Thermophysical testing of flow behaviors of composite liquid media
Keywords
Abstract
The method of thermophysical testing of complex liquid media is proposed to assess the nature of their behavior (Newtonian or Non-Newtonian) in conditions close to real heat engineering processes. The experimental results of the interconnection of the equivalents of effective viscosity and shear rate in complex mixtures under complex thermodynamic conditions are analyzed.
The expediency of the proposed method of thermophysical testing of the handling of complex liquid media used in heat technology equipment for the processing of agricultural products, as well as for the utilization of animal waste by fermentation with the production of biogas and fertilizers, is substantiated.
The analysis of the existing literary information on the determination of rheological properties of viscous fluid media, the thermophysical and rheological characteristics of which have not been studied or studied in part. Viscometric and rheometric methods of testing complex liquids are considered. In nonisothermal viscometry, we try to exclude the effect of self-heating on the indicators that are determined or to use this effect to determine the rheological parameters, depending on the temperature. Using the results of rotational viscometry, introducing significant simplifications, mathematical models of thermal and hydrodynamic calculations are created. For hydraulic calculations, this approach is acceptable unlike thermal. To estimate the coefficient of heat transfer to a complex poly-component multiphase liquid medium, it is necessary to first identify its behavior — characteristic of Newtonian fluid or structured non-Newtonian.
It is shown the expediency of combining viscosimetric and rheometric methods with thermophysical methods for evaluation of liquid media behavior. The method can be regarded as a possible alternative to rotary viscometry, since it takes into account the shear stresses and gradients of shear rates that arise from the joint effect of temperature difference and mechanical perturbation in the medium. The use of this method in conditions close to the actual technological can accelerate the introduction of the results of traditional studies of non-Newtonian fluids into engineering practice
