熔盐球床堆堆芯入口热工水力特性数值分析

堆芯入口流场设计是小型固态燃料熔盐堆系统项目内容之一,它对反应堆结构的稳定性、堆芯温度和流场分布有着非常重要的影响。研究了熔盐流道流通面积变化对堆芯入口温度、流场分布及压降的影响,优化熔盐流道几何结构。以小型熔盐球床堆模型为研究对象,取符合实际边界条件的输入参数,通过改变熔盐流道流通面积,使用计算流体力学(Computational Fluid Dynamics,CFD)通用程序Fluent 16.0对堆芯入口内熔盐的热工水力特性进行数值模拟。在考虑实际下反射层流道的流通面积占比最大为18.14%下,研究了熔盐流道流通面积占比在区间[0,15.00%]变化。结果表明,堆芯活性区熔盐最高局部热点温度随熔盐流道流通面积比的增大而增高;堆芯入口内的压降随下反射层熔盐流道流通面积比的减小而增大;在径向方向上流进孔道的熔盐流速随着孔道远离堆芯位置而增大。本研究可为小型固态燃料球床熔盐堆优化设计提供一定的参考价值。

Thermal-hydraulics numerical analyses of molten salt pebble-bed reactor core inlet

Background: The flow field design at the core inlet has a particularly important influence on structure stability, temperature distribution and flow field of a small solid fuel salt reactor system.Purpose: This study aims to optimize the flow channel structure by analyzing the effect of the thermal-hydraulic characteristics.Methods:Base on the design of a small molten salt pebble-bed reactor, input parameters of the practical boundary conditions were adopted for simulation study using Fluent 16.0 of computational fluid dynamics (CFD). Thermal-hydraulic characteristics such as temperature field, flow field and pressure drop, of core inlet were simulated through changing the flow areas.Results: The computational results showed that when proportion of the flow area was in the range of [0, 15.00%], the maximum local temperature in the active core region increased and the pressure drop in the core inlet decreased with the increase of the flow area. As the channel is far away from the core position, salt velocity increases gradually along the radial direction.Conclusion: The numerical results provide a useful proposal to optimize the design of a small solid fuel salt reactor.