Pipe joint for plate heat exchanger

Abstract

The pipe joint comprises an upper portion, a middle portion and a lower portion, and the upper portion, the middle portion and the lower portion jointly form a through circulation channel. An annular insertion block is arranged on the top face of the upper portion, a circle of platform is arranged on the periphery of the annular insertion block, a sunken solder groove is formed in the side, close to the annular insertion block, of the surface of the platform, and dual positioning of the annular insertion block and the platform facilitates reduction of welding alignment errors. A plurality of through screw holes are formed in the lower part; the outer diameter of the cylindrical structure where the first vertical face is located is larger than the outer diameter of the middle portion and smaller than the outer diameter of the lower portion, the middle portion is concave inwards relative to the upper portion and the lower portion, and the concave structure of the middle portion serves as a thermal expansion buffer area and is matched with smooth transition of the first inclined face, so that the welding thermal stress concentration coefficient can be effectively reduced, thermal deformation is reduced, and the welding seam cracking rate is reduced. According to the pipe joint for the plate heat exchanger, through the stepped axial structure, a multi-stage positioning reference and stress dispersion system is formed, and the comprehensive performance of the pipe joint can be remarkably improved.

Description

Technical Field

[0001] This application relates to the field of pipe fitting technology, and in particular to a pipe fitting for a plate heat exchanger. Background Technology

[0002] Plate heat exchangers, as high-efficiency heat exchange equipment, are widely used in refrigeration, HVAC, chemical and other fields. The reliability of their inlet and outlet pipe joints directly affects the sealing and stability of the heat exchange system.

[0003] Traditional pipe fittings and heat exchanger panels are typically welded manually, lacking precise mechanical positioning structures. This makes them prone to misalignment or displacement during welding, and the solder cannot evenly fill the mating surface. Furthermore, because traditional fittings do not have independent solder wells, the solder tends to flow and overflow at high temperatures, making it difficult to form a stable, sealed weld. Long-term use can lead to leaks, compromising system safety.

[0004] In addition, traditional pipe fittings mostly adopt a cylindrical structure with equal diameter. During the welding process, the single cross section is prone to deformation due to thermal stress concentration, which can lead to flow channel distortion or connection failure. At the same time, the straight axial structure is also prone to fatigue fracture due to stress concentration under fluid impact or vibration load. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the prior art and provide a pipe fitting for a plate heat exchanger.

[0006] This application provides a pipe fitting for a plate heat exchanger, characterized in that it comprises an upper, middle, and lower part that coaxially extend through each other, forming a through flow channel; the upper part is a welding end; the top surface of the upper part is provided with a protruding annular insert, which can be inserted into the connection hole of the heat exchanger; a platform is provided around the annular insert, which can fit against the heat exchanger panel after the annular insert is inserted into the connection hole; a recessed solder groove is provided on the side of the platform near the annular insert, the solder groove surrounds the annular insert, and the solder groove is used to fill solder to facilitate welding and fixing of the pipe. The joint and heat exchanger are connected; the lower part is a spare end; the lower part has multiple through bolt holes, which are evenly distributed along the circumference to facilitate the fixed connection between the lower part and the flange of the external pipeline; the middle part connects the upper and lower parts; the outer diameter of the middle part is smaller than the outer diameter of the lower part; the outer wall of the upper part is composed of a first vertical surface and a first inclined surface, the outer diameter of the columnar structure where the first vertical surface is located is larger than the outer diameter of the middle part and smaller than the outer diameter of the lower part, and the first inclined surface connects the first vertical surface and the middle part; the middle part is concave inward compared to the upper and lower parts to compensate for welding heat deformation and reduce flow resistance.

[0007] Furthermore, the end of the flow channel near the welding end is the outlet, and the other end near the standby end is the inlet; the diameter of the outlet is larger than the diameter of the inlet; the inner wall of the outlet side of the flow channel is composed of a second vertical surface and a second inclined surface, which can reduce fluid impact resistance and improve flow uniformity.

[0008] Furthermore, the second inclined plane forms an angle of 30-45° with the central axis of the flow channel to facilitate the smooth flow of fluid into the heat exchanger channel.

[0009] Furthermore, the connection between the second vertical surface and the second inclined surface is rounded with a radius of 3mm; the connection between the second inclined surface and the vertical inner wall on the inlet side is also rounded with a radius of 3mm.

[0010] Furthermore, the solder bath has a depth of 1.5-3mm and a width of 2-4mm. The solder bath is used to contain the solder and form a sealing weld.

