Hot welding process suitable for heat exchanger machining

Abstract

The invention provides a hot welding process suitable for heat exchanger processing, which comprises the following operations: S1, a heat effect amplifying agent is arranged on a flat tube, the heat effect amplifying agent is arranged at the joint of the flat tube and a fin, and the heat effect amplifying agent comprises a material capable of generating an exothermic reaction under a heating condition; s2, the flat pipes and the fins are pre-assembled; and S3, the heat effect amplifying agent is heated to trigger the heat effect amplifying agent to generate an exothermic reaction, the heat generated by the exothermic reaction is used for melting the area, connected with the flat pipe, of the heat effect amplifying agent and / or the fin, and therefore welding of the flat pipe and the fin is achieved. Compared with a brazing process commonly used for heat exchanger machining at present, the hot welding process effectively improves the surface smoothness of the connecting positions of the flat pipes and the fins in the heat exchanger, then the situation that the heat exchanger is prone to frosting and freezing is prevented, and the heating effect of the heat exchanger is optimized.

Description

Technical Field

[0001] The invention belongs to the technical field of welding technology, and in particular, relates to a thermal welding technology suitable for processing a heat exchanger. Background Art

[0002] At present, the heat exchangers on the market generally include fins and flat tubes. During the processing of the heat exchanger, the connection between the fins and the flat tubes is often achieved through the brazing process. The application of the brazing process introduces brazing material into the heat exchanger. In the finished heat exchanger, the brazing material will adhere to the fins after processing. The residual brazing material increases the surface roughness of the fins and forms a rough structure on the surface of the fins. On the one hand, such a rough structure is easy to absorb water and affect the drainage of the fins. On the other hand, when the fins are cold and frosted, they are easy to become condensation nuclei. This will accelerate the frosting and ice formation of the temperature control system of the heat exchanger, making its heating effect worse and affecting the user experience. Summary of the invention

[0003] The present invention optimizes the heating effect of the heat exchanger by providing a thermal welding process suitable for processing the heat exchanger.

[0004] According to one aspect of the present invention, a heat welding process suitable for heat exchanger processing is provided. The heat welding process is used to realize the welding of fins and flat tubes included in the heat exchanger. The fins are metal workpieces. The heat welding process includes the following operations: S1. A thermal effect amplifier is arranged on the flat tube. The thermal effect amplifier is arranged at the connection between the flat tube and the fin. The thermal effect amplifier includes a material that can undergo an exothermic reaction under heating conditions; S2. The flat tube and the fin are preassembled so that the positional relationship between the two is consistent with the positional relationship after the welding is completed; S3. The thermal effect amplifier is heated to trigger the thermal effect amplifier to undergo an exothermic reaction. The heat generated by the exothermic reaction is used to melt the thermal effect amplifier and / or the fin in the area where it is connected to the flat tube, thereby realizing the fusion of the flat tube and the fin. In the above-mentioned heat welding process, the welding of the flat tube and the fin can be realized directly through the melted thermal effect amplifier or the partially melted fin. Therefore, there is no need to introduce brazing material into the heat exchanger in order to realize the welding between the flat tube and the fin. Compared with the brazing process currently commonly used in heat exchanger processing, the heat welding process provided by the present invention effectively improves the surface smoothness of the connection between the flat tube and the fin in the heat exchanger, thereby preventing the heat exchanger from being easily frosted and easily iced, and the heating effect of the heat exchanger is optimized. Among them, the above-mentioned thermal effect amplifier can be calcium carbonate (the decomposition reaction generated by heating is an exothermic reaction), or it can be a thermite (the thermite reaction generated by heating is an exothermic reaction), or it can be a mixture of iron powder and sulfur powder (elemental iron and elemental sulfur generate ferrous sulfide after heating to release heat). In S3 of the above-mentioned hot welding process: the heating method of the thermal effect amplifier can be direct heating of the thermal effect amplifier, or it can be indirect heating of the thermal effect amplifier; the above-mentioned indirect heating method can be by heating the components included in the heat exchanger such as the flat tube, so that the heat generated thereby is transferred to the thermal effect amplifier.

