Plate type liquid distribution structure and micro-channel heat exchanger

Abstract

The application discloses a plate type liquid distribution structure and a micro-channel heat exchanger. The plate type liquid distribution structure comprises an inlet pipe, a liquid distribution plate, a header and a liquid distribution flat pipe. The liquid distribution plate is provided with an inlet hole, an internal passage and four external passages. The internal passage is located in the interior of the liquid distribution plate, and the inlet hole and the external passages are respectively located on the front face and the back face of the liquid distribution plate. The header comprises a body structure, and the body structure is provided with a flat pipe groove. One end of the flat pipe groove is provided with an entrance hole. The outlets of the first, second, third and fourth external passages are respectively communicated with one entrance hole of the header. The liquid distribution flat pipe is internally provided with a plurality of micro-channels. One end of the liquid distribution flat pipe is inserted into the flat pipe groove, and the micro-channels are communicated with the interior of the flat pipe groove. The application mainly adopts the plate type structure to form a liquid distribution flow path. The local resistance of the distribution points is kept consistent by using the flow path arrangement, so that the liquid distribution uniformity is better.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration technology and equipment technology, and relates to a plate-type liquid distribution structure and a microchannel heat exchanger. Background Technology

[0002] Microchannel heat exchangers are high-efficiency, compact heat exchangers, mainly composed of flat tubes with multiple microchannels and manifolds for flow distribution and convergence. At the evaporator inlet, the refrigerant is typically in a gas-liquid two-phase state. When the liquid distribution in the microchannel heat exchanger is uneven, branches with less liquid will experience dry evaporation and superheating, while branches with more liquid will experience liquid carryover at the outlet, thus hindering the heat exchanger's capacity. To improve the performance of microchannel heat exchangers, a reasonable liquid distribution system is essential, and the design of the liquid distribution structure often needs to consider multiple factors such as complexity, manufacturing difficulty, and production cost.

[0003] The existing disadvantages of the liquid separation structure of microchannel heat exchangers are:

[0004] 1. Traditional external distributors are mature in copper tube heat exchangers, but microchannel heat exchangers have a large number of flat tubes. Using external distributors results in a complex structure, higher cost, and is not conducive to compressing space and forming an integrated liquid distribution structure.

[0005] 2. Setting up a liquid distribution structure on the manifold of a microchannel heat exchanger can achieve integrated flow distribution, but limited space and complex processes are the main limitations for practical applications. Summary of the Invention

[0006] In view of this, the present invention provides a plate-type liquid distribution structure and a microchannel heat exchanger, which mainly adopts a plate structure to form a liquid distribution flow path. The flow path arrangement makes the local resistance at the distribution point consistent, thereby achieving better liquid distribution uniformity.

[0007] To address the aforementioned problems, embodiments of the present invention provide a plate-type liquid distribution structure, characterized in that:

[0008] It includes inlet pipe, separator plate, manifold and separator flat tube.

[0009] The separatory plate has an inlet hole, an internal channel, and four external channels; the internal channels are located inside the separatory plate, and the inlet hole and external channels are located on the front and back of the separatory plate, respectively.

[0010] The internal channels include a vertically arranged first channel, the middle of which is connected to an inlet pipe through an inlet hole; the upper end of the first channel leads into the middle of a second channel, which is horizontally arranged, and its two ends are respectively connected to a third vertical channel and a fourth vertical channel, the outlets of which are respectively connected to the hollow channels of the third and fourth external channels; the lower end of the first channel leads into the middle of a third channel, which is horizontally arranged, and its two ends are respectively connected to the first vertical channel and a second vertical channel, the outlets of which are respectively connected to the hollow channels of the first and second external channels.

[0011] The manifold includes a body structure with a flat tube groove on it; one end of the flat tube groove has an inlet hole; the outlets of the first external channel, the second external channel, the third external channel and the fourth external channel are respectively connected to an inlet hole of the manifold.

[0012] The liquid separating flat tube has several microchannels inside. One end of the liquid separating flat tube is inserted into the flat tube groove, and its microchannels are connected to the inside of the flat tube groove.

