Rasul M G, Ahmed S, Sattar M A, Jahirul M I
School of Engineering and Technology, Central Queensland University, Rockhampton, Queensland, 4702, Australia.
Mechanical and Product Design Engineering, Swinburne University of Technology, Hawthorn, 3122, Australia.
Heliyon. 2023 Aug 29;9(9):e19623. doi: 10.1016/j.heliyon.2023.e19623. eCollection 2023 Sep.
Purification of wastewater is essential for human being as well as for the flora and fauna, and sustainable environment. Photocatalytic reactor with TiO coated layer can be used to degrade the pollutants but without proper pollutant mass transfer in the reactive surface, photocatalytic reactor decreases its effectiveness. The baffles and rough surface in the flow path can improve the fluid mixing to enhance pollutant mass transfer to improve the reactor's performance. In this study, a computational fluid dynamics (CFD) model has been developed to investigate the effect of four top baffles and three rough surfaces (semi-circular, triangle, and rectangle) on pressure drops, mass transfer and the hydrodynamic performance of the reactor. The experimental investigation was carried out using Formic Acid (FA) as pollutant in feed water for model validation. The simulated result varies only within 5% with the experimental data of FA concentration versus feed flow rate and fluid velocity. The model was run at fluid velocity of 0.15 m/s and 0.5 m/s (Reynolds number of 2150 (laminar flow) and 7500 (turbulent flow), respectively. The simulation result shows that the addition of baffles and roughness on the reactive surfaces increases the turbulent kinetic energy (minimum increase 8%) and consequently increases the mass transfer (maximum increase 37%) of the pollutant. The highest wall shear was observed to be 40 Pa when both square and triangular elements were used as roughness elements at turbulent flow condition. The results also shows that the highest pressure-drop of 8 kPa was found when the square roughness element was used at turbulent flow condition. Overall, the photocatalytic reactor performance is significantly enhanced by the application of combined baffles and roughness elements in the reactive surface.
废水净化对人类、动植物以及可持续环境至关重要。带有二氧化钛涂层的光催化反应器可用于降解污染物，但如果反应表面没有适当的污染物传质，光催化反应器的效率就会降低。流道中的挡板和粗糙表面可以改善流体混合，增强污染物传质，从而提高反应器的性能。在本研究中，开发了一种计算流体动力学（CFD）模型，以研究四个顶部挡板和三种粗糙表面（半圆形、三角形和矩形）对反应器压降、传质和流体动力学性能的影响。以甲酸（FA）作为进水污染物进行实验研究，以验证模型。FA浓度与进水流量和流体速度的实验数据表明，模拟结果的变化仅在5%以内。该模型在流体速度为0.15 m/s和0.5 m/s（雷诺数分别为2150（层流）和7500（湍流））的条件下运行。模拟结果表明，在反应表面添加挡板和粗糙度会增加湍动能（最小增加8%），从而增加污染物的传质（最大增加37%）。在湍流条件下，当方形和三角形元件都用作粗糙度元件时，观察到最高壁面剪应力为40 Pa。结果还表明，在湍流条件下使用方形粗糙度元件时，发现最高压降为8 kPa。总体而言，通过在反应表面应用组合挡板和粗糙度元件，光催化反应器的性能得到了显著提高。
