Density measurements of seven methane-rich binary mixtures over the temperature range from (100 to 180) K at pressures up to 9.7 MPa

Density Measurements of (0.99 Methane + 0.01 Butane) and (0.98 Methane + 0.02 Isopentane) over the Temperature Range from (100 to 160) K at Pressures up to 10.8 MPa

“…Filling the densimeter and the basic procedure of running the apparatus were described exhaustively by Richter et al [11]. This procedure was already used for our previous density measurements on synthetic LNG mixtures and methanerich binary mixtures [5,11,12]. In the present work, this established procedure was applied for the density measurements on the (0.989 955 methane + 0.010 045 butane) mixture.…”

“…The design of the cryogenic densimeter, the temperature and pressure measurement and the implementation of a special "VLE-cell" as a novel feature were described in detail previously [9][10][11]. In our latest paper [5], we presented some improvements of the core apparatus to reduce diffusion effects and the force-transmission error (FTE) [22,23]. Here, for the convenience of the readers of the present data paper, we summarize the description of the apparatus presented by Richter et al [11].…”

“…where u( ) , u(T) and u(p) are the standard uncertainties in density, temperature and pressure, respectively; u( (x)) corresponds to the standard uncertainty in the density resulting from the uncertainty of the gas composition; u repro accounts for an additional uncertainty from the reproducibility of our measurements; and u corr takes into account the uncertainty of the correction of the force-transmission error. Detailed description of the uncertainty analysis was given in previous works [5,11,12]. The expanded combined uncertainty in measurement was determined for each measured state point.…”

“…Stateof-the-art online density measurements would result in larger uncertainties in the calculated energy quantity compared to well-established equations of state (EOS) or correlation equations that are commonly used to calculate the density through online measurements of temperature, pressure and LNG composition as input variables. In our previous paper [5], we presented density data for seven binary methane-rich mixtures, including (methane + isobutane) and (methane + pentane) mixtures that were used for the development of a new fundamental equation of state for liquefied natural gases (EOS-LNG) by Thol et al [6] in 2019. The EOS-LNG is based on the GERG-2008 equation of state by Kunz and Wagner [7], which was adopted as an ISO-standard for the calculation of thermodynamic properties of natural gas [8].…”

“…Such measurements of binary mixtures, in particular in the homogeneous liquid and the supercritical region, at low temperatures and over a wide pressure range are unique thus far. To the best of our knowledge, measurements like reported here have not been carried out elsewhere before as already discussed in our earlier work [5,[9][10][11][12]; other authors only measured data for saturated-liquid densities of binary mixtures and LNG-like mixtures [13][14][15][16][17][18][19][20][21] but not in the homogeneous liquid region below the cricondenbar pressure. For the presented two mixtures, however, no measurements of saturated-liquid densities could be found in literature.…”