| The high latent heat and high stability of solid-liquid phase change materials make it widely used in energy storage and temperature control,but the low thermal conductivity severely limits the large-scale application of phase change materials.Reasonable implantation of high thermal conductivity materials can effectively overcome the shortcomings of low thermal conductivity,thereby greatly improving the utilization of phase change materials.However,the current research still mostly stays in the direct application of high thermal conductivity materials,and lacks feasible structural design.The rapid development of additive manufacturing provides strong technical support for the design of thermal conductivity reinforcements.Starting from the two enhancement mechanisms of heat conduction and heat convection,this paper makes a reasonable configuration design and performance analysis of the embedded heat conduction reinforcement structure.Firstly,the phase change temperature control device with gradient porous metal was designed and fabricated by additive manufacturing technology.The effectiveness of thermal conductivity enhancement by gradient design was verified by numerical analysis and experimental comparison.Secondly,the special fin structure design was discussed.The contribution of natural convection to the phase-change thermal performance of porous metal is discussed.Finally,for a typical engineering application,a structural design scheme considering the effects of two different enhancement mechanisms is designed and its performance is evaluated.The specific research contents are as follows:(1)Numerical simulation and experimental study on the manufacture of phase change thermostat with integrated porous material.In this paper,a three-dimensional numerical analysis method for manufacturing phase change thermostats with integrated gradient porous materials is proposed.At the same time,an experimental platform is built to verify the validity of the numerical model.The numerical results show that the simulation and experimental results are in good agreement under different working conditions(heating power),and the effectiveness of the method is verified.The temperature of the key points is used as the evaluation standard to discuss the existence and wall of the package structure.The influence of design factors such as thick and porous medium porosity gradient distribution on phase change temperature control shows that the presence or absence of package structure and wall thickness have great influence on phase change temperature control.Compared with uniform metal porous media,reasonable gradient design can significantly improve the temperature control ability of phase change materials.(2)Structural design of phase change thermal conductivity reinforcement considering natural convection strengthening.The introduction of the thermally conductive reinforcement weakens the natural convection of the liquid phase change material,especially the porous metal material with a large specific surface area severely suppresses the generation of natural convection,making heat conduction the main mechanism of heat transfer.In this paper,the enhancement of natural convection in the phase-change heat process with heatconducting reinforcement is studied by numerical method.The purpose is to explore the possibility of simultaneously exerting two mechanisms of heat conduction and natural convection in the phase-change heat process.The results show that the influence of the existence of natural convection on the phase transformation thermal process cannot be neglected,and at the same time,the two enhancement mechanisms can break through the limit of the phase transformation heat capacity under pure heat conduction.(3)Design of Typical Engineering Phase Change Thermostat Based on Multiple Heat Transfer Enhancement Mechanism.With the increasing demand for functions,the thermal environment that CCD components are subjected to during their work is becoming more and more demanding,and their ability to dissipate heat is facing a huge test.The high latent heat and good stability of the phase change material make the phase change heat sink more prominent than the traditional heat dissipation method.In this paper,the lower temperature level,the smaller temperature rise rate and the longer working time are the optimization objectives.Considering the gradient design of the thermal rib and the natural convection of the phase change material melting,the configuration of a certain CCD component is carried out.The design and results are improved in each optimization target parameter compared with other people's literature,which proves the effectiveness of this configuration design. |
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