具有不同孔隙率多孔介质内的蒸发特性

发布时间：2018-03-06 00:21

本文选题：多孔介质　切入点：微通道　出处：《化工学报》2017年09期 　论文类型：期刊论文

【摘要】：制作了具有3种不同孔隙率(0.85、0.75和0.60)的多孔镍粉样本,并进行了毛细抽吸实验和蒸发冷却实验(包括稳态冷却实验,初始状态为干态和湿态的冷却实验),以探究多孔介质抽吸和蒸发过程规律。毛细抽吸实验发现孔隙率大的镍粉样本抽吸速率更快,且根据毛细单管抽吸实验和毛细抽吸理论分析结果表明:孔隙率大的镍粉样本具有更大孔径是其抽吸速率更快的根本原因。稳态冷却实验结果表明孔隙率0.85的镍粉样本具有最快的蒸发速率,0.60镍粉样本蒸发速率最慢,这是受到多孔样本抽吸速率主导的结果。在初始干态冷却实验中,孔隙率为0.85的镍粉样本具有最大的瞬态冷却热通量,但要达到最大冷却温度幅度须取得瞬态冷却热流与冷却时间的平衡,因此孔隙率0.75样本冷却温度幅度最大。在初始湿态实验中,孔隙率为0.85的镍粉样本具有最高的烧干温度和最长的烧干时间,表现出最强的抗烧干性能,但是孔隙率0.75样本剧烈蒸发过热度最小且剧烈蒸发时间最长,最能有效抑制样本热端温度升高。
[Abstract]:Three kinds of porous nickel powder samples with different porosity (0.85% 0.75 and 0.60) were prepared, and capillary suction experiments and evaporative cooling experiments (including steady state cooling experiments) were carried out. The initial state is dry and wet cooling experiments to explore the process of porous media suction and evaporation. Capillary suction experiment found that the high porosity of nickel powder sample suction rate is faster. According to the experiment of capillary single tube suction and the theoretical analysis of capillary suction, it is shown that the larger pore size of nickel powder sample with large porosity is the fundamental reason for the faster suction rate, and the steady state cooling experiment shows that the nickel with high porosity of 0.85 is the main reason for faster suction rate. The sample of powder has the fastest rate of evaporation, and the sample of nickel powder has the slowest evaporation rate. In the initial dry cooling experiment, the sample of nickel powder with porosity of 0.85 has the largest transient cooling heat flux. However, in order to achieve the maximum cooling temperature amplitude, the equilibrium between transient cooling heat flow and cooling time must be obtained, so the porosity 0.75 sample cooling temperature amplitude is the largest. The sample of nickel powder with porosity of 0.85 had the highest drying temperature and the longest drying time, which showed the strongest anti-drying performance, but the porosity of 0.75 sample had the smallest superheat of intense evaporation and the longest time of intense evaporation. It is the most effective method to restrain the temperature rise at the hot end of the sample.
【作者单位】：山东大学能源与动力工程学院;
【基金】：国家自然科学基金项目(51641607)~~
【分类号】：TQ02

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