[0005] Preferably, the thermal effect amplifier is evenly distributed in the contact area between the flat tube and the fin. As the raw material of the exothermic reaction, the distribution position of the thermal effect amplifier determines the regional distribution of the thermal effect generated by the exothermic reaction. At the same time, the thermal effect amplifier can be used as a solder to realize the welding of the flat tube and the fin, and its distribution position determines the position distribution of the connection between the flat tube and the fin. By evenly arranging the thermal effect amplifier, on the one hand, it can ensure that the thermal effect generated by the exothermic reaction acts evenly on the flat tube and the fin, avoiding uneven deformation of the workpiece due to local overheating. On the other hand, it can ensure that the connection points between the flat tube and the fin are evenly distributed, which is beneficial to improve the connection stability between the flat tube and the fin.

[0006] Preferably, a plurality of thermal effect amplifier filling parts are provided on the flat tube, the thermal effect amplifier is filled in the thermal effect amplifier filling parts, and the plurality of thermal effect amplifier filling parts are arranged at intervals.

[0007] Preferably, the thermal effect amplifier includes thermite. Further, by using the thermal effect amplifier containing thermite to introduce the application of thermite reaction in the welding process of the present invention, thermite reaction is easy to trigger and reacts quickly, and the thermal effect it produces is obvious. Under the action of the strong thermal effect, the welding of the flat tube and the fin can be completed without the need for an external high-energy energy source, which is beneficial to saving energy and improving the production efficiency of the heat exchanger processing.

[0008] Preferably, the thermite includes elemental aluminum and copper oxide, and the mass ratio of elemental aluminum to copper oxide is 0.8 to 1.2: 3. The use of the thermite with the above formula composition can further improve the surface smoothness of the connection between the flat tube and the fin, thereby further optimizing the heating effect of the heat exchanger.

[0009] Preferably, the thermal effect amplifier also includes an oxidant.

[0010] Preferably, the oxidizing agent comprises potassium chlorate.

[0011] Preferably, the average particle size D of the thermal effect amplifier is 50 ≤50μm. The particle size of the thermal effect amplifier used is within the above range. The thermal effect amplifier is easy to melt under the action of thermal effect. On the one hand, it can improve the welding efficiency between the flat tube and the fin. On the other hand, it effectively avoids the situation where uneven thermal effect amplifier particles remain at the connection between the flat tube and the fin, and the surface smoothness of the connection between the flat tube and the fin is further improved. Preferably, the number of fins is A, the thickness of the fin is B, the gap formed between the fin and the flat tube before welding is completed is C, and the volume of the thermal effect amplifier is V, V: A×B×C=1.05~1.2.

[0012] Preferably, in S3, the thermal effect amplifier is heated by heating the flat tubes using the heat generated by the flat tubes.

[0013] Preferably, a conductor is provided in the flat tube, and in S3, the flat tube is heated by causing the conductor to generate a current thermal effect. The above method can accurately control the external thermal effect, which can not only achieve energy saving, but also avoid thermal runaway caused by excessive external thermal effect.

[0014] Preferably, the conductor is selected from titanium alloy superconducting material or graphene.

[0015] Preferably, the material of the flat tube includes graphene. Graphene has the characteristics of high thermal conductivity and high strength. When the flat tube is made of graphene, the heat generated by the flat tube after being heated can be efficiently transferred to the position where the thermal effect amplifier is provided, and the exothermic reaction can be efficiently triggered. At the same time, the flat tube has excellent structural strength, so that it is not easy to break during the welding process, and the finished product can have good structural stability.

[0016] Preferably, the material of the fins includes single element aluminum. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only embodiments of a part of the present invention, rather than all embodiments.

[0018] Example 1

[0019] In this embodiment, a heat exchanger is prepared by welding aluminum fins on a graphene flat tube. According to different welding processes, it is specifically divided into treatment group 1A, treatment group 2A, treatment group 3A, treatment group 4A, treatment group 5A, control group 1, control group 2, and control group 3. The materials, shapes, and quantities of the flat tubes and fins used in the above treatment groups and control groups are the same. Among them, the relevant information of the components and materials used in each treatment group and control group of this embodiment is as follows: the flat tube used is a hollow tubular structure, its material is graphene, and the length of the flat tube is; the fin used is a straight sheet, its material is simple aluminum, the length of one side of the fin used for welding with the flat tube is 7mm, and the thickness of the fin is 0.1mm; the thermite used is prepared by simple aluminum and copper oxide in a mass ratio of 1:3, and the average particle size D of the thermite is 50 is 45μm.

