting portion 317. Therefore, the connecting portion 317 is connected only to one end 315A of each of the multiple partition walls 315 on one side in the plate thickness direction. Therefore, the connecting portion 317 can function as a restrictor that partially blocks the parallel flow path 318. Note that in the example of Figure 7, the portion of the partition wall 315 from approximately the center in the plate thickness direction to the one end 315A is connected to the connecting portion 317.

According to the inventors' speculation, the pressure of the first fluid F1 flowing through the parallel flow path 318 may fluctuate significantly. For example, pressure fluctuations due to boiling of the liquid phase first fluid F1 (bubbles are indicated by the symbol Bu in the enlarged view at the bottom of FIG. 4 ) or differences in the dryness of the first fluid F1 may cause differences in pressure. In such cases, drift of the first fluid F1 is likely to occur.
In this regard, according to the above configuration, the connecting portion 317 is connected to only one end 315A of each partition wall 315 in the plate thickness direction. Therefore, the connecting portion 317 also functions as a throttle that partially blocks the parallel flow paths 318. This causes an appropriate pressure loss in the connecting portion 317, making it possible to reduce the pressure difference between the multiple parallel flow paths 318 caused by the pressure fluctuations described above.
Therefore, the first fluid F1 can easily flow through the communication passages 316 defined by the notches 314, thereby suppressing the weaving of the first fluid F1 in the multiple parallel flow passages 318. Therefore, the first heat exchanger plate 31 can achieve a high heat transfer coefficient.

4, the connecting portions 317 and the notches 314 are configured to be aligned horizontally, but the present disclosure is not limited to this. For example, the connecting portions 317 may be arranged to be aligned horizontally at positions that avoid the notches 314. As one example, the connecting portions 317 may be arranged in a row so as to connect the upstream ends of the multiple partition walls 315 (i.e., so as to face the inlet header 311). As another example, the connecting portions 317 may be arranged in a row so as to connect the downstream ends of the multiple partition walls 315 (i.e., so as to face the outlet header 312). As yet another example, the connecting portions 317 may be arranged in a row between the notches 314A and 314D, between the notches 314D and 314C, or between the notches 314C and 314B shown in FIG. 4. The connecting portions 317 may be arranged at regular intervals from the inlet header 311 toward the outlet header 312. In this case, one of the connecting portions 317 arranged at regular intervals in the flow direction of the first fluid F1 is aligned left and right with the notch 314. Note that the connecting portions 317 do not have to be arranged at equal intervals from the inlet header 311 toward the outlet header 312.

As shown in Figures 6 and 7, the notch 314 in this embodiment is formed at the other end 315B of each of the multiple partition walls 315, which is the other end in the plate thickness direction. The notch bottom 309 of the notch 314 and the other surface 317F of the connecting portion 317 are located at the same position in the plate thickness direction. In other words, the surface 317F of the connecting portion 317 is directly connected to the notch bottom 309. With this configuration, the first fluid F1 that passes through the connecting passage 316 defined by the notch 314 can flow into the parallel flow passage 318 along the other surface 317F of the connecting portion 317. The first fluid F1 passing through the connecting portion 317 mixes and branches as it flows from the connecting passage 316 to the parallel flow passage 318. This suppresses the weaving of the first fluid F1 in the multiple parallel flow passages 318, allowing the first heat exchanger plate 31 to achieve a high overall heat transfer coefficient.

Furthermore, as shown in FIG. 6 , the upstream end 399 of the connecting portion 317 in the flow direction of the first fluid F1 is recessed in an arc shape toward the downstream side. This configuration makes it possible to prevent excessive pressure loss that occurs when the first fluid F1 passes through the connecting portion 317 along the flow direction of the first fluid F1. This makes it possible to prevent separation of the flow of the first fluid F1 along the extension direction of the partition wall 315. Therefore, it is possible to prevent an increase in pressure loss.

Furthermore, in the flow direction of the first fluid F1, both ends of the connecting portion 317 are located outward relative to both ends of the notch 314. This configuration prevents the connecting portion 317 from deforming the shape of the partition wall 315 or the parallel flow path 328.

<2-2. Example of arrangement of notch 314 (communication passage 316)>
4, an example of the arrangement of the notch 314 will be described. Note that, in the following description, an embodiment will be illustrated in which the notch 314 and the connecting portion 317 are arranged at the same position relative to each other in the flow direction of the first fluid F1, but the positions of the notch 314 and the connecting portion 317 in the flow direction may be different.

