Plate heat exchanger and method for selecting plate heat exchanger

Abstract

The present invention provides a plate heat exchanger and a method for selecting a plate heat exchanger. The plate heat exchanger includes: a first heat exchange fin, the first heat exchange fin includes a first heat exchange plate and a first connection plate connected to each other, and a first liquid inlet connection hole is provided on the first connection plate; a second heat exchange fin, the second heat exchange fin includes a second heat exchange plate and a second connection plate connected to each other, a heat exchange flow channel is provided between the second heat exchange plate and the first heat exchange plate, a second liquid inlet connection hole is provided on the second connection plate, the second liquid inlet connection hole is arranged opposite to the first liquid inlet connection hole and forms a liquid inlet hole; wherein, the second connection plate is connected to the first connection plate, a liquid inlet channel is provided between the second connection plate and the first connection plate, one end of the liquid inlet channel is communicated with the liquid inlet hole, and the other end of the liquid inlet channel is communicated with the heat exchange flow channel. Through the technical solution provided by the present invention, the technical problem of uneven fluid distribution in the plate heat exchanger in the prior art can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of plate heat exchangers, and in particular, to a plate heat exchanger and a method for selecting a plate heat exchanger. Background Art

[0002] Currently, the plate heat exchanger in the prior art is a heat exchange device formed by stacking a series of metal sheets with a certain corrugated shape, which has the advantages of high heat transfer efficiency, light weight, small occupied space, compact structure, easy maintenance, etc., and is widely used in industries such as petrochemical, aerospace, refrigeration and heating.

[0003] When the working fluid of the heat exchanger is in a two-phase state, due to the complexity and uncertainty of two-phase flow, the phenomenon of uneven fluid distribution will occur, resulting in the underutilization of the heat transfer area and affecting the overall performance of the heat exchanger. Summary of the Invention

[0004] The main object of the present invention is to provide a plate heat exchanger and a method for selecting a plate heat exchanger to solve the technical problem of uneven fluid distribution in the plate heat exchanger in the prior art.

[0005] To achieve the above object, according to one aspect of the present invention, there is provided a plate heat exchanger, including: a first heat exchange sheet, the first heat exchange sheet includes a first heat exchange plate and a first connection plate connected to each other, and a first liquid inlet connection hole is provided on the first connection plate; a second heat exchange sheet, the second heat exchange sheet includes a second heat exchange plate and a second connection plate connected to each other, a heat exchange flow channel is provided between the second heat exchange plate and the first heat exchange plate, a second liquid inlet connection hole is provided on the second connection plate, the second liquid inlet connection hole is disposed opposite to the first liquid inlet connection hole and forms a liquid inlet hole; wherein, the second connection plate is connected to the first connection plate, a liquid inlet channel is provided between the second connection plate and the first connection plate, one end of the liquid inlet channel is communicated with the liquid inlet hole, and the other end of the liquid inlet channel is communicated with the heat exchange flow channel.

[0006] Further, a relief groove is provided on the first connection plate and / or the second connection plate, one end of the relief groove is communicated with the liquid inlet hole, and the other end of the relief groove is communicated with the heat exchange flow channel, so that the relief groove encloses the liquid inlet channel.

[0007] Further, a first relief groove is provided on the first connection plate, a second relief groove is provided on the second connection plate, and the first relief groove and the second relief groove are disposed opposite to each other to enclose the liquid inlet channel.

[0008] Further, the thickness of the heat exchange flow channel is h, the flow-through surface of the liquid inlet channel is a circular surface, the diameter of the flow-through surface of the liquid inlet channel is D, and 1 mm ≤ D ≤ h.

[0009] Further, there are a plurality of first avoidance grooves, and the plurality of first avoidance grooves are arranged at intervals on the first connecting plate; there are a plurality of second avoidance grooves, and the plurality of second avoidance grooves are arranged at intervals on the second connecting plate. The plurality of first avoidance grooves and the plurality of second avoidance grooves are arranged in one-to-one correspondence, and each first avoidance groove and the corresponding second avoidance groove are arranged opposite to each other to enclose a plurality of liquid inlet channels.

[0010] Further, a first liquid outlet connection hole is also arranged on the first heat exchange fin, and the first liquid inlet connection hole and the first liquid outlet connection hole are arranged at intervals along the extending direction of the first heat exchange fin; the liquid inlet channel includes a first liquid inlet channel, and the first liquid inlet channel is arranged on the side of the first liquid inlet connection hole away from the first liquid outlet connection hole.

[0011] Further, the included angle between the extending direction of the first liquid inlet channel and the extending direction of the first heat exchange fin is α, and 10° ≤ α ≤ 20°.

[0012] Further, the liquid inlet channel further includes a second liquid inlet channel, the second liquid inlet channel is arranged at intervals with the first liquid inlet channel, and the included angle between the liquid inlet direction of the second liquid inlet channel and the extending direction of the first liquid inlet channel is β, and 90° ≤ β ≤ 150°.

[0013] Further, the first liquid inlet channel has a first liquid inlet and a first liquid outlet that are communicated with each other, and the flow area of the first liquid outlet is smaller than the flow area of the first liquid inlet; and / or, the second liquid inlet channel has a second liquid inlet and a second liquid outlet that are communicated with each other, and the flow area of the second liquid outlet is smaller than the flow area of the second liquid inlet.

