Determination of the Viscosity of a Multiphase Medium Using the Theory of Similarity and the Theory of the Regular Thermal Regime

Abstract

The properties of each liquid can be characterized by a whole complex of various physical quantities: values of density, viscosity, electrical conductivity, heat capacity, surface tension, etc. At the current stage of technological development, the measurement of liquid viscosity is an urgent task in various areas of human life: automotive, oil and gas, aviation, food, medical and a number of other industries. Viscosity (internal friction) is the property of fluid bodies (liquids and gases) to resist the movement of one of their parts relative to another. Viscosity is a non-constant value and changes depending on the temperature of the liquid medium, the presence of impurities in its composition, and the value of the resource. It can be kinematic, dynamic, conditional and specific. However, indicators of kinematic or dynamic viscosity are most often used. The experimental results of viscosity determination were obtained on the stand, which is a component of the experimental and calculation method. The main elements of the experimental setup are two working cavities - external and internal. Criterion equations in the first and second approximation, consisting of similarity criteria, namely the Reynolds criterion and the Prandtl criterion, were developed to describe the heat transfer to three-phase media. Viscosity was determined in the first approximation using the criterion equation for "model liquids", and in the second approximation using the criterion equation obtained jointly for "model liquids" and the substrate. The difference between the viscosity found in the two approximations is up to ±30...40%. Key words: regular thermal mode, biogas, substrate, biogas installation, thermal stabilization, thermophysical properties, experimental and calculation method, mathematical model.