Corrosion-resistant condensing heat exchanger and method of manufacturing the same

Abstract

The application discloses a kind of corrosion-resistant condensing heat exchanger, including: by cooling pipe component, fixed to the header of the tube component both ends, with the condensate reservoir of the tube component connection, with the tube component both ends connection pipe joint.The application also discloses a kind of corrosion-resistant condensing heat exchanger manufacturing method, the method includes the following steps: before pipe head implements welding operation, pipe head is partitioned and identified;When welding, according to the window of welding protection and deformation prevention tool design, symmetric welding is carried out;After welding is completed in window, window is rotated, and then continue welding;According to the sequence of installation tool, protection gas is filled, welding window is opened, symmetric welding, tool rotation degree, alternate welding;By detecting and judging welding quality to weld joint.The whole condensing heat exchanger of the application adopts titanium alloy one kind of material to avoid galvanic corrosion, adopts fusion welding to avoid weak link such as brazing filler metal, realizes excellent corrosion resistance in long-term operation process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid cooling systems, and particularly relates to a corrosion-resistant condensing heat exchanger and a manufacturing method thereof. BACKGROUND

[0002] The condensing heat exchanger is a gas-liquid heat exchanger, which transmits the heat of air to the coolant of a cooling loop and removes the excess water vapor in the air in a condensing manner, so as to achieve the purpose of cooling and drying the air. The working medium of the condensing heat exchanger is hot and humid air in the running process, and the coolant of the cooling loop is the cold side.

[0003] Due to the long-term condensing and dehumidifying use mode and the complexity of the air environment, the condensate water generated on the surface of the heat exchanger contains corrosive ions such as Cl-, SO42- and NH4+, and the corrosion resistance of the heat exchanger is very high. It not only needs to meet the long-term compatibility with the internal cooling medium, but also needs to meet the corrosion resistance requirements of the condensate water corrosive ions.

[0004] Aluminum is a kind of active metal, and its corrosion resistance depends on the passivity caused by the protective oxide film. The chromate chemical passivation treatment is used on the surface of the condensing heat exchanger, which can cover a dense chemical passivation film layer on the surface of the aluminum alloy. The chemical passivation film is a good chemical passivation film at present, which is mainly composed of chromium oxides such as CrO3. The dense and water-insoluble Cr oxides isolate the contact between the cooling medium and the aluminum alloy substrate on the surface of the aluminum alloy, so that the aluminum alloy is protected from corrosion. However, in the condensate water, because the medium contains active anions (such as chloride ions), the chloride ions can selectively adsorb on the Cr oxides, expel the oxygen atoms, and then combine with the chromium cations in the chromium oxide to form soluble chlorides. At the place where the soluble chlorides are formed, the aluminum alloy substrate is exposed, which constitutes a small anode for corrosion, and the whole place without damage constitutes a large cathode for corrosion. Under the galvanic action of the small anode and the large cathode, the exposed place becomes the source of corrosion and starts to corrode. With the progress of corrosion, a closed cell is formed in the corrosion area, which accelerates the development of pitting corrosion and finally causes perforation. Therefore, the corrosion resistance scheme of the aluminum alloy material using the chromate passivation film cannot meet the requirements.

[0005] Titanium is known as "space metal" due to its stable chemical properties, good high-temperature resistance, low-temperature resistance, strong acid resistance, strong alkali resistance, high strength and low density. The corrosion resistance of titanium is due to a stable and strongly adhered oxide film on the surface. When the fresh surface of titanium is exposed to air or moisture, the oxide film is immediately formed. The passivation film of titanium alloy is usually very thin, which is an adsorption film or a three-dimensional phase film with a single molecular layer to several molecular layers. The existence of the passivation film of titanium alloy reduces the area of the metal electrode surface for active dissolution, or hinders the transmission of reaction particles to reduce or inhibit the dissolution of titanium alloy in the corrosion medium, so that the passivation phenomenon occurs. The self-corrosion potential of titanium and titanium alloy after passivation is greatly increased. The passivation film of titanium has good self-healing property, and when the passivation film is damaged, it can quickly repair and form a new protective film. Therefore, titanium alloy has good corrosion resistance. By using brazing method, a titanium alloy condensing heat exchanger is manufactured, and it is found through corrosion test that the corrosion resistance of the titanium alloy base material is excellent; the corrosion resistance of the titanium tube is much better than that of the aluminum tube. However, since the corrosion resistance of the filler metal is poorer than that of the base material, galvanic corrosion occurs at the filler metal, which still cannot meet the corrosion resistance requirement. SUMMARY

[0006] The purpose of the present application is to solve the problem of the influence of galvanic corrosion of the condensing heat exchanger on the service life.

