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Prediction Model of Heat and Mass Transfer in Metal Hydride Packed Beds

金属氢化物填充床传热传质预测模型

基本信息

批准号：
12650210
负责人：
MORI Hideo
金额：
$ 2.69万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650210/
关键词：
Metal Hydride Packed Bed Heat and Mass Transfer Adsorption desorption Experiment Numerical Analysis Physical Model

项目摘要

Experiments and numerical analyses were made on heat and mass transfer in thin packed beds of LaNi_5 and Lm-Ni metal hydride to develop the prediction model.1. The effective thermal conductivity of LaNi5 and Lm-Ni beds was measured under vacuum condition.2. For each metal hydride bed, the equilibrium absorption isotherms (Pressure-Composition isotherms) were measured and the value of the heat of reaction was determined based on measured isotherms.3. The changes of bed temperature, system pressure and amount of adsorbed hydrogen with time after the beginning of reaction were systematically measured during both of the adsorption and desorption processes in beds of different heat exchanging surface temperatures, final equilibrium pressures and bed thicknesses.4. The adsorption/desorption reaction proceeds fast, as the difference between the system pressure and the plateau equilibrium pressure corresponding to the heat exchanging surface temperature, and the reaction rate reduces as the bed thickness increases.5. Numerical analyses were carried out on heat and mass transfer during adsorption and desorption in LaNi_5 and LmNi metal hydride packed beds, based on a physical model taking account of all elemental heat and mass transfer processes which take place in the bed. Comparing the experimental data, it was clarified that the reaction rate is dominated mainly by the resistance to heat transfer (heat conduction) within the bed and more or less by the resistance to mass transfer (diffusion of hydrogen) within the metal particles, and that the effects of the resistance to mass transfer between metal particles (hydrogen gas permeation) and to heat and mass transfer at the meat particle surface are negligibly small.6. Based on the model considering both of the bed heat conduction resistance and the particle diffusion resistance, calculations of the adsorption/desorption rate were in good agreement with measurements.

对LaNi_5和Lm-Ni金属氢化物薄填充床内的传热传质过程进行了实验和数值分析，建立了预测模型.在真空条件下测量了LaNi 5和Lm-Ni床层的有效热导率.对于每个金属氢化物床，测量平衡吸收等温线（压力-组成等温线），并基于测量的等温线确定反应热的值。系统测定了不同换热表面温度、最终平衡压力和床层厚度的床层在吸附和解吸过程中，床层温度、系统压力和吸附氢量随反应开始后时间的变化.系统压力与平台平衡压力之差对应于换热表面温度，吸附/脱附反应进行快，反应速率随床层厚度的增加而减小.基于一个考虑了床层内所有基本传热传质过程的物理模型，对LaNi_5和LmNi金属氢化物填充床吸附和脱附过程中的传热传质进行了数值分析。通过对实验数据的比较，阐明了反应速率主要受传热阻力的影响（热传导）和或多或少的阻力的传质（氢的扩散）在金属颗粒内，金属颗粒之间的传质阻力的影响（氢气渗透）和在肉颗粒表面的热量和质量传递是可忽略不计的小。基于同时考虑床层导热阻力和颗粒扩散阻力的模型，对吸附/脱附速率的计算结果与实测值吻合较好。