In this embodiment, multiple notches 314 are arranged in the width direction of the parallel flow path 318, in four rows along the flow direction of the first fluid F1. Of the four rows of notches 314, the notch 314 in the row located most upstream is the first notch 314A, and the notch 314 in the row located most downstream is the second notch 314B. The notch 314 adjacent to the second notch 314B in the flow direction of the first fluid F1 is the third notch 314C, and the notches 314 adjacent to both the first notch 314A and the third notch 314C are the fourth notch 314D. That is, the multiple notches 314 include, from the upstream side, multiple first notches 314A (first row), multiple fourth notches 314D (second row), multiple third notches 314C (third row), and multiple second notches 314B (fourth row). The communication passage 316 defined by the first notches 314A is the first communication passage 316A. Similarly, the communication passages 316 defined by the second notches 314B, third notches 314C, and fourth notches 314D are the second communication passage 316B, third communication passage 316C, and fourth communication passage 316D, respectively. Note that in this embodiment, as an example, the numbers of first notches 314A, second notches 314B, third notches 314C, and fourth notches 314D are the same.

In the present embodiment, a first distance between the inlet header 311 and the one or more notches 314 in the flow direction of the first fluid F1 is shorter than a second distance between the outlet header 312 and the one or more notches 314 in the flow direction of the first fluid F1. As a more specific example, the first distance is the shortest distance (dimension L1) from the inlet header 311 to the center of the first notch 314A, and the second distance is the shortest distance (dimension L2) from the outlet header 312 to the center of the second notch 314B. According to the above configuration, because the first distance is shorter than the second distance, the first communication passage 316A (communication passage 316) defined by the first notch 314A approaches the inlet header 311. As a result, even if bubbles are generated or grow due to boiling of the liquid phase of the first fluid F1 between the inlet header 311 and the first notches 314A, the bubbles can be guided to the first communication passages 316A formed by the first notches 314A. Therefore, uneven flow of the first fluid F1 in the multiple parallel flow passages 318 caused by bubbles flowing back into the inlet header 311 is suppressed, and a first heat exchanger plate 31 with a high overall heat transfer coefficient can be provided.
In other embodiments, the notches 314 may not include at least one of the first notch 314A, the second notch 314B, the third notch 314C, and the fourth notch 314D. For example, in an embodiment in which the second notch 314B, the third notch 314C, and the fourth notch 314D are not provided, the second distance is the distance (dimension M) between the first notch 314A and the outlet header 312. Even in this case, the above-described advantages can be obtained. Similarly, in an embodiment in which only the third notch 314C and the fourth notch 314D are provided among the second notch 314B, the third notch 314C, and the fourth notch 314D, the second distance is the distance between the third notch 314C and the outlet header 312.

Furthermore, in this embodiment, one or more notches 314 are included in each of the multiple partition walls 315, and multiple first notches 314A are provided that are arranged at the same position relative to one another in the flow direction of the first fluid F1. Therefore, the first communication passages 316A, which are communication passages 316 defined by the first notches 314A, are aligned in the width direction of the parallel flow passages 318. With this configuration, even if bubbles are generated in any of the multiple parallel flow passages 318, they can flow into any of the first communication passages 316A, thereby suppressing drift of the first fluid F1 and preventing bubbles from flowing back into the inlet header 311.

In this embodiment, the first distance (dimension L1 in the example of FIG. 4 ) is greater than 0% and less than 10% of the total length (dimension K) of the parallel flow path 318, and more preferably greater than 0% and 5% or less. The effects brought about by this configuration are as follows.
According to the above configuration, the first distance is greater than 0% and less than 10% of the total length of the parallel flow paths 318, so that the first fluid F1 that has just flowed from the inlet header 311 into each of the multiple parallel flow paths 318 mixes through the first communication passage 316A formed by the first notch 314A. That is, the first communication passage 316A functions similarly to the inlet header 311, and the first fluid F1 that has flowed from the inlet header 311 into the parallel flow paths 318 passes through the throttles of each parallel flow path 318 and is supplied downstream. Furthermore, unlike the inlet header 311, the first communication passage 316A does not have a rightward (unidirectional) flow; instead, it allows flow in both directions. Therefore, even if there is an imbalance in the gas-liquid ratio (dryness fraction) among the multiple parallel flow paths 318, the first fluid F1 can be mixed and redistributed within the first communication passage 316A to eliminate this imbalance. Furthermore, even if bubbles are generated in the first fluid F1 in the parallel flow paths 318 and cause a backflow, the bubbles are mixed with the flow from the inlet header 311 in the first communication passage 316A, redistributed, and supplied to the parallel flow paths 318. Therefore, the dryness fraction of the first fluid F1 on the upstream side of the multiple parallel flow paths 318 can be equalized, and uneven flow of the first fluid F1 can be suppressed. Therefore, a first heat exchanger plate 31 with a high overall heat transfer coefficient can be provided.

