Critical parameters for isobutane determined by the image analysis

Abstract

p, q, T) Measurements and visual observations of the meniscus for isobutane were carried out carefully in the critical region over the range of temperatures: À15 mK 6 (T À T c ) 6 35 mK, and of densities: À7.5 kg AE m À3 6 (q À q c ) 6 7.5 kg AE m À3 by a metal-bellows volumometer with an optical cell. Vapor pressures were also measured at T = (310, 405, 406, 407, and 407.5) K. The critical point of T c and q c was determined by the image analysis of the critical opalescence which is proposed in this study. The critical pressure p c was determined to be the pressure measurement at the critical point. Comparisons of the critical parameters with values given in the literature are presented.

Saturated liquid densities of propane at T = (280 to 365) K

“…, Reamer et al [9]; +, Helgeson and Sage [10]; ·, Sliwinski [11]; À, McClune [5]; r, Haynes and Hiza [6]; m, Orrit and Laupretre [7]; j, Ely and Kobayashi [8]; h, Thomas and Harrison [12]; s, this work; n, Glos et al [13]; }, Kayukawa et al [14]; Á Á Á, Younglove and Ely model [19]; -, Miyamoto and Watanabe model [4]; --, Span and Wagner model [20]. where [18]. Throughout the fitting of the present correlation, we adopted our data above 280 K, and reliable data by Orrit and Laupretre [7] below 244 K as input data.…”

Measurements of saturated-liquid densities for isobutane at T=(280 to 407)K

“…In this correlation, x = 1 À T/T C , where T C denotes the critical temperature, 407.885 K and q C is the critical density, 227.5 kg Á m À3 determined by Masui et al [22] with same isobutane sample as that for this study. They determined the critical pressure, density, and temperature by visual observation of the meniscus disappearance by means of other apparatus of our group.…”

Viscosity and density of isobutane measured in wide ranges of temperature and pressure including the near‐critical region

“…Then, the deviations increase with decreasing density up to −2.46% at . Similar differences appear for the saturated liquid, the largest with −3.18% at for 407 K. Masui et al, from the same working group, performed pρT measurements between 405 and 410 K in the compressed gas phase and in the supercritical fluid. The results of this dataset, labeled below as the second one from this work, are regrettably distinguished by greater uncertainties at subcritical temperatures.…”