Bell Ian H
Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, Colorado 80305, United States.
Ind Eng Chem Res. 2024 Jul;63(31). doi: 10.1021/acs.iecr.4c01631.
A relatively succinct set of property calculations can be used to construct efficient (in memory and speed) numerical approximations of that function in a rectangular domain. Through the use of adaptive subdivision with quadtrees and bi-Chebyshev expansions in each leaf, the function can be practically represented to the order of the noise in the function to be approximated. A further benefit is that evaluation of the approximation is noniterative and thus cannot fail to converge (a relatively common problem in thermophysical property libraries, especially for mixtures). Evaluation of the approximation function requires only a few bisection steps to identify the leaf of interest such that evaluation of the approximation data structure takes less than a microsecond. The technique is demonstrated by application to the vapor-liquid-equilibria evaluated with two different models (COSMO-SAC activity coefficient model and multifluid model). For the more expensive COSMO-SAC case, the approximation function is more than 2000 times faster to evaluate, and deviations in pressure are less than a part in 10 which is practically equal to the iteration convergence criterion.
可以使用一组相对简洁的属性计算，在矩形域中构建该函数的高效（在内存和速度方面）数值近似。通过在四叉树中使用自适应细分以及在每个叶节点中进行双切比雪夫展开，该函数实际上可以表示到要近似的函数中的噪声阶数。另一个好处是，近似值的评估是非迭代的，因此不会不收敛（这在热物理性质库中是一个相对常见的问题，特别是对于混合物）。评估近似函数只需要几个二分步骤来识别感兴趣的叶节点，这样评估近似数据结构所需的时间不到一微秒。通过应用于用两种不同模型（COSMO-SAC活度系数模型和多流体模型）评估的气液平衡来证明该技术。对于更耗时的COSMO-SAC情况，评估近似函数的速度要快2000倍以上，压力偏差小于千分之一，这实际上等于迭代收敛标准。