[0013] In some embodiments, the liquid-dispensing flat tube is further included, wherein the microchannels of the liquid-dispensing flat tube are symmetrical about the central axis, and the two symmetrical microchannels are connected to each other, and a through hole is provided on the central axis of the liquid-dispensing flat tube.

[0014] The flat tube has the same structure as the liquid separator flat tube; the through holes on the flat tube are respectively connected to one through hole of the liquid separator flat tube.

[0015] In some embodiments, the system further includes a flat tube, wherein the microchannels of the dispensing flat tube are divided into a symmetrical left half and a right half along the central axis; the microchannels of the left half are symmetrical about the central axis and are connected to each other, and the two symmetrical microchannels are connected to each other, with a through hole provided on the central axis;

[0016] The flat tube has the same structure as the liquid separator flat tube; the through holes on the flat tube are respectively connected to one through hole of the liquid separator flat tube.

[0017] In some embodiments, the external channel is a block structure, and the hollow channel is disposed inside the block structure. Two through holes with opposite directions are provided at both ends of the channel. One through hole is connected to its corresponding vertical channel, and the other through hole is an outlet hole that is connected to an inlet hole of the manifold.

[0018] In some embodiments, the outlet holes of the first external channel, the second external channel, the third external channel and the fourth external channel are equidistant in the vertical direction.

[0019] In some embodiments, the inlet hole penetrates the body structure of the manifold, the flat tube groove is connected to the inlet hole, one end of the inlet hole is connected to the outlet hole of the external channel, and the other end of the inlet hole is blocked by a side plate.

[0020] This invention also proposes another plate-type liquid separation structure, which is characterized by:

[0021] It includes an inlet pipe, a separating plate, a manifold, and a separating flat tube. The separating plate has an inlet hole, an internal channel, and eight external channels. The internal channels are located inside the separating plate, while the inlet hole and external channels are located on the front and back of the separating plate, respectively.

[0022] The internal channels include a vertically arranged first channel, the middle of which is connected to an inlet pipe through an inlet hole; the upper end of the first channel leads into the middle of a second channel, which is horizontally arranged, and its two ends are connected to a third and a fourth vertical channel, respectively; the bottom end of the third vertical channel splits into two paths that enter one vertical channel, the outlet of one vertical channel is connected to the first external hollow channel, and the outlet of the other vertical channel is connected to the hollow channel of the third external channel; the bottom end of the fourth vertical channel splits into two paths that enter one vertical channel, the outlet of one vertical channel is connected to the hollow channel of the second external channel, and the outlet of the other vertical channel is connected to the hollow channel of the fourth external channel.

[0023] The lower end of the first channel leads into the middle of the third channel. The third channel is horizontally positioned, and its two ends are connected to the first vertical channel and the second vertical channel, respectively. The bottom end of the first vertical channel splits into two paths, each entering a separate vertical channel. The outlet of one vertical channel is connected to the hollow channel of the seventh external channel, and the outlet of the other vertical channel is connected to the hollow channel of the fifth external channel. The bottom end of the second vertical channel splits into two paths, each entering a separate vertical channel. The outlet of one vertical channel is connected to the hollow channel of the sixth external channel, and the outlet of the other vertical channel is connected to the hollow channel of the eighth external channel.

[0024] The manifold includes a body structure with a flat tube groove on it; one end of the flat tube groove has an inlet hole; the outlets of the first external channel to the eighth external channel are respectively connected to an inlet hole of the manifold.

[0025] The liquid separating flat tube has several microchannels inside. One end of the liquid separating flat tube is inserted into the flat tube groove, and its microchannels are connected to the inside of the flat tube groove.

[0026] In some embodiments, the liquid-dispensing flat tube is further included, wherein the microchannels of the liquid-dispensing flat tube are symmetrical about the central axis, and the two symmetrical microchannels are connected to each other, and a through hole is provided on the central axis of the liquid-dispensing flat tube.

[0027] The flat tube has the same structure as the liquid separator flat tube; the through holes on the flat tube are respectively connected to one through hole of the liquid separator flat tube.

[0028] In some embodiments, the system further includes a flat tube, wherein the microchannels of the dispensing flat tube are divided into a symmetrical left half and a right half along the central axis; the microchannels of the left half are symmetrical about the central axis and are connected to each other, and the two symmetrical microchannels are connected to each other, with a through hole provided on the central axis;

[0029] The flat tube has the same structure as the liquid separator flat tube; the through holes on the flat tube are respectively connected to one through hole of the liquid separator flat tube.

