Liquid density measurement of n-decane with a random temperature signal cross-correlation densimeter at high temperatures and pressures

A novel densimeter based on a random temperature signal cross-correlation method was designed and constructed. Liquid densities of n -decane were measured at T  = (293.2–493.5) K and p  = (0.1–20.0) MPa. The expanded uncertainties in liquid density measurements are 1.16%, with a confidence level of 0.95 ( k  = 2). This experimental study provides new n -decane densities to examine Lemmon's equations' accuracy at high temperatures and pressures, where few experimental densities are yet to be reported. The experimental data's average absolute deviation ( AAD ) and maximum absolute deviation ( MAD ) compared to the fitted data from Lemmon's equations are 0.15% and 0.43%, respectively. The liquid densities at high temperatures and pressures were fitted with a Tait-type equation. The physical meaning and temperature behavior of the Tait correlation's parameters were discussed. The average absolute deviation ( AAD ) between the experimental and calculated data from the Tait-type equation is 0.23%.