[0007] The purpose of the present application is achieved by adopting the following technical solutions:

[0008] A corrosion-resistant condensing heat exchanger, comprising: a tube bundle assembly composed of cooling tubes, a header cover fixed to both ends of the tube bundle assembly, and a condensate water reservoir connected with the tube bundle assembly; the tube bundle assembly and the header cover are made of the same metal material; the tube bundle assembly is welded by micro-beam plasma arc welding.

[0009] Preferably, the metal material comprises titanium alloy.

[0010] Preferably, the tube bundle assembly is a hollow columnar array composed of multiple groups of tube bundles uniformly distributed in the circumferential direction.

[0011] Preferably, the tube bundle assembly comprises multiple groups of tube bundles arranged in an array structure in parallel, annular end plates welded to both ends of the tube bundles, and heat dissipation fins connected to the outer sides of the tube bundles.

[0012] Preferably, the annular end plate comprises heat dissipation tube openings and welding grooves located around the heat dissipation tube openings.

[0013] Preferably, the heat dissipation fins have multiple expansion joints for preventing thermal stress.

[0014] Preferably, the header cover comprises a header groove and a cooling working medium interface in communication with the header groove.

[0015] Preferably, the condensed water reservoir comprises a condensed water collection cone fixed with the tube bundle assembly and a drain pipe connected with the condensed water collection cone.

[0016] Preferably, the condensed water collection cone is installed inside the tube bundle assembly for air guiding.

[0017] Based on the same inventive concept, the application also provides a manufacturing method of a corrosion-resistant condensing heat exchanger, which comprises the following steps: partition identification of the tube heads;

[0018] During welding, the tube bundle in the partition is welded through the window of the tooling design;

[0019] After the tube heads in the window are welded, the tooling is rotated to switch to the next window for continuous welding;

[0020] The welding quality is determined by detecting the weld.

[0021] The cooling working medium flows inside the heat exchange tube bundle, so that the temperature of the cooling working medium is lower than the dew point temperature of the humid hot air. When the humid hot air passes through the heat exchange tube bundle, it condenses on the surface of the tube bundle to achieve the purpose of dehumidification and cooling.

[0022] The heat exchanger tube bundle assembly is composed of 52 groups of tube bundles uniformly distributed in the circumferential direction. Each group of tube bundles is divided into 8 layers from the outside to the inside, each layer has 2, a total of 16, and the entire heat exchanger has a total of 832 tube bundles, and the single tube size is Φ4×0.3. Through the heat exchange inside and outside the tube bundle, high-efficiency heat exchange and dehumidification are realized.

[0023] In order to resist the corrosion of the internal cooling working medium and the external condensed water, the tube bundle assembly is made of titanium alloy material, and the entire heat exchanger is made of one kind of material to avoid galvanic corrosion caused by different potentials; the welding adopts a solder-free manual fusion welding method to avoid the presence of weak links such as solder to realize overall corrosion resistance.

[0024] The heat exchange tube is small in size, the tube plate area is small, and the tube holes are densely distributed. Combined with the welding characteristics of titanium material, the welding method of micro-beam plasma arc welding is selected for the welding of the tube head and the tube plate. Micro-beam plasma arc welding has concentrated energy, can accurately control the welding parameters, has small welding heat input, and high welding quality, which avoids the phenomenon of causing local heat input of the tube plate to be too large, causing grain coarsening, or the melting amount of the tube head and the tube plate being too large, causing deformation.

[0025] According to the characteristics of the tube bundle and the micro-beam plasma welding characteristics, a welding groove is designed around the heat exchange tube hole, which can well control the weld width and penetration depth, and effectively separate the welding influence of adjacent tube heads.

