Manufacturing process of high-voltage and high-purity pump-driven two-phase liquid cooling CDU

Abstract

The application relates to the field of manufacturing and processing technology, in particular to a manufacturing process of a high-pressure-resistant and high-cleanliness pump-driven two-phase liquid cooling CDU (central data unit), after initial installation of a single machine device and local pipeline prefabrication, the system undergoes strict initial pressure test and overall disassembly pipe pickling treatment. The pipe fittings qualified by pickling are immediately transferred to a controlled dust-free room for secondary resetting assembly, combined with high-pressure pure nitrogen rough detection and helium mass spectrometry micro-leakage precision detection composite detection means, residual assembly stress generated by multi-pipeline butt joint is completely released. Relying on large-flow turbulent circulation flushing and extreme vacuum dehydration technology, the pipeline interior can be strongly stripped of blind area impurities and an ultraclean oxygen-free fluid environment is constructed. Subsequent implementation of electrical connection at all levels and multi-stage progressive dynamic joint debugging verification realizes early calibration of system control precision. The process greatly strengthens the physical pressure resistance integrity of complex thermal management equipment under extreme high-pressure working conditions, and significantly improves the running life and operation reliability of the terminal product.

Description

Technical Field

[0001] This invention relates to the field of manufacturing technology, specifically to a manufacturing process for a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU. Background Technology

[0002] As the core hub of the thermal management system for high-power electronic equipment, the pump-driven two-phase liquid-cooled CDU plays a crucial role in driving the circulation of phase-change working fluid to achieve efficient heat transfer. During operation, this type of equipment typically operates under extremely high internal pressure. Microscopic impurities or residues within the flow channels can easily circulate rapidly with the working fluid, leading to serious malfunctions such as pipe blockage, valve jamming, or a sharp drop in heat exchange efficiency. This necessitates that CDU products possess excellent structural sealing and stringent internal cleanliness during the manufacturing process to support the long-term stable operation of the two-phase fluid.

[0003] Existing processing technologies primarily focus on the forming and strengthening of individual components. Chinese patent publications CN111468557A and CN111482483A disclose cold drawing and cold rolling processes for seamless stainless steel tubes. These technologies demonstrate high processing efficiency in improving the surface quality and dimensional accuracy of individual seamless tubes. However, existing technologies often prioritize improving the physical properties of individual tubes or components, lacking a holistic perspective on the integration of complex multi-component systems and failing to establish a complete assembly specification for high-pressure, high-cleanliness testing benches or system equipment.

[0004] Conventional component manufacturing technologies have significant limitations when translated into complete system integration processes, struggling to handle the combined complexities of automated integration, system commissioning, and final delivery. In complex assembly scenarios involving multi-component piping splicing, large-diameter valve connections, and precision sensor installations, traditional processes fail to effectively address minute leaks caused by assembly stress. Furthermore, there are technological gaps in key areas such as foreign matter control during processing, deep dehydration and degassing, and comprehensive system commissioning and verification. This directly results in thermal management equipment failing to meet high-level design requirements for pressure integrity and fluid cleanliness, significantly reducing the long-term operational reliability of test benches or terminal refrigeration systems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a manufacturing process for a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU. The aim is to completely solve the manufacturing challenges of complex fluid integrated pipelines in high-pressure and cleanliness-sensitive scenarios by introducing a hierarchical, modular assembly and inspection system that includes multiple resets.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a manufacturing process for a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU, comprising the following steps: S1. Material and Structure Preparation Stage The qualified components are assembled and fixed as individual equipment. Then, the pipeline prefabrication and preliminary installation are carried out to complete the first assembly. The welded local pipeline system is pressure tested for leaks for the first time. After the air tightness meets the standard, all pipeline components are removed and the pipes are disassembled and acid-washed. S2. Clean Assembly and Sealing Verification Phase After acid cleaning, the pipeline is placed in a dust-free environment for secondary assembly and reassembly. High-pressure pressure testing is carried out for the entire system to confirm that the system meets the sealing requirements under the design pressure. A special circulating cleaning device is used to clean the internal parts of the system until the particle size test meets the standard. Then, the vacuum equipment is started to evacuate the internal parts of the system to the ultimate vacuum state. S3. Electronic Control Integration and System Verification Phase Based on thermal control requirements, insulation layers are applied to the outer walls of pipelines and main equipment. Then, communication cables and electrical connections between pumps, valve actuators, and electrical control boxes are completed. Individual component response tests, CDU whole-machine operation debugging, and load simulation commissioning are carried out in sequence. After generating a certificate of conformity based on the test parameters, the entire manufacturing process is completed.

