Orthobaric liquid densities and excess volumes for binary mixtures of low molarmass alkanes and nitrogen between 105 and 140 K

Abstract

A magnetic suspension densimeter has been used to determine orthobaric liquid densities of gravimetrically prepared binary mixtures of the major components of liquefied natural gas (LNG) i.e. nitrogen, methane, ethane, propane, i-butane, and n-butane, generally between 105 and 140 K. All binary combinations were included in this study, with the exception of nitrogen + i-butane and nitrogen + n-butane. Uncertainties in the reported liquid-mixture densities are discussed in detail. Comparisons are made between excess volumes computed from the present results and comparable values from the literature. It was found that the volumetric properties of binary liquid mixtures of the heavy hydrocarbons (those mixtures not containing nitrogen or methane) are closely approximated by ideal mixing. Some observations are included on the use of excess volumes of the heavy hydrocarbon systems to determine effective molar volumes of n-butane in liquid mixtures below its triple-point temperature. For mixtures containing nitrogen or methane, approximate total vapor pressures are given.