[0020] Treatment Group 1A

[0021] S1. A plurality of thermal effect amplifier filling parts are arranged on the flat tube and are evenly distributed on the surface thereof, and an equal amount of thermal effect amplifier is filled into each thermal effect amplifier filling part. The thermal effect amplifier is compounded by potassium chlorate and thermite in a mass ratio of 1:9. The total amount of the thermal effect amplifier is determined as follows: the number of fins is A, the thickness of the fins is B, the gap formed between the fins and the flat tube before welding is completed is C, and the volume of the thermal effect amplifier is V, V: A×B×C=1.05~1.2.

[0022] S2. Pre-assemble the fins to be welded on both sides of the flat tube, and make the fins and the flat tube contact each other.

[0023] S3. Directly use the electric heating sleeve to heat the flat tube to increase the temperature of the flat tube. The flat tube is heated and transfers the heat to the thermal effect amplifier filling part, triggering the thermal effect amplifier filled in the thermal effect amplifier filling part to produce thermite reaction. The thermite and the area on the fin that contacts the flat tube melt, and the molten material thus formed realizes the welding between the flat tube and the fin.

[0024] Treatment Group 2A

[0025] S1. Evenly spray a thermal effect amplifier on one side of the flat tube for connection with the fin, wherein the amount and composition of the thermal effect amplifier are consistent with the amount of the thermal effect amplifier in treatment group 1A.

[0026] S2. Pre-assemble the fins to be welded on both sides of the flat tube, and make the fins and the flat tube contact each other.

[0027] S3. Directly use the electric heating sleeve to heat the flat tube to increase the temperature of the flat tube. The flat tube is heated and transfers the heat to the thermal effect amplifier filling part, triggering the thermal effect amplifier filled in the thermal effect amplifier filling part to produce thermite reaction. The thermite and the area on the fin that contacts the flat tube melt, and the molten material thus formed realizes the welding between the flat tube and the fin.

[0028] Treatment Group 3A

[0029] S1. A plurality of thermal effect amplifier filling parts are arranged on the flat tube and are evenly distributed on the surface thereof, and an equal amount of thermal effect amplifier is filled into each thermal effect amplifier filling part. The amount and composition of the thermal effect amplifier and the arrangement of the thermal effect amplifier filling parts are consistent with those of treatment group 1A.

[0030] S2. Pre-assemble the fins to be welded on both sides of the flat tube, and make the fins and the flat tube contact each other.

[0031] S3. Place titanium alloy superconducting material into the hollow tube of the flat tube, and connect the titanium alloy superconducting material to the circuit through a wire, start the power supply, supply power to the titanium alloy superconducting material to generate electric current thermal effect, and utilize the electric current thermal effect to heat the flat tube. The flat tube is heated and transfers the heat to the thermal effect amplifier filling part, triggering the thermal effect amplifier filled in the thermal effect amplifier filling part to cause thermite reaction, and the thermite and the area on the fin that contacts the flat tube melt, and the molten material thus formed realizes the welding between the flat tube and the fin.

[0032] Treatment Group 4A

[0033] S1. Evenly spray a thermal effect amplifier on one side of the flat tube for connection with the fins. The amount and composition of the thermal effect amplifier are consistent with those of treatment group 1A.

[0034] S2. Pre-assemble the fins to be welded on both sides of the flat tube, and make the fins and the flat tube contact each other.

[0035] S3. Place titanium alloy superconducting material into the hollow pipe of the flat tube, and connect the titanium alloy superconducting material to the circuit through a wire, start the power supply, and supply power to the titanium alloy superconducting material to generate electric current thermal effect. The flat tube is heated and transfers heat to the thermal effect amplifier filling part, triggering the thermite filled in the thermal effect amplifier filling part to cause thermite reaction. The thermite and the area on the fin that contacts the flat tube melt, and the molten material thus formed realizes the welding between the flat tube and the fin.

