Steady-state measurements in a thermogravitational microcolumn using optical digital interferometry are presented here for the first time in the literature in the case of ternary mixtures. These measurements enabled the subsequent obtaining of thermodiffusion coefficients of a ternary mixture once convection reaches the steady-state. The ternary mixture used was the benchmark one, tetrahydronaphthalene (THN) – isobutylbenzene (IBB) and n-dodecane (nC12) with mass fraction of 0.8-0.1-0.1 respectively. Contrast factors due to the change in the concentration field were measured and compared with the corresponding ones in the literature. Uncertainty in the results was found to be of similar order of magnitude as in the case of Selectable Optical Diagnostic Instrument (SODI), which means that the condition number of that contrast factor matrix is almost equal to the present one. Final values of thermodiffusion coefficients were compared with the results reported from other optical techniques, as well as with the results obtained by the traditional long opaque thermogravitational columns (TGC). Some proposals were then made in order to improve accuracy reducing the condition number of the contrast factor matrix.

对于三元混合物，本文首次使用光学数字干涉仪在热引力微柱中进行稳态测量。一旦对流达到稳态，这些测量结果就可以随后获得三元混合物的热扩散系数。所用的三元混合物是基准化合物，质量分数为0.8-0.1-0.1的四氢萘（THN）-异丁苯（IBB）和正十二烷（nC12）。测量了由浓度场变化引起的对比因素，并将其与文献中的相应因素进行了比较。发现结果的不确定性与可选光学诊断仪（SODI）的数量级相似，这意味着该对比度因子矩阵的条件数几乎等于当前条件矩阵的条件数。将热扩散系数的最终值与其他光学技术报告的结果以及传统的不透明长热引力柱（TGC）获得的结果进行比较。然后提出了一些建议，以提高准确性，减少对比因子矩阵的条件数。