Chapter 2 - Experimental methods, apparatuses and results of experimental measurements of the thermodynamic properties

Abstract

This chapter briefly describes the methodology for estimating the errors in the results of an experimental study. It presents the designs of experimental setups for the study of density, saturated vapor pressure, melting line, isobaric heat capacity, and surface tension developed in the Industrial Thermophysical Laboratory, and also describes the experimental methods and test results. At these setups, studies of the thermodynamic properties of hydrocarbons are carried out in the temperature range from the melting point to ~700K at pressures up to 100 MPa, including phase transition lines and the critical region. The results of experimental study of p, v, T-, and Cp, p, T-dependences, surface tension of hydrocarbons, and primary processing of experimental data are discussed. Methodological issues and results of developing the Tate equation for describing the density of the liquid phase, thermal multi-constant equations of state common for liquid and gas phases, and determining virial coefficients are also considered. A brief review and results of empirical and semi-empirical methods for calculating the isobaric heat capacity of hydrocarbons are presented. Experimental setups and methods for measuring the isochoric heat capacity and the speed of sound are described, with the help of which the corresponding experimental data were obtained in other laboratories in a wide range of parameters and which were used by the authors to develop the fundamental equations of state.