规整结构催化剂内多尺度多场耦合热质传递机理研究

Catalytic combustion becomes the research hotspot for its high efficiency and cleaning in recent years. The catalytic combustion in the monolithic catalyst involves the multi-scale space from micro and nano scale pore boundary to macro scale channel, which couples the complex process of catalytic reaction and radiation in the pore boundary. The mechanism of multi-scale and multi-field heat and mass transfer in the monolithic catalyst is not revealed at present. The experimental and theoretical methods are adopted to study those complex problems systematically and deeply in this project. The computational method for the radiation in porous medium is established by using Monte Carlo method. The influence law of different factors on the radiation characteristics in the porous medium is explored based that. Then the empirical formula for the apparent radiation of the porous medium is obtained. The LBM mathematical and physical models for the flow and mass transfer coupling catalytic reaction in the multi-scale space are developed. After that, the mass transfer charateristics of the catalytic reaction in the pore boundary and the interaction mechanism between the catalytic reaction process in the pore boundary and the flow characteristics of the main flow is explored. Finally, the multi-scale mathematical and physical models including the catalytic reaction in the pore boundary, the apparent radiation of the porous medium and the heat and mass transfer of the macro channel are established. The effects of different parameters on the distribution of the velocity filed, concentration field and temperature field are studied. And the mechanism of multi-scale and multi-field heat and mass transfer coupling the catalytic reaction and radiation in the pore boundary is revealed. The measures for the process enhancement and controlling of the heat and mass transfer in the monolithic catalyst are obtained. The investigation in this project can provide the important theoretical basis and key technical support for the optimization design, controlling and running of the catalytic combustion in the apparent catalyst.

催化燃烧作为一项高效清洁燃烧技术，成为近年来的研究热点。规整结构催化剂内催化燃烧过程涉及微纳尺度孔隙边界与宏观尺寸通道的多尺度空间，耦合了孔隙边界催化反应与孔隙辐射等复杂过程，其多尺度多场耦合的热质传递机理尚不明确。本项目采用实验与理论相结合，对相关问题进行系统深入研究：建立蒙特卡洛法多孔介质辐射计算过程，探索各因素对多孔介质辐射特性的影响规律，获得其表观辐射特性计算经验公式；发展耦合催化反应的多尺度流动扩散LBM数理模型，探索孔隙边界催化反应质量传输特性及其与主流流动特性间的相互作用机制；进一步建立耦合孔隙边界催化反应、多孔介质表观辐射与宏观通道热质传递的跨尺度数理模型，探索各参数对速度场、浓度场与温度场分布的作用特性，揭示耦合孔隙边界催化反应与辐射的多尺度多场协同热质传递机理，获得规整结构催化剂内热质传递过程强化与控制措施，为系统优化设计、控制与运行提供重要理论依据与关键技术支撑。

催化燃烧作为一项高效清洁燃烧技术，成为近年来的研究热点，其中规整结构催化剂是最具发展前景的选择。规整结构催化剂内催化燃烧过程涉及微纳尺度孔隙边界与宏观尺寸通道的多尺度空间，耦合了孔隙边界催化反应与孔隙辐射等复杂过程，其多尺度多场耦合的热质传递机理尚不明确。本项目针对该问题，开展了多孔介质孔隙辐射特性研究、孔隙边界与宏观通道流动特性耦合作用机制研究、规整结构催化剂内多尺度多场耦合热质传递机理及协同机制研究。通过相关研究，获得了多孔介质孔隙率、孔隙密度、孔隙结构以及材料等对多孔介质光谱透射和反射特性的作用规律，建立了多孔介质有效辐射导热系数计算公式，获得了不同散射率下多孔介质有效辐射导热系数随温度的变化规律，揭示了孔隙结构参数与表观辐射特性间的内在联系与作用规律。研究了催化剂涂层对规整结构催化剂通道内流动传热特性影响规律，获得了涂层对金属泡沫有效导热、气固传热及辐射传热特性的影响规律，揭示了催化剂涂层多孔介质内有/无粘性流体流动条件下的气-固界面速度分布、流动阻力变化特性及其耦合传热机制。研究了规整结构催化反应器内丙酮加氢放热催化反应过程的温度、速度以及浓度场分布特性，获得了体积参数、催化剂参数以及壁面传热等条件下催化剂多孔介质涂层厚度对反应转化率、泵功转化量以及反应选择性的影响规律，揭示了规整结构催化反应器结构参数变化对其压降特性、温度与浓度分布特性的作用机制，获得了不用条件下规整结构催化反应器内催化剂涂层最优厚度范围与最佳运行参数条件，大大提高了规整结构催化反应器的整体性能。相关研究可用于指导规整结构催化反应器的设计，提高反应转换能力；也可以指导催化燃烧反应器的设计，用于工业低浓度、低热值废气去除和利用，以及用于低温燃烧场合，降低NOx排放，提高燃烧稳定性，为相关行业的发展提供关键技术支持。