[0011] Furthermore, the connection between the first vertical surface and the first inclined surface is rounded with a radius of 3mm; the connection between the first inclined surface and the middle part is also rounded with a radius of 3mm.

[0012] Furthermore, the connection between the middle and lower parts is rounded with a radius of 5mm, which helps to reduce fluid flow resistance and enhance structural strength.

[0013] Furthermore, the platform surface is also provided with a sealing groove, which surrounds the solder groove and is arranged coaxially with the solder groove. The sealing groove is used to install a sealing ring.

[0014] Furthermore, a flow guide plate is detachably installed at the outlet of the flow channel; the flow guide plate is provided with radially distributed flow guide grooves, the extension direction of which is parallel to the corrugation direction of the first layer plate of the heat exchanger; the width of the flow guide grooves gradually expands from the center to the edge.

[0015] Furthermore, an anti-clogging filter cup is provided at the center of the flow guide plate; the anti-clogging filter cup is set in a conical shape, with the cone tip facing the inlet of the flow channel.

[0016] This application provides a pipe joint for a plate heat exchanger, comprising an upper part, a middle part, and a lower part, which together form a through-flow channel. The upper part has an annular insert on its top surface, and a platform surrounds the annular insert. A recessed solder groove is located on the platform surface near the annular insert. The lower part has multiple through-holes. The outer diameter of the cylindrical structure containing the first vertical surface is larger than the outer diameter of the middle part but smaller than the outer diameter of the lower part; the middle part is recessed inwards compared to the upper and lower parts. The pipe joint for the plate heat exchanger provided in this application, through a stepped axial structure, forms a multi-level positioning reference and stress dispersion system, which can significantly improve performance. The overall performance of the pipe fitting is significantly improved: the dual positioning of the annular insert and the platform helps reduce welding alignment errors and ensures that the pipe fitting is parallel, aligned, and coaxial with the heat exchanger panel during installation; the concave structure in the middle acts as a thermal expansion buffer, and together with the smooth transition of the first inclined surface, it can effectively reduce the welding thermal stress concentration coefficient, reduce thermal deformation, and reduce the weld cracking rate, thereby avoiding weld cracking or flow channel distortion caused by thermal deformation; the stepped design can also enhance structural rigidity and improve torsional strength, thereby extending fatigue life under vibration conditions and ensuring sealing reliability under working pressure. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of a pipe joint for a plate heat exchanger provided in this application;

[0018] Figure 2 A schematic diagram of another type of pipe fitting for a plate heat exchanger provided in this application. Detailed Implementation

[0019] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0020] Pipe fittings are key components connecting heat exchangers to external heat / cold source pipelines. Pipe fittings allow heat sources (such as steam, hot water) or cold sources (such as chilled water, cooling water) and heat exchange media to flow in and out of the heat exchanger in an orderly manner, ensuring full contact with the plates for heat exchange.

[0021] This application provides a pipe fitting for a plate heat exchanger, characterized in that it comprises an upper part 1, a middle part 2, and a lower part 3 that are coaxially connected, forming a through flow channel 4; the upper part 1 is a welding end; the top surface of the upper part 1 is provided with a protruding annular insert 11, which can be inserted into the connection hole of the heat exchanger; a platform 12 is provided around the annular insert 11, which can fit against the heat exchanger panel after the annular insert 11 is inserted into the connection hole of the heat exchanger; a recessed solder groove 13 is provided on the side of the platform 12 near the annular insert 11, the solder groove 13 surrounds the annular insert 11, and the solder groove 13 is used to fill solder to facilitate welding and fixing of the pipe. The joint and heat exchanger; the lower part 3 is a spare end; the lower part 3 is provided with multiple through screw holes 31, which are evenly distributed along the circumference to facilitate the fixed connection between the lower part 3 and the flange of the external pipe; the middle part 2 connects the upper part 1 and the lower part 3; the outer diameter of the middle part 2 is smaller than the outer diameter of the lower part 3; the outer wall of the upper part 1 is composed of a first vertical surface 14 and a first inclined surface 15. The outer diameter of the columnar structure where the first vertical surface 14 is located is larger than the outer diameter of the middle part 2 and smaller than the outer diameter of the lower part 3. The first inclined surface 15 connects the first vertical surface 14 and the middle part 2; the middle part 2 is concave inward compared to the upper part 1 and the lower part 3 to compensate for welding heat deformation and to reduce flow resistance.

