High-Pressure Viscosity of Soybean-Oil-Based Biodiesel Blends with Ultra-Low-Sulfur Diesel Fuel

Abstract

Current and future injector designs for diesel engines approach pressures of greater than 100 MPa. However, the high-pressure physical properties, such as viscosity, of biodiesel blends with diesel fuel are nearly absent in the literature. This study focuses on the viscosity of biodiesel, diesel, and several biodiesel blends from 283.15 to 373.15 K and pressures up to 131 MPa. Soybean biodiesel (B100) and ultra-low-sulfur diesel (ULSD, B0) were combined to form biodiesel/diesel blends: B5, B10, B20, B40, B60, and B80. The viscosity of the samples increases linearly with the pressure until approximately 35 MPa, followed by a higher order response to pressure. The biodiesel blends with low biodiesel content (B5, B10, and B20) had very similar viscosities to ULSD. The normalized viscosity increased with a decreasing temperature and a decreasing biodiesel blend fraction. The viscosity of the various blends increased above the ambient pressure viscosity ranging from 164% at 373.15 K to 547% at 283.15 K at the highest pressure of 131 MPa. The biodiesel and some biodiesel blend samples at 283.15 K experienced pressure-induced cloud points (solid–liquid equilibrium) from 70 to 131 MPa. The Tait–Litovitz equation was found to correlate the biodiesel and diesel data with an absolute average relative deviation (AARD) of less than 1% over the large range of both temperature and pressure, and Kay’s mixing rule predicted the viscosity of the biodiesel blends with an AARD of 1.75%.

Density and Viscosity Measurement of Diesel Fuels at Combined High Pressure and Elevated Temperature

“…Equations such as the Tait equation are useful and reliable but rely of the evaluation of many constants. More simple models have been developed, with some success, which require a single constant [4,5]. Certainly, the reliability and accuracy of experimental data from the high-pressure viscometer and micro-pVT instruments are imperative if the data is to be meaningful for design, operational, and fiscal purposes.…”

“…Understanding of the behavior of these hydrocarbon fuels is therefore crucial [3]. While there are reports on the measurement and prediction of diesel properties at ambient or high temperature conditions, comparatively little work has been reported at high pressure and temperature [4,5]. Temperature effects on the dynamic viscosity and density of hydrocarbon and petroleum distillation cuts at high pressure are well known as is the phenomenon of pressure-freezing [6].…”

Investigating the compression ignition combustion of multiple biodiesel/ULSD (ultra-low sulfur diesel) blends via common-rail injection

“…Of note, there is a strong inverse relationship between biodiesel blend percentage and energy content, as expected due to the increasing oxygen content in the mixture with additional biodiesel [2,3,22,25]. The initially measured viscosity values for intermediate jatropha biodiesel blends appeared to be inconsistent, particularly when compared with concurrent high-pressure viscosity measurements of this fuel performed elsewhere [34], and were replaced with weighted-average values in Table 3 [34]. Similarly, reliable measurements for energy content of the intermediate soybean biodiesel blends were not obtained, but weighted averaged values from neat soybean biodiesel and ULSD are included in Table 4 for comparative purposes.…”

An Experimental Study on the Performance Characteristics of a Diesel Engine Fueled with ULSD-Biodiesel Blends

“…Furthermore, an improvement in fuel injection characteristics such as the penetration length and cone angle of the spraying was confirmed in the study ) which has performed simulate the use of ultrasonic energy for blending ULSD and BO fuels. Furthermore, (Duncan et al (2012)) studied a biofuel blending system of crude palm oil and free fatty acids by combining a mixer and intense ultrasonic waves. With power output up to 1000W and continuous operation at 18kHz in a 100ml mixer.…”

“…(Pham et al 2018) conducted experimental studies by examining liquid flow at low temperature, cold filter plugging point and the cloud point of 7 different biofuels blending with ULSD to provide data on the liquid-cooled flow of ULSD used in diesel engines. Andrew M. Duncan (Duncan 2012) predicted that after blending ULSD with Biodiesel at the rates of 5, 10, 20, 40, 80%, the viscosity of the fuel achieved optimal results with the ratio of 5, 10 and 20% biodiesel. The viscosity of the different blends increased by about 164% at ambient pressure and 373.15K and 547% at 283.15K and the highest pressure (131Mpa).…”