EXPERIMENTAL SETUP FOR MEASURING THERMAL CONDUCTIVITY OF LIQUIDS AND SOLUTIONS AT DIFFERENT PRESSURES AND TEMPERATURES

The results of experimental studies of the thermal conductivity of single-walled carbon nanotubes and their mixtures in technical solutions are presented. The experimental setup was used to measure the thermal conductivity of liquid diethyl ether both in pure form and with the addition of various carbon nanoparticles (SWCNT), with the addition of SWCNT and water, depending on the temperature T = (293–673) K at P = (0.101–49.01) MPa with the addition of 0 to 0.5% (with an interval of 0.05%) nanoparticles. The results of the study showed that the thermal conductivity of the samples decreases with increasing temperature, and increases with increasing pressure. For the sample "diethyl ether + 0.4% SWCNT" at room temperature 298 K and pressure change to 49.01 MPa, the thermal conductivity increases by 14.6%, and for this sample at a temperature of 672 K, this change reaches 16.5%. The addition of 0.5% SWCNT leads to an increase in the thermal conductivity of diethyl ether (P = 0.101 MPa and T = 293 K) by 19.9%, and at P = 14.01 MPa and T = 293 K, the thermal conductivity increases by 18.4%. Calculations showed that the maximum total relative error of the experimental data on thermal conductivity at a confidence level α = 0.95 does not exceed 4.2%. Methods for measuring thermal conductivity are divided into two groups. The first group includes methods based on the regularities of a stationary thermal regime. These methods are based on the Fourier hypothesis about the proportionality of the heat flow to the temperature gradient. The second group of methods is based on the regularities of a non-stationary thermal regime, in which the body temperature is a function of not only coordinates but also time.