[0022] For details, please refer to Figure 1 In the illustrated embodiment, the pipe joint has an overall structure that is thinner in the middle and thicker at both ends, and the outer diameter of the lower part 3, which serves as the spare end, is larger than the outer diameter of the upper part 1, which serves as the welding end. The pipe joint is provided with a flow channel 4 that runs through it from top to bottom.

[0023] Continue to refer to Figure 1 The upper part 1 has a raised annular insert 11 on its top surface. The annular insert 11 can be precisely inserted into the connection hole of the heat exchanger panel to achieve mechanical positioning. The platform 12 surrounds the insert 11, and there is a height difference between the platform 12 and the insert 11. After the insert 11 is inserted into the connection hole, the platform 12 can fit against the surface of the heat exchanger panel to form a support plane during welding, ensuring that the pipe joint is parallel and aligned with the panel.

[0024] Continue to refer to Figure 1 The platform 12 is provided with a recessed solder groove 13, which is in close contact with the insert block 11. During welding, the solder groove 13 is used to fill the solder (such as alloy solder). The solder is constrained by the groove to prevent overflow and helps to form a continuous and sealed weld.

[0025] Continue to refer to Figure 1 The lower part 3 is roughly cylindrical, and eight through-holes 31 are evenly distributed on its surface. In use, the pipe fitting can be fixedly connected to the flange of the external pipeline by M8 bolts through the screw holes 31.

[0026] Continue to refer to Figure 1The outer diameter of the middle part 2 is smaller than that of the lower part 3, and it is concave inward to form a stepped structure. The upper end of the middle part 2 is connected to the first vertical surface 14 of the upper part 1 through the first inclined surface 15, and the lower end is connected to the lower part 3.

[0027] Continue to refer to Figure 1 The outer diameter of the cylindrical structure containing the first vertical surface 14 is larger than that of the middle section 2 and smaller than that of the lower section 3, forming a stepped transition. The first vertical surface 14 is used to initially position the structure with the heat exchanger panel, helping the annular insert 11 to maintain vertical alignment when inserted into the hole, avoiding welding deviations caused by tilting. In addition, the diameter difference design (outer diameter of the first vertical surface 14 > outer diameter of the middle section 2) creates a step between the upper section 1 and the middle section 2. During welding, this step can abut against the outer side of the heat exchanger panel, further restricting the axial movement of the joint and improving positioning reliability.

[0028] The first vertical surface 14, the first inclined surface 15, and the central recess 6 form a stepped axial structure, which can disperse welding thermal stress through abrupt changes in cross-section. During welding, the thermal expansion caused by high temperature can be partially released through the recessed structure of the central part 2, reducing stress concentration at the connection between the upper part 1 and the heat exchanger panel, and avoiding weld cracking or flow channel distortion caused by thermal deformation.

[0029] Continue to refer to Figure 1 The first inclined surface 15 connects the first vertical surface 14 to the middle part 2. The angle of the inclined surface allows for a smooth connection between the upper part 1 and the middle part 2, avoiding stress concentration caused by sharp angles or right angles. During welding, thermal stress can be gradually released along the inclined surface, reducing deformation caused by abrupt changes in cross-section. In use, under fluid impact or vibration conditions, the stress of the pipe joint can be evenly transmitted to the middle part 2 through the inclined surface, reducing the risk of fatigue fracture.

[0030] The plate heat exchanger pipe joint provided in this application, through a stepped axial structure (a diameter difference design of "lower 3 outer diameter > upper 1 outer diameter > middle 2 outer diameter"), forms a multi-level positioning reference and stress dispersion system, which can significantly improve the overall performance of the pipe joint: the dual positioning of the annular insert 11 and the platform helps to reduce welding alignment errors and ensures that the pipe joint and the heat exchanger panel are parallel, aligned, and coaxial during installation; the recessed structure of the middle 2 serves as a thermal expansion buffer, and together with the smooth transition of the first inclined surface 15, it can effectively reduce the welding thermal stress concentration coefficient, reduce the amount of thermal deformation, and reduce the weld cracking rate, thereby avoiding weld cracking or flow channel distortion caused by thermal deformation; the stepped structure can also enhance structural rigidity and improve torsional strength, thereby extending fatigue life under vibration conditions and ensuring sealing reliability under working pressure. Furthermore, the plate heat exchanger pipe fittings provided in this application can be processed and formed in one step, and are compatible with DN50-DN200 series heat exchangers. This achieves synergistic optimization of high-precision assembly, low-stress welding, high-efficiency fluid transportation and process economy, and comprehensively solves the technical bottlenecks of traditional pipe fittings, such as difficult positioning, easy deformation and high flow resistance.

