My scientific career, from the methodological point of view, has followed a continuous evolution. During my thesis, I was focused on the development, implementation and improvement of new measurement techniques for the density and viscosity at high pressure. Several experimental devices were used to study different lubricants and mixtures refrigerant–lubricant. Nevertheless, it is impossible to measure all the systems of interest in the whole range of temperature and pressure needed for their applicative use. This makes necessary the development and validation of theoretical models adapted to describe the properties studied experimentally. I was interested in the development and evalua...