[0030] In some embodiments, the external channel is a block structure, and the hollow channel is disposed inside the block structure. Two through holes with opposite directions are provided at both ends of the channel. One through hole is connected to its corresponding vertical channel, and the other through hole is an outlet hole, which is connected to an inlet hole of the manifold.

[0031] In some embodiments, the outlet holes of the first external channel to the eighth external channel are equidistant in the vertical direction.

[0032] In some embodiments, the inlet hole penetrates the body structure of the manifold, the flat tube groove is connected to the inlet hole, one end of the inlet hole is connected to the outlet hole of the external channel, and the other end of the inlet hole is blocked by a side plate.

[0033] The present invention also proposes a microchannel heat exchanger, which is characterized by including the above-mentioned plate-type liquid distribution structure.

[0034] Compared with the prior art, the plate-type liquid distribution structure and microchannel heat exchanger of the present invention have at least the following beneficial effects:

[0035] 1. The arrangement of the liquid distribution flow path in this invention ensures that the local resistance at the distribution point remains consistent, thereby achieving better liquid distribution uniformity.

[0036] 2. For microchannel inlet flow rates that are linearly or symmetrically distributed, the dispensing flat tube can effectively improve the uniformity of dispensing between microchannels.

[0037] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This invention provides a plate-type liquid separator structure for achieving four-way liquid separation;

[0040] Figure 2 for Figure 1 A structural diagram of the separatory plate in the middle;

[0041] Figure 3 for Figure 1 Structural diagram of the manifold;

[0042] Figure 4 for Figure 1 The diagram shows the separation flat tube and the structure of the flat tube.

[0043] Figure 5 This is a structural diagram of another type of liquid separatory flat tube and flat tube;

[0044] Figure 6 This invention provides a plate-type liquid separator structure for achieving 8-channel liquid separation;

[0045] Figure 7 for Figure 6 The structural diagram of the separatory plate in the image. Detailed Implementation

[0046] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0047] In the description of this invention, it should be clearly stated that the terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence; the terms "vertical," "lateral," "longitudinal," "front," "rear," "left," "right," "up," "down," "horizontal," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, and are merely for the convenience of describing this invention, and do not mean that the device or element referred to must have a specific orientation or position, and therefore should not be construed as a limitation of this invention.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] Example 1

[0050] This embodiment provides a plate-type liquid distribution structure for achieving four-way liquid distribution. See [link to relevant documentation]. Figures 1-3 It includes inlet pipe 1, liquid distribution plate 2, manifold 3 and liquid distribution flat tube 4.

[0051] The liquid separation plate 2 is provided with several liquid separation units.

[0052] Each dispensing unit includes an inlet hole 201, an internal channel, and four external channels 203; the internal channels are located inside the dispensing plate 2, and the inlet hole 201 and the external channels 203 are located on the front and back sides of the dispensing plate 2, respectively.

[0053] The internal channels include a vertically arranged first channel, the middle of which is connected to the inlet pipe 1 through an inlet hole 201; the upper end of the first channel leads into the middle of a second channel, which is horizontally arranged, and its two ends are respectively connected to a third vertical channel and a fourth vertical channel, the outlets of which are respectively connected to the hollow channels of the third and fourth external channels. The lower end of the first channel leads into the middle of the third channel, which is horizontally arranged, and its two ends are respectively connected to the first vertical channel and a second vertical channel, the outlets of which are respectively connected to the hollow channels of the first and second external channels.

[0054] The manifold 3 includes a body structure with a flat tube groove 302 on it; one end of the flat tube groove 302 is provided with an inlet hole 301; the outlet holes 204 of the first external channel, the second external channel, the third external channel and the fourth external channel are respectively connected to one inlet hole 301 of the manifold 3; the liquid separating flat tube 4 is provided with a plurality of microchannels inside, and one end of the liquid separating flat tube 4 is inserted into the flat tube groove 302, and its microchannels are connected to the inside of the flat tube groove 302.