[0036] Treatment Group 5A

[0037] S1. A plurality of thermal effect amplifier filling parts are arranged on the flat tube and are evenly distributed on the surface thereof, and an equal amount of thermal effect amplifier is filled into each thermal effect amplifier filling part. The thermal effect amplifier is composed of calcium carbonate. The amount of the thermal effect amplifier is consistent with the amount of the thermal effect amplifier used in the treatment group 1A, and the arrangement of the thermal effect amplifier filling parts is consistent with that of the treatment group 1A.

[0038] S2. Pre-assemble the fins to be welded on both sides of the flat tube, and make the fins and the flat tube contact each other.

[0039] S3. Place titanium alloy superconducting material into the hollow tube of the flat tube, and connect the titanium alloy superconducting material to the circuit through a wire, start the power supply, and supply power to the titanium alloy superconducting material to generate electric current thermal effect. The flat tube is heated and transfers heat to the thermal effect amplifier filling part, triggering the thermal effect amplifier filled in the thermal effect amplifier filling part to produce an exothermic reaction, and the thermal effect amplifier and the area on the fin that contacts the flat tube melt, and the molten material thus formed realizes the welding between the flat tube and the fin.

[0040] Control group 1

[0041] S1. Pre-assemble the fins to be welded on both sides of the flat tube and make the fins and the flat tube contact each other.

[0042] S2. Evenly spray Al-Si series brazing filler metal at the connection between the flat tube and the fin. The amount of Al-Si series brazing filler metal used is consistent with the amount of thermite used in treatment group 1A.

[0043] S3. Use a welding gun to heat the Al-Si series brazing filler metal attached to the connection between the flat tube and the fin, and use the molten Al-Si series brazing filler metal to achieve welding between the flat tube and the fin.

[0044] Control group 2

[0045] S1. Pre-assemble the fins to be welded on both sides of the flat tube and make the fins and the flat tube contact each other.

[0046] S2. Evenly spray Al-Si-Cu series solder at the connection between the flat tube and the fin. The amount of Al-Si-Cu series solder is consistent with the amount of thermite in treatment group 1A.

[0047] S3. Use a welding gun to heat the Al-Si-Cu series brazing filler metal attached to the connection between the flat tube and the fin, and use the molten Al-Si-Cu series brazing filler metal to achieve welding between the flat tube and the fin.

[0048] Control group 3

[0049] S1. Pre-assemble the fins to be welded on both sides of the flat tube and make the fins and the flat tube contact each other.

[0050] S2. Evenly spray Al-Ag-Cu-Zn series solder at the connection between the flat tube and the fin. The amount of Al-Ag-Cu-Zn series solder is consistent with the amount of thermite in treatment group 1A.

[0051] S3. Use a welding gun to heat the Al-Ag-Cu-Zn series solder attached to the connection between the flat tube and the fin, and use the molten Al-Ag-Cu-Zn series solder to achieve welding between the flat tube and the fin.

[0052] Test Example 1

[0053] 1. Test subjects

[0054] This test example uses the heat exchanger prepared in Example 1 as the test object. In the test items of this test example, each heat exchanger is set to be repeated five times, and one heat exchanger is one repetition. The test results obtained below are the average values ​​of the parallel repeated experimental results of the same heat exchanger.

[0055] 2. Test items

[0056] Fin frost area ratio test

[0057] To simulate the outdoor low temperature condition, at a temperature of -2℃ and a humidity of 75%, the heat exchanger was operated in heating mode for 5 hours. The frost on the surface of the fin was photographed by a camera. The frost area on the surface of the fin was determined by image recognition technology, and the ratio of the frost area on the fin to the total surface area of ​​the fin was calculated, recorded as S%.