[0026] Welding process quality control: before the pipe head implements the welding operation, the pipe head is marked by partition, the symmetric welding is carried out according to the window of the welding protection and the deformation prevention tooling design, after the pipe head in the window is welded, the window is rotated, and then the welding is continued, and the sequence is carried out (installation tooling - protection gas filling - welding window opening - symmetric welding - tooling rotation angle - alternate welding). The same parameters are used to weld the welding sample before each welding, and after the welding method is stable, the pipe head welding of the heat exchanger is carried out, and the welding seam of the sample is detected to determine the stability of the welding quality of the region.

[0027] The condensing heat exchanger adopts titanium alloy material, and the whole heat exchanger is made of one kind of material, so that the galvanic corrosion caused by different potentials can be effectively avoided; the solderless manual fusion welding method is adopted for welding, so that the weak link such as solder is avoided, and excellent overall corrosion resistance is realized. The condensing heat exchanger has excellent corrosion resistance in long-term operation, and can effectively solve the problem of galvanic corrosion affecting the service life of the condensing heat exchanger. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The condensing heat exchanger structure principle diagram of the application is shown in the figure;

[0029] Figure 2 The tube layout diagram of the tube assembly is shown in the figure;

[0030] Figure 3 The welding groove schematic diagram is shown in the figure;

[0031] Figure 4 The welding protection and deformation prevention tool section view is shown in the figure;

[0032] Figure 5 The welding protection and deformation prevention tool top view is shown in the figure;

[0033] 1-tube assembly, 2-collector cover, 3-condensed water reservoir, 11-tube, 12-annular end plate, 13-radiating fin, 21-cooling working medium interface, 31-condensed water collection cone, 32-drain pipe, 50-tooling, 101-radiating pipe opening, 102-welding groove, 501- boss, 502-window. DETAILED DESCRIPTION

[0034] The technical solutions are further described below in combination with the drawings and specific embodiments, so as to help understand the content of the application.

[0035] The application designs a condensing heat exchanger, which realizes the purposes of cooling and drying air by using the condensing and dehumidifying principle. The condensing heat exchanger has very good corrosion resistance.

[0036] As Figure 1As shown in the drawings, the condensing heat exchanger comprises a tube bank assembly 1 composed of cooling tubes, a header cover 2 fixed at both ends of the tube bank assembly 1, and a condensate water reservoir 3 connected with the tube bank assembly 1; the tube bank assembly 1 and the header cover 2 are made of the same metal material; the tube bank assembly 1 is welded by micro-beam plasma arc welding.

[0037] The metal material comprises titanium alloy.

[0038] The tube bank assembly 1 is a hollow columnar array composed of multiple groups of tube banks uniformly distributed in the circumferential direction.

[0039] As shown in the drawings, Figure 1 and Figure 2 The tube bank assembly 1 comprises multiple groups of tube banks 11 arranged in an array structure in parallel, annular end plates 12 welded at both ends of the tube banks 11, and heat dissipation fins 13 connected with the outer sides of the tube banks 11.

[0040] As shown in the drawings, Figure 2 and Figure 3 The annular end plate 12 comprises heat dissipation tube openings 101 and welding grooves 102 located around the heat dissipation tube openings 101.

[0041] The heat dissipation fin 13 has multiple expansion joints for preventing thermal stress.

[0042] The header cover 2 comprises a header groove and a cooling working medium interface 21 in communication with the header groove.

[0043] The condensate water reservoir 3 comprises a condensate water collection cone 31 fixed with the tube bank assembly 1 and a drain pipe 32 connected with the condensate water collection cone 31.

[0044] As shown in the drawings, Figure 1 The condensate water collection cone 31 is installed inside the tube bank assembly 1 for air flow guiding.

[0045] Based on the same inventive concept, the application further provides a manufacturing method of the corrosion-resistant condensing heat exchanger, which comprises the following steps: partitioning and marking the tube heads;

[0046] Welding the tube banks in the partition through the window of the tooling during welding;

[0047] After the tube heads in the window are welded, the tooling is rotated to switch to the next window for continuous welding;

[0048] The welding quality is detected and determined.

[0049] As shown in the drawings, Figure 4As shown, the tooling (other auxiliary components not shown) includes a cover plate 50 that matches the top shape and size of the tube bundle assembly 1, the center of the cover plate 50 has a boss 501 for positioning on the tube bundle assembly.