[0007] Preferably, in the pipeline prefabrication and preliminary installation process, the design operating pressure of the pump-driven two-phase liquid-cooled CDU involved is ≥3MPa, and the connection of all pipeline nodes adopts argon arc welding process. In order to prevent the generation of oxide impurities on the inner wall of the pipeline during the welding process, high-purity inert protective gas must be simultaneously filled into the pipeline for back protection throughout the welding process, and batch welding operation is promoted after the first piece confirmation and parameter solidification are completed.

[0008] Preferably, the specific operation of the disassembly and pickling process is as follows: after the pipeline is disassembled and pre-positioned in one assembly, it needs to be immersed in a pickling solution with a specific ratio to remove residual metal shavings, oil stains and oxide scale. After neutralization, rinsing with pure water and drying, the pipe wall and joint sealing surface are microscopically inspected. The judgment criteria clearly require that there are absolutely no deep scratches, dents, cracks and corrosion spots on the surface.

[0009] Preferably, the high-pressure pressure testing of the entire system after secondary assembly and reassembly adopts a composite leak detection method. The specific operation is as follows: using 1.5 times the design pressure as the test benchmark, a rough overall pressure test is performed by filling with high-pressure nitrogen and checking for leaks with soapy water. After the pressure stabilizes, a helium mass spectrometer is used to perform high-precision micro-leak detection on all flange interfaces and welds to ensure structural integrity under extreme working conditions.

[0010] Preferably, when performing the cleaning of excess material, the external dedicated circulating cleaning device is equipped with multi-stage precision filter cartridges. The rinsing liquid reaches a turbulent state in the pipeline to fully remove the attached particles. The cleaning process is carried out in multiple rounds of alternating circulation. The cleanliness of the effluent is judged by an online or offline particle counter. The cleaning process can only be terminated when it is confirmed that there are no particles with a diameter greater than 40μm in the test sample.

[0011] Preferably, after the excess material is cleaned to the standard and the pipeline is emptied, a vacuum pump truck is immediately connected to perform a deep vacuuming process. The residual gas and trace amounts of free water vapor in the system are completely discharged under continuous suction, and the absolute pressure is stably reduced to below 5 Pa and maintained for a set time, thereby creating a high-purity oxygen-free internal environment before the two-phase fluidized bed is filled.

[0012] Preferably, the single-component response test covers the signal calibration of the sensor and the opening and closing dead zone verification of the fluid valve. The whole machine operation and debugging requires real-time recording and comparison of the fluctuation range of system flow, pump drive head and temperature control curve under full-load power simulation conditions. The load simulation commissioning connects the CDU with the heat source simulation tooling of external high-power electronic equipment to verify its long-term operation reliability under cyclic dynamic conditions.

[0013] Preferably, the assembly of the single-unit equipment and the prefabrication of the primary pipeline are completed in the conventional machining area. The parts after pickling are immediately transferred to a Class 10,000 cleanroom. Subsequent secondary assembly, helium mass spectrometry leak detection, particulate matter detection and vacuuming processes are all operated in a closed loop under controlled clean environment.

[0014] Preferably, the flushing medium of the dedicated circulating cleaning device is a high-purity cleaning fluid of the same source that is compatible with the two-phase fluidized bed that is ultimately filled into the system. The set value of the flushing flow rate is greater than 1.2 times the rated operating flow rate of the system, thereby enhancing the flushing effect in the pipeline blind zone and diameter change section by increasing the local Reynolds number.

[0015] This invention provides a manufacturing process for a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU. It offers the following advantages: 1. This invention employs a three-stage assembly strategy—preliminary pre-assembly, overall disassembly and acid washing, and high-cleanliness secondary reassembly—combined with a composite technology of nitrogen coarse inspection at 1.5 times the design pressure and helium mass spectrometry for fine micro-leak detection. This process thoroughly releases the residual assembly stress generated during forced alignment and docking of complex multi-component pipelines. This deep integration of stress release and high-precision leak detection significantly improves the physical compressive strength and ultimate sealing performance of fluid pipelines and system flange joints under high-pressure operating environments (design pressure ≥ 3MPa), effectively eliminating the potential for micro-leakage caused by high-frequency thermal shocks.