[0058] 3. Test results

[0059] After welding, the treatment groups 1A to 5A and the control groups 1 to 3 of Example 1 can achieve a stable connection between the flat tubes and the fins of the heat exchanger. However, by observing and touching the connection between the flat tubes and the fins in the heat exchangers prepared by the treatment groups and the control group in Example 1, it can be clearly distinguished that compared with the heat exchangers prepared by the control groups 1 to 3, the surface smoothness of the connection between the flat tubes and the fins in the heat exchangers prepared by the treatment groups 1A to 5A is relatively high, and there are no obvious irregular particles on the surface. Relatively speaking, in the heat exchangers prepared by the control groups 1 to 3, the connection between the flat tubes and the fins is obviously rougher. Combined with the settings of the treatment groups and the control group in Example 1, it can be seen that in the process of preparing the heat exchanger, the control groups 1 to 3 use the traditional brazing process to achieve the welding between the flat tubes and the fins. Therefore, the fins of the heat exchangers prepared by these control groups are all attached with brazing material introduced by brazing. The residual brazing material increases the surface roughness of the fins and forms a rough structure on the surface of the fins. Treatment groups 1A to 5A all use heat-triggered thermal effect amplifiers to generate exothermic reactions, and then use the thermal effect of the exothermic reaction to melt the fins at the position where they contact the flat tubes, thereby indirectly completing the welding of the flat tubes and fins. The application of brazing material is not involved in the welding process, so there is no brazing material residue on the fins of the heat exchanger prepared. The test results of this test example are shown in Table 1. From the data shown in Table 1, it can be seen that among the test objects, compared with the heat exchangers provided by control groups 1 to 3, the heat exchangers provided by treatment groups 1A to 5A have a relatively low measured fin frosting area. The reason for the above phenomenon is that in the heat exchangers provided by control groups 1 to 3, the brazing material remaining on the fins acts as a frosting condensation nucleus when the fins are cold, making the heat exchanger more prone to frost and ice, which is reflected in the increase of the frosting temperature of the heat exchanger. Since no brazing material is used in treatment groups 1A to 5A, the connection between the fins and the flat tubes in the heat exchangers produced therefrom has a smooth surface and a smooth transition, which can prevent the fins from frosting or icing when exposed to cold, so that the heating effect of the heat exchanger can be maintained at a good level for a long time. In treatment groups 1A to 5A, the fin frosting area ratio measured in the heat exchangers provided by treatments 1A to 4A is lower. In the process of processing the heat exchangers of treatments 1A to 4A, thermite is used as a thermal effect amplifier. Since the fins used are aluminum workpieces, they can be well fused with thermite to improve the surface smoothness of the connection between the fins and the flat tubes. In addition, the thermal effect of thermite reaction is obvious, which can efficiently generate a melt at the connection between the fins and the flat tubes, and quickly complete the welding between the fins and the flat tubes.

[0060] Table 1. Test results statistics of test items in this test case

[0061]

[0062]

[0063] Example 2

[0064] Based on the test results of the test example, this embodiment uses treatment group 3A of embodiment 1 as a control to prepare a heat exchanger. Taking the composition of the thermite used in the welding process between the flat tube and the fin as a variable, different treatment groups are set and marked as treatment group 1B, treatment group 2B, treatment group 3B, treatment group 4B, treatment group 5B, and treatment group 6B, respectively. Since treatment group 3A of embodiment 1 is used as a control, treatment group 3A of embodiment 1 is marked as the control group in this embodiment. The specific composition of the thermite used in the control group and the above treatment groups is shown in Table 2. The difference between the treatment groups is only that the composition of the thermite used is different. In addition, other components, materials and process operations used to prepare the heat exchanger are strictly kept consistent.

[0065] Table 2. Specific composition of thermite used in the control group and each treatment group of this example

[0066] Group Thermite formula composition (mass ratio) Control group Elemental aluminum: copper oxide = 1:3 Treatment Group 1B Elemental aluminum: copper oxide = 0.6:3 Treatment Group 2B Elemental aluminum: copper oxide = 0.8:3 Treatment Group 3B Elemental aluminum: copper oxide = 1.2:3 Treatment Group 4B Elemental aluminum: copper oxide = 1.5:3 Treatment Group 5B Elemental aluminum: ferric oxide = 1:3 Treatment Group 6B Elemental aluminum: manganese dioxide = 1:3

[0067] Test Example 2

[0068] 1. Test subjects

[0069] This test example uses the heat exchanger prepared in Example 2 as the test object. In the test items of this test example, each heat exchanger is set to be repeated five times, and one heat exchanger is one repetition. The test results obtained below are the average values ​​of the parallel repeated experimental results of the same heat exchanger.

