共查询到20条相似文献,搜索用时 250 毫秒
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由于金刚石具有室温下最高的热导率,因此用化学气相沉积(CVD)制备的金刚石膜是大功率发光二极管(LED)理想的散热材料.本文利用微波等离子体CVD研究了不同沉积工艺下金刚石薄膜的生长.用扫描电子显微镜(SEM)和拉曼光谱对得到的金刚石薄膜进行了表征,并将金刚石薄膜用作LED散热片的散热效果进行了检测.结果表明:在硅衬底上沉积20-30μm的CVD金刚石薄膜可以有效地降低LED的工作温度;在相同的制备成本下,提高薄膜的厚度(甲烷浓度4%)比提高薄膜的质量(甲烷浓度2%)更有利于提高LED的散热效果.本研究表明微波等离子体CVD制备的金刚石薄膜是大功率LED的理想散热衬底材料. 相似文献
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《锻压技术》2021,46(10):112-118
为了探究液冷板冲压结构对电池模组散热性能的影响,对液冷板的冲压结构参数进行了分析与设计,采用CFD(计算流体动力学)流固热耦合数值计算方法,对不同液冷板流道结构参数下的散热性能、能耗以及均温性能进行了分析。结果表明:减小中心流道宽度,液冷系统的散热均温性能提升明显;中心流道宽度W5等于7 mm时,平均温度降低了2.5%,而最大温差降低了7.7%。流道深度越小,系统的散热均温性能越好,能耗亦大幅增加;流道深度为2 mm时,平均温度下降了26.9%,最大温差下降了32.7%,流阻升高了3.4倍。添加强化传热结构后,液冷系统的平均温度降低了3.8%、最大温差下降了15.1%;相比整体区域添加强化传热结构,部分区域添加强化传热结构可以减小流阻、降低能耗,而不引起系统的散热均温性能的显著变化。 相似文献
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针对传统流道静止或转速代入经验公式计算散热系数、难以精确表征大功率永磁偶合器旋转离心水冷温度场分布的难题,提出流固耦合传热结合MRF模型的方法,并以800 kW永磁偶合器为例进行仿真计算和散热优化,得到流道流场分布及整机温度分布结果。结论如下:冷却水流速随离心作用加速,在出口直角弯处能量损失后速度降低至67 m/s; 60 kW热损耗下温度分布沿径向逐步升高,最高温度为131℃,最低为76℃;对比不同热损耗、不同流道个数对温度、阻力矩、漏磁系数等参量影响规律可知,40个流道个数为最优,相较于原模型36个流道情况下温度降低6~8℃。 相似文献
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双区加热定向凝固液相温度梯度研究 总被引:2,自引:0,他引:2
在分析双区加热定向凝固热流的基础上推导出了液相中温度梯度(GL)的关系式,提出了提高GL的途径。结果表明:在双区加热时采用液体金属冷却在结晶生长速度较大时仍可获得很高的GL;当辐射挡板的厚度为30mm,双区加热上下区的功率比为1:2时,定向凝固温度较高,并可以进一步提高GL。 相似文献
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大容量圆柱动力电池在电动汽车上的广泛应用导致电池包轻量化和热管理设计需求日益突出。以新型4680大号圆柱电池为研究对象,设计具有4种不同微通道网络(平行、分叉、蛇形和螺旋)的碳纤维增强复合材料(CFRP)圆筒散热结构,并分析微通道网络结构、冷却剂流速、微通道直径以及微通道进出口数量对其散热性能的影响规律。结果表明,在4种微通道CFRP圆筒结构中,平行网络微通道CFRP圆筒结构的整体换热性能最佳;微通道直径对CFRP圆筒散热性能的影响较小,但对泵压影响较大;二进二出CFRP散热圆筒的换热性能比一进一出圆筒换热结构具备明显优势。 相似文献
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Present trend of semi-solid processing is directed towards rheocasting route which allows manufacturing of near-net-shape cast components directly from the prepared semi-solid slurry. Generation of globular equi-axed grains during solidification of rheocast components, compared to the columnar dendritic structure of conventional casting routes, facilitates the manufacturing of components with improved mechanical properties and structural integrity. In the present investigation, a cooling slope has been designed and indigenously fabricated to produce semi solid slurry of Al-Si-Mg (A356) alloy and successively cast in a metallic mould. The scope of the present work discusses about development of a numerical model to simulate the liquid metal flow through cooling slope using Eulerian two-phase flow approach and to investigate the effect of pouring temperature on cooling slope semi-solid slurry generation process. The two phases considered in the present model are liquid metal and air. Solid fraction evolution of the solidifying melt is tracked at different locations of the cooling slope, following Schiel s equation. The continuity equation, momentum equation and energy equation are solved considering thin wall boundary condition approach. During solidification of the liquid metal, a modified temperature recovery scheme has been employed taking care of the latent heat release and change of fraction of liquid. The results obtained from simulations are compared with experimental findings and good agreement has been found. 相似文献
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电磁悬浮熔炼试样的最低温度计算分析 总被引:1,自引:0,他引:1
根据Clemente R A计算电磁悬浮熔炼最低温度的办法,导出存考虑辐射散热和保护性气体自然对流散热联合作用情况下,球形试样电磁恳浮熔炼最低温度的计算模型。利用该模犁计算了不考虑气体散热、氩气自然对流散热、氦气自然对流散热3种情况下电磁恳浮熔炼球形试样的最低温度范围。通过对比,发现对于冷却能力筹的氩气,温度计算时可以不考虑气体散热;而对于冷却能力较大的氦气,对于高密度、高电阻率、低辐射率试样只考虑辐射散热计算球形试样最低电磁悬浮熔炼温度可行;而对于低密度、低电阻率、高辐射率试样,则必须考虑氦气散热与辐射散热联合作用计算球形试样最低电磁悬浮熔炼温度。不存存外部强制冷却的情况下,高熔点、低电阻率、低密度、高辐射率的试样,保护性气体冷却能力较强,试样易于在重力环境下实现悬浮过冷;而低熔点、高电阻率、高密度、低辐射率的试样,保护性气体冷却能力较差,试样难以在重力环境下实现悬浮过冷。 相似文献
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R. Haghayeghi V. Khalajzadeh M. Farmahini Farahani H. Bahai 《Journal of Materials Processing Technology》2010,210(11):1464-1471
Twin screw melt conditioners are used for mixing purposes and are mainly used for polymer processing. These conditioners (extruders) can be used for liquid metal processing in which liquid metal/slurry is subjected to high shear stress. This process results in grain refinement of structure. In this article, in a co-rotating twin screw melt conditioner, the solidification process of a liquid along with temperature variations of the melt with regard to the complexity of the flow has been examined. With the aid of dynamic mesh scheme, a Computational Fluid Dynamic (CFD) simulation was performed. The achieved results were in good agreement with values based on the experimental measurements. It was concluded that shearing and pouring temperatures play important roles in solidification progression and the main reason of surviving nuclei is heat dissipation from the barrel. Also, the main factor affecting the grain size is the temperature differences between the pouring and the setting temperature. It was observed that, the twin screw melt conditioner can decrease the temperature gradient and with the help of turbulence, providing appropriate conditions for formation of fine and equiaxed grains. 相似文献