Experimental measurement and modeling of high-pressure density of n-alkanols (C4–C7) up to 200 MPa

High-pressure density data of n -alkanols are essential for the design of biodiesel blended fuels and fuel injection in marine engines. However, reliable experimental data for n -alkanols (C4–C7) under high pressures (up to 200 MPa) remain scarce. In this study, a high-pressure density measurement system based on the variable-volume method was established, achieving a combined expanded uncertainty of 0.27% ( k = 2). The densities of n -alkanols (C4–C7) were measured over the temperature range of 303.15–383.15 K and pressures up to 200 MPa. The measured data were accurately correlated using the Tammann-Tait equation, and the derived thermodynamic properties were obtained. Then, the parameters of the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS) for n -alkanols were optimized using the 2B association scheme. Within the experimental range, the average absolute relative deviation (AARD) between the calculated and experimental densities was <0.1%, demonstrating the applicability of the model for ultra-high-pressure volumetric calculations. This study addresses the gap in high-pressure property data for n -alkanols (C4–C7) and provides a critical experimental and modeling foundation for the development of efficient and clean marine power systems. Download: Download high-res image (351KB) Download: Download full-size image