[0055] Figure 2 The arrows in the right view (b) indicate the direction of refrigerant flow, and the various channels are separated from each other. The external channel 203 is a hollow aluminum block with holes at both ends as the inlet and outlet of the channel. For a liquid distribution unit, the liquid distribution plate 2 has one inlet hole 201 and four outlet holes, and completes four-way liquid distribution through two bi-divisions within its internal channel.

[0056] In this embodiment, see Figure 2 The refrigerant enters the internal channel of the distributor plate 2 through inlet hole 201. One stream flows upward along the upper half of the first channel, splits into two streams at the top, entering the left and right halves of the second channel respectively, and then flowing downward into the third and fourth vertical channels respectively, exiting from channel outlet 202. The other stream flows downward along the lower half of the first channel, splits into two streams at the bottom, entering the left and right halves of the third channel respectively, and then flowing upward into the first and second vertical channels respectively, exiting from channel outlet 202. The local resistance at each split point is the same. Each channel outlet 202 connects to the external channel 203, and finally flows out from the outlet hole 204 of the external channel 203, completing the liquid separation.

[0057] As a preferred embodiment of the present invention, see [link to previous document]. Figure 2 The first external channel, the second external channel, the third external channel and the fourth external channel are arranged sequentially from top to bottom, and the outlet holes of the first external channel, the second external channel, the third external channel and the fourth external channel are equidistant in the vertical direction.

[0058] As a preferred embodiment of the present invention, see [link to previous document]. Figure 3 The inlet hole 301 penetrates the main body structure of the manifold 3. The flat tube groove 302 is connected to the inlet hole 301. One end of the inlet hole 301 is connected to the outlet hole of the external channel, and the other end of the inlet hole 301 is blocked by the side plate 303.

[0059] Example 2

[0060] See Figure 6 and Figure 7 A plate-type liquid distribution structure for achieving 8-way liquid distribution includes an inlet pipe 1, a liquid distribution plate 2, a manifold 3, a liquid distribution flat tube 4, and a flat tube 5.

[0061] The liquid distribution plate 2 is provided with several liquid distribution units. Each liquid distribution unit includes an inlet hole 201, an internal channel and eight external channels 203; the internal channels are located inside the liquid distribution plate 2, and the inlet hole 201 and the external channels are located on the front and back of the liquid distribution plate 2, respectively.

[0062] The internal channels include a vertically arranged first channel, the middle of which is connected to the inlet pipe 1 through an inlet hole 201; the upper end of the first channel leads into the middle of the second channel, which is horizontally arranged, and the two ends of the second channel are respectively connected to a third vertical channel and a fourth vertical channel; the bottom end of the third vertical channel splits into two paths that enter one vertical channel respectively, the channel outlet of one vertical channel is connected to the first external hollow channel, and the channel outlet of the other vertical channel is connected to the hollow channel of the third external channel; the bottom end of the fourth vertical channel splits into two paths that enter one vertical channel respectively, the channel outlet of one vertical channel is connected to the hollow channel of the second external channel, and the channel outlet of the other vertical channel is connected to the hollow channel of the fourth external channel.

[0063] The lower end of the first channel leads into the middle of the third channel. The third channel is horizontally positioned, and its two ends connect to the first and second vertical channels, respectively. The bottom end of the first vertical channel splits into two paths, each entering a separate vertical channel. The outlet of one vertical channel connects to the hollow channel of the seventh external channel, and the outlet of the other vertical channel connects to the hollow channel of the fifth external channel. Similarly, the bottom end of the second vertical channel splits into two paths, each entering a separate vertical channel. The outlet of one vertical channel connects to the hollow channel of the sixth external channel, and the outlet of the other vertical channel connects to the hollow channel of the eighth external channel. The first to eighth external channels are arranged vertically from top to bottom, and their outlet holes are equidistant in the vertical direction.

[0064] The manifold 3 includes a body structure, on which a flat tube groove 302 is provided; one end of the flat tube groove 302 is provided with an inlet hole 301; the outlets of the first external channel to the eighth external channel are respectively connected to an inlet hole 301 of the manifold 3; the liquid separating flat tube 4 is provided with a plurality of microchannels inside, and one end of the liquid separating flat tube 4 is inserted into the flat tube groove 302, and its microchannels are connected to the inside of the flat tube groove 302.