[0014] Further, the first liquid inlet channel has a first tapered section, and the outlet end of the first tapered section forms the first liquid outlet; along the liquid inlet direction of the first liquid inlet channel, the flow area of the first tapered section gradually decreases; and / or, the second liquid inlet channel has a second tapered section, and the outlet end of the second tapered section forms the second liquid outlet; along the liquid inlet direction of the second liquid inlet channel, the flow area of the second tapered section gradually decreases.

[0015] According to another aspect of the present invention, a method for selecting a plate heat exchanger is provided. The method for selecting a plate heat exchanger is applicable to the plate heat exchanger provided above. The method for selecting a plate heat exchanger includes: introducing a certain amount of fluid into a preselected plate heat exchanger and controlling the outlet temperature of the fluid to be T1, and detecting the inlet temperature T2 of the corresponding fluid; detecting whether the temperature difference T between the outlet temperature T1 and the inlet temperature T2 meets a preset condition; when the temperature difference T meets the preset condition, it is determined that the fluid distribution uniformity in the preselected plate heat exchanger meets the requirements; when the temperature difference T does not meet the preset condition, it is determined that the fluid distribution uniformity in the liquid inlet channel of the preselected plate heat exchanger does not meet the requirements, and the plate heat exchanger is reselected.

[0016] Furthermore, the method for detecting whether the temperature difference T between the outlet temperature T1 and the outlet temperature T2 meets the preset condition includes: comparing the temperature difference T with the preset temperature difference A; when T≥A, determining that the temperature difference T meets the preset condition; when T<A, determining that the temperature difference does not meet the preset condition.

[0017] Furthermore, the method for reselecting a plate heat exchanger includes: selecting the number of liquid inlet channels of the plate heat exchanger as n; selecting the maximum included angle among the n liquid inlet channels as γ, and detecting the reselected plate heat exchanger to determine whether the fluid distribution uniformity in the reselected plate heat exchanger meets the requirements.

[0018] Furthermore, the method for selecting the maximum included angle γ among the n liquid inlet channels includes: controlling the maximum included angle γ among the n liquid inlet channels to be between 90° and 150°.

[0019] Applying the technical solution of the present invention, by connecting the first connecting plate and the second connecting plate, and having a liquid inlet channel between the second connecting plate and the first connecting plate, in this way, the liquid in the liquid inlet hole flows into the heat exchange flow channel through the liquid inlet channel for heat exchange. The liquid inlet channel between the first connecting plate and the second connecting plate functions as liquid distribution, which is beneficial to improving the uniformity of liquid distribution. In addition, for the plate heat exchanger provided in this embodiment, there is no need to provide an additional distribution structure at the liquid inlet, and only the corresponding stamping process needs to be performed on the first heat exchange fin and the second heat exchange fin, which also reduces the manufacturing cost of the plate heat exchanger. Therefore, through the technical solution provided by the present invention, the technical problem of uneven fluid distribution in the plate heat exchanger in the prior art can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0021] Figure 1 shows a schematic structural diagram of a plate heat exchanger provided by an embodiment of the present invention;

[0022] Figure 2 shows a schematic structural diagram of a first heat exchange fin provided by an embodiment of the present invention;

[0023] Figure 3 shows a schematic structural diagram of a second heat exchange fin provided by an embodiment of the present invention;

[0024] Figure 4 shows a partially enlarged schematic view of the liquid inlet hole provided by an embodiment of the present invention;

[0025] Figure 5 Shows a layout schematic diagram between a first liquid inlet channel and a second liquid inlet channel provided according to an embodiment of the present invention;

[0026] Figure 6 Shows a partial cross-sectional view at the liquid inlet hole provided according to an embodiment of the present invention;

[0027] Figure 7 Shows a cross-sectional view of a plate heat exchanger provided according to an embodiment of the present invention;

[0028] Figure 8 Shows a schematic flow diagram of a method for selecting a plate heat exchanger provided according to an embodiment of the present invention;

[0029] Figure 9 Shows a comparison chart of the heat exchange capacity of a plate heat exchanger provided according to an embodiment of the present invention (where a single hole corresponds to the structure of one liquid inlet channel, and a double hole corresponds to the structure of two liquid inlet channels);

[0030] Figure 10 Shows the liquid phase flow rate ratio of a single hole and a double hole for distributing each parallel flow channel provided according to an embodiment of the present invention;

[0031] Figure 11 Shows the temperature difference of the water outlet between the heat exchange flow channel closest to the first end plate and the heat exchange flow channel closest to the second end plate provided according to an embodiment of the present invention;

[0032] Figure 12 Shows the lateral difference in the water outlet temperature in the heat exchange flow channel closest to the first end plate provided according to an embodiment of the present invention;

[0033] Figure 13 Shows a curve of the degree of superheat changing with the refrigerant mass flow rate provided according to an embodiment of the present invention;

[0034] Figure 14 Shows a curve of the heat exchange amount changing with the refrigerant mass flow rate provided according to an embodiment of the present invention.

