Thermophysical Properties of IoNanofluids Composed of 1-ethyl-3-methylimidazolium Thiocyanate and Carboxyl-functionalized Long Multi-walled Carbon Nanotubes

The concept of IoNanofluids (INFs) as the stable dispersions of nanoparticles in ionic liquids was proposed in 2009 by Nieto de Castro’s group. INFs characterize exciting properties such as improved thermal conductivity, non-volatility, and non-flammability. This work is a continuation of our studies on the morphology and physicochemistry of carbon-based nanomaterials affecting thermal conductivity, viscosity, and density of INFs. We focus on the characterization of dispersions composed of long carboxylic group-functionalized multi-walled carbon nanotubes and 1-ethyl-3-methylimidazolium thiocyanate. The thermal conductivity of INFs was measured using KD2 Pro Thermal Properties Analyzer (Decagon Devices Inc., Pullman, WA, USA). The viscosity was investigated using rotary viscometer LV DV-II+Pro (Brookfield Engineering, Middleboro, MA, USA). The density of INFs was measured using a vibrating tube densimeter Anton Paar DMA 5000 (Graz, Austria). The maximum thermal conductivity enhancement of 22% was observed for INF composed of 1 wt% long carboxylic group-functionalized multi-walled carbon nanotubes.

Calibration Fluids and Calibration Equations: How Choices May Affect the Results of Density Measurements Made with U-Tube Densimeters

Data on the calibration fluids water and toluene individually, and the combination of those two sets of data, were correlated with two different equations (resulting in six sets of calibration equation parameters) to analyze data measured with a vibrating-tube densimeter on the lubricants pentaerythritol tetrapentanoate (POE5), pentaerythritol tetraheptanoate (POE7), and pentaerythritol tetranonanoate (POE9) at temperatures from 270 K to 470 K and pressures from 0.5 MPa to 50 MPa. The objective was to explore how the calculated densities of the lubricants would differ based on the calibration equations and calibration fluid(s). The viscosities of the measured lubricants are much greater than those of the calibration fluids, and because there has long been a question of how measurements of higher viscosity fluids are affected when measured with a vibrating-tube densimeter, combinations of calibration fluid(s) and equations were tested to explore the role they play in obtaining accurate results. For the lubricants studied herein, more accurate results were obtained with a calibration fitted to multiple calibration fluids, while the consistency of results was more equation dependent.

Investigation of the thermodynamic properties of the binary system vitamin K3/carbon dioxide

The binary system of vitamin K3 and CO2 was investigated at temperatures of 40, 60 and 80 ?C up to a pressure of 40 MPa. Solubility was measured by a static-analytic method. Partial molar volumes were determined by a method involving a vibrating tube densimeter. The solubility of vitamin K3 in CO2 is found as a function of pressure and temperature. The highest solubility (31.16?10-4 mol?mol-1) was attained at a pressure of 25.40 MPa at temperature of 40?C. However, at temperature of 60?C and a pressure of 24.02 MPa, the solubility was 18.79?10-4 mol?mol-1. Solubility was lower at a temperature of 80?C and a pressure of 22.06 MPa (6.48?10-4 mol?mol-1). The partial molar volumes are negative and the dissolved vitamin K3 has a minor impact on the density of the solution of K3 in CO2 compared to the density of the pure CO2.