Measurements and Modeling of Volumetric and Phase Behavior of Carbon Dioxide + Higher Alkanes: CO2 + n-Pentadecane at Temperatures 313 to 410 K and Pressures up to 77 MPa

Abstract

Experimental compressed liquid density and bubble pressure of {xCO2 + (1 – x)C15H32} are reported for x = 0.376, 0.562, and 0.757 at temperatures from 313, 363, and 410 K and pressures from bubble points up to about 77 MPa. Density was measured using a vibrating U-tube driven and scanned in frequency domain by a lock-in amplifier to accurately measure the resonance peak in complex form where density is determined with an expanded uncertainty of U(ρ) = 0.003ρ. The experimental measurements are compared with cubic equations of state of Redlich–Kwong–Soave (RKS), Peng–Robinson 1976 (PR76), and the improved version Peng–Robinson 1978 (PR78) with and without volume translation correction. PR78 EOS gives best predictions with an average deviation of 1.2%. The deviations are maximum near the bubble points and increase in a systematic manner with increasing CO2 mole fraction x. Bubble pressures were determined from the discontinuity of p–V plots completed during a series of isothermal constant composition expansi...