Turbulent Flow Simulation of Supercritical Hydrothermal Synthesis in T-Shaped Channel
Turbulent Flow Simulation of Supercritical Hydrothermal Synthesis in T-Shaped Channel
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T型通道中超临界水热合成的湍流模拟
DOI：
10.1115/fedsm2021-66023
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Adschiri Tadafumi
中科院分区：
文献类型：
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作者：
Furusawa Takashi;Matsui Kenta;Yatsuyanagi Shuto;Yamamoto Satoru;Yoko Akira;Adschiri Tadafumi
采用雷诺平均Navier-Stokes（RANS）方法研究了超临界水与金属盐溶液的湍流混合流动。考虑水热反应产物的影响，将水溶液中金属盐和金属氧化物的质量守恒方程与Navier-Stokes方程和剪切应力输运（SST）湍流模型耦合求解。利用实验数据对数值模拟中的反应速率进行线性插值。数值模拟了不同雷诺数下T形通道内的混合流动。流体混合导致高温区域中的水热反应。在低温和低雷诺数的情况下，混合变成稳定状态，并且金属氧化物沿着通道壁生成。当雷诺数较高时，混合点处出现周期性涡，流体温度迅速升高。数值模拟再现了实验测量的表观反应速率，除了低雷诺数的情况下。时均温度分布表明，混合反应器内的升温速率取决于入口超临界水温度，从而影响金属氧化物的浓度分布。如果在低温情况下忽略湍流效应，则表观反应速率估计相当低。湍流扩散系数和导热系数对转化率有重要影响，特别是在低雷诺数条件下。
Turbulent mixing flows of supercritical water and a metal-salt solution were investigated using Reynolds-averaged Navier–Stokes (RANS) simulations. The mass conservation equations for metal-salt and metal-oxide in an aqueous solution, which were coupled with Navier–Stokes equations and the Shear Stress Transport (SST) turbulence model, were solved by considering production by the hydrothermal reaction. The reaction rate in the numerical simulation was interpolated linearly using the experimental data. The mixing flows in a T-shaped channel for various Reynolds numbers were simulated numerically. Fluid mixing causes a hydrothermal reaction in a high temperature region. In a situation with a low temperature and low Reynolds number, the mixing became a steady state, and the metal oxide was generated along the channel wall. For a high Reynolds number, the periodic vortexes were observed at the mixing point and the fluid temperature increased rapidly. A numerical simulation reproduced the apparent reaction rate of the experimental measurements, except for the low Reynolds number case. The time-averaged temperature distributions indicated that the increasing temperature rate in the mixing reactor depends on the inlet supercritical water temperature, which affects the distribution of the concentration of metal oxide. If the turbulence effects were ignored in low-temperature instances, the apparent reaction rate was estimated to be quite low. The turbulent diffusivity and thermal conductivity crucially affected the conversion rate, especially for conditions with a low Reynolds number.