[0031] Furthermore, the end of the flow channel 4 near the welding end is the outlet, and the other end near the standby end is the inlet; the diameter of the outlet is larger than the diameter of the inlet; the inner wall of the outlet side of the flow channel 4 is composed of a second vertical surface 41 and a second inclined surface 42, which can reduce fluid impact resistance and improve flow uniformity.

[0032] This design allows for a small inlet diameter (lower three sides) and a large outlet diameter (upper one side), creating a gradually expanding cross-section similar to a Venturi tube. During operation, the fluid flows in through the smaller inlet, and due to the increased outlet cross-sectional area, the flow velocity decreases and the pressure distribution becomes more uniform. This avoids the turbulent flow losses caused by fluid impacting the heat exchanger plates due to abrupt changes in cross-section, as seen in traditional constant-diameter flow channels. The enlarged outlet diameter also creates a stable, low-velocity flow field before the fluid enters the heat exchanger, preventing high-speed fluid from concentrating and impacting a specific area of ​​the plates, thus ensuring a uniform flow distribution across the entire heat exchange area.

[0033] The combination of the second inclined surface 42 and the large-diameter outlet guides the fluid to diffuse at a gentle angle into the gaps between the heat exchanger plates, further reducing impact noise and energy loss. The enlarged outlet diameter provides a wider diffusion space for the fluid, matching the corrugation direction of the first layer of heat exchanger plates, allowing the fluid to flow efficiently along the plate corrugations and enhancing the heat exchange contact area.

[0034] Optionally, the second inclined surface 42 forms an angle of 30-45° with the central axis of the flow channel 4, so as to guide the fluid to enter the heat exchanger channel smoothly.

[0035] The corrugated spacing of plate heat exchanger plates is typically 3-6 mm. A 30-45° angle ensures that the diffusion angle of the fluid exiting the outlet (approximately a 60-90° cone angle) matches the fluid receiving range between the plates, thus guaranteeing uniform fluid coverage of the heat exchange surface of the first layer of plates. Simultaneously, the 30-45° angle range allows the fluid to maintain laminar flow along the inclined surface, preventing boundary layer detachment from the wall due to excessively steep angles, thereby reducing eddy current generation (according to Bernoulli's equation, stable laminar flow reduces energy loss). Furthermore, the 30-45° angled gradually expanding channel falls within the "hydraulic optimal expansion angle" range, maximizing static pressure recovery and minimizing local resistance during flow. This contrasts sharply with the straight-wall outlet of traditional pipe fittings (0° angle), which causes the fluid to directly impact the plates at high speed, resulting in a significant pressure drop.

[0036] Furthermore, the connection between the second vertical surface 41 and the second inclined surface 42 is rounded with a radius of 3mm; the connection between the second inclined surface 42 and the vertical inner wall on the inlet side is also rounded with a radius of 3mm.

[0037] Rounding the corners at the connection between the second inclined surface 42 and the vertical inner wall on the inlet side can prevent "inlet impact" caused by the abrupt change in cross-section when the fluid enters the inclined surface from the straight inlet section of the lower part 3, thus reducing energy loss when the fluid enters the inclined surface section. In addition, under the action of high fluid pressure, the connection between the vertical inner wall on the inlet side and the inclined surface is prone to shear stress due to the pressure gradient. Rounding the corners can transform the stress concentration point into a circular arc bearing surface, thereby reducing the stress concentration factor.

[0038] Rounding the corners at the connection between the second inclined surface 42 and the second vertical surface 41 ensures smooth diffusion of the fluid as it transitions from the inclined surface to the straight section at the outlet, avoiding the "wake vortex" problem present in traditional right-angle outlets and further reducing flow resistance. Furthermore, during welding, the high-temperature area on the outlet side (near the heat exchanger panel) is prone to thermal deformation; rounding the corners compensates for thermal stress through geometric flexibility, preventing cracking at the weld-to-flow-channel connection.

[0039] Traditional right-angle structures tend to form "fluid stagnation zones" at both ends, leading to the deposition of particulate impurities or the concentration of corrosive media (such as chloride ion enrichment). In contrast, rounded transitions allow the fluid to maintain continuous flow, facilitating the discharge of impurities with the main fluid and reducing the risk of under-deposit corrosion and erosion.

[0040] A 3mm fillet radius ensures a smooth inlet transition without significantly reducing the effective cross-sectional area of ​​the flow channel (if the radius is too large, such as 5mm, it may cause necking of the inlet section, increasing pressure drop). Furthermore, since the outlet inner diameter is larger than the inlet inner diameter, a 3mm fillet radius can still maintain a reasonable transition curvature under larger diameters, avoiding a "broken line" effect due to an excessively small radius or structural redundancy due to an excessively large radius.