The first heat exchanger plate 31 of this embodiment also includes one or more adjacent notches 313 located downstream of the first notch 314A and adjacent to the first notch 314A in the flow direction of the first fluid F1. In this example, the fourth notch 314D corresponds to the adjacent notch 313. The adjacent distance (dimension A), which is the shortest distance between the first notch 314A and the adjacent notch 313, is 25% or more and less than 90% of the total length of the parallel flow path 318. It is more preferable that this adjacent distance be 25% or more and less than 35% of the total length of the parallel flow path 318.
If the first notch 314A and the adjacent notch 313 are too close to each other in the flow direction, the flow of the first fluid F1 in the communicating passage 316 (the fourth communicating passage 316D in this example) formed by the adjacent notch 313 becomes excessively weak, making it difficult for the first fluid F1 to mix among the multiple parallel flow passages 318. In this regard, with the above configuration, the first notch 314A and the adjacent notch 313 are appropriately spaced apart from each other, which optimizes the flow of the first fluid F1 in the communicating passage 316 and promotes mixing of the first fluid F1 in the multiple parallel flow passages 318. Therefore, a heat exchanger plate with a high overall heat transfer coefficient can be achieved.

Note that the present disclosure is not limited to embodiments in which the fourth notch 314D corresponds to the adjacent notch 313. In embodiments in which the fourth notch 314D is not provided among the second notch 314B, the third notch 314C, and the fourth notch 314D, the third notch 314C corresponds to the adjacent notch 313 adjacent to the first notch 314A in the flow direction of the first fluid F1. In this case, the adjacent distance is preferably 50% or more and less than 60% of the total length of the parallel flow path 318.

In this embodiment, as described above, the one or more notches 314 include a first notch 314A and a second notch 314B. With this configuration, the first fluid F1 can flow between the multiple parallel flow paths 318 via the second communication path 316B, which is the communication path 316 formed by the second notch 314B located downstream of the first notch 314A. Therefore, the first fluid F1 can be appropriately mixed between the multiple parallel flow paths 318. This prevents the first fluid F1 from drifting between the multiple parallel flow paths 318, allowing the heat exchanger plate to achieve a high overall heat transfer coefficient.

In this embodiment, the second distance (dimension L2 in the example shown in Figure 4) is 10% or more and 35% or less of the total length of the parallel flow paths 318. According to the inventors' findings, when the first heat exchanger plate 31 is used so that the first fluid F1 in a gas-liquid two-phase state is supplied to the inlet header 311, the dryness fraction tends to vary depending on the parallel flow paths 318 upstream of the multiple parallel flow paths 318. In particular, the dryness fraction of the first fluid F1 tends to be higher in the parallel flow paths 318 connected to the upstream portion (the portion close to the first communication port 41) of the first openings 111 forming the inlet header 311, and dryout tends to occur more easily downstream in the flow direction of the parallel flow paths 318. On the other hand, a thinner liquid film of the liquid-phase first fluid F1 flowing through the parallel flow paths 318 exhibits a higher heat transfer coefficient. Therefore, it is preferable that the position where the first fluid F1 flows into a parallel flow path 318 where dryout may occur from another parallel flow path 318 be close to the position where dryout may occur. In this regard, with the above configuration, the second communication path 316B defined by the second notch 314B is appropriately separated from the outlet header 312, thereby promoting mixed flow of the first fluid F1 slightly upstream of the region where dryout is expected to occur. Therefore, the first heat exchanger plate 31 can effectively suppress dryout of the first fluid F1 while suppressing a decrease in the overall heat transfer coefficient.

As described above, the notch 314 in this embodiment further includes one or more third notches 314C. The third notch 314C is located between the first notch 314A and the second notch 314B and adjacent to the second notch 314B in the flow direction of the first fluid F1. The distance (dimension B) between the inlet header 311 and the third notch 314C is greater than or equal to 50% and less than 60% of the total length of the parallel flow path 318. According to the above configuration, the first fluid F1 mixes among the multiple parallel flow paths 318 via the third communication path 316C, which is the communication path 316 formed by the third notch 314C. In addition to increasing the opportunities for the first fluid F1 to mix, the first notch 314A and the third notch 314C are appropriately spaced apart, ensuring the flow of the first fluid F1 in the third communication passage 316C and further effectively promoting the mixing of the first fluid F1 between the multiple parallel flow passages 318.