[0035] Among them, the above-mentioned drawings include the following reference numerals:

[0036] 10. First heat exchange fin; 11. First heat exchange plate; 12. First connecting plate; 13. First liquid inlet connection hole; 14. First avoidance groove; 15. First liquid outlet connection hole; 20. Second heat exchange fin; 21. Second heat exchange plate; 22. Second connecting plate; 23. Second liquid inlet connection hole; 24. Second avoidance groove; 31. Liquid inlet hole; 32. First liquid inlet channel; 321. First tapered section; 33. Second liquid inlet channel; 331. Second tapered section; 34. Heat exchange flow channel; 41. First end plate; 42. Second end plate; 50. Nozzle. Specific Embodiment

[0037] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0038] As Figures 1 to 7 shown, Embodiment 1 of the present invention provides a plate heat exchanger, which includes a first heat exchange fin 10 and a second heat exchange fin 20. The first heat exchange fin 10 includes a first heat exchange plate 11 and a first connecting plate 12 that are connected to each other, and a first liquid inlet connection hole 13 is provided on the first connecting plate 12. The second heat exchange fin 20 includes a second heat exchange plate 21 and a second connecting plate 22 that are connected to each other. There is a heat exchange flow channel 34 between the second heat exchange plate 21 and the first heat exchange plate 11. A second liquid inlet connection hole 23 is provided on the second connecting plate 22. The second liquid inlet connection hole 23 is disposed opposite to the first liquid inlet connection hole 13 and forms a liquid inlet hole 31. Among them, the second connecting plate 22 is connected to the first connecting plate 12, and there is a liquid inlet channel between the second connecting plate 22 and the first connecting plate 12. One end of the liquid inlet channel is communicated with the liquid inlet hole 31, and the other end of the liquid inlet channel is communicated with the heat exchange flow channel 34. Specifically, a refrigerant can be introduced into the liquid inlet channel in this embodiment.

[0039] With such a structural arrangement, by connecting the first connecting plate 12 and the second connecting plate 22, and having a liquid inlet channel between the second connecting plate 22 and the first connecting plate 12, in this way, the liquid in the liquid inlet hole 31 flows into the heat exchange flow channel 34 through the liquid inlet channel for heat exchange. The liquid inlet channel between the first connecting plate 12 and the second connecting plate 22 functions as a liquid distributor, which is beneficial to improving the uniformity of liquid distribution. The plate heat exchanger in this embodiment includes a plurality of first heat exchange fins 10 and a plurality of second heat exchange fins 20. The plurality of first heat exchange fins 10 and the plurality of second heat exchange fins 20 are arranged in cooperation. There is a heat exchange flow channel 34 between each first heat exchange fin 10 and the corresponding second heat exchange fin 20. The liquid inlet channels between each first heat exchange fin 10 and the corresponding second heat exchange fin 20 are communicated with the corresponding heat exchange flow channels 34. In this way, through a plurality of liquid inlet channels, liquid distribution can be effectively carried out, so that the liquid enters the corresponding heat exchange flow channels 34 through each liquid inlet channel for heat exchange. In addition, by using the plate heat exchanger provided in this embodiment, there is no need to provide an additional distribution structure at the liquid inlet, and only the corresponding stamping process needs to be performed on the first heat exchange fin 10 and the second heat exchange fin 20, which also reduces the manufacturing cost of the plate heat exchanger.

[0040] Specifically, an avoidance groove may be provided on the first connecting plate 12; or an avoidance groove may be provided on the second connecting plate 22; or avoidance grooves may be provided on both the first connecting plate 12 and the second connecting plate 22. In the above structure, one end of the avoidance groove is communicated with the liquid inlet hole 31, and the other end of the avoidance groove is communicated with the heat exchange flow channel 34, so that the avoidance groove encloses a liquid inlet channel. With such a structural arrangement, it is only necessary to stamp an avoidance groove on the first connecting plate 12, or the second connecting plate 22, or both the first connecting plate 12 and the second connecting plate 22. The structure is simple and convenient for production and manufacturing.

[0041] Preferably, a first avoidance groove 14 is provided on the first connecting plate 12 in this embodiment, and a second avoidance groove 24 is provided on the second connecting plate 22. The first avoidance groove 14 and the second avoidance groove 24 are arranged opposite to each other to enclose a liquid inlet channel. With such a structural arrangement, it is convenient to form a liquid inlet channel between the first connecting plate 12 and the second connecting plate 22. The structure is simple and convenient for production and manufacturing.

[0042] In this embodiment, the thickness of the heat exchange flow channel 34 is h, the flow-through surface of the liquid inlet channel is a circular surface, and the diameter of the flow-through surface of the liquid inlet channel is D, where 1mm ≤ D ≤ h. With such a structural arrangement, on the one hand, it can ensure that the liquid inlet channel can smoothly inlet liquid, and on the other hand, it can avoid that the size of the liquid inlet channel is larger than that of the heat exchange flow channel 34, which is not conducive to throttling.

[0043] Specifically, there are multiple first avoidance grooves 14 in this embodiment, and the multiple first avoidance grooves 14 are arranged at intervals on the first connecting plate 12; there are multiple second avoidance grooves 24, and the multiple second avoidance grooves 24 are arranged at intervals on the second connecting plate 22. The multiple first avoidance grooves 14 and the multiple second avoidance grooves 24 are arranged in one-to-one correspondence, and each first avoidance groove 14 and the corresponding second avoidance groove 24 are arranged opposite to each other to enclose multiple liquid inlet channels. With such a structural arrangement, the liquid enters the heat exchange flow channel 34 after passing through the multiple liquid inlet channels arranged at intervals, which is convenient for the liquid to flow in after being dispersed, so as to better improve the uniformity of liquid distribution.

