小型压水堆螺旋管式直流蒸汽发生器热工水力特性试验及数值模拟研究

Experimental and Numerical Study on Thermal-hydraulics of Helical-coiled Once-through Steam Generator of Small Modular Pressurized Water Reactor

螺旋管式直流蒸汽发生器(H-OTSG)因结构紧凑和换热效率高等特点被广泛应用于小型模块化反应堆。本文开展了在不同热功率下的全尺寸H-OTSG热工水力特性试验。稳态传热特性试验结果表明,随着功率增加,H-OTSG平均传热系数先增加后减小。流动不稳定性试验结果表明,随着功率增加,临界入口节流系数降低,即系统稳定性随着功率的增加而提高。开展了H-OTSG稳态传热特性和流动不稳定性的参数敏感性研究,结果表明在热功率较低时平均传热系数对管侧压力和壳侧入口温度不敏感;当热功率大于1.2 MW时,随管侧压力的降低和壳侧入口温度的升高,H-OTSG平均传热系数增加但也降低了系统的稳定性。本文还开展了H-OTSG热工水力特性的数值模拟,验证了一维程序SGTH-1D在预测H-OTSG稳态传热特性和流动不稳定性的准确性。

The helical-coiled once-through steam generator(H-OTSG)is widely used in small modular reactors due to its compactness and higher heat transfer efficiency.In this study,an experimental and numerical simulation study of the thermal-hydraulics characteristics of H-OTSG under different thermal power conditions was carried out,and the experimental results were used to verify the one-dimensional system code SGTH-1 D.The configuration consists of 85 helically coiled tubes divided into ten layers according to the coil diameter.Both steady-state experiments and flow instability experiments were conducted under thermal power condition ranging from 0.6 MW to 2.3 MW.Firstly,the steady-state experimental results show the difference between the shell-side inlet temperature and the tube-side outlet temperature increases with thermal power,which is due to the decreasing of the heat transfer capacity of the H-OTSG.Sensitivity analysis of the system parameters shows that the shell-side pressure has little effect on the average heat transfer coefficient.And the average heat transfer coefficient also is insensitive to tube-side pressure and shell-side inlet temperature under low thermal power conditions.However,under low thermal power conditions,the average heat transfer coefficient increases with the decrease of the tube-side pressure and the increases of the shell-side inlet temperature.Secondly,the flow instability experimental results show that the increase of the thermal power can stabilize the H-OTSG and decrease the inlet throttling of the flow instability thresholds because the length of the subcooled single-phase region increases with the thermal power.The sensitivity analysis of the system parameters shows that the increase of the tube-side pressure and the decrease of the shell-side inlet temperature are beneficial to the stability of the system.The influence of the shell-side parameters on the flow instability threshold is weaker than that of the tube-side parameters.Finally,a numerical study on the thermal-hydraulics characteristics of the configuration was carried out in the present study.By comparing the experimental data with the numerical simulation results of the SGTH-1 D code,the accuracy of the SGTH-1 D code in predicting the steady-state heat transfer characteristics and flow instability of configuration was verified.The SGTH-1 D code can accurately predict the heat transfer rate of the H-OTSG under various thermal power conditions,and the prediction errors of shell-side and tube-side outlet temperatures are within±1℃.The numerical results of flow instability characteristics of the SGTH-1 D code are conservative at low thermal power condition,and the error of numerical results is within±20%when the thermal power is larger than 1.2 MW.