[0065] The separation plate in this embodiment has a similar structure to the separation plate in the previous embodiment. Figure 2 The arrows in the right view of (b) indicate the direction of refrigerant flow, and the various channels are separated from each other. The external channel 203 is a hollow aluminum block with holes at both ends as the inlet and outlet of the channel. For a liquid distribution unit, the liquid distribution plate 2 has one inlet hole 201 and eight outlet holes, and completes eight-way liquid distribution through three dichotomies within its internal channel.

[0066] As a preferred embodiment of this invention, see [link to example]. Figure 3The inlet hole 301 penetrates the main body structure of the manifold 3. The flat tube groove 302 is connected to the inlet hole 301. One end of the inlet hole 301 is connected to the outlet hole of the external channel, and the other end of the inlet hole 301 is blocked by the side plate 303.

[0067] Example 3

[0068] Based on Examples 1 and 2, the plate-type liquid separation structure further includes a flat tube 5.

[0069] See Figure 4 The microchannels of the separating flat tube 4 are symmetrical about the central axis, and the two symmetrical microchannels are connected. A through hole is provided on the central axis of the separating flat tube 4. The flat tube 5 has the same structure as the separating flat tube 4; the through hole on the flat tube 5 is connected to one of the through holes of the separating flat tube 4.

[0070] After the refrigerant enters the manifold 3, it is distributed into the microchannels of the distribution flat tube 4 inserted into the flat tube groove 302. Uneven distribution of the refrigerant occurs between the microchannels as it enters. [This is in response to...] Figure 4 The inlet flow rate is linearly distributed. The flow channels of the distributor flat tube 4 are symmetrical about the central axis and connected left and right. That is, the leftmost microchannel is connected to the rightmost microchannel, the next leftmost microchannel is connected to the next rightmost microchannel, and so on. The outlet hole 401 of the distributor flat tube 4 is located on the central axis. Therefore, when the refrigerant flows out of the outlet hole 401, the refrigerant in the leftmost microchannel and the rightmost microchannel mixes with each other, and the other microchannels are similar.

[0071] The inlet hole 501 of the flat tube 5 corresponds one-to-one with the outlet hole 401 of the dispensing flat tube 4. After the refrigerant enters the inlet hole 501, it is divided into two streams, which enter the left and right microchannels respectively. Therefore, the refrigerant in the two microchannels is first mixed and then evenly distributed. When the inlet flow rate is linearly distributed, the leftmost microchannel is connected to the rightmost microchannel, so that the channel with the highest flow rate and the channel with the lowest flow rate mix with each other, complete the complementarity, and then redistribute the refrigerant, ultimately achieving uniform liquid distribution between the microchannels.

[0072] Example 4

[0073] Based on Examples 1 and 2, the plate-type liquid separation structure further includes a flat tube 5.

[0074] See Figure 5 The microchannel of the liquid separating flat tube 4 is divided into a symmetrical left half and a right half along the central axis; the microchannel of the left half is symmetrical about the central axis and is connected to the left and right sides, and the two symmetrical microchannels are connected to each other, and a through hole is provided on the central axis; the flat tube 5 has the same structure as the liquid separating flat tube 4; the through hole on the flat tube 5 is connected to one through hole of the liquid separating flat tube 4.

[0075] This structure addresses the symmetrical distribution of flow rate at the microchannel inlet, including both a symmetrical distribution with higher flow rate in the center and lower flow rate on both sides, and a symmetrical distribution with lower flow rate in the center and higher flow rate on both sides. The outlet orifice 401 of the dispensing flat tube 4 is divided into two rows. The microchannel is divided into left and right parts along the central axis. In the left half, the leftmost microchannel is connected to the rightmost microchannel, the next leftmost microchannel is connected to the next rightmost microchannel, and so on. In the right half, the leftmost microchannel is connected to the rightmost microchannel, the next leftmost microchannel is connected to the next rightmost microchannel, and so on.