[0044] In this embodiment, a first liquid outlet connection hole 15 is further provided on the first heat exchange fin 10, and the first liquid inlet connection hole 13 and the first liquid outlet connection hole 15 are arranged at intervals along the extending direction of the first heat exchange fin 10. The liquid inlet channel includes a first liquid inlet channel 32, and the first liquid inlet channel 32 is arranged on the side of the first liquid inlet connection hole 13 away from the first liquid outlet connection hole 15. With such a structural arrangement, it is convenient to smoothly inlet liquid into the heat exchange flow channel 34 through the first liquid inlet channel 32, and avoid the situation that some liquid cannot be better filled into the heat exchange flow channel 34 for heat exchange, thereby effectively ensuring the heat exchange performance.

[0045] Specifically, the included angle α between the extending direction of the first liquid inlet channel 32 and the extending direction of the first heat exchange fin 10 in this embodiment is such that 10° ≤ α ≤ 20°. When the included angle α is within this range, more refrigerant can flow to the heat exchange area of the heat exchange channel 34 for heat exchange, preventing the refrigerant from entering the flow dead zone (where the refrigerant cannot flow smoothly and cannot effectively conduct heat exchange), thereby facilitating better improvement of the heat exchange effect. It should be noted that the heat exchange area of the heat exchange channel 34 in this embodiment mainly refers to the area between the first liquid inlet connection hole 13 and the first liquid outlet connection hole 15. The flow dead zone of the heat exchange channel 34 in this embodiment is mainly the four corners of the flow channel. There are no corrugations at the four corners, and almost no heat exchange occurs, and the fluid cannot flow out normally from the inlet. The flow dead zone includes the area where the first liquid inlet connection hole 13 is far from the first liquid outlet connection hole 15 and the area where the first liquid outlet connection hole 15 is far from the first liquid inlet connection hole 13.

[0046] In this embodiment, the liquid inlet channel further includes a second liquid inlet channel 33. The second liquid inlet channel 33 is arranged at an interval from the first liquid inlet channel 32. The included angle β between the liquid inlet direction of the second liquid inlet channel 33 and the extending direction of the first liquid inlet channel 32 is such that 90° ≤ β ≤ 150°. By making β greater than or equal to 90°, it can be ensured that the refrigerant flowing out from the first liquid inlet channel 32 and the second liquid inlet channel 33 can directly enter the heat exchange area of the heat exchange channel 34 for heat exchange, avoiding the situation where the refrigerant in the first liquid inlet channel 32 and the second liquid inlet channel 33 enters the flow dead zone; by making β less than 150°, it can be avoided that the first liquid inlet channel 32 and the second liquid inlet channel 33 are too close to each other, so that the refrigerant can flow out from two different directions, facilitating better improvement of the liquid distribution uniformity of the refrigerant in the heat exchange channel 34. In this way, by setting the included angle between the liquid inlet direction of the second liquid inlet channel 33 and the extending direction of the first liquid inlet channel 32 within the above angle range, it is convenient to better improve the liquid distribution uniformity, ensure the uniform distribution of the liquid in each heat exchange channel 34, and also facilitate effectively ensuring the heat exchange effect.

[0047] Specifically, the first liquid inlet channel 32 has a first liquid inlet and a first liquid outlet that are interconnected, and the flow area of the first liquid outlet is smaller than the flow area of the first liquid inlet. Alternatively, the second liquid inlet channel 33 has a second liquid inlet and a second liquid outlet that are interconnected, and the flow area of the second liquid outlet is smaller than the flow area of the second liquid inlet. Alternatively, the first liquid inlet channel 32 has a first liquid inlet and a first liquid outlet that are interconnected, and the flow area of the first liquid outlet is smaller than the flow area of the first liquid inlet; the second liquid inlet channel 33 has a second liquid inlet and a second liquid outlet that are interconnected, and the flow area of the second liquid outlet is smaller than the flow area of the second liquid inlet.

[0048] Preferably, the first liquid inlet passage 32 in this embodiment has a first liquid inlet and a first liquid outlet that are interconnected, and the flow area of the first liquid outlet is smaller than that of the first liquid inlet; the second liquid inlet passage 33 has a second liquid inlet and a second liquid outlet that are interconnected, and the flow area of the second liquid outlet is smaller than that of the second liquid inlet. With such a structural arrangement, it is possible to facilitate increasing the liquid outlet speed of the first liquid outlet and the second liquid outlet, so as to facilitate throttling and enable the liquid to better enter the heat exchange passage 34 for heat exchange.

[0049] Specifically, the first liquid inlet passage 32 has a first tapered section 321, and the outlet end of the first tapered section 321 forms the first liquid outlet; along the liquid inlet direction of the first liquid inlet passage 32, the flow area of the first tapered section 321 gradually decreases. Alternatively, the second liquid inlet passage 33 has a second tapered section 331, and the outlet end of the second tapered section 331 forms the second liquid outlet; along the liquid inlet direction of the second liquid inlet passage 33, the flow area of the second tapered section 331 gradually decreases. Alternatively, the first liquid inlet passage 32 has a first tapered section 321, and the outlet end of the first tapered section 321 forms the first liquid outlet; along the liquid inlet direction of the first liquid inlet passage 32, the flow area of the first tapered section 321 gradually decreases; the second liquid inlet passage 33 has a second tapered section 331, and the outlet end of the second tapered section 331 forms the second liquid outlet; along the liquid inlet direction of the second liquid inlet passage 33, the flow area of the second tapered section 331 gradually decreases.