[0041] In one specific embodiment, refer to Figure 1 The flow channel 4 consists of a vertical inlet section, a sloping expansion section, and a vertical outlet section. The inlet section has a diameter of 82.5 mm, and the outlet section has a diameter of 98 mm. A second sloping surface 42 connects the vertical inlet section and the vertical outlet section, forming a gradually expanding flow channel structure. The second sloping surface 42 forms a 45° angle with the central axis of the flow channel, and both ends of the sloping surface are rounded.

[0042] Furthermore, the solder groove 13 has a depth of 1.5-3 mm and a width of 2-4 mm. The solder groove 13 is used to contain solder and form a sealing weld.

[0043] This size range ensures the reliability and sealing of the solder filler. The minimum depth of 1.5mm meets the minimum penetration requirements of conventional alloy solders such as silver-based and copper-based solders, allowing the solder to penetrate to the mating surface between the pipe joint and the heat exchanger panel, ultimately forming an effective weld of ≥1mm and preventing "false welds" and leaks. The maximum depth of 3mm prevents excessive solder from dripping into the heat exchanger plates at high temperatures and clogging the flow channels. The minimum width of 2mm provides lateral flow space for the solder, ensuring a continuous and uninterrupted circumferential weld and facilitating precise alignment of the welding tools. The maximum width of 4mm prevents excessive solder diffusion on the platform surface, maintaining the adhesion accuracy between the platform and the panel and the strength of the mechanical support.

[0044] Furthermore, from a structural strength perspective, when the depth is ≤3mm, the wall thickness at the root of the annular insert is ≥2mm, which can prevent plastic deformation during positioning; the width is ≤4mm, ensuring that the remaining load-bearing area of ​​platform 12 is ≥70%, thus maintaining the mechanical connection strength. The narrow slot design also concentrates the welding heat-affected zone, reducing axial thermal deformation; the uniform solder layer thickness can reduce the risk of cooling shrinkage cracking.

[0045] This size limit is highly compatible with the physical properties of the solder. The surface tension of the molten solder can keep it stable in the tank and prevent it from overflowing. At the same time, it matches the capillary penetration ability of the solder to ensure that the solder can be evenly spread in the tank. It is compatible with the laser spot and wire feeding path of manual welding visual operation and automated welding, improving process adaptability.

[0046] Furthermore, the connection between the first vertical surface 14 and the first inclined surface 15 is rounded with a radius of 3mm; the connection between the first inclined surface 15 and the middle part 2 is also rounded with a radius of 3mm.

[0047] Traditional right-angle connections are prone to stress concentration under welding thermal stress or fluid impact, leading to crack initiation. The rounded corners at both ends of the first bevel 15 transform stress concentration points into circular bearing surfaces, thereby reducing the stress concentration factor. For example, the expansion stress generated by high temperatures during welding can be evenly diffused along the circular arc, thus avoiding local cracking caused by abrupt changes in right angles; under fluid flow or vibration loads, the circular arc transition can disperse mechanical stress and extend the fatigue life of the joint.

[0048] The outer diameter of the first vertical surface 14 of the upper part 1 is larger than that of the middle part 2. A radius of 3mm can create a reasonable transition ratio between the two. For example, if the outer diameter of the first vertical surface is 32.5mm and the outer diameter of the middle part 2 is 28mm, a 3mm radius can keep the inclination angle of the first inclined surface 15 at 20-30°, which meets the engineering flow guidance requirements. This avoids the abrupt transition caused by an excessively small radius, and also prevents the wall thickness of the pipe joint from being weakened by an excessively large radius.

[0049] Furthermore, the connection between the middle part 2 and the lower part 3 is rounded with a radius of 5mm, which helps to reduce fluid flow resistance and enhance structural strength.

[0050] The 5mm radius fillet significantly reduces fluid flow resistance. Since the outer diameter of the middle section 2 is smaller than that of the lower section 3, the stepped structure between them is prone to fluid turbulence due to abrupt changes in cross-section. The 5mm radius fillet ensures a smooth transition in the flow channel. When the fluid enters the concave section of the middle section 2 from the cylindrical section of the lower section 3, it can gently contract along the inner wall of the radius fillet, avoiding eddy current losses caused by right-angle corners and improving fluid throughput. Secondly, the large radius fillet enhances structural strength. During welding, this area is prone to deformation due to concentrated thermal stress. The 5mm radius fillet increases the cross-sectional area of ​​the transition region, dispersing welding thermal stress and mechanical vibration stress, reducing the risk of fatigue fracture, and is particularly suitable for high-pressure or high-frequency vibration conditions. Furthermore, the 5mm radius is compatible with machining processes. This size avoids the abrupt transition caused by an excessively small radius and requires no special machining equipment (it can be achieved using conventional lathes or grinders). While ensuring flow channel performance and structural strength, it also considers manufacturing convenience and cost control.