[0070] 2. Test items

[0071] (1) Test on the proportion of fin frosting area

[0072] To simulate the outdoor low temperature condition, at a temperature of -2℃ and a humidity of 75%, the heat exchanger was operated in heating mode for 5 hours. The frost on the surface of the fin was photographed by a camera. The frost area on the surface of the fin was determined by image recognition technology, and the ratio of the frost area on the fin to the total surface area of ​​the fin was calculated, recorded as S%.

[0073] (2) Evaluation of welding quality between fins and flat tubes

[0074] According to GB / T 11345-2013, the connection between the fin and the flat tube is examined, and the connection between a fin and a flat tube is regarded as a weld. The proportion of primary welds to the total number of welds in the heat exchanger is calculated. The higher the proportion, the better the welding quality between the fin and the flat tube.

[0075] 3. Test results

[0076] In the multiple treatment groups set in Example 2, the thermites used in treatment groups 1B to 4B and the control group are all compounded with elemental aluminum and copper oxide, while the thermites used in treatment groups 5B and 6B are compounded with elemental aluminum and other oxides different from copper oxide. It can be seen from the test results shown in Table 3 that the fin frosting area measured by the test heat exchangers provided by treatment groups 5B and 6B is higher than that of the control group and treatment groups 1B to 4B, which shows that the thermites compounded with copper oxide and elemental aluminum are more suitable for welding between the flat tubes and fins of the heat exchanger. In treatment groups 1B to 4B and the control group, thermites compounded with copper oxide and elemental aluminum are used. From the test results of this test example, it can be seen that the fin frosting area ratio of the heat exchangers provided by the above groups can be kept within a low range. However, the heat exchangers provided by the above groups show certain differences in the evaluation of welding quality between the fins and flat tubes. Although the control group and treatment groups 1B to 4B can achieve stable connection between the flat tube and the fin, in the thermite used in the control group and treatment groups 1B to 4B, with the increase of the elemental aluminum content in the thermite, the proportion of the primary weld between the flat tube and the fin to the total number of welds shows a trend of first increasing and then decreasing, and the turning point of the trend appears near the elemental aluminum: copper oxide = 1:1 (mass ratio) in the thermite, and the elemental aluminum: copper oxide = 0.8 to 1.2 (mass ratio) in the thermite used can achieve excellent welding quality between the flat tube and the fin welded using the thermite.

[0077] Table 3. Test results statistics of test items in this test case

[0078]

[0079]

[0080] Example 3

[0081] Based on the test results of the test example, this embodiment uses the treatment group 3A of Example 1 as a control to prepare a heat exchanger, so that the average particle size D of the thermite used in the welding process between the flat tube and the fin is 50 As a variable, different treatment groups were set and marked as treatment group 1C, treatment group 2C, and treatment group 3C. Since treatment group 3A of Example 1 was used as a control, treatment group 3A of Example 1 was marked as the control group in this example. The average particle size of thermite used in the control group and the above treatment groups is shown in Table 4. The difference between the treatment groups and each treatment group is only the average particle size D of the thermite used. 50 Apart from this, other components, materials and process operations used to prepare the heat exchanger are strictly kept consistent.

[0082] Table 4. Average particle size of thermite used in the control group and each treatment group of this example

[0083] Group <![CDATA[Average particle size D of thermite 50 > Control group 45μm Treatment Group 1C 30μm Treatment Group 2C 50μm Treatment Group 3C 60μm

[0084] Test Example 3

[0085] 1. Test subjects

[0086] This test example uses the heat exchanger prepared in Example 3 as the test object. In the test items of this test example, each heat exchanger is set to be repeated five times, and one heat exchanger is one repetition. The test results obtained below are the average values ​​of the parallel repeated experimental results of the same heat exchanger.