[0050] Preferably, the first liquid inlet passage 32 in this embodiment has a first tapered section 321, and the outlet end of the first tapered section 321 forms the first liquid outlet; along the liquid inlet direction of the first liquid inlet passage 32, the flow area of the first tapered section 321 gradually decreases; the second liquid inlet passage 33 has a second tapered section 331, and the outlet end of the second tapered section 331 forms the second liquid outlet; along the liquid inlet direction of the second liquid inlet passage 33, the flow area of the second tapered section 331 gradually decreases. With such a structural arrangement, by providing the first tapered section 321, it is possible to facilitate better throttling of the liquid in the first tapered section 321, so as to better increase the liquid outlet speed at the first liquid outlet and optimize the structural performance of the first liquid inlet passage 32. By providing the second tapered section 331, it is possible to facilitate better throttling of the liquid in the second tapered section 331, so as to better increase the liquid outlet speed at the second liquid outlet and optimize the structural performance of the second liquid inlet passage 33.

[0051] Specifically, after the refrigerant flows in through the liquid inlet hole 31, due to the different velocities of the gas-liquid two-phase, phase separation occurs at the branch ports of each flow channel. Since the density of the gas phase is relatively small and the inertial force for forward movement is small, it is more likely to flow out at the front end, resulting in uneven distribution. After adding a distributor with a small-hole flow channel (the small-hole flow channel is the liquid inlet channel between the first connecting plate 12 and the second connecting plate 22) at the inlet of the flow channel, the resistance of the fluid entering the flow channel is increased. The gaseous refrigerant drives the liquid-phase refrigerant to move backward and flow into the end flow channel, which can improve the unevenness of fluid distribution between the parallel flow channels.

[0052] Meanwhile, the design of the double distribution holes (the double distribution holes are two liquid inlet channels, specifically the first liquid inlet channel 32 and the second liquid inlet channel 33) enables the fluid to enter the heat exchange flow channel 34 along two different directions simultaneously, avoiding the generation of deviation flow and local flow dead zones, significantly promoting the diffusion of the fluid in the heat exchange flow channel 34, and improving the uniformity of the lateral distribution of the fluid in a single liquid inlet channel. The capacity differences of plate heat exchangers under different distributor forms were compared through experiments. Under different refrigerant flow rates, the comparison of the heat transfer capacity is as Figure 9 shown. Under the same working conditions, the heat transfer capacity of the heat exchanger with a double-hole distributor is higher. Compared with the heat exchanger with a single-hole distributor, the heat transfer capacity is increased by about 400 W, and the overall heat transfer effect is improved by about 4%.

[0053] For the traditional distribution pipe and distribution ring structure, separate machining is required for forming, and accurate positioning is needed during assembly, increasing the processing and installation costs. The distribution holes (the distribution holes are the liquid inlet channels) formed by stamping in the present invention are integrated on the plate, and the forming of the distribution holes is completed during the stamping process of the plate type. The process flow is simple and no independent installation is required, effectively solving the above problems.

[0054] In this embodiment, the periphery of the refrigerant inlet corner hole (the inlet corner hole is the liquid inlet hole 31) of the plate heat exchanger is a distribution structure, and the refrigerant enters the heat exchange flow channel 34 through the distribution structure.

[0055] The distribution structure in this embodiment is composed of multiple distribution holes. The first distribution hole (which is the first liquid inlet channel 32) is close to the bottom end face. The vertical axis passing through the center of the corner hole forms an angle α with the central axis of the first distribution hole, and the angle α shall not be less than 10° and shall not exceed 20° at most. The second distribution hole (which is the second liquid inlet channel 33) is close to the side wall surface of the heat exchanger. The central axis passing through the second distribution hole forms an angle β with the central axis of the first distribution hole, and the angle β shall not be less than 90° and shall not exceed 150° at most.

[0056] The distribution structure in this embodiment is formed by stamping two heat exchange plates (the two heat exchange plates include the first heat exchange plate 10 and the second heat exchange plate 20), and the outer periphery of the corner hole is bent inward to form a depression (i.e., an avoidance groove), and the heat exchange plates contact each other at the depression to form an annular sealing ring and a cylindrical distribution through hole. The diameter of the distribution hole is not less than 1mm and does not exceed the thickness of the heat exchange channel 34 at most.

[0057] The present invention is a plate heat exchanger that can achieve uniform distribution of fluid. Figure 1 As shown in the figure, the main structure of the heat exchanger is composed of a pipe 50, a front end plate (first end plate 41), a rear end plate (second end plate 42) and heat exchange fins (including first heat exchange fins 10 and second heat exchange fins 20), and two adjacent heat exchange fins are brazed to form a closed heat exchange flow channel 34. Four corner holes are opened on the front end plate and each plate, and they are connected from front to back to form an inlet / outlet liquid channel.

[0058] The structure of the heat exchanger is as follows Figure 2 As shown, the middle is the main heat exchange area, which is a herringbone corrugated structure. The plates are surrounded by fluid inlet and outlet corner holes, and the outer circle of the refrigerant inlet corner holes is a distribution structure. Figure 4 The figure shows a partial enlarged view of the refrigerant liquid inlet angle hole. Two adjacent heat exchange plates are punched inward at the same time to form a depression. The depressions are in contact with each other to form an annular sealing ring (the sealing ring is formed by connecting the first connecting plate 12 and the second connecting plate 22) and a distribution hole. The annular sealing ring and the distribution hole together constitute a distribution structure. After the refrigerant flows in from the connecting pipe 50, it is blocked by the sealing ring and can only enter the heat exchange flow channel 34 through the distribution hole.

