太阳能驱动甲烷干重整Ni泡沫反应器的设计与优化

Design and optimization of solar energy driven Ni foam reactor for methane dry reforming

太阳能驱动甲烷干重整转化技术可将CO_(2)和CH_(4)协同转化为燃料,是实现太阳能储存和CO_(2)减排的有效途径。多孔泡沫反应器因具有良好的热导率、较高的机械强度和气体渗透性,而成为太阳能驱动甲烷干重整转化技术规模化应用的研究热点。通过计算流体动力学模拟(CFD)研究了入口条件对反应器反应性能的影响。结果表明,入射总辐射量为130.8 W、入口流速为0.85 L/min时反应器反应性能最好,CH_(4)、CO_(2)转化率和光-燃料效率分别为79.73%、87.53%和37.03%。通过CFD耦合遗传算法(GA)对均匀多孔Ni泡沫反应器(简称“Ni泡沫反应器”)的孔结构与反应性能之间的关系进行了研究。结果表明,增大孔隙率可以在一定程度内提高Ni泡沫反应器的反应性能,而随着孔径的增大,反应性能先提高后降低,其中当孔隙率为0.93、孔径为1.72 mm时获得的Ni泡沫反应器(结构3)具有最优的反应性能,其CH_(4)、CO_(2)转化率和光-燃料效率分别为83.55%、89.53%和46.47%。之后提出两种双梯度渐变孔径Ni泡沫反应器的设计优化策略(分别为孔径轴向上由大变小、径向上由小变大渐变(结构1)和孔径轴向、径向上都由大到小渐变(结构2))。与结构3相比,结构1有助于辐射深入的同时保证中心区域温度更高,光-燃料效率为55.00%;结构2有助于太阳能的逐步吸收,进而提高温度均匀性,光-燃料效率为52.20%。

The solar energy driven methane dry reforming and conversion technology can convert CO_(2)and CH_(4)into fuel synergistically,which is an effective way to achieve solar energy storage and CO_(2)emission reduction.Because of its good thermal conductivity,high mechanical strength and gas permeability,the porous foam reactor has become a research hotspot in the large-scale energy application of solar energy driven methane dry reforming and conversion technology.The effect of inlet conditions on the reactor performance was studied by computational fluid dynamics simulation(CFD).The results show that the reaction performance is best when the total incident radiation is 130.8 W and inlet flow rate is 0.85 L/min,and the conversion rates of CH_(4)and CO_(2),and light-fuel efficiency are 79.73%,87.53%and 37.03%,respectively.The relationship between pore structure and reaction performance of uniformly porous Ni foam reactor(“Ni foam reactor”for short)was studied by CFD coupled with genetic algorithm(GA).The results show that the reaction performance of the Ni foam reactor can be improved to a certain extent by increasing the porosity,and the reaction performance increases first and then decreases with the increase of the pore size.The Ni foam reactor(structure 3)with porosity of 0.93 and the pore size of 1.72 mm has the best reaction performance.The conversion rates of CH_(4)and CO_(2),and light-fuel efficiency are 83.55%,89.53%and 46.47%,respectively.Then,two optimization strategies for the design of Ni foam reactors with double gradient gradient aperture are proposed,namely,the gradient from large to small in the axial direction and from small to large in the radial direction(structure 1)and the gradient from large to small in both the axial and radial direction of the aperture(structure 2).Comparing with structure 3,structure 1 helps to penetrate the radiation while ensuring a higher temperature in the central region,and the light-fuel efficiency is 55.00%.And structure 2 contributes to the gradual absorption of solar energy,which in turn enhances temperature uniformity,with a light-fuel efficiency of 52.20%.