TOPAZ-II反应堆是使用固体金属氢化物为慢化剂的微型空间堆,常用的慢化剂材料是氢化锆。近年来,由于金属钇的制造成本降低,氢化钇逐渐成为TOPAZ-II反应堆慢化剂材料的新选择。使用MCNP程序对TOPAZ-II反应堆进行功率分布计算,分别研究氢...TOPAZ-II反应堆是使用固体金属氢化物为慢化剂的微型空间堆,常用的慢化剂材料是氢化锆。近年来,由于金属钇的制造成本降低,氢化钇逐渐成为TOPAZ-II反应堆慢化剂材料的新选择。使用MCNP程序对TOPAZ-II反应堆进行功率分布计算,分别研究氢化锆和氢化钇在不同条件下对反应堆功率的影响。计算结果表明:改变金属氢化物慢化剂的氢含量和温度参数时,堆芯径向功率峰因子的变化趋势决定了功率不均匀系数的变化趋势;慢化剂的氢含量和温度参数的改变会导致堆芯热中子分布发生变化,进而影响反应堆功率分布,低能热中子占中子群份额越高,堆芯径向功率峰因子越小;慢化剂周围的CO2气体环境导致氢损失速率较小,对反应堆功率分布的影响很小;两种慢化剂呈正温度效应,氢化钇的温度系数比氢化锆的温度系数小,且以氢化钇为慢化剂的反应堆keff更高。The TOPAZ-II reactor is a micro-space reactor that uses solid metal hydride as the moderator, with zirconium hydride being the commonly used moderator material. In recent years, the reduced manufacturing cost of yttrium has led to yttrium hydride gradually becoming a new choice of moderator material for the TOPAZ-II reactor. The MCNP program was used to calculate the power distribution of the TOPAZ-II reactor and research the influence of zirconium hydride and yttrium hydride on the reactor power under different conditions. The calculation results show that the trend of the variation in radial power peak factor determines the trend of the variation in power inhomogeneous coefficient when changing the hydrogen content and temperature parameters of the metal hydride moderator. Changes in hydrogen content and temperature parameters of the moderator can cause changes in the thermal neutron distribution in the core, thereby affecting the reactor power distribution. The higher the proportion of low-energy thermal neutrons in the neutron group, the smaller the radial power peak factor in reaction core. The CO2 gas environment surrounding the moderator causes a lower rate of hydrogen loss, resulting in minimal impact on the reactor power distribution. Both moderators exhibit positive temperature effects, with the temperature coefficient of hydrogenated yttrium being smaller than that of hydrogenated zirconium, and the keff of the reactor with hydrogenated yttrium as the moderator is higher.展开更多
多孔材料作为一种新型材料,因其轻质、高导热等特性应用于多个领域。对于多孔材料进行数值重构,并研究其传热特性对工程应用具有重要意义。本文根据多孔材料内部的复杂结构进行建模,应用格子玻尔兹曼方法计算多孔材料的等效导热系数,进...多孔材料作为一种新型材料,因其轻质、高导热等特性应用于多个领域。对于多孔材料进行数值重构,并研究其传热特性对工程应用具有重要意义。本文根据多孔材料内部的复杂结构进行建模,应用格子玻尔兹曼方法计算多孔材料的等效导热系数,进行算法验证,并分析网格数目和两相导热系数比对等效导热系数计算结果的影响。其中,等效导热系数模拟结果会在一定网格区间内趋于准确,并且两相导热系数比越大,等效导热系数变化越平稳,趋于定值。As a new kind of material, porous material is applied in many fields because of its light weight and high thermal conductivity. The numerical reconstruction of porous materials and the study of their heat transfer characteristics are of great significance for engineering applications. In this paper, the complex structure of porous material is modeled, and the lattice Ludwig Boltzmann method is used to calculate the effective thermal conductivity of porous material, validate the algorithm, and analyze the influence of mesh number and two-phase thermal conductivity ratio on the calculation results of equivalent thermal conductivity. The simulation results of equivalent thermal conductivity tend to be accurate in a certain grid range, and the higher the two-phase thermal conductivity ratio, the more stable the change of equivalent thermal conductivity, tending to a fixed value.展开更多
文摘TOPAZ-II反应堆是使用固体金属氢化物为慢化剂的微型空间堆,常用的慢化剂材料是氢化锆。近年来,由于金属钇的制造成本降低,氢化钇逐渐成为TOPAZ-II反应堆慢化剂材料的新选择。使用MCNP程序对TOPAZ-II反应堆进行功率分布计算,分别研究氢化锆和氢化钇在不同条件下对反应堆功率的影响。计算结果表明:改变金属氢化物慢化剂的氢含量和温度参数时,堆芯径向功率峰因子的变化趋势决定了功率不均匀系数的变化趋势;慢化剂的氢含量和温度参数的改变会导致堆芯热中子分布发生变化,进而影响反应堆功率分布,低能热中子占中子群份额越高,堆芯径向功率峰因子越小;慢化剂周围的CO2气体环境导致氢损失速率较小,对反应堆功率分布的影响很小;两种慢化剂呈正温度效应,氢化钇的温度系数比氢化锆的温度系数小,且以氢化钇为慢化剂的反应堆keff更高。The TOPAZ-II reactor is a micro-space reactor that uses solid metal hydride as the moderator, with zirconium hydride being the commonly used moderator material. In recent years, the reduced manufacturing cost of yttrium has led to yttrium hydride gradually becoming a new choice of moderator material for the TOPAZ-II reactor. The MCNP program was used to calculate the power distribution of the TOPAZ-II reactor and research the influence of zirconium hydride and yttrium hydride on the reactor power under different conditions. The calculation results show that the trend of the variation in radial power peak factor determines the trend of the variation in power inhomogeneous coefficient when changing the hydrogen content and temperature parameters of the metal hydride moderator. Changes in hydrogen content and temperature parameters of the moderator can cause changes in the thermal neutron distribution in the core, thereby affecting the reactor power distribution. The higher the proportion of low-energy thermal neutrons in the neutron group, the smaller the radial power peak factor in reaction core. The CO2 gas environment surrounding the moderator causes a lower rate of hydrogen loss, resulting in minimal impact on the reactor power distribution. Both moderators exhibit positive temperature effects, with the temperature coefficient of hydrogenated yttrium being smaller than that of hydrogenated zirconium, and the keff of the reactor with hydrogenated yttrium as the moderator is higher.
文摘多孔材料作为一种新型材料,因其轻质、高导热等特性应用于多个领域。对于多孔材料进行数值重构,并研究其传热特性对工程应用具有重要意义。本文根据多孔材料内部的复杂结构进行建模,应用格子玻尔兹曼方法计算多孔材料的等效导热系数,进行算法验证,并分析网格数目和两相导热系数比对等效导热系数计算结果的影响。其中,等效导热系数模拟结果会在一定网格区间内趋于准确,并且两相导热系数比越大,等效导热系数变化越平稳,趋于定值。As a new kind of material, porous material is applied in many fields because of its light weight and high thermal conductivity. The numerical reconstruction of porous materials and the study of their heat transfer characteristics are of great significance for engineering applications. In this paper, the complex structure of porous material is modeled, and the lattice Ludwig Boltzmann method is used to calculate the effective thermal conductivity of porous material, validate the algorithm, and analyze the influence of mesh number and two-phase thermal conductivity ratio on the calculation results of equivalent thermal conductivity. The simulation results of equivalent thermal conductivity tend to be accurate in a certain grid range, and the higher the two-phase thermal conductivity ratio, the more stable the change of equivalent thermal conductivity, tending to a fixed value.
