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The axial concentration distribution of both particles with better wetting (forming non-attached system) and poorer wetting (forming attached system) was investigated in a vertical gas-liquid-solid fluidized bed of 4.2 cm in diameter and 130 cm in height with the solids holdup less than 0.05. The one-dimensional sedimentation-dispersion model could be used satisfactorily to describe the axial distribution of solids holdup by modifying only a model parameter, i.e. by means of the terminal settling velocity minus a certain value, which is a function of gas velocity and considers the effect of an additional drag force resulted from attached rising bubbles. The axial profiles of solid concentration predicted are in good agreement with experimental results. This model also explains reasonably the different axial distributions of solid concentration, i.e. the solids holdup decreases as the axial height increases in non-attached system, but increases with the axial height in attached system at a given gas veloc 相似文献
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分别对TEC1-12704和TEC1-12706两种型号半导体制冷片的热端进行了散热器有热管散热与散热器无热管散热的试验装置设计,同时设计了分离电流输入两级制冷散热器有热管散热的试验装置,并分析了热端散热工况对冷端温度的影响。试验结果显示:散热器有热管散热可强化热端散热,半导体制冷片冷端温度与散热器散热能力有关,在有限散热能力条件下,冷端温度随输入电流的增加先增大后减小;保证散热能力条件下,冷端温度随输入电流增大而减小、随热端温度减小而减小;对双片TEC1-12706半导体制冷片采用分离电流输入两级制冷,冷端最低温度可达到-38.6℃。试验结果表明:改善热端散热条件能够提高单片半导体制冷片性能,同时在试验测试的最佳散热条件下采用分离电流输入两级制冷可使冷端温度大幅降低,这对提高半导体制冷片工作温差着重要的意义。 相似文献
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重构状态的表示以及重构中相同子结构的搜索是产品重构规划研究的两项重要内容。可重构产品由模块构成,本文使用接口状态数与邻接关系图相结合的方法对模块的重构状态进行描述,考虑了模块接口的信息。基于此描述方法,改进子图同构的VF2算法,提出了一种适合产品重构的同构搜索算法,快速有效地搜索出产品重构中的相同子结构。同构搜索算法在Visual C 下实现,最后以可重构并联机器在不同构型间重构的实验作为例子验证了此方法。 相似文献
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气液固流化床固体轴向浓度分布模型的研究进展 总被引:3,自引:0,他引:3
综述了描述气液固三相流化床中固体颗粒轴向浓度分布的沉降-分散模型和尾涡夹带机理模型,以及它们的推广与应用,同时指出这些模型在应用中的局限性。 相似文献
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