超级开架式气化器新型传热管内流场及对流换热的数值模拟

超级开架式气化器(Super ORV)新型传热管主要是在普通传热管的内管中加入了十字螺旋扰流杆,以强化传热管的换热效果。为了研究该装置的换热效率,建立了与新型传热管和普通传热管相对应的数学和模型物理模型,采用数值模拟的方法对两种传热管内流场及对流换热性能进行了对比分析,得到了传热管内流道的努赛尔数随入口速度的变化图,以及传热管不同位置处温度和传热系数的分布规律。通过对现有实验进行数值模拟,对比分析了模拟结果与实验结果。结果表明:(1)FLUENT数值模拟方法能准确描述传热管的传热特性;(2)十字螺旋扰流杆的存在,不仅能够加强流体的湍流强度,而且还能有效减小边界层厚度,产生强烈的二次流,加强了流体在径向上的热交换,提高了传热管的整体换热能力;(3)流体入口速度与努赛尔数的增长幅度呈正比,传热系数随着温度的升高而增加,在相同的雷诺数下,新型传热管内流体的平均温度明显高于普通传热管内流体温度。该研究成果能够为超级开架式气化器国产化进程提供参考。

Numerical simulation analysis on the flow field and convection heat transfer in a new heat transfer tube of SuperORV

A new heat transfer tube of SuperORV (super open rack vaporizer) is developed by adding a Phillips screw spoiler lever to the inner tube of the traditional heat transfer tube to strengthen the heat transfer efficiency. Mathematical and physical models corresponding to the new and the traditional heat transfer tubes were built to study the heat transfer efficiency of this new device. Two types of heat transfer tubes were compared in terms of their flow fields and convection heat transfer performances by means of numerical simulation. As a result, the relationship diagram of inlet velocity vs. Nusselt Number of flow path in heat transfer tubes was worked out, and the distribution laws of temperature and heat transfer coefficient at different positions of heat transfer tubes were drawn. After numerical simulation was carried out on the existing experiments, simulation results and experimental data were compared and analyzed. It is shown that based on the FLUENT numerical simulation method, the heat transfer characteristics can be described accurately. By virtue of screw spoiler levers, not only the turbulence intensity of the fluid is enhanced, but the boundary layer thickness is reduced effectively with a strong secondary flow, so the radial heat exchange of the fluid is strengthened and the overall heat transfer capacity of heat transfer tubes is improved. Inlet flow velocity is proportional to the increasing rate of Nusselt Number, and heat transfer coefficient increases with the rise of temperature. With the same Reynolds number, the average temperature of the fluid inside the new heat transfer tube is significantly higher than that in the traditional transfer tube. These results provide reference for the localization of SuperORV.