Direct Measurement of the Fluid Phase Diagram

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• 作者：Bo Bao ; Jason Riordon ; Yi Xu ; Huawei Li ; David Sinton
• 刊名：Analytical Chemistry
• 出版年：2016
• 出版时间：July 19, 2016
• 年：2016
• 卷：88
• 期：14
• 页码：6986-6989
• 全文大小：318K
• 年卷期：0
• ISSN：1520-6882

文摘

The thermodynamic phase of a fluid (liquid, vapor or supercritical) is fundamental to all chemical processes, and the critical point is particularly important for supercritical chemical extraction. Conventional phase measurement methods require hours to obtain a single datum on the pressure and temperature diagram. Here, we present the direct measurement of the full pressure–temperature phase diagram, with 10 000 microwells. Orthogonal, linear, pressure and temperature gradients are obtained with 100 parallel microchannels (spanning the pressure range), each with 100 microwells (spanning the temperature range). The phase-mapping approach is demonstrated with both a pure substance (CO₂) and a mixture (95% CO₂ + 5% N₂). Liquid, vapor, and supercritical regions are clearly differentiated, and the critical pressure is measured at 1.2% error with respect to the NIST standard. This approach provides over 100-fold improvement in measurement speed over conventional methods.