Concentration-Dependent Diffusion Coefficients of Binary Gas Mixtures Using a Loschmidt Cell with Holographic Interferometry
Concentration-Dependent Diffusion Coefficients of Binary Gas Mixtures Using a Loschmidt Cell with Holographic Interferometry
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DOI：
10.1007/s10765-018-2450-8
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发表时间：
2018-10
影响因子：
2.2
通讯作者：
Ludger Wolff;Pouria Zangi;Thorsten Brands;M. Rausch;H. Koß;A. Fröba;A. Bardow
中科院分区：
文献类型：
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作者：
Ludger Wolff;Pouria Zangi;Thorsten Brands;M. Rausch;H. Koß;A. Fröba;A. Bardow
提出了一种改进的Loschmidt池与干涉法相结合测量浓度依赖的二元扩散系数的实验装置和数据评估程序。我们克服了在文献中发现的关于集中度依赖的长期差异。通过对参数估计残差的系统分析，改进了实验装置，确定了相关的拟合参数。特别是，我们发现，考虑到(1)初始条件中的不确定性，(2)光学装置的热稳定性，以及(3)相机校准中的不确定性是至关重要的。改进的实验装置和数据评估程序通过氦-氪系统的扩散测量得到了验证。通过对不同初始组成的混合气体的多次实验，成功地确定了扩散系数的浓度依赖关系。与文献数据的一致性和良好的拟合质量允许对结果有很高的信心。在本论文的第二部分(Wolff等人，在Int J ThermPhys，2018年，https://doi.org/10.1007/s10765-018-2451-7)中，改进的测量设置与改进的扩散模型相结合，以从混合纯气体的单次测量确定依赖于浓度的扩散系数。
An improved experimental setup and data evaluation procedure are presented for a Loschmidt cell combined with interferometry to measure concentration-dependent binary diffusion coefficients. We overcome long-standing discrepancies about the concentration dependence found in the literature. The systematic analysis of the residuals from parameter estimation enabled the improvement of the experimental setup and the identification of relevant fitting parameters. In particular, we found that it is crucial to account for uncertainties (1) in the initial conditions, (2) in the thermal stability of the optical setup, and (3) in camera calibration. The improved experimental setup and data evaluation procedure are validated with diffusion measurements of the system helium–krypton. The concentration dependence of the diffusion coefficient is successfully determined from multiple experiments with gas mixtures of various initial compositions in the half-cells of the Loschmidt cell. The agreement with literature data and the excellent quality of fit allow for high confidence in the results. In Part II of this paper (Wolff et al., in Int J Thermophys, 2018, https://doi.org/10.1007/s10765-018-2451-7 ), the improved measurement setup is combined with a refined diffusion model to determine concentration-dependent diffusion coefficients from single measurements of mixing pure gases.