[0076] The inlet hole 501 of the flat tube 5 corresponds one-to-one with the outlet hole 401 of the dispensing flat tube 4. After the refrigerant enters the inlet hole 501, it is divided into two streams, which enter the left and right microchannels respectively. Thus, the refrigerant in the two microchannels first mixes and then is evenly distributed. When the inlet flow rate is symmetrically distributed, the channel with the highest and lowest flow rate in the left half mixes with each other, complements each other, and then redistributes; similarly, the channel with the highest and lowest flow rate in the right half mixes with each other, complements each other, and then redistributes, ultimately achieving uniform liquid distribution between the microchannels.

[0077] Similarly, the approach provided by this invention can be used to design a system that evenly distributes the flow entering from the inlet pipe. n The structure of the road will not be listed here.

[0078] Example 6

[0079] A microchannel heat exchanger includes the plate-type liquid distribution structure described above. Thus, the microchannel heat exchanger also contains all the functions and effects of the aforementioned manifold liquid distribution structure, which will not be elaborated here.

[0080] It will be readily understood by those skilled in the art that, without conflict, the aforementioned advantageous technical features can be freely combined and superimposed.

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A plate type liquid distribution structure, characterized in that: comprising an inlet pipe (1), a distribution plate (2), a header (3) and a distribution flat pipe (4); the distribution plate (2) is provided with an inlet hole (201), an internal passage and four external passages; the internal passage is located in the inside of the distribution plate (2), and the inlet hole (201) and the external passages are located on the front and back of the distribution plate (2) respectively; the internal passage comprises a first passage arranged vertically, the middle part of the first passage is communicated with the inlet pipe (1) through the inlet hole (201); the upper end of the first passage is communicated with the middle part of a second passage, the second passage is arranged horizontally, the two ends of the second passage are connected with a third vertical passage and a fourth vertical passage respectively, and the passage outlets on the third vertical passage and the fourth vertical passage are communicated with the hollow passages of the third external passage and the fourth external passage respectively; the lower end of the first passage is communicated with the middle part of a third passage, the third passage is arranged horizontally, the two ends of the third passage are connected with a first vertical passage and a second vertical passage respectively, and the passage outlets on the first vertical passage and the second vertical passage are communicated with the hollow passages of the first external passage and the second external passage respectively; the header (3) comprises a body structure, and the body structure is provided with a flat pipe groove (302); one end of the flat pipe groove (302) is provided with an entry hole (301); the outlets of the first external passage, the second external passage, the third external passage and the fourth external passage are communicated with one entry hole (301) of the header (3) respectively; the inside of the distribution flat pipe (4) is provided with a plurality of micro-passage, one end of the distribution flat pipe (4) is inserted into the flat pipe groove (302), and the micro-passage of the distribution flat pipe (4) is communicated with the inside of the flat pipe groove (302); further comprising a flat pipe (5), the micro-passage of the distribution flat pipe (4) is symmetrical about the central axis, the two micro-passage which are symmetrical are communicated, and the central axis of the distribution flat pipe (4) is provided with a through hole; the distribution form of the through hole on the flat pipe (5) is same as that of the micro-passage and the through hole of the distribution flat pipe (4); the through hole on the flat pipe (5) is communicated with one through hole of the distribution flat pipe (4) respectively; or, the micro-passage of the distribution flat pipe (4) is divided into symmetrical left half and right half along the central axis; the micro-passage of the left half is symmetrical about the center line and communicated, the two micro-passage which are symmetrical are communicated, and the center line is provided with a through hole; the distribution form of the through hole on the flat pipe (5) is same as that of the micro-passage and the through hole of the distribution flat pipe (4); the through hole on the flat pipe (5) is communicated with one through hole of the distribution flat pipe (4) respectively. 2.A plate type liquid distribution structure according to claim 1, characterized in that: the external passage is a block structure, the hollow passage is arranged in the inside of the block structure, the two ends of the passage are respectively provided with two through holes with opposite directions, one of the through holes is communicated with the corresponding vertical passage, and the other through hole is an outlet hole which is communicated with one entry hole (301) of the header (3); the outlet holes of the first external passage, the second external passage, the third external passage and the fourth external passage are arranged equidistantly in the vertical direction. 3.A plate type liquid distribution structure according to claim 2, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The entering hole (301) penetrates the body structure of the header (3), the flat tube groove (302) is communicated with the entering hole (301), one end of the entering hole (301) is communicated with the outlet hole of the external channel, and the other end of the entering hole (301) is blocked by the side plate (303).