[0059] like Figure 5 As shown, the first distribution hole is close to the bottom end face, and the vertical axis through the center of the corner hole forms an angle α with the central axis of the first distribution hole. The angle α shall not be less than 10° and the maximum shall not exceed 20°. When the angle is within this range, it can ensure that the fluid flows out through the distribution hole, impacts the bottom end face and flows along the wall, increasing the flow on the other side of the flow channel. The second distribution hole is close to the left wall of the heat exchanger, and the central axis through the second distribution hole forms an angle β with the central axis of the first distribution hole. The angle β shall not be less than 90° and the maximum shall not exceed 150°. When the angle is within this range, the fluid can impact the side wall and then disperse and flow into the main heat exchange area.

[0060] It should be noted that the number of distribution holes of the distribution structure is not limited thereto, and can be adjusted according to working conditions and usage requirements, and can include three, four, or more distribution holes.

[0061] The simulation method is as follows: the Euler model is used, and the velocity inlet is used as the inlet boundary condition. Therefore, the gas-liquid phase velocity is converted according to the cavitation coefficient (α). For refrigerant R32, the cavitation coefficient model uses the Zivil model, and the specific calculation formula is as follows:

[0062]

[0063] In the formula, x is the dryness; ρg is the density of the gaseous refrigerant, kg / m3; ρl is the density of the liquid refrigerant, kg / m3.

[0064] According to the refrigerant inlet pressure measured by experiments, calculate the gas-liquid density of the refrigerant in this state, and then determine the inlet dryness from the enthalpy value before throttling. The gas-liquid flow velocities at the inlet can be obtained through formulas (2) and (3).

[0065]

[0066]

[0067] In the formula, m is the total mass flow rate, kg / s; A is the inlet cross-sectional area, m2.

[0068] The shear stress transport (SST) model is selected for the turbulence model, the pressure outlet is selected at the outlet, and the no-slip velocity boundary condition is selected for all walls.

[0069] Due to the different velocities of the gas-liquid two-phase, phase separation will occur at the inlet of each flow channel, resulting in differences in fluid distribution among the parallel flow channels. Therefore, a gas-liquid two-phase flow model is established to simulate the flow rate distribution of each parallel flow channel under different distributor forms. The Fluent software is used for simulation calculation. According to the simulation method described above, the distribution performance of the double-hole (α = 20°, β = 120°) and single-hole distributors among the parallel flow channels and within a single flow channel is compared and analyzed. Figure 10 The liquid-phase flow rate ratios of each parallel flow channel are shown. When the flow rate ratio is closer to 1, it indicates that the flow rate distribution of this flow channel is closer to the average level. Since the single-hole distribution significantly increases the resistance of the fluid entering the flow channel, the fluid tends to flow forward along the liquid inlet channel, and the distribution of the liquid-phase flow rate shows an increasing trend; while the double-hole distributor adds a distribution hole, which appropriately reduces the resistance of the fluid entering the flow channel, making the fluid tend to flow into the front-end flow channels first, and the distribution of the liquid-phase flow rate first shows a decreasing trend. At the end of the liquid inlet channel, the fluid flow direction changes due to the blockage of the tail end face, and the liquid-phase flow rate of the end flow channel is relatively large. It is calculated that the non-uniformity of the single-hole distribution is 0.1, and the non-uniformity of the double-hole distribution is 0.04. When using the double-hole distribution, the distribution of the refrigerant among the parallel flow channels is more uniform.

[0070] When there is only one distribution hole (the distribution hole is also the liquid inlet channel), the fluid in a single heat exchange channel flows out from the single distribution hole. After impacting the bottom end face, the refrigerant flows along the wall surface, significantly increasing the flow rate on the right side of the heat exchange channel 34, while the flow rate on the left side of the heat exchange channel 34 is small and the flow velocity is low. When using double-hole distribution, the fluid enters the heat exchange channel 34 along two different directions simultaneously, avoiding the generation of flow deviation and local flow dead zones, significantly promoting the diffusion of the fluid in the heat exchange channel 34, and improving the uniformity of the lateral distribution of the fluid in a single heat exchange channel 34. The standard deviation of the velocity for double-hole distribution at the same position is 0.0026, while that for single-hole distribution is 0.0073. The above results show that the uniformity of the fluid distribution inside the heat exchanger can be significantly improved by using double-hole distribution.

[0071] Furthermore, the temperature differences of the water outlet in the front-end channel and the end-channel of the plate heat exchanger during single-hole and double-hole distribution were compared through experiments. The experimental results are as Figure 11 shown. When using single-hole distribution, the maximum temperature difference of the water outlet in the front and end channels is about 2 - 3 °C. When using double-hole distribution, it does not exceed 0.5 °C under different flow rates. Usually, the refrigerant-side inlet is a gas-liquid two-phase mixture. Since the velocities of the gas and liquid phases are different, phase separation will occur at the inlet of each channel, resulting in differences in the fluid distribution among the parallel channels. The more the two-phase refrigerant is distributed in a single channel, the greater the heat exchange amount of the water in the adjacent channels. When the inlet water temperature and flow rate of each channel are the same, the difference in the outlet water temperature can reflect the uniformity of the refrigerant distribution among the parallel channels. The experimental results also show that the uniformity of the refrigerant distribution among the parallel channels is better when using double-hole distribution. It should be noted that the front-end channel refers to the heat exchange channel 34 closest to the first end plate 41, which can also be understood as the heat exchange channel 34 located at the topmost position. The end-channel refers to the heat exchange channel 34 closest to the second end plate 42, which can also be understood as the heat exchange channel 34 located at the bottommost position.