[0016] 2. This invention employs a comprehensive fluid purification technology encompassing deep pipe disassembly and acid washing, high-flow-rate turbulent circulation flushing, multi-stage precision filtration, and ultimate vacuum dehydration and degassing. This process effectively removes and thoroughly discharges residual metal shavings, stubborn oxide scale, and trace amounts of free water vapor from the pipeline's blind spots. The internal fluid pipeline achieves an ultra-clean, oxygen-free environment free of particles larger than 40μm and with an absolute pressure below 5Pa. This fundamentally eliminates the risk of microchannel heat exchanger blockage and circulating pump impeller wear caused by foreign matter intrusion into the two-phase fluidized bed, significantly extending the service life of the CDU equipment's core components.

[0017] 3. This invention employs a three-stage progressive full-condition verification technique, encompassing single-component calibration, whole-machine fluid circulation, and external load-bearing commissioning. This process overcomes the limitations of traditional chiller testing, which only involves static pressure holding. The electrical control system and fluid mechanical devices undergo dynamic interactive verification under simulated heat loads of varying power, ensuring precise correction of sensor response dead zones and that flow and pressure control curves strictly adhere to design requirements. This systematic verification mechanism exposes and eliminates integration defects before equipment delivery, significantly shortening the on-site delivery cycle and guaranteeing immediate and efficient operation of the thermal management test bench after its setup. Attached Figure Description

[0018] Figure 1 This is a flowchart of the manufacturing process of the two-phase liquid-cooled CDU of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example: like Figure 1 As shown, this embodiment of the invention provides a manufacturing process for a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU. This embodiment uses a thermal management test bench specifically designed for cooling high-power electronic devices as its application background. This equipment is a high-pressure (design pressure ≥ 3MPa) pump-driven two-phase liquid-cooled CDU product, and its internal working fluid is a fluorinated liquid that is extremely sensitive to impurities and moisture. The entire manufacturing process strictly follows a progressive logic of pre-assembly followed by cleaning, leak detection followed by purification, and single-unit operation followed by system operation, specifically covering three major operational stages.

[0021] In the material and structure preparation phase, incoming material inspection is conducted by professional quality inspectors based on the "Material Requirements Requisition Form." This involves accurately verifying the specifications, undamaged appearance, and dimensional tolerances of key flange interfaces for pipes, fasteners, pumps, heat exchangers, and valves. After this initial screening is passed, the components are transferred to the conventional machining area for individual equipment assembly. Assembly personnel use standard fasteners to fix the main heating and drive equipment to the base bracket. Using dial indicators based on the 3D model drawings, they verify the horizontal and vertical positions of the installation reference surface to ensure the stability of the load-bearing structure. Subsequently, Assembly 1, namely pipeline prefabrication and preliminary installation, is carried out. Pipeline cuts undergo strict chamfering and deburring treatment, and argon arc welding is used for pipeline splicing. Throughout the welding process, high-purity argon gas is forcibly and synchronously injected into the pipeline for back protection, preventing oxide scale formation on the high-temperature weld inner wall. Each main weld is required to undergo first-piece flaw detection confirmation, and the welding parameters are recorded and solidified. After the local pipeline is connected, an initial pressure test and leak detection are immediately performed by connecting a gas source. The basic pressure resistance and sealing performance of the initial welds and flange faces are verified according to the "Inspection Specification for Thermal Control Systems". After the initial airtightness meets the standard, all the newly assembled pipeline components are completely disassembled and disassembled, and then proceed to the pipe disassembly and acid washing (pipeline cleaning) process. The disassembled pipes are immersed in a pickling tank with a specific ratio to dissolve the residual metal dust and oil on the inner wall. After neutralization with alkaline solution and multiple rounds of ultrasonic cleaning with pure water and drying, the pipe walls and joint sealing surfaces are self-inspected using an endoscope, and any deep scratches, dents, cracks and corrosion spots are strictly prohibited.

