Comprehensive studies of the physical and thermophysical properties of wort

Abstract

The study is devoted to the study of physical and thermophysical properties of hoped, filtered beer wort in order to obtain graphical and mathematical relationships to calculate the numerical values of density, thermal conductivity and thermal conductivity coefficients, as well as the study of rheological properties. This will allow specialists in various fields related to heat and mass exchange processes to apply a science-based approach in hydraulic and thermal calculations when designing modern designs of heat and mass exchange apparatuses and technological pipelines connecting them. The study of physical properties, particularly rheological properties, was carried out in the temperature range from 283 to 343 K, density and thermophysical properties – from 293 to 353 K. Dry matter content varied from 10.2 to 72.4% dry wt. Density of the solutions was determined using an electronic Excellence D4 Mettler Toledo density meter. The mathematical dependence suggested for its calculation is linear and depends on temperature and dry matter content. Rheological tests were carried out for high-solids solutions with the Rheotest RN 4.1 Rotary Viscometer and for low-viscosity solutions with the Geppler Falling-Ball Viscometer HÖPPLER® KF 3.2. In studies on the rotary viscometer the shear rate gradient varied from 1 to 500 s−1. It was found that at shear rates up to 50 s−1 the solutions exhibit pseudoplastic properties and above Newtonian properties. Thermal conductivity and thermal diffusivity were measured using a Hot Disk TPS 2500S analyzer based on the unsteady plane heat source method. The results of the study are recommended to be used for calculation of density, heat conductivity and diffusivity that will allow further calculation of the specific heat capacity according to the known equation, solving technological problems of the brewing industry, and the data on rheology can be used in the calculation practice.

Keywords

• wort
• density
• momentum transfer
• dynamic viscosity
• temperature conductivity
• thermal conductivity