共查询到17条相似文献,搜索用时 218 毫秒
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以应用密度锁的非能动余热排出系统为背景,结合实验研究和理论分析,对密度锁自平衡启动的运行特性及可行性进行研究。结果表明:自平衡启动可分为关阀预热和开阀平衡两个阶段,在这两个阶段内能分别实现密度锁“关闭”所必需满足的两个条件,达到隔离非能动余热排出回路与主回路的目的。在关阀预热阶段,密度锁借助其特殊结构,有效地控制了传热方式转变点的位置,促进了热/冷流体交界面的形成;在开阀平衡阶段,借助其水力平衡的自稳定特性,有效地控制了热/冷流体交界面的移动,建立了密度锁内的水力平衡。所得结果充分证明了自平衡启动方法的可行性。 相似文献
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热管作为一种具有高热导率的传热装置,工作核心在于其内部工作流体的蒸发和冷凝。若热管工作过程中气腔内存在不凝性气体,主流区中蒸气和不凝性气体在对流运动的作用下将一起移动到气-液分界面,不凝性气体的存在阻碍了工作流体在气-液交界面处的正常冷凝。本文基于热阻网络法添加了不凝性气体区域传热模型,研究了不凝性气体对高温锂热管稳态传热特性的影响。结果表明,热管达到稳态时不凝性气体的存在缩短了热管的有效传热长度,破坏了热管的等温性和良好的传热效率。此外随着不凝性气体体积份额的增大,不凝性气体区域温度降低幅度越大;随着热管蒸发段输入功率的增大,热管正常工作区域整体温度越高,相同质量的不凝性气体占据的体积份额越小,热管壁面温度出现明显温度梯度降低的位置随着功率升高而向下游移动。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(9):703-711
The operation of a PIUS-type reactor requires controlling the reactor pump speed to keep stationary the hot/cold liquid interfaces between the reactor coolant and cold borated water. The dynamic response of the interface location to pump speed perturbations is analyzed for an experimental loop simulating a PIUS-type reactor. The transfer function between the pump speed and the interface location is obtained by perturbing and Laplace-transforming the one-dimensional fluid momentum equations. The analytical results agree well with experimental data taken from the same facility. It is shown that the magnitude of the phase lag in the response of the interface location, which needs to be considered in designing a pump speed controller, primarily depends on the fluid inertia in the loop, the density lock flow area, and the density difference between the simulated reactor coolant and borated water. 相似文献
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以基于密度锁的非能动余热排出系统(PRHRS)为研究背景,实验验证了密度锁自平衡启动方案的可行性。结果表明:主回路流量接近平衡流量启动PRHRS时,密度锁内冷热流体温度分界面将在不平衡力作用下向上或向下移动,减小或增大了余热排出回路重位压差,使密度锁内冷热流体温度分界面在新的位置达到受力平衡,最终实现密度锁的自平衡启动,以及余热排出回路与主回路的隔离。依据一维连续性方程、能量方程及动量方程建立数学模型,用Matlab语言编程,对密度锁启动过程进行了数值模拟分析,证明了密度锁自平衡启动方案合理、有效。计算值与实验值符合较好,用该程序可较好地模拟密度锁自平衡启动过程中系统的瞬态运行特性。 相似文献
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为了提高核反应堆系统的经济性和安全性,本文采用CFD方法对棒束子通道间湍流交混效应进行研究。对子通道建模,选取SST k-ω模型进行计算,完成了网格敏感性分析。采用类比浓度计算法与间隙湍流热流法对湍流交混系数进行计算。计算结果表明:雷诺数较小时,单相湍流交混系数随雷诺数的增大而增大;当雷诺数达到一定值时,单相湍流交混系数近似为定值;采用类比浓度计算法与间隙湍流热流法计算所得的湍流交混系数无太大差别。本文拟合得到了适用于单相工况的湍流交混系数计算公式。 相似文献
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Gaojian Dang Yushan Luo Haijun Wang Tingkuan Chen Qing Mao Yixiong Zhang 《Nuclear Engineering and Design》2008,238(7):1828-1837
Thermal fatigue is a potentially significant degradation mechanism in Nuclear Power Plants (NPP). For the fatigue analysis, the thermal load information about components must be determined firstly. In this paper, an experimental study was carried out to obtain local fluid temperatures and local heat transfer coefficients for the safety injection nozzle component in reactor coolant system (RCS). In this mixing tee component a hot jet issues into a cold cross-flow stream from an oblique pipe and the turbulent mixing of two fluids induces local cycling stresses on the adjacent piping wall. Experiments were performed using a special-made heat fluxmeter, which can measure the mixed fluid temperature close to the wall and the heat transfer coefficient between the fluid and the wall. Plexiglass and metallic 1/9-scale mockups were manufactured for flow visualization and heat transfer tests, respectively. All tests were conducted at range of 0–40 for the jet-to-cross-flow velocity ratio. The flow visualization test has obtained general pattern of the flow and identified sensitive zones in the component where the jet and cross-flow interact intensively to cause thermal fatigue more possibly. In the heat transfer test, heat fluxmeters were positioned in the wall at these sensitive zones. The measurement results of temperatures and heat transfer coefficients have been discussed in detail in the paper. These experimental results allow us improving the state of knowledge of the thermal load to be used in the industrial mixing tees in operating for long lifetime assessment and for the design in the basic Nuclear Power Plants. 相似文献