Contributions of homogeneous and heterogeneous chemistry in the catalytically supported thermal combustion of methane-air mixtures at very high flow rates

The contributions of homogeneous and heterogeneous chemistry are directed to the catalytically supported thermal combustion of methane-air mixtures at very high flow rates. The catalytically supported thermal combustion of methane-air mixtures is modeled using detailed chemistry by decoupling the homogeneous and heterogeneous chemistry in a flow model. Detailed homogeneous reaction mechanisms with several hundred elementary reactions steps and dozens of species are used to simulate the catalytically supported thermal combustion process. The microchannel reactor comprises a concentric annular channel, wherein the concentric annular channel further comprises an inner annular channel and an outer annular channel. A platinum catalyst is deposited only upon the interior surface of the inner channel, and the wall of the outer channel is chemically inert and catalytically inactive. The reactant stream flows through the catalytically-coated inner channel and the product stream flows out of the outer non-catalytic channel. Fuel is present for combustion in both the catalytic and non-catalytic channels. The concentrically arranged annular channel is 5.0 millimeters in inner channel length, 5.6 millimeters in outer channel length, 0.8 millimeters in innermost diameter, 2.6 millimeters in outermost diameter, 0.1 millimeters in catalyst layer thickness, and 0.2 millimeters in wall thickness. The spacing between the inner channel and the outer channel is 0.4 millimeters and remains constant. The system can have any dimension unless restricted by design requirements. All the walls have the same thickness. One of the potential problems associated with the system, as with all micro-scale combustion systems, continues to be combustion stability. The maximum Reynolds number is less than 360 at the flow inlet and 960 when the velocity of the flow of the fluid is highest in the channels. The model is implemented in commercially available software FLUENT to obtain the solution of the problem. Detailed chemistry is included in the model. Detailed chemical mechanisms are playing an increasingly important role in developing chemical kinetics models for combustion. Detailed chemical mechanisms are incorporated into the reacting flow for the system. The homogeneous combustion is modeled with the detailed chemical mechanism for methane oxidation in CHEMKIN format. Detailed heterogeneous chemistry in SURFACE-CHEMKIN format is included in the model. Contributor: Junjie Chen, E-mail address: [e-mail], ORCID: 0000-0002-5022-6863, Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R. China本数据集聚焦高速流动工况下负载催化的甲烷-空气混合气热燃烧过程，系统考量均相化学（homogeneous chemistry）与非均相化学（heterogeneous chemistry）的贡献。本研究通过在流动模型中解耦均相与非均相化学过程，采用详细化学反应机理对该负载催化热燃烧过程进行建模。模拟所用的详细均相反应机理包含数百个基元反应步骤与数十种组分，用于复现完整的负载催化热燃烧过程。所采用的微通道反应器（microchannel reactor）为同心环形通道（concentric annular channel）结构，分为内环形通道与外环形通道。仅在内通道的内表面沉积铂催化剂（platinum catalyst），外通道壁面则为化学惰性且无催化活性。反应物流经涂覆催化剂的内通道，产物物流从无催化活性的外通道流出。催化通道与非催化通道内均含有用于燃烧的燃料。该同心环形通道的内通道长度为5.0毫米，外通道长度为5.6毫米；最内侧直径为0.8毫米，最外侧直径为2.6毫米；催化剂层厚度为0.1毫米，壁面厚度为0.2毫米。内通道与外通道的间距为0.4毫米且保持恒定。本系统的尺寸可根据设计需求灵活调整，所有壁面厚度均保持一致。与所有微型燃烧系统类似，本系统面临的核心潜在问题之一仍是燃烧稳定性。流体入口处的最大雷诺数（Reynolds number）小于360，当通道内流体流速达到峰值时，雷诺数最大值为960。本模型通过商用软件FLUENT实现求解，且集成了详细化学反应机理。详细化学反应机理在燃烧化学动力学模型的开发中占据愈发重要的地位，本系统的反应流动模型已嵌入详细化学机理。其中，均相燃烧采用CHEMKIN格式的甲烷氧化详细化学机理进行建模，模型同时包含SURFACE-CHEMKIN格式的详细非均相化学过程。贡献者：陈俊杰，电子邮箱：[e-mail]，ORCID：0000-0002-5022-6863，河南理工大学机械与动力工程学院能源与动力工程系，河南省焦作市世纪大道2000号，454000，中华人民共和国