[0022] The process then transitions to clean assembly and sealing verification. Fittings that have passed acid pickling are immediately sealed and transferred to a Class 10,000 cleanroom. In this controlled environment, Assembly 2, or the secondary assembly and reassembly of the fittings, is performed. Operators double-check the pipe joint positions using a 3D coordinate diagram, ensuring smooth bolt tightening to prevent stress from forced alignment that could damage the subsequent sealing structure. With the mechanical components integrated, a more rigorous composite pressure test is conducted. High-pressure pure nitrogen is introduced into the entire system, pressurized to 4.5 MPa (1.5 times the design pressure) for a preliminary pressure test. During this process, foaming liquid is applied to all connection points to check for obvious leaks. After the pressure stabilizes and meets the required standard, the system switches to high-precision detection mode, using a helium mass spectrometer leak detector to scan all flange faces, threaded interfaces, and welds at the microscopic molecular level to ensure the CDU can withstand extreme high-pressure operation. Once the system is confirmed to be leak-free, the process of cleaning away excess material continues. An external high-precision circulating cleaning device is connected to the main inlet and outlet of the CDU. The cleaning medium is a high-purity homologous cleaning solution compatible with the final fluorinated solution. The output flow rate of the cleaning pump is set to more than 1.2 times the rated operating flow rate of the system, creating a strong turbulent effect inside the pipeline to flush out blind areas and transition sections. A multi-stage precision filter is installed in the cleaning solution return path. During multiple rounds of alternating flushing, samples of the effluent are periodically extracted from the sampling valve. An online particulate counter is used to optically inspect the samples until the data panel shows that there are no particles larger than 40μm in the fluid sample. Only then can the circulating cleaning device be disconnected and the liquid drained. Immediately following, a vacuuming operation is performed, using a high-power vacuum pump truck to continuously evacuate the sealed internal pipelines of the CDU for an extended period. Residual gas and microscopic moisture inside the system are forcibly vaporized and extracted, the internal absolute pressure is lowered and stabilized below 5Pa. After continuous vacuuming to verify no rebound, the pipeline is sealed for liquid injection.

[0023] During the electrical control integration and system verification phase, operators, following thermal design specifications, used flame-retardant closed-cell rubber and plastic foam material to tightly wrap and adhere the cold flow pipelines and the outer walls of key heat exchangers, eliminating cold bridge leaks. Moving to the electrical assembly stage 3, the power and signal lines of actuators such as the variable frequency drive pump, temperature and pressure sensors, and proportional control valves were led to the electrical control box along a pre-set cable tray, and continuity and insulation resistance self-tests were performed according to the electrical drawings. System debugging and verification consisted of three progressive steps. Debugging 1 focused on single-machine response testing, individually powering each sensor and actuator, calibrating sensor feedback accuracy, and eliminating valve dead zones. Debugging 2 involved overall machine debugging, running the CDU internal circulation under low-pressure test fluid, calibrating the variable frequency pump flow curve, pipeline resistance pressure drop, and the PID control accuracy of the temperature controller, and recording all operating characteristic parameters. Debugging 3 involved system integration debugging, forcibly connecting the CDU supply pipeline to an external heat load simulation device, applying a simulated heat source equivalent to the heat generated by high-power electronic equipment. Under long-term cyclic dynamic operating conditions, the phase change heat transfer efficiency of the two-phase working fluid and the system pressure fluctuation threshold are monitored. After obtaining all performance and reliability test data, the factory inspection process is initiated. The quality inspection department verifies the final appearance checklist of the equipment against all the aforementioned performance test reports and in accordance with the product inspection specifications. Once all indicators meet the specification requirements, a product qualification certificate is issued. At this point, the complete manufacturing and verification process of the high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU is declared complete.

[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A manufacturing process for a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU, characterized in that, Includes the following steps: S1. Material and Structure Preparation Stage The qualified components are assembled and fixed as individual equipment. Then, the pipeline prefabrication and preliminary installation are carried out to complete the first assembly. The welded local pipeline system is pressure tested for leaks for the first time. After the air tightness meets the standard, all pipeline components are removed and the pipes are disassembled and acid-washed. S2. Clean Assembly and Sealing Verification Phase After acid cleaning, the pipeline is placed in a dust-free environment for secondary assembly and reassembly. High-pressure pressure testing is carried out for the entire system to confirm that the system meets the sealing requirements under the design pressure. A special circulating cleaning device is used to clean the internal parts of the system until the particle size test meets the standard. Then, the vacuum equipment is started to evacuate the internal parts of the system to the ultimate vacuum state. S3. Electronic Control Integration and System Verification Phase Based on thermal control requirements, insulation layers are applied to the outer walls of pipelines and main equipment. Then, communication cables and electrical connections between pumps, valve actuators, and electrical control boxes are completed. Individual component response tests, CDU whole-machine operation debugging, and load simulation commissioning are carried out in sequence. After generating a certificate of conformity based on the test parameters, the entire manufacturing process is completed.

