Derivation of van der Waals Type Liquid Density Equation and Estimation of High Pressure Density of Lubricants

Abstract

In this study, I investigated the relationship between the high pressure density of lubricant and pressure and temperature. As a result, the van der Waals type liquid density equation was derived consisting of three material-specific constants: absolute zero density ρ_t=0[g/cm³], density constant 1/E[(g/cm³)GPa/K] and pressure constant F/E[GPa]. It was found that the absolute zero density ρ_t=0 and the pressure constant F/E in the liquid density equation are equivalent to the inverse of the absolute zero specific volume V_t=0 [cm³/g] and the corrected pressure P_R for pressure drop due to the intermolecular force in the van der Waals type liquid state equation. This equation also agrees with the ideal liquid model density equation. This made it possible to estimate the high pressure density of lubricant.