Efficient In-Situ and Reduced Chemistry Algorithms for Chemical Process Flow Simulation

该项目的主要目标是开发和实施有效的原位和减少化学算法，详细的化学过程流程模拟。 应用计算流体动力学（CFD）对化学反应器内的流场和化学组分分布进行更全面的描述是化工过程流动模拟的发展趋势。 对于化学反应流，处理由复杂动力学方案（即大于10至20种物质）产生的化学源项通常是流模拟中计算最密集的部分。 因此，通过利用复杂动力学方案的两个共同特征，即化学时间尺度（相对于流动时间尺度）的大分离和“访问区域”的紧凑性（即，在特定模拟中实际出现的成分）。 两种方法，利用这些功能将进行调查。 第一，在原位自适应制表（ISAT），是适用于中等规模的动力学计划（约20种化学品），由于其灵活的实施，应该是强大的化学工艺流程模拟。 第二，内在的低维流形（ILDM）的方法，是适用于较大的动力学计划（只要大多数的化学时间尺度小于流动的时间尺度），但计算上更难以实现，因为它需要retablation后的动力学计划或流动参数的每一个变化。 为了克服每一个单独的算法的缺点，一个组合的ILDM-ISAT算法的实现将被探索。 该算法将在一个现有的全概率密度函数（PDF）代码设计的湍流反应流模拟。 两个工业化学反应方案（甲烷的热氯化和乙烯的自由基聚合）的全pdf模拟将进行，以验证和记录的算法在广泛的实际工厂反应器条件下的效率。

The principal objectives of this project are the development and implementation of efficient in-situ and reduced chemistry algorithms for detailed chemical process flow simulation. The current trend in flow simulation in the chemical process industries is towards the application of computational fluid dynamics (CFD) to obtain a more complete descriptions of the flow field and chemical species distribution inside chemical reactors. For chemically reacting flows, treatment of the chemical source terms resulting from complex kinetic schemes (i.e. greater than 10 to 20 species) is often the most computationally intensive part of a flow simulation. Considerable gains in computational efficiency are thus possible by exploiting two common features of complex kinetic schemes, namely, the large separation in chemical time scales (relative to flow time scales), and the compactness of the "accessed region" (i.e., the compositions that actually occur in a particular simulation). Two methodologies that make use of these features will be investigated. The first, in-situ adaptive tabulation (ISAT), is applicable to moderately large kinetic schemes (around 20 chemical species) and, due to its flexibility of implementation, should be powerful for chemical process flow simulations. The second, intrinsic low-dimensional manifold (ILDM) method, is applicable to larger kinetic schemes (provided that the majority of the chemical time scales are smaller than the flow time scales), but computationally more difficult to implement since it requires retabulation after each change in the kinetic scheme or flow parameters. In order to overcome the shortcomings of each individual algorithm, implementations of a combined ILDM-ISAT algorithm will be explored. The algorithms will be implemented in an existing full probability density function (PDF) code designed for turbulent reacting flow simulation. Full pdf simulations of two industrial chemical reaction schemes (thermochlorination of methane and free-radical poly merization of ethylene) will be carried out in order to validate and document the efficiency of the algorithms under a wide range of actual plant reactor conditions.