Abstract In this paper, we calculate the heat transfer effective coefficients for a Liquid Metal-Cooled Fast Reactor. We upscaled the local energy equation of a fuel pin and its surrounding liquid metal (cooler fluid) to the whole fuel assembly representing the entire nuclear reactor core. Such an upscaling procedure was carried out within the volume averaging framework. The upscaled model contains two coupled energy equations, and jointly three closure problems are presented which assist to numerically compute the effective coefficients. The closure problems consist of boundary-value problems, whose solution must be carried out in a representative geometry of fuel assembly. The closure problems were solved to obtain the closure variables, with which the effective coefficients related to conductivity and convection heat transfer were obtained. The upscaled model results were compared with the more-intensive numerical solution of the pin-scale mathematical model. An acceptable agreement was found validating the mathematical structure of the upscaled model, the closure problems, and the definitions of effective parameters.

中文翻译：

---

液态金属冷却快核反应堆的升级传热系数

摘要 在本文中，我们计算了液态金属冷却快堆的传热有效系数。我们将燃料棒及其周围液态金属（冷却器流体）的局部能量方程放大到代表整个核反应堆堆芯的整个燃料组件。这种放大程序是在体积平均框架内进行的。放大后的模型包含两个耦合能量方程，并联合提出了三个闭合问题，有助于数值计算有效系数。闭合问题由边界值问题组成，其求解必须在燃料组件的代表性几何结构中进行。求解闭合问题，得到闭合变量，得到与传导率和对流传热有关的有效系数。将放大后的模型结果与针尺度数学模型的更密集的数值解进行比较。发现了一个可接受的协议，验证了放大模型的数学结构、闭合问题和有效参数的定义。