[0072] Figure 12 shown as the lateral difference in the water outlet temperature of the heat exchange channel 34 closest to the first end plate 41 (the lateral difference refers to the difference between the highest value and the lowest value of the water outlet temperature along the width direction of the plate). It can be seen from the figure that the lateral difference in the water outlet temperature during single-hole distribution is about 2.5 - 3.5 °C, while during double-hole distribution, it does not exceed 1 °C. The uniformity of the lateral distribution of the refrigerant in a single channel after flowing out from the distribution hole is the main factor affecting the heat exchange amount at different lateral positions on the water side. The experimental results also show that the uniformity of the lateral distribution in a single channel is better after using double-hole distribution, and the fluid distribution inside the heat exchanger is more uniform.

[0073] The differences in the heat exchange performance of the plate heat exchanger during single-hole and double-hole distribution were compared on the heat exchanger performance test bench. Figure 13It shows the change of the superheat degree of two plate heat exchangers with the refrigerant mass flow rate. When using double-hole distribution, the superheat degree of the heat exchanger is the highest, about 3.5 °C under different flow rates; when using single-hole distribution, it does not exceed 1 °C under different flow rates. The more uniform the internal fluid distribution of the heat exchanger is, the better the heat transfer effect and the greater the heat transfer amount. During the experimental test, the inlet state on the refrigerant side is the same, that is, the inlet enthalpy value is the same. Under the same flow rate, the greater the heat transfer amount, the greater the enthalpy difference between the inlet and outlet, and the higher the superheat degree at the outlet of the heat exchanger. Using double-hole distribution, the fluid distribution is more uniform, and the superheat degree of the heat exchanger is also higher.

[0074] Figure 14 It is the curve of the heat transfer amount of two plate heat exchangers changing with the refrigerant mass flow rate. Under the same flow rate, the plate heat exchanger using double-hole distribution has the highest superheat degree and the largest heat transfer amount. Compared with the plate heat exchanger using single-hole distribution, its heat transfer amount is about 400 W higher, that is, the heat transfer amount is increased by about 4%.

[0075] As Figure 6 shown, the distribution hole is approximately a cylindrical through hole, and its diameter shall not be less than 1 mm and shall not exceed the thickness of the heat transfer channel 34 at most. When the diameter is too small, it will significantly increase the resistance of the fluid entering the channel, and the movement of the liquid phase fluid to the end channel becomes more obvious, and the unevenness of the liquid phase flow rate distribution between the channels increases, reducing the performance of the heat exchanger.

[0076] The structure of the present invention is simple and has strong versatility. It can realize the uniform distribution of the fluid on the basis of not increasing the manufacturing cost of the plate heat exchanger, and effectively improve the overall performance of the heat exchanger.

[0077] As Figure 8 shown, Embodiment 2 of the present invention provides a method for selecting a plate heat exchanger. The method for selecting a plate heat exchanger is applicable to the plate heat exchanger provided above. The method for selecting a plate heat exchanger includes introducing a certain amount of fluid into the preselected plate heat exchanger and controlling the outlet temperature of the fluid to be T1, and detecting the inlet temperature T2 of the corresponding fluid; detecting whether the temperature difference T between the outlet temperature T1 and the inlet temperature T2 meets a preset condition; when the temperature difference T meets the preset condition, it is determined that the fluid distribution uniformity in the preselected plate heat exchanger meets the requirements; when the temperature difference T does not meet the preset condition, it is determined that the fluid distribution uniformity in the inlet channel of the preselected plate heat exchanger does not meet the requirements, and the plate heat exchanger is reselected.

[0078] It should be noted that the selection of the plate heat exchanger here mainly includes the selection of the number of inlet channels of the plate heat exchanger; if there are multiple inlet channels, the maximum angle between the multiple inlet channels also needs to be selected.

[0079] By adopting the above method, it is convenient to determine whether the liquid distribution uniformity of the preselected plate heat exchanger can meet the requirements, so as to ensure the heat exchange effect. The above method steps are simple and clear, and are convenient for operation and judgment.

[0080] Specifically, in this embodiment, the method for detecting whether the temperature difference T between the outlet temperature T1 and the outlet temperature T2 meets the preset condition includes: comparing the temperature difference T with the preset temperature difference A; when T≥A, it is determined that the temperature difference T meets the preset condition; when T<A, it is determined that the temperature difference does not meet the preset condition. Such an operation method is simple, convenient for judgment, and convenient for rapid type selection.

[0081] In this embodiment, the method for reselecting the plate heat exchanger includes: selecting the number of inlet channels of the plate heat exchanger as n; selecting the maximum included angle of the n inlet channels as γ, and detecting the reselected plate heat exchanger to judge whether the fluid distribution uniformity in the reselected plate heat exchanger meets the requirements. It should be noted that "the maximum included angle of the n inlet channels is γ" means that the included angle between the two inlet channels with the largest angle selected from the n inlet channels is γ, and the remaining inlet channels are evenly distributed between these two inlet channels.

[0082] By adopting such a structural setting, it is convenient to quickly and effectively select the number of inlet channels and the maximum included angle of the plate heat exchanger, which is convenient for operation and also convenient to ensure the liquid distribution effect and the heat exchange effect.