[0051] Optionally, the surface of the platform 12 is also provided with a sealing groove 16, which surrounds the solder groove 13 and is arranged coaxially with the solder groove 13. The sealing groove 16 is used to install a sealing ring.

[0052] For details, please refer to Figure 2 In the illustrated embodiment, the platform 12 is provided with a solder groove 13 and a sealing groove 16. The sealing groove 16 surrounds the solder groove 13, and the centers of the two are at the same point.

[0053] Before welding the pipe joint to the heat exchanger, a sealing ring (such as a high-temperature resistant rubber ring or a metal spiral wound gasket) is pre-installed in the sealing groove 16. Initial sealing can be achieved through mechanical extrusion. The sealing ring can prevent the solder from overflowing from the gap between the platform and the heat exchanger panel in a high-temperature molten state, thus avoiding solder from flowing into the heat exchanger channel and causing contamination or blockage.

[0054] After welding, the sealing ring 16 and the weld in the solder groove 13 form a double-protection structure of "mechanical seal + welding seal". At this time, the sealing ring 16 can absorb the displacement caused by vibration or thermal deformation and relieve the shear stress borne by the weld. Especially under high-frequency vibration conditions, it can effectively prevent leakage caused by weld fatigue cracking.

[0055] The dual-seal design also expands the applicability of the pipe fitting. Under low-pressure conditions, even if the sealing performance of the solder groove 13 decreases slightly, the sealing ring 16 can still independently maintain the system's sealing performance; under high-pressure conditions, the two work together to further improve sealing reliability, forming multi-layer protection.

[0056] In one specific embodiment, the sealing groove 16 has a depth of 1.5-2 mm and a width of 1.5-2 mm, and is adapted to fit O-rings with a cross-sectional diameter of 1.5-2 mm (such as silicone rubber or fluororubber). Before welding, the sealing ring is pre-placed in the sealing groove 16, and the pipe joint is pressed onto the heat exchanger panel using a tooling. The sealing ring is compressed and undergoes elastic deformation, forming an initial mechanical sealing layer.

[0057] The narrow groove depth and width of 1.5-2mm form a physical barrier, and the elastic deformation of the sealing ring 16 fills the microscopic gap between the platform and the panel, preventing high-temperature solder from overflowing from the interface into the heat exchanger channel. The shallow groove design of 1.5-2mm avoids excessively weakening the structural strength of the platform 12, and is suitable for the sealing requirements of thin heat exchanger panels (thickness ≤5mm). By adjusting the compression of the sealing ring, uniform sealing can be achieved under different panel flatness conditions, thereby enhancing the environmental adaptability of the pipe joint.

[0058] Optionally, a flow guide plate 5 is detachably installed at the outlet of the flow channel 4; the flow guide plate 5 is provided with radially distributed flow guide grooves, the extension direction of which is parallel to the corrugation direction of the first layer plate of the heat exchanger; the width of the flow guide grooves gradually expands from the center to the edge.

[0059] The flow guide plate 5 can be detachably connected to the inner wall of the flow channel 4 by any means such as screwing, plugging, or snapping. This application does not limit the specific installation method of the flow guide plate 5.

[0060] By setting the flow guide plate 5 to be detachable, the flow guide plate 5 with different flow guide grooves can be replaced according to specific flow guide needs.

[0061] In one specific embodiment, the flow guide plate 5 has a disc-shaped structure, and its outer diameter is consistent with the inner diameter of the vertical outlet section of the flow channel 4 (e.g., when the inner diameter of the vertical outlet section is 98mm, the outer diameter of the plate is also 98mm), to ensure that the flow guide plate 5 is tightly fitted to the inner wall of the flow channel 4. The flow guide plate 5 is provided with radially distributed flow guide grooves, which penetrate the flow guide plate 5 vertically. The width of the flow guide grooves gradually expands from 2mm at the center to 8mm at the edge, and the extension direction of the flow guide grooves is parallel to the corrugation direction of the first layer of the heat exchanger plates.