As described above, the notches 314 in this embodiment include one or more fourth notches 314D. The fourth notches 314D are located between the first notches 314A and the second notches 314B and adjacent to the first notches 314A in the flow direction of the first fluid F1. The shortest distance (dimension A) between the inlet header 311 and the fourth notches 314D is 25% or more and less than 35% of the total length of the parallel flow paths 318. According to the above configuration, the first fluid F1 mixes among the multiple parallel flow paths 318 via the fourth communication path 316D, which is the communication path 316 formed by the fourth notches 314D located between the first notches 314A and the second notches 314B. In addition to increasing the opportunities for the first fluid F1 to mix, the first notch 314A and the fourth notch 314D are appropriately spaced apart from each other, ensuring the flow of the first fluid F1 in the fourth communication passage 316D and further effectively promoting the mixing of the first fluid F1 between the multiple parallel flow passages 318.

3. Details of the Configuration of the Second Heat Exchanger Plate 32
5 , the configuration of the second heat exchanger plate 32 is illustrated in detail. The second heat exchanger plate 32 has a configuration similar to that of the first heat exchanger plate 31. Specifically, the second heat exchanger plate 32 includes an inlet header 321 formed in the first opening 221, an outlet header 322 formed by the second opening 222, and a plurality of partition walls 325 provided between the inlet header 321 and the outlet header 322. The plurality of partition walls 325 are provided to separate the flow path of the second fluid F2 from the inlet header 321 toward the outlet header 322.

<5. Other>
The present disclosure is not limited to the above-described embodiments. The parallel flow paths 318 may partially include flow paths formed in a zigzag pattern instead of extending linearly over the entire length of the parallel flow paths 318. The zigzag pattern is a concept that includes a pattern with curved corners and a pattern with straight bent corners.

<6. Summary>
The present disclosure can be understood, for example, as follows.

1) The heat exchanger plate (first heat exchanger plate 31) according to at least one embodiment of the present disclosure is
an inlet header (311) formed by a first opening (111);
an outlet header (312) formed by the second opening (122);
a plurality of partition walls (315) provided between the inlet header and the outlet header so as to divide a flow path of a fluid (first fluid F1) flowing from the inlet header to the outlet header into a plurality of parallel flow paths (318);
A connecting portion (317) that connects the plurality of partition walls;
Equipped with
At least one of the plurality of partition walls has a notch (314) at a position of the connection portion in the flow direction of the fluid;
The pair of parallel flow paths on both sides of the partition wall having the notch communicate with each other via the notch.

The above configuration 1) prevents deformation of the partition walls and parallel flow paths, which are issues when fabricating compact heat exchangers with high overall heat transfer coefficients using double-sided etching, and the resulting poor bonding during assembly. Furthermore, fluid can move between multiple parallel flow paths via the communication paths defined by the notches. This allows fluids with different dryness levels to mix, equalizing the flow patterns of the fluids in the multiple parallel flow paths. This prevents localized dryout in the parallel flow paths, in which liquid fluid disappears, and allows the heat exchanger plate to achieve a high overall heat transfer coefficient. As a result, a heat exchanger plate that achieves both compactness and a high overall heat transfer coefficient can be provided.

2) In some embodiments, the heat exchanger plate according to 1) above,
The connecting portion is connected to only one end (315A) of each of the partition walls on one side of both ends of each of the partition walls in the plate thickness direction.

According to the inventors' speculation, the pressure of the fluid flowing through the parallel flow paths can fluctuate significantly. For example, if bubbles are generated or grow in a particular parallel flow path due to the evaporation of the fluid, the fluid pressure in that parallel flow path fluctuates significantly. To give another example, if the dryness fraction of the fluid increases as the fluid flows through the parallel flow paths, the fluid pressure will fluctuate significantly as well. In this regard, with the configuration of 2) above, the connecting portion is connected to only one end of each partition wall in the plate thickness direction. Therefore, the connecting portion also functions as a throttle that partially blocks the parallel flow path. This generates an appropriate pressure loss at the connecting portion, minimizing the pressure difference between the multiple parallel flow paths due to the pressure fluctuations described above. Therefore, the fluid flows more easily through the connecting passages defined by the notches, suppressing the weaving of the fluid in the multiple parallel flow paths. This allows the heat exchanger plate to achieve a high overall heat transfer coefficient.

3) In some embodiments, the heat exchanger plate according to 1) or 2) above,
The notch is formed at the other end (315B) of the plurality of partition walls in the plate thickness direction,
The notch bottom (309) of the notch and the surface (317F) on the other side of the connecting portion are at the same position in the plate thickness direction.

