摘要
基于Brinkman扩展达西模型,采用直角坐标系下的压力与速度耦合SIMPLE算法,对竖直线热源下松散颗粒的物料传热特性进行了数值模拟.结果表明,竖直线热源作用下的松散颗粒物料中存在明显对流换热效应,且与粒度大小和空隙率无明显相关性.热源表面平均Nusselt数Nuavg随瑞利数Ra增大呈线性增加趋势,而热源表面局部Nusselt数NuR与Ra之间的关系较复杂,但除热源表面顶端位置外,其余位置均可由关联式NuR?a Ra2+b Ra+c表示.为降低对流换热的影响,利用热源表面温升数据测算试样导热系数时(交叉热线法),实验时间不宜超过120 s;而基于平行热线法测热物性参数,温度测点宜布置在试样筒中下部位置处(Y?0.33).利用本模型计算的典型测点温升与实测结果较吻合,而利用热传导模型计算的部分测点温升与实测值最大偏差达17℃,中下部区域则较小.
Based on Brinkman-extended Darcy model, using pressure and velocity coupling SIMPLE under algorithm rectangular coordinate system, heat transfer characteristics of loose granular material under the vertical diraction heat source were simulated. The results showed that the granular material under the vertical line heat source had obvious convective heat exchange effect, and no obvious correlation with grain size and porosity. The average heat source surface Nusselt number, Nuavg, linearly increased with increasing of Ra, and the relationship between local heat source surface Nusselt number, NuR, and Ra was relatively complicated, but except the top of the heat source surface, the measuring positions could be described by NuR-a Ra2＋b Ra＋c. Thus, in order to reduce the effect of convective heat exchange, when the data of heat surface temperature were used to evaluate the thermal conductivity coefficient of sample（cross line method）, the experimental time should not be more than 120 s. When the thermal physical parameters of sample were measured by parallel line method, the appropriate temperature measuring points should be located at its tube part positions（Y-0.33）. the model prediction of temperature rise at typical measuring points was coincident with the measured results. But there was the maximum temperature deviation of 17 ℃ between the prediction of heat conduction model and measured results. The measuring point temperatures in the middle and low area had smaller deviation.
出处
《过程工程学报》
CAS
CSCD
北大核心
2015年第5期729-736,共8页
The Chinese Journal of Process Engineering
基金
安徽省自然科学基金资助项目(编号:1408085ME107)
中国博士后科学基金资助项目(编号:2014M561807)
关键词
松散颗粒物料
竖直线热源
传热
自然对流
模拟
loose granular material
vertical direaction heat source
heat transfer
natural convection
simulation
