Observation of critical behaviors and Determination of critical points of (H2O - (CO2) - NaCl) systems by spectroscopic measurement

Abstract

Spectroscopic measurements in the range from 400 nm to 890 nm for pure H₂O, CO₂, C₂H₅OH and NaCl aqueous solution under high temperatures and pressures were carried out to observe critical phenomena by using visible-type autoclave. Intensity of transmitted light through the fluid became low drastically around the critical point in each fluid. The minimum intensity of transmitted light was corresponded to critical temperature and pressure of each fluid. Experimentally determined critical temperatures and pressures well coincided to reference data and it is possible to evaluate critical temperature and pressure of multicomponent geofluids by using spectroscopic measurement under hydrothermal conditions.