[0050] As shown, the cover plate 50 is provided with a plurality of windows 502 at different positions, the windows 502 are uniformly distributed in the circumferential direction of the cover plate 50 and are divided into three areas in the radial direction, each area is symmetrically distributed relative to the geometric center of the cover plate 50, and the regular switching of the partition of the tube bundle assembly 1 is realized by the rotation of the tooling relative to the tube bundle assembly 1, so as to realize symmetrical and balanced welding and to reduce the welding stress of the tube bundle assembly 1 to the greatest extent. Figure 5

[0051] The main technical features of the present application are:

[0052] (1) The overall compact structure of the condenser heat exchanger and the tube arrangement mode: the heat exchange tubes are arranged in the outer circle, 52 groups of tubes are uniformly distributed in the circumferential direction, each group of tubes is divided into 8 layers from the outside to the inside, and each layer has 2 tubes, a total of 16 tubes, the entire heat exchanger has a total of 832 tubes, and the single tube size is Φ4*0.3.

[0053] (2) The overall scheme adopted for corrosion resistance: in order to resist the corrosion of the internal cooling medium and the external condensate water, the tube bundle assembly is made of titanium alloy material, the entire heat exchanger is made of one kind of material, and galvanic corrosion caused by different potentials is avoided; the heat exchanger is welded by a solder-free manual fusion welding method, so as to avoid the existence of weak links such as solder, and realize the overall corrosion resistance.

[0054] (3) Adopting a suitable welding method: the heat exchanger tube is small in size, the tube plate area is small, and the tube holes are densely distributed. Combined with the welding characteristics of titanium material, the welding method of micro-beam plasma arc welding is selected for the welding of the tube head and the tube plate. The micro-beam plasma arc welding has concentrated energy, can accurately control the welding parameters, has small welding heat input, and has high welding quality, which avoids the phenomenon that the local heat input of the tube plate is too large, the grain is coarse, or the melting amount of the tube head and the tube plate is too large, and deformation occurs.

[0055] (4) Designing a welding groove: according to the characteristics of the tube and the characteristics of the micro-beam plasma welding, a welding groove is designed around the heat exchange tube hole, which can well control the weld width and penetration depth, and effectively separate the welding influence of adjacent tube heads.

[0056] ​(5) Design a welding protection and anti-deformation tool: in order to control the quality of the welding process, the pipe head is marked before the welding operation, and the symmetric welding is carried out according to the window designed by the welding protection and anti-deformation tool, after the pipe head in the window is welded, the window is rotated, and the welding is continued, and the sequence is (install tool-protection gas-charging welding window-symmetric welding-tool rotation angle-alternating welding). The same parameters are used to weld the welding sample before each welding, and after the welding method is stable, the pipe head welding of the heat exchanger is carried out, and the weld of the sample is detected to further determine the stability of the welding quality of the area.

[0057] The above is only an embodiment of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application is included in the scope of the claims of the application to be approved.

Claims

1. A corrosion resistant condensing heat exchanger characterized by, The condensing heat exchanger comprises: a tube bank assembly composed of cooling tubes, header covers fixed at both ends of the tube bank assembly, and a condensate water reservoir connected with the tube bank assembly; the tube bank assembly and the header covers are made of the same metal material; the tube bank assembly is welded by micro-beam plasma arc welding; The metal material comprises titanium alloy; The tube bank assembly is a hollow columnar array composed of multiple groups of tubes uniformly distributed along the circumferential direction; The tube bank assembly comprises multiple groups of tubes arranged in parallel and in an array structure, annular end plates welded at both ends of the tubes, and heat dissipation fins connected with the outer sides of the tubes; The annular end plate comprises heat dissipation tube openings and welding grooves located around the heat dissipation tube openings; The heat dissipation fins have multiple expansion joints for preventing thermal stress; The header cover comprises a header groove and a cooling working medium interface in communication with the header groove; The condensate water reservoir comprises a condensate water collection cone fixed with the tube bank assembly and a drain pipe connected with the condensate water collection cone; The condensate water collection cone is installed inside the tube bank assembly for air flow guiding.

2. A method of manufacturing a corrosion resistant condensing heat exchanger as claimed in claim 1, wherein, The method comprises the following steps: partition identification is performed on the tube heads; During welding, the tubes in the partition are welded through the window designed by the tooling; After the tube heads in the window are welded, the tooling is rotated to switch to the next window for continuous welding; The welding quality is determined by detecting the welds.

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