[0062] Because the guide plate 5 has the same inner diameter as the outlet, when the fluid flows from the center to the edge of the guide plate 5, it is forcibly guided by the radial guide grooves and strictly enters the flow channel along the corrugation direction of the heat exchanger plate. This avoids the impact loss caused by the fluid directly hitting the plate when there is no guide structure in the past. For example, when the plate corrugation is inclined at 45°, the guide groove is simultaneously set to a 45° radial direction to ensure that the fluid smoothly cuts in along the corrugation angle and increases the heat exchange contact area.

[0063] The design of the groove width gradually widening from the center to the edge is based on the characteristic that fluid pressure decreases radially. The fluid pressure is higher in the central area, and the narrow groove (2mm) can limit the flow velocity to avoid excessive impact; the fluid pressure is lower in the edge area, and the wide groove (8mm) can reduce flow resistance to increase flow rate, thereby making the fluid evenly distributed across the entire width of the plate, thus solving the "underflow" problem that exists at the edge of traditional straight flow channels.

[0064] It should be explained that the corrugations of the first layer of plates in a plate heat exchanger are usually at a certain angle (such as 30°, 45° or 60°). When the guide groove extends in the same direction, after the fluid flows out from the outlet of the flow channel 4, it can directly cut into the gap of the plate corrugations along the guide groove, thereby avoiding the "opposition impact" caused by the deviation of the flow direction, so that the fluid can participate in heat exchange in a laminar or low turbulent state, and improve the heat transfer efficiency.

[0065] It is easy to understand that if the direction of the guide channel is misaligned with the corrugations of the plate, the fluid needs to adjust its flow direction after entering the plate. At this time, vortex zones are easily formed locally, resulting in increased pressure drop and uneven flow (such as excessive flow in the central area and insufficient flow in the edge area). This application uses a "pre-guiding" mechanism to ensure that the fluid has a velocity vector that matches the corrugations before entering the plate, thereby achieving flow balance across the entire width of the plate.

[0066] Optionally, an anti-clogging filter cup 6 is provided at the center of the flow guide plate 5; the anti-clogging filter cup 6 is set in a conical shape, with the cone tip facing the inlet of the flow channel 4.

[0067] For details, please refer to Figure 2 In the illustrated embodiment, a flow guide plate 5 is installed at the outlet of the flow channel 4, and a cone-shaped anti-clogging filter cup 6 with its apex pointing downwards is located at the center of the flow guide plate 5. The surface of the anti-clogging filter cup 6 is densely covered with mesh holes with a mesh diameter ≤1.5mm, which can effectively intercept particles with a diameter >1.5mm such as welding slag, scale, and metal shavings in the fluid, thereby preventing impurities from entering the gaps between the heat exchanger plates and causing flow channel blockage or scratching of the plate surface.

[0068] The anti-clogging filter cup 6 can guide impurities to gather towards the center of the filter cup through its conical shape and by using the principle of fluid dynamics. It can also allow impurities that have been accidentally punctured to slide down the conical surface to the bottom of the cup and deposit, rather than accumulating on the surface of the filter screen and clogging the filter holes.

[0069] The anti-clogging filter cup 6 is located at the center of the flow guide plate 5, and works in conjunction with the radially distributed flow guide grooves on the flow guide plate 5: after the fluid is filtered by the filter cup, the clean fluid diffuses along the flow guide grooves to the heat exchanger, while impurities are blocked by the anti-clogging filter cup 6 or isolated in the anti-clogging filter cup 6. The anti-clogging filter cup 6 can also prevent the filtered impurities from being mixed into the main fluid again, ensuring that the flow guide grooves and plate channels remain unobstructed for a long time.

[0070] Optionally, the anti-clogging filter cup 6 is detachably disposed at the center of the flow guide plate 5.

[0071] The anti-clogging filter cup 6 can be detachably connected to the flow guide plate 5 by any means such as screwing, plugging, or snapping. This application does not limit the specific installation method of the anti-clogging filter cup 6.

[0072] When the equipment has been running for a certain period (e.g., 500 hours cumulatively) or when a significant increase in flow channel pressure drop is observed, the guide grid 5 can be removed, and the anti-clogging filter cup 6 can be taken out for cleaning or replacement separately. By replacing the anti-clogging filter cup 6 with one of different filtration precision (e.g., custom-made filter screens with pore sizes of 0.5mm, 1mm, etc.), it is possible to adapt to scenarios with varying fluid impurity content. For example, using a fine-pore filter cup under high impurity conditions and replacing it with a loose-pore filter cup under clean conditions helps improve system adaptability. Regularly disassembling and cleaning the filter cup can prevent long-term accumulation of impurities that could lead to filter screen damage or corrosion, avoid metal debris from damaged filter screens entering the flow channel and causing secondary damage, and maintain the filter cup's interception efficiency, indirectly protecting the heat exchanger plates from impurity impact and wear.