[0087] 2. Test items

[0088] Fin frost area ratio test

[0089] To simulate the outdoor low temperature condition, at a temperature of -2℃ and a humidity of 75%, the heat exchanger was operated in heating mode for 5 hours. The frost on the surface of the fin was photographed by a camera. The frost area on the surface of the fin was determined by image recognition technology, and the ratio of the frost area on the fin to the total surface area of ​​the fin was calculated, recorded as S%.

[0090] 3. Test results

[0091] The test results of this test example are shown in Table 5. Among the test objects of this test example, the average particle size of the thermite used in treatment group 3C of Example 3 is the largest. Referring to Table 5, the heat exchanger prepared by this treatment group has a slightly higher measured fin frosting area ratio, while the heat exchangers prepared by the control group of Example 3 and treatment groups 1C and 2C all have a lower measured fin frosting area ratio. Based on this test result and the product condition after welding, it can be seen that the average particle size D 50 Thermite welding of flat tubes and fins with a thickness not exceeding 50 μm is conducive to further improving the surface smoothness of the connection between the flat tubes and the fins, thereby further optimizing the heat transfer effect of the heat exchanger.

[0092] Table 5. Test results statistics of test items in this test case

[0093] Group Fin frosting area percentage S% Control group 5％ Treatment Group 1C 5％ Treatment Group 2C 8％ Treatment Group 3C 14％

[0094] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A heat welding process suitable for heat exchanger processing, the heat welding process is used to realize the welding of fins and flat tubes included in the heat exchanger, the fins are metal workpieces, It is characterized in that The thermal welding process includes the following operations: S1. A thermal effect amplifier is provided on the flat tube, the thermal effect amplifier is provided at the connection between the flat tube and the fin, and the thermal effect amplifier includes a material that can undergo an exothermic reaction under heating conditions; S2. The flat tube and the fin are preassembled so that the positional relationship between the two matches the positional relationship after the welding is completed; S3. Heating the thermal effect amplifier to trigger an exothermic reaction in the thermal effect amplifier, and utilizing the heat generated by the exothermic reaction to melt the thermal effect amplifier and / or the fin in the area where the fin is connected to the flat tube, thereby achieving welding of the flat tube and the fin.

2. The thermal welding process suitable for heat exchanger processing as claimed in claim 1, Features: The thermal effect amplifier is evenly distributed in the contact area between the flat tube and the fin.

3. The thermal welding process suitable for heat exchanger processing as claimed in claim 2, Features: The flat tube is provided with a plurality of thermal effect amplifier filling parts, the thermal effect amplifier is filled in the thermal effect amplifier filling parts, and the plurality of thermal effect amplifier filling parts are arranged at intervals.

4. The thermal welding process suitable for heat exchanger processing as claimed in claim 1, Features: The thermal effect amplifier includes thermite, which includes elemental aluminum and copper oxide. The ratio of the mass of the elemental aluminum to the mass of the copper oxide is 0.8 to 1.2:

3.

5. The thermal welding process suitable for heat exchanger processing as claimed in claim 4, Features: The average particle size D of the thermal effect amplifier 50 ≤50μm.

6. The thermal welding process suitable for heat exchanger processing as claimed in claim 4, Features: The number of the fins is A, the thickness of the fins is B, the gap between the fins and the flat tubes before welding is C, and the volume of the thermal effect amplifier is V, V: A×B×C=1.05~1.

2.

7. The thermal welding process suitable for heating a heat exchanger as claimed in claim 1, Features: In S3, the flat tube is heated to heat the thermal effect amplifier using the heat generated by the flat tube.

8. The thermal welding process for heat exchanger heating as claimed in claim 7, Features: The flat tube is provided with a conductor, and in S3, the flat tube is heated by causing the conductor to generate a current thermal effect.

9. The thermal welding process for heat exchanger heating as claimed in claim 8, Features: The conductor is selected from titanium alloy superconducting material or graphene.

10. The thermal welding process suitable for heat exchanger processing according to any one of claims 7 to 9, Features: The material of the flat tube includes graphene.

11. The thermal welding process suitable for heat exchanger processing as claimed in claim 1, Features: The material of the fins includes single element aluminum.

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