ac6b01725_si_002.avi (14.09 MB)
Direct Measurement of the Fluid Phase Diagram
media
posted on 2016-06-22, 00:00 authored by Bo Bao, Jason Riordon, Yi Xu, Huawei Li, David SintonThe 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.