According to the configuration of 3) above, fluid that passes through the communication passage defined by the notch can flow along the other surface of the connecting portion into the parallel passage. By passing the fluid through the connecting portion, excessive pressure loss of the fluid flowing from the communication passage to the parallel passage can be prevented, and fluid stagnation in the communication passage can be suppressed. This prevents fluid from becoming intertwined in the multiple parallel passages, allowing the heat exchanger plate to achieve a high heat transfer coefficient.

4) In some embodiments, the heat exchanger plate according to 2) or 3) above,
An upstream end (399) of the connecting portion in the flow direction of the fluid is recessed in an arc shape toward the downstream side.

The configuration described in 4) above prevents excessive pressure loss that occurs when fluid passes through the connecting section in the flow direction, and prevents the flow of fluid in the flow direction from the upstream side to the downstream side of the connecting section from weakening excessively. In other words, the fluid flow in the connecting passage defined by the notch can be prevented from becoming excessively dominant, thereby equalizing the flow patterns of the fluid among the multiple parallel flow paths.

5) In some embodiments, the heat exchanger plate according to any one of 1) to 4) above,
In the direction of flow of the fluid, both ends of the connecting portion are positioned outward relative to both ends of the notch.

The configuration described in 5) above prevents deformation of the partition wall and parallel flow path shape due to the connecting portion.

6) In some embodiments, the plate stack (30) for a heat exchanger according to any one of 1) to 5) above is
The heat exchanger includes a plurality of first heat exchanger plates (first heat exchanger plates 31) according to any one of 1) to 5) above.

The configuration of 6) above makes it possible to provide a heat exchanger plate stack that is both compact and has a high heat transfer coefficient, for the same reasons as 1) above.

7) In some embodiments, the microchannel heat exchanger described in 6) above comprises:
The heat exchanger plate stack according to 6) above is provided.

The configuration of 7) above makes it possible to provide a heat exchanger that is both compact and has a high heat transfer coefficient, for the same reasons as 1) above.

1: Heat exchanger (microchannel heat exchanger)
30: Plate stack 31: First heat exchanger plate 32: Second heat exchanger plate 35: Plates 111, 122: First openings 122, 222: Second opening 309: Notch bottoms 311, 321: Inlet headers 312, 322: Outlet headers 314, 324: Notches 315, 325: Partition wall 315A: One end 317, 327: Connection portion 317F: Surfaces 318, 328: Parallel flow path 325: Partition wall 327: Connection portion 399: Upstream end F1: First fluid F2: Second fluid

Claims (7)

an inlet header defined by a first opening;
an outlet header formed by the second opening;
a plurality of partition walls provided between the inlet header and the outlet header so as to divide a fluid flow path from the inlet header to the outlet header into a plurality of parallel flow paths;
a connecting portion that connects the plurality of partition walls in a partial region of an area in which the plurality of partition walls extend along the flow direction of the fluid; and
Equipped with
one or more of the partition walls has a notch at a position of the connecting portion in the flow direction of the fluid,
The pair of parallel flow paths on both sides of the partition wall having the notch communicate with each other via the notch,
A heat exchanger plate, wherein a pair of adjacent partition walls sandwiching one of the parallel flow paths in the width direction of the flow paths are separated from each other in a region other than the partial region of the range. The heat exchanger plate according to claim 1 , wherein the connecting portion is connected to only one end of each of the plurality of partition walls in the plate thickness direction, the end being located on one side. the notch is formed at an end of one of the plurality of partition walls on the other side in the plate thickness direction,
3. The heat exchanger plate according to claim 2, wherein the bottom of the notch and the surface on the other side of the connecting portion are located at the same position in the plate thickness direction. an inlet header defined by a first opening;
an outlet header formed by the second opening;
a plurality of partition walls provided between the inlet header and the outlet header so as to divide a fluid flow path from the inlet header to the outlet header into a plurality of parallel flow paths;
a connecting portion that connects the plurality of partition walls;
Equipped with
one or more of the partition walls has a notch at a position of the connecting portion in the flow direction of the fluid,
a pair of the parallel flow paths on both sides of the partition wall having the notch communicate with each other via the notch;
the connecting portion is connected to only one end of each of the partition walls on one side of both ends of the partition walls in the plate thickness direction,
The heat exchanger plate has an upstream end of the connecting portion in the flow direction of the fluid that is recessed in an arc shape toward the downstream side. 5. The heat exchanger plate according to claim 1, wherein both ends of the connecting portion are positioned outward relative to both ends of the notch in the direction of fluid flow. A heat exchanger plate stack comprising a plurality of first heat exchanger plates according to any one of claims 1 to 5. A microchannel heat exchanger comprising the heat exchanger plate stack described in claim 6.