Brillouin scattering study of equation of state of multicomponent liquids: Model oil samples

Abstract

Brillouin scattering technique has been used to measure the pressure dependence of sound velocity vs(P) in model oil samples (each containing 5-hydrocarbon liquids) at room temperature T=201 °C. Experimental results are reported on two blends of model oil, each containing a mixture of n-heptane, n-tetradecane, cyclo-hexane, benzene, and toluene in different volume fractions. The compositions of these two differed in their cyclohexane and toluene contents. The pressure dependence of vs(P) has been measured up to 815 bars and the results could be least-square fitted to vs(P)=A0+A1P+A2P2 within the limits of experimental error (±1%). The modified Tait’s equation and linear pressure dependence of bulk modulii have been used in consistence with an earlier work to interpret the parabolic pressure dependence of vs(P). This yields the values of Tait parameters (B and C) and hence allows the explicit pressure dependence of density and compressibility of these multicomponent liquids to be evaluated.