Diffuse Interface Method for Nucleate Boiling Simulations
Diffuse Interface Method for Nucleate Boiling Simulations
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用于核沸腾模拟的扩散界面方法
DOI：
10.11159/icmfht22.159
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Minozzi G
中科院分区：
文献类型：
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作者：
Minozzi G
由于其优异的传热系数，沸腾在许多工业应用中是一种有效的传热机制。由于相变过程和表面过程中传热传质的复杂耦合而产生的非平衡态热力学，使得这类系统难以精确描述。 然而，相关的发展已经取得了计算方法，使详细研究核态沸腾现象的高性能并行数值模拟的基础上不同的数值方法。 我们正在开发一个直接的数值模拟框架，使用我们的内部TPLS求解器[1]应用扩散界面方法[2]，该方法求解Cahn-Hilliard方程以描述液-汽界面的演变。该方法消除了三相接触线处的应力奇异性，从而能够通过接触角边界条件来规定表面润湿性[3]。因此，我们能够分析表面润湿性的核态沸腾传热系数，气泡的生长和离开的作用。 通过模拟得到了成核单气泡的生长速率和脱离位置随基底润湿性的变化。该模型框架也被扩展到模拟多个气泡，以分析气泡的相互作用，不同润湿性的气泡尺寸和尺寸。 我们的模拟结果表明，表面张力的偏离条件的重要性，这表明在高润湿性的情况下，更好的散热。相反，我们已经发现在低润湿性表面中的有限生长速率，这可能促进随后形成的气泡的生长。
Boiling is an efficient mechanism for heat transfer in several industrial applications due to its excellent heat transfer coefficient. The non-equilibrium thermodynamics, raised by the complex coupling of the heat and mass transfer in phase change and surface processes, makes these systems difficult to describe accurately. However, relevant developments have been made in computational methods enabling a detailed study of nucleate boiling phenomena with high performance parallelised numerical simulations based on different numerical methods. We are developing a direct numerical simulation framework using our in-house TPLS solver [1] applying the diffuse interface method [2] which solves the Cahn-Hilliard equation to describe evolution of the liquid-vapour interface. This method removes the stress singularity at three-phase contact line and consequently enables to prescribe the surface wettability via contact-angle boundary conditions [3]. We are thus able to analyse the role of surface wettability on nucleate boiling heat transfer coefficient, bubble growth and departure. The growth rates and departure of nucleating single bubbles have been obtained through simulations as a function of substrate wettability. The modelling framework has also been extended to simulate multiple bubbles to analyse the bubble interaction, the superheat and bubble size for different wettabilities. Our simulation results show the importance of surface tension on the departure conditions, suggesting a better heat removal in high wettability cases. Conversely, we have found a limited growth rate in low wettability surfaces, which might promote the growth of subsequently forming bubbles.