40 research outputs found
Density, Speed of Sound, and Viscosity Measurements of Reference Materials for Biofuels
Measurements of density, speed of sound, and viscosity
have been
carried out on liquid certified reference materials for biofuels as
a function of temperature at ambient pressure. The samples included
anhydrous and hydrated bioethanol and two biodiesel fuels from different
feedstocks, soy and animal fat. The ethanol samples were measured
from a maximum temperature of 60 to 5 °C (speed of sound) and
to −10 °C (density and viscosity), respectively. The biodiesel
samples were characterized from 100 °C (density and viscosity)
and from 70 °C (speed of sound) to 10 °C (animal fat-based)
and 5 °C (soy-based). Densities were measured with two vibrating-tube
instruments of different accuracy. The speeds of sound were measured
with a propagation-time method in an acoustic cell that was combined
with one of the densimeters. Viscosities were measured with an open
gravitational capillary viscometer and with a rotating concentric
cylinder viscometer, according to Stabinger. The measurement results
are reported with detailed uncertainty analyses
Measurement and Correlation of Densities and Dynamic Viscosities of Perfluoropolyether Oils
The
densities and dynamic viscosities of five different polydisperse
perfluoropolyethers (PFPE) were measured at atmospheric pressure over
the combined temperature range 263.15–373.15 K. For one PFPE
being considered as a high-temperature high-pressure viscosity standard
reference material, measurements were made on two separate samples
to examine the lot-to-lot variability in density and viscosity; significant
variability was observed only for the viscosity data. Experimental
data were correlated as a function of temperature. A simple quadratic
equation was used for density, while three equations (DIPPR, VFT,
and Waterman) were applied to the viscosity data. The DIPPR equation
represented the viscosity data with deviations approximately an order
of magnitude lower than the other two equations