Experimental measurements and equation of state modeling of liquid densities for long-chain n-alkanes at pressures to 265 MPa and temperatures to 523 K

Experimental densities are reported for n-hexadecane, n-octadecane, and n-eicosane at pressures to ∼265 MPa and temperatures of 323.15, 423.15, and 523.15 K. The reported densities are in good agreement with the available literature data that cover limited pressure and temperature ranges. The Peng–Robinson equation of state (PR EOS), a new high-temperature high-pressure volume-translated Soave–Redlich–Kwong equation of state (HTHP-VT SRK EOS), and the perturbed-chain statistical associating fluid theory (PC-SAFT) are used to predict the reported densities. Both the HTHP-VT SRK and PC-SAFT equations exhibit mean absolute percent deviation (MAPD) values of 2.4–1.3% for the densities of all three hydrocarbons while the MAPD values for the PR EOS are all near 16%.

► A straightforward technique is used to measure hydrocarbon densities to ∼265 MPa and 523 K.
► A new VT-SRK and the PC-SAFT equations can accurately predict the reported densities.
► Both equations offer design tools for optimizing the processing of hydrocarbons.