2. The manufacturing process of a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU according to claim 1, characterized in that, In the pipeline prefabrication and preliminary installation process, the design operating pressure of the pump-driven two-phase liquid-cooled CDU is ≥3MPa. All pipeline joints are connected using argon arc welding. To prevent the generation of oxide impurities on the inner wall of the pipeline during the welding process, high-purity inert protective gas must be simultaneously injected into the pipeline for back protection throughout the welding process. Batch welding operations are carried out after the first piece is confirmed and the parameters are solidified.

3. The manufacturing process of a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU according to claim 1, characterized in that, The specific operation of the disassembly and pickling process is as follows: After the pipeline is disassembled and pre-positioned in one assembly, it needs to be immersed in a pickling solution with a specific ratio to remove residual metal shavings, oil stains and oxide scale. After neutralization, rinsing with pure water and drying, the pipe wall and joint sealing surface are microscopically inspected. The judgment criteria clearly require that there be absolutely no deep scratches, dents, cracks and corrosion spots on the surface.

4. The manufacturing process of a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU according to claim 1, characterized in that, After secondary assembly and resetting, the high-pressure pressure testing of the entire system adopts a composite leak detection method. The specific operation is as follows: using 1.5 times the design pressure as the test benchmark, high-pressure nitrogen is used to conduct a rough overall pressure test and soap water is used to check for leaks. After the pressure stabilizes, a helium mass spectrometer is used to perform high-precision micro-leak detection on all flange interfaces and welds to ensure structural integrity under extreme working conditions.

5. The manufacturing process of a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU according to claim 1, characterized in that, When performing the aforementioned cleaning of foreign matter, the external dedicated circulating cleaning device is equipped with multi-stage precision filter cartridges. The rinsing liquid reaches a turbulent state in the pipeline to fully remove the attached particles. The cleaning process involves multiple rounds of alternating circulation. The cleanliness of the effluent is judged by an online or offline particle counter. The cleaning process can only be terminated when it is confirmed that there are no particles larger than 40μm in the test sample.

6. The manufacturing process of a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU according to claim 1, characterized in that, After the excess material is cleaned to the standard and the pipeline is emptied, the vacuum pump truck is immediately connected to perform a deep vacuuming process. The residual gas and trace amounts of free water vapor in the system are completely discharged under continuous suction, and the absolute pressure is stably reduced to below 5 Pa and maintained for the set time, thereby creating a high-purity oxygen-free internal environment before the two-phase fluidized bed is filled.

7. The manufacturing process of a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU according to claim 1, characterized in that, The single-component response test covers the signal calibration of sensors and the opening and closing dead zone verification of fluid valves. The whole machine operation and debugging requires real-time recording and comparison of the fluctuation range of system flow, pump drive head and temperature control curve under full-load power simulation conditions. The load simulation commissioning connects the CDU with the heat source simulation tooling of external high-power electronic equipment to verify its long-term operational reliability under cyclic dynamic conditions.

8. The manufacturing process of a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU according to any one of claims 1-7, characterized in that, The assembly of the single-unit equipment and the prefabrication of the primary pipeline are completed in the conventional machining area. After the components are pickled, they are immediately transferred to a Class 10,000 cleanroom. Subsequent secondary assembly, helium mass spectrometry leak detection, particulate matter detection and vacuuming processes are all carried out in a closed loop under controlled clean environment.

9. The manufacturing process of a high-pressure, high-cleanliness pump-driven two-phase liquid-cooled CDU according to claim 5, characterized in that, The flushing medium of the dedicated circulating cleaning device is a high-purity cleaning fluid of the same source that is compatible with the two-phase fluidized bed that is ultimately filled into the system. The set value of the flushing flow rate is 1.2 times greater than the rated operating flow rate of the system, thereby enhancing the flushing effect in the pipeline blind zone and diameter change section by increasing the local Reynolds number.

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