Parametric studies of heat transfer and fluid flow are very important research of interest because the design and operation of fluid flow and heat transfer systems are guided by these parametric studies. The safety of the system operation and system optimization can be determined by decreasing or increasing particular fluid flow and heat transfer parameter while keeping other parameters constant. The parameters that can be varied in order to determine safe and optimized system include system pressure, mass flow rate, heat flux and coolant inlet temperature among other parameters. The fluid flow and heat transfer systems can also be enhanced by the presence of or without the presence of particular effects including gravity effect among others. The advanced Generation IV reactors to be deployed for large electricity production, have proven to be more thermally efficient (approximately 45% thermal efficiency) than the current light water reactors with a thermal efficiency of approximately 33 °C. SCWR is one of the Generation IV reactors intended for electricity generation. High Performance Light Water Reactor (HPLWR) is a SCWR type which is under consideration in this study. One-eighth of a proposed fuel assembly design for HPLWR consisting of 7 fuel/rod bundles with 9 coolant sub-channels was the geometry considered in this study to examine the effects of system pressure and mass flow rate on wall and fluid temperatures. Gravity effect on wall and fluid temperatures were also examined on this one-eighth fuel assembly geometry. Computational Fluid Dynamics (CFD) code, STAR-CCM+, was used to obtain the results of the numerical simulations. Based on the parametric analysis carried out, sub-channel 4 performed better in terms of heat transfer because temperatures predicted in sub-channel 9 (corner sub-channel) were higher than the ones obtained in sub-channel 4 (central sub-channel). The influence of system mass flow rate, pressure and gravity seem similar in both sub-channels 4 and 9 with temperature distributions higher in sub-channel 9 than in sub-channel 4. In most of the cases considered, temperature distributions (for both fluid and wall) obtained at 25 MPa are higher than those obtained at 23 MPa, temperature distributions obtained at 601.2 kg/h are higher than those obtained at 561.2 kg/h, and temperature distributions obtained without gravity effect are higher than those obtained with gravity effect. The results show that effects of system pressure, mass flowrate and gravity on fluid flow and heat transfer are significant and therefore parametric studies need to be performed to determine safe and optimum operating conditions of fluid flow and heat transfer systems.

传热和流体流动的参数研究是非常重要的研究，因为流体流动和传热系统的设计和操作是由这些参数研究指导的。系统操作和系统优化的安全性可以通过减少或增加特定的流体流量和传热参数同时保持其他参数不变来确定。可以改变以确定安全和优化系统的参数包括系统压力、质量流量、热通量和冷却剂入口温度等参数。流体流动和传热系统也可以通过存在或不存在包括重力效应在内的特定效应来增强。用于大规模发电的先进第四代反应堆，已被证明比目前热效率约为 33 °C 的轻水反应堆具有更高的热效率（约 45% 的热效率）。SCWR 是用于发电的第四代反应堆之一。高性能轻水反应堆 (HPLWR) 是本研究中正在考虑的 SCWR 类型。由 7 个燃料/棒束和 9 个冷却剂子通道组成的 HPLWR 燃料组件设计的八分之一是本研究中考虑的几何形状，以检查系统压力和质量流量对壁面和流体温度的影响。在这种八分之一的燃料组件几何形状上也检查了重力对壁和流体温度的影响。计算流体动力学 (CFD) 代码 STAR-CCM+ 用于获得数值模拟的结果。基于进行的参数分析，子通道 4 在传热方面表现更好，因为子通道 9（角子通道）中预测的温度高于子通道 4（中央子通道）中获得的温度. 系统质量流量、压力和重力的影响在子通道 4 和 9 中似乎相似，子通道 9 中的温度分布高于子通道 4。在考虑的大多数情况下，温度分布（对于两种流体25 MPa 时得到的温度分布高于 23 MPa 时得到的温度分布，601.2 kg/h 时得到的温度分布高于 561.2 kg/h 时得到的温度分布，没有重力效应得到的温度分布高于有重力效应得到的温度分布. 结果表明，系统压力的影响，