物性参数对氟盐球床堆传热模型不确定性和敏感性的影响分析

Effects of Physical Parameters on Uncertainty and Sensitivity Analysis of Heat Transfer Model of Fluoride Salt-Cooled Pebble-Bed Reactor

为了确保氟盐球床堆堆芯传热模型的预测能力满足安全限制,研究了氟盐冷却剂的物性参数对堆芯传热模型不确定度和敏感性的影响。采用统计学不确定性评估方法,将氟盐冷却剂物性参数(包括动力粘度、密度、比热容、导热系数)作为输入参数,选取经典传热关联式作为计算模型,分析了努赛尔数(Nu)的不确定性及其对物性参数的敏感性程度。结果表明,无论氟盐物性参数的概率分布为正态分布或均匀分布,计算得到的Nu的平均值非常接近,其分布形式都接近正态分布;同时发现,动力粘度是物性参数中对Nu影响最大的参数,并且呈负相关;导热系数对Nu的影响为负相关,密度和比热容对Nu的影响较小且均为正相关。

To ensure that the predictive capability of the core heat transfer model can meet the safety constraints, the effects of fluoride salt coolant physical parameters on the uncertainty and sensitivity of the core heat transfer models are studied. Statistical uncertainty evaluation method is adopted in this paper. The physical parameters of the coolant including dynamic viscosity, density, heat capacity and thermal conductivity are taken as input parameters, and the classical heat transfer correlation is chosen as the calculation model. The uncertainty of Nu number and its sensitivity to physical parameters are obtained. The results show that the average values of the calculated Nu number are very close and the distribution forms of Nu number are both nearly the normal distributions, regardless of whether the probability distribution of input physical parameters is normal or uniform. At the same time, it is found that the dynamic viscosity is the most important physical parameter that affects the Nu number, and it is negatively correlated. Thermal conductivity is negatively correlated with Nu number. Density and heat capacity have less positive correlations with Nu number.