[0073] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A pipe fitting for a plate heat exchanger, characterized in that, It includes the coaxially connected upper (1), middle (2) and lower (3) parts, which together form a through-flow channel (4). The upper part (1) is the welding end; The top surface of the upper part (1) is provided with a protruding annular insert (11), which can be inserted into the connection hole of the heat exchanger; The annular insert (11) is surrounded by a platform (12). After the annular insert (11) is inserted into the connection hole of the heat exchanger, the platform (12) can fit against the panel of the heat exchanger. The platform (12) has a recessed solder groove (13) on the side of the surface near the annular plug (11). The solder groove (13) surrounds the annular plug (11) and is used to fill the solder to facilitate welding and fixing of pipe joints and heat exchangers. The lower part (3) is a spare end; The lower part (3) is provided with a plurality of through screw holes (31), which are evenly distributed along the circumferential direction to facilitate the fixed connection between the lower part (3) and the flange of the external pipe. The middle part (2) connects the upper part (1) and the lower part (3); The outer diameter of the middle part (2) is smaller than the outer diameter of the lower part (3); The outer wall of the upper part (1) is composed of a first vertical surface (14) and a first inclined surface (15). The outer diameter of the columnar structure where the first vertical surface (14) is located is larger than the outer diameter of the middle part (2) and smaller than the outer diameter of the lower part (3). The first inclined surface (15) connects the first vertical surface (14) and the middle part (2). The middle part (2) is recessed inward compared to the upper part (1) and the lower part (3) to compensate for welding heat deformation and to reduce flow resistance.

2. The pipe fitting for a plate heat exchanger according to claim 1, characterized in that, The flow channel (4) has an outlet at one end near the welding end and an inlet at the other end near the spare end; The diameter of the outlet is larger than the diameter of the inlet; The inner wall of the outlet side of the flow channel (4) is composed of a second vertical surface (41) and a second inclined surface (42), which can reduce fluid impact resistance and improve flow uniformity.

3. The pipe fitting for a plate heat exchanger according to claim 2, characterized in that, The second inclined plane (42) forms an angle of 30-45° with the central axis of the flow channel (4) to facilitate the smooth flow of fluid into the heat exchanger channel.

4. The pipe fitting for a plate heat exchanger according to claim 2, characterized in that, The connection between the second vertical surface (41) and the second inclined surface (42) is rounded with a radius of 3mm. The connection between the second inclined surface (42) and the vertical inner wall on the inlet side is also rounded with a radius of 3mm.

5. The pipe fitting for a plate heat exchanger according to claim 1, characterized in that, The depth of the solder groove (13) is 1.5-3mm and the width is 2-4mm. The solder groove (13) is used to contain solder and form a sealing weld.

6. The pipe fitting for a plate heat exchanger according to claim 1, characterized in that, The connection between the first vertical surface (14) and the first inclined surface (15) is rounded with a radius of 3mm. The connection between the first inclined surface (15) and the middle part (2) is rounded with a radius of 3mm.

7. The pipe fitting for a plate heat exchanger according to claim 1, characterized in that, The connection between the middle part (2) and the lower part (3) is rounded with a radius of 5mm, which helps to reduce fluid flow resistance and enhance structural strength.

8. The pipe fitting for a plate heat exchanger according to any one of claims 1-7, characterized in that, The platform (12) surface is also provided with a sealing groove (16), which surrounds the solder groove (13) and is arranged coaxially with the solder groove (13). The sealing groove (16) is used to install a sealing ring.

9. The pipe fitting for a plate heat exchanger according to claim 1, characterized in that, A flow guide plate (5) is detachably installed at the outlet of the flow channel (4). The flow guide plate (5) is provided with radially distributed flow guide grooves, and the extension direction of the flow guide grooves is parallel to the corrugation direction of the first layer plate of the heat exchanger. The width of the guide channel gradually increases from the center to the edge.

10. The pipe fitting for a plate heat exchanger according to claim 9, characterized in that, The flow guide plate (5) is provided with an anti-clogging filter cup (6) at its center. The anti-clogging filter cup (6) is set in a conical shape, with the cone tip facing the inlet of the flow channel (4).

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