Effect of Composition, Temperature, and Pressure on the Viscosities and Densities of Three Diesel Fuels

Abstract

In this work, a Rolling-Ball Viscometer/Densimeter is used to measure high-pressure, hightemperature (HPHT) density and viscosity data from 298.2 to 532.6 K and pressures up to 300.0 MPa for three different diesel fuels. The densities and viscosities have combined expanded uncertainties of 0.6% and 2.5%, respectively, with a coverage factor, k = 2. Two of the diesels, Highly Paraffinic (HPF) and Highly Aromatic (HAR), contain a larger paraffinic and aromatic content relative to the others, and are standard engine test fuels. The third is a Ultra-Low Sulfur Diesel (ULSD) that resembles an unfinished commercial diesel. Detailed compositional information is also reported for each diesel that provides a basis for interpreting the impact of composition on density and viscosity at high pressures. Both density and viscosity data are correlated to Tait-type equations with uncertainties of 0.6% and 4.0%, respectively. The Tait equations provide a facile means to compare observed differences in the density-pressure and viscosity-pressure profiles of the three different diesels. Density data are modeled with the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS) with pure component parameters calculated representing diesel as a single, pseudo-component only requiring average molecular weight (Mave) and hydrogen to carbon ratio (RH/C) as inputs. Viscosity data are modeled reasonably well using entropy scaling coupled with the PC-SAFT EoS and information on the diesel Mave and RH/C. The HPHT viscosity data are also modeled reasonably well with Free Volume Theory (FVT) with model parameters correlated to Mave and RH/C.

Experimental and modeling investigations of the phase behavior and densities of diesel + nitrogen mixtures

“…It is interesting that the best-fit kij values for each GC method have opposite signs and different absolute values, which is a direct reflection of the impact of the very different pseudo-component parameters calculated with each GC method. The kij values found with the S-GC method are similar to those reported for PC-SAFT phase behavior calculations for hexadecane + N2 20,31 and heptamethylnonane + N2 mixtures 29 .…”

“…Table 1 lists the hydrogen to carbon ratio, RH/C and average molecular weight, Mave, for the fuels used in this study as determined from gas chromatography analysis results 18,19 (Triton Analytical Corporation). Table 2 provides information on the amount of n-paraffins, i-paraffins, saturated cyclics, aromatics, naphthoaromatics, and heteroatoms found in the three diesels, with further details given elsewhere 20 .…”

“…Finally, the parameters C, a0, a1, a2, b0, b1, and b2 are refit simultaneously to all of the mixture density, isothermal isopleths by minimizing ΔAAD and constraining Δbias to zero. The SI provides tables listing the parameters used with equations 4 to 6 for all three diesel + N2 systems at each mixture composition where parameters for neat diesel are from our previous study 20 . With this calculation scheme the ΔAAD is less than 0.4% and the ΔMAX varies from 0.3 to 1.5% at temperatures from 298 to 534 K and pressures from each respective BP to 165 MPa although the Tait equation, with appropriate parameters, is valid up to 300 MPa for the densities of the neat diesels.…”

Transient Cavitation and Friction-Induced Heating Effects of Diesel Fuel during the Needle Valve Early Opening Stages for Discharge Pressures up to 450 MPa

“…Furthermore, these works utilized the fuel properties from [31] and did not consider the link between cavitation and induced erosion. Recently, new experiments on the properties of diesel fuel at elevated pressures and temperatures have been performed, allowing for the development and calibration of perturbed chain statistical associating fluid theory (PC-SAFT) EoS, as reported by the authors in [32][33][34][35][36][37][38][39]. Another study accurately predicted the thermal conductivity of fuels at high temperature and 450-MPa pressure conditions using entropy scaling [34].…”

“…The aim of the current work is to address these phenomena and to simulate the flow inside a highpressure diesel injector discharging at 180 MPa, 350 MPa, and 450 MPa of pressure. For this purpose, the explicit, density-based flow solver reported in [59] has been implemented in OpenFOAM and has been coupled with the tabulated fuel property data derived from PC-SAFT EoS, as documented in [34][35][36][37][38][39][40][41]. All of the phases are represented by the HEM approach; the cavitation model is based on a thermodynamic multiphase equilibrium assumption.…”