球床中传热与流动数值模拟研究

Numerical Simulation Research on Heat Transfer and Fluid Flow for Pebble Beds

中文关键词: 球床  气固两相  多孔介质  有效热导率  

英文关键词: Pebble  beds, Gas-solid  flow, Porous  media, Effective  Thermal Conductivity

中文摘要:

      针对球床中气固两相传热与流动过程，本文给出考虑Forchheimer阻力以及孔隙率分布的多孔介质计算模型。计算表明固定达西数Da随着瑞利数Ra的增加，平均换热系数Nuavg随之显著上升。有效热导率是球床的重要参数，改进后的ZBS模型与实验结果符合一致，在高温堆正常运行工况下(~900℃)辐射换热起主导作用。随着球床加热功率的升高以及气体压力的降低，气体流动换热强度逐渐降低。

英文摘要:

      For the processes of gas-solid two phase heat transfer and fluid flow in pebble beds, a numerical porous media model is proposed which takes Forchheimer resistance and porosity distribution into consideration. It reveals that average heat transfer coefficient Nuavg will increase significantly at higher Rayleigh number (Ra) with a given Darcy number (Da). Effective thermal conductivity is an important parameter for pebble beds, the modified ZBS model for which has good agreement with experimental data. At normal operating condition (about 900℃) for high temperature gas-cooled reactor(HTGR),radiation heat transfer plays a domain role. With the increase of heating power and decrease of gas pressure, a lower heat transfer intensity for gas flow will be performed in pebble beds.