| With the continuous advancement of space exploration missions,the heating power of electronic components in spacecraft loads is rapidly increasing,resulting in ultra-high heat flux density of key electronic components within spacecraft in a very small space.Achieving efficient heat dissipation in complex spaces within spacecraft loads has become a major technical challenge in the field of spacecraft thermal control technology.The vapor chamber has excellent thermal conductivity,large heat transfer area,and good temperature equalization performance,which is currently a hot research topic in the field of spacecraft thermal control.The capillary wick is the core component of the vapor chamber,which provides power and flow channels for the circulation of liquid working fluids inside the vapor chamber.Currently,traditional manufacturing processes face bottlenecks in high-performance capillary wick manufacturing,which cannot effectively balance the contradiction between the capillary force and permeability of the capillary wick structure,and there are problems such as long processing cycles and high processing costs.In recent years,with the rapid development of metal additive manufacturing technology,it has been possible to initially achieve the precise controlled forming of micro pore porous structures.Therefore,applying additive manufacturing technology to the design and manufacture of capillary wicks to improve the existing capillary wick structure is of great significance for improving the heat transfer performance of the vapor chamber.In this paper,the additive manufacturing process of porous structures,the forming state and various properties of3D printed porous structures,the modular design and overall printing manufacturing method of capillary wicks,the hybrid manufacturing method of vapor chambers,and the heat transfer performance of 3D printed capillary wick vapor chambers have been systematically studied.Firstly,the paper conducts 3D printing manufacturing and performance testing of porous structures.The additive manufacturing process of cubic frame structure and two TPMS porous structures was studied.A series of 3D printed porous structure samples with different unit sizes were fabricated using SLM technology.Microscopic observations indicate that the 3D printed porous structure has a better forming state when the unit size increases.The porosity,effective capillary radius,and permeability of 3D printed porous structure samples were tested.The fitting equations for various performance parameters of the cubic frame porous structure sample were obtained through data fitting.The ratio of permeability to effective capillary radius(K reff)was used to evaluate the capillary performance of 3D printed cubic frame porous structures.When the unit size is 300μm,the porosity of 3D printed cubic frame is 55.49%,the effective capillary radius is 102.27μm,the permeability is 5.86×10-11m2,and the capillary factor is 0.57μm.A comparison between 3D printed porous structures and capillary wick porous structures produced by traditional processing techniques shows that 3D printed porous structures have higher porosity,excellent permeability,and good capillary properties.Each functional module of the capillary wick structure obtained by SLM process has a relatively definite structure type and structure size.Based on this,the heat transfer process of the 3D printed capillary wick vapor chamber is analyzed.The heat transfer process of the vapor chamber is divided into multiple heat transfer links.By calculating the equivalent heat transfer thermal resistance of each heat transfer link,a heat transfer thermal resistance model of the 3D printing capillary wick vapor chamber is obtained.The thermal resistance model can be used as a reference for the design of 3D printing capillary wick vapor chambers.Based on the advantage that additive manufacturing technology can be freely formed,a modular design method for the capillary wick of the vapor chamber were proposed.Combined with the performance test results of the porous structure,the structure types and unit sizes of the porous structures in different functional modules of the capillary wick were designed respectively,and two kinds of capillary wick structures integrating the advantages of different porous structures were obtained:single pore size capillary wick structure and hybrid pore size capillary wick structure.Then,the manufacturing method of integral printing for the capillary wick was studied,and two different capillary wick structures were integrally printed using SLM technology.A hybrid manufacturing method combining additive manufacturing technology and traditional processing technology was used to manufacture the vapor chamber,and two 3D printed capillary wick vapor chambers with different capillary wick structures were obtained.A water-cooling test platform was built to test the heat transfer performance of 3D printing capillary wick vapor chambers under different heat transfer conditions.Finally,the performance test results of the 3D printed capillary wick vapor chambers are analyzed.The results show that the 3D printed capillary wick vapor chamber can conduct efficient heat transfer in the range of 10W～100W.When the heat source power is 100W,the minimum heat transfer thermal resistance of the single pore size 3D printing capillary wick vapor chamber and the hybrid pore size D printing capillary wick vapor chamber are 0.153℃/W and 0.077℃/W,respectively.The heat source power,heat source area,and cooling water temperature have a significant impact on the temperature uniformity and heat transfer resistance of the vapor chambers.The hybrid pore size structure can improve the heat transfer performance of 3D printing capillary wick vapor chambers.Compared to some vapor chambers manufactured by traditional processing techniques,3D printing capillary wick vapor chambers have smaller heat transfer thermal resistance.The results of performance testing and comparative analysis of the vapor chamber show that:the modular design method and integral printing process based on additive manufacturing technology can be used to improve the performance of vapor chamber capillary wick and improve the forming efficiency of complex capillary wick structure;the hybrid manufacturing method combining additive manufacturing technology and traditional processing technology can realize the production of high performance vapor chamber,shorten the manufacturing cycle and reduce the processing cost. |
