An additivity of thermal conductivity coefficients in binary solutions of some liquids. Experiment

Аuthors

Boboshina S. B., S. , Poberegsky S. A., Cherepanov V. V.^*, Shirokova E. K.

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: vvcherepanov@yandex.ru

Abstract

The article presents the experimental study results at room temperature of the thermal con- ductivity coefficient of a number of organic liquids solutions taken in different volume shares. Liquids that can used as refrigerants/ heat carries in heat exchangers or other technical devices had been selected for the study. The studied solutions mixing were carried out taking into ac- count the Evell’s classification. Measurements were carried. Out by the Express diagnostics based on the heated thread method allowing to operate with small volumes of substances. In the experiments, there were used the original measuring device which combines the functions of a transmitter (a source of a heating pulse) and a receiver of a thermal signal carrying useful in- formation about the studied sample. The device contains the original bridge compensation scheme, the branches of which the measuring and compensation sensors are included. The im- plemented technique reduces the determination of the thermal conductivity coefficient to the measurement of the electrical resistance of the sensors and the bridge branches. For all the mix- tures considered, while at different concentrations of their initial components in the solution, the experimental values, taking into account the measurement error (up to 2%), coincided with the values calculated on the basis of the assumption of the additive nature of the thermal con- ductivity. This result is important from a practical point of view, because it greatly simplifies the thermal conductivity calculation of such solutions used in technique. Determining the de- gree of statistical reliability of the conclusion about the thermal conductivity additivity and the determination of the specific physical reasons for the effect obtained requires additional re- search. In particular, it was not possible to establish the relationship between the thermal con- ductivity additivity and the presence or absence of hydrogen bonds in molecules.

Keywords:

organic liquid, solution, thermal conductivity coefficient, measuring sensor, ad- ditivity, concentration.