Numerical and experimental study of the glass-transition temperature of a non-Newtonian fluid in a dynamic scraped surface heat exchanger

Dynamic scraped surface heat exchangers (DSSHE) use a rotor shaft assembly with scraping blades to homogenize viscous fluids during the heat transfer process. Due to the continuous shaft rotating periods, in-situ measurements to provide a basis for empirical studies inside the chamber are constrained. Alternatively, theoretical studies implemented on Computational fluid dynamics (CFD) simulations found in literature provide useful information about the flow behavior around the scraper blades for a variety of fluids, rotor speeds, and blade geometries at different temperatures. However, computational approaches often focus on the fluid dynamics and heat transfer phenomena of Taylor-Couette flows while ignoring the glass-transition temperature and freezing point depression of the fluid. The goal of this research was to investigate and validate through experiments the turbulent multi-phase fluid dynamics and freezing point depression of a multi-phase flow inside a DSSHE with non-isothermal conditions. Results show that the freezing point depression is significantly affected by the viscous and inertial forces present in the flow. Pressure and temperature values were measured experimentally in-situ to validate the CFD simulation and supported with optical microscopy. The numerical solution shows quantitative agreement with experimental values and Non-dimensional correlations were computed to describe the flow behavior. (C) 2020 Elsevier Ltd. All rights reserved.