[0083] Specifically, the method for selecting the maximum included angle γ of the n inlet channels includes: controlling the maximum included angle γ of the n inlet channels to be between 90° and 150°. In this way, it is convenient to quickly select the type within the above range, and corresponding tests are carried out for different angles to facilitate selecting the optimal angle value, thereby improving the heat exchange effect.

[0084] The implementation scheme of the type selection method of the plate heat exchanger is specifically as follows:

[0085] Adopt the measurement method of constant water flow and outlet water temperature, that is, the water flow and the outlet water temperature remain unchanged, and monitor the change of the inlet water temperature;

[0086] Define the temperature difference between the inlet and outlet water as the T value, and select a suitable plate type by judging whether the T value meets the size of the preset value;

[0087] When the number of distribution holes is two, by monitoring the T value of the plate types when the included angle γ of the plate type is 100° and 130° respectively, the included angles of 100° and 130° listed in the present invention are preferred values, which are not limited to this value, and the included angle values within the range of 90° to 150° are within the protection scope of the present invention;

[0088] When the number of distribution holes is three, by monitoring the T - value of the plate type when the included angle γ of the plate type is 110° and 140° respectively, the included angle γ represents the maximum angle between the distribution holes. The included angles of 110° and 140° listed in the present invention are preferred values, not limited to these values. The included - angle values within the range of 90° to 150° are all within the protection scope of the present invention;

[0089] When the number of distribution holes is four, by monitoring the T - value of the plate type when the included angle γ of the plate type is 120° and 150° respectively, the included angle γ represents the maximum angle between the distribution holes. The included angles of 120° and 150° listed in the present invention are preferred values, not limited to these values. The included - angle values within the range of 90° to 150° are all within the protection scope of the present invention;

[0090] Confirm the number of holes and the included - angle value when the T - value meets the preset value. If multiple conditions are met, take the optimal value among them.

[0091] From the above description, it can be seen that the above - mentioned embodiments of the present invention achieve the following technical effects: the processing technology of the plate - type heat exchanger is simple, the production cost is low, the reliability is strong, and the test verification and simulation analysis results show that the distribution effect of the structure of the plate - type heat exchanger is excellent, and it has a good heat - exchange effect.

[0092] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or their combinations.

[0093] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0094] In the description of the present application, it should be understood that the orientation or positional relationship indicated by orientation terms such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description. Without contrary explanation, these orientation terms do not indicate or imply that the device or component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present application; the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0095] For convenience of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above-mentioned", etc. can be used here to describe the spatial positional relationship between a device or feature shown in the drawings and other devices or features. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the drawings for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0096] In addition, it should be noted that the use of words such as "first", "second", etc. to limit components is only for the convenience of distinguishing the corresponding components. Without separate statement, the above-mentioned words have no special meaning. Therefore, it should not be construed as a limitation on the protection scope of the present application.

[0097] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for selecting a plate heat exchanger, characterized in that, The method for selecting the plate heat exchanger is applicable to plate heat exchangers, and the plate heat exchanger includes: A first heat exchange fin, the first heat exchange fin includes a first heat exchange plate and a first connecting plate connected to each other, and a first liquid inlet connection hole is provided on the first connecting plate; A second heat exchange fin, the second heat exchange fin includes a second heat exchange plate and a second connecting plate connected to each other, there is a heat exchange flow channel between the second heat exchange plate and the first heat exchange plate, a second liquid inlet connection hole is provided on the second connecting plate, and the second liquid inlet connection hole is arranged opposite to the first liquid inlet connection hole to form a liquid inlet hole; Wherein, the second connecting plate is connected to the first connecting plate, there is a liquid inlet channel between the second connecting plate and the first connecting plate, one end of the liquid inlet channel is communicated with the liquid inlet hole, and the other end of the liquid inlet channel is communicated with the heat exchange flow channel; The method for selecting the plate heat exchanger includes: Introduce a certain amount of fluid into the preselected plate heat exchanger and control the outlet temperature of the fluid to be T1, and detect the inlet temperature T2 of the corresponding fluid; Detect whether the temperature difference T between the outlet temperature T1 and the inlet temperature T2 meets a preset condition; When the temperature difference T meets the preset condition, it is determined that the fluid distribution uniformity in the preselected plate heat exchanger meets the requirements; When the temperature difference T does not meet the preset condition, it is determined that the fluid distribution uniformity in the liquid inlet channel of the preselected plate heat exchanger does not meet the requirements, and the plate heat exchanger is reselected; The method for reselecting the plate heat exchanger includes: Select the number of liquid inlet channels of the plate heat exchanger to be n; Select the maximum included angle of the n liquid inlet channels to be γ, and detect the reselected plate heat exchanger to determine whether the fluid distribution uniformity in the reselected plate heat exchanger meets the requirements; The γ is the included angle between the two liquid inlet channels with the largest angle among the n liquid inlet channels, and the remaining liquid inlet channels are evenly distributed between the two liquid inlet channels with the largest angle.

2. The method for selecting a plate heat exchanger according to claim 1, characterized in that, The method for detecting whether the temperature difference T between the outlet temperature T1 and the outlet temperature T2 meets the preset condition includes: Compare the temperature difference T with a preset temperature difference A; When T≥A, it is determined that the temperature difference T meets the preset condition; When T<A, it is determined that the temperature difference does not meet the preset condition.

3. The method for selecting a plate heat exchanger according to claim 1, characterized in that, The method for selecting the maximum included angle γ of the n liquid inlet channels includes: Control the maximum included angle γ of the n liquid inlet channels to be between 90° and 150°.

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