4. A plate type liquid distribution structure, characterized in that: It comprises an inlet pipe (1), a liquid distribution plate (2), a header (3) and a liquid distribution flat tube (4), The liquid distribution plate (2) is provided with an inlet hole (201), an internal channel and eight external channels; The internal channel is located in the inside of the liquid distribution plate (2), and the inlet hole (201) and the external channels are respectively located on the front and back surfaces of the liquid distribution plate (2); The internal channel comprises a first channel arranged vertically, and the middle part of the first channel is communicated with the inlet pipe (1) through the inlet hole (201); The upper end of the first channel is communicated with the middle part of a second channel, the second channel is arranged horizontally, and the two ends of the second channel are respectively connected with a third vertical channel and a fourth vertical channel; the bottom end of the third vertical channel is divided into two paths and respectively enters a vertical channel, the channel outlet of one of the vertical channels is communicated with the hollow channel of the first external channel, and the channel outlet of the other vertical channel is communicated with the hollow channel of the third external channel; the bottom end of the fourth vertical channel is divided into two paths and respectively enters a vertical channel, the channel outlet of one of the vertical channels is communicated with the hollow channel of the second external channel, and the channel outlet of the other vertical channel is communicated with the hollow channel of the fourth external channel; The lower end of the first channel is communicated with the middle part of a third channel, the third channel is arranged horizontally, and the two ends of the third channel are respectively connected with a first vertical channel and a second vertical channel; the bottom end of the first vertical channel is divided into two paths and respectively enters a vertical channel, the channel outlet of one of the vertical channels is communicated with the hollow channel of the seventh external channel, and the channel outlet of the other vertical channel is communicated with the hollow channel of the fifth external channel; the bottom end of the second vertical channel is divided into two paths and respectively enters a vertical channel, the channel outlet of one of the vertical channels is communicated with the hollow channel of the sixth external channel, and the channel outlet of the other vertical channel is communicated with the hollow channel of the eighth external channel; The header (3) comprises a body structure, and the body structure is provided with a flat tube groove (302); one end of the flat tube groove (302) is provided with an entering hole (301); the outlets of the first external channel to the eighth external channel are respectively communicated with one entering hole (301) of the header (3); The inside of the liquid distribution flat tube (4) is provided with a plurality of micro-channels, one end of the liquid distribution flat tube (4) is inserted into the flat tube groove (302), and the micro-channels are communicated with the inside of the flat tube groove (302).

5. The plate type liquid distribution structure according to claim 4, characterized in that: It further comprises a flat tube (5), the micro-channels of the liquid distribution flat tube (4) are symmetrical about a central axis, the two symmetrical micro-channels are communicated, and a through hole is arranged on the central axis of the liquid distribution flat tube (4); The flat tube (5) and the micro-channels and the through hole of the liquid distribution flat tube (4) have the same distribution form; and the through holes on the flat tube (5) are respectively communicated with one through hole of the liquid distribution flat tube (4).

6. The plate type liquid distribution structure according to claim 4, characterized in that: Further comprising a flat tube (5), the microchannels of the flat tube (4) are divided into symmetrical left and right halves along the central axis; the microchannels of the left half are symmetrical about the center line and are connected left and right, and the two microchannels symmetrical left and right are connected; The distribution of the microchannels and the through holes of the flat tube (5) and the flat tube (4) are the same; the through holes on the flat tube (5) are respectively connected with one through hole of the flat tube (4).

7. The plate type liquid distribution structure according to any one of claims 4-6, characterized in that: The external channels are block structures, the hollow channels are arranged inside the block structures, two through holes with opposite directions are arranged at both ends of the channels, one of the through holes is connected with the corresponding vertical channel, and the other through hole is an outlet hole which is connected with one inlet hole (301) of the header (3); the outlet holes of the first to eighth external channels are arranged equidistantly in the vertical direction; The inlet hole (301) penetrates through the body structure of the header (3), the flat tube groove (302) is connected with the inlet hole (301), one end of the inlet hole (301) is connected with the outlet hole of the external channel, and the other end of the inlet hole (301) is blocked by the side plate (303).

8. A microchannel heat exchanger, characterized in that: It comprises the plate type liquid distribution structure according to any one of claims 1-7.

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