Deposition of colloidal particles in a microchannel at elevated temperatures

Abstract

This work reports an experimental study of the thermal effect on the deposition of microparticles onto a solid surface in a microfluidic system, which allows a precise control of the solution temperature and enables the real-time monitoring of the deposition kinetics at the increased temperature. The static particle deposition rate (Sherwood number) has been measured over a range of temperatures between 20 and 70 °C. It is found that the Sherwood number is monotonically increased up to 265 %, with the solution temperature within the test range. A model including the Derjaguin–Landau–Verwey–Overbeek theory-based colloidal surface forces and gravity force is employed, taking into account temperature effects, to qualitatively interpret the experimental findings. The model shows that, by increasing the solution temperature, the attraction energy (van der Waals force) between the particles and the solid surface is increased while the repulsive energy (electric double layer force) is decreased. These findings demonstrate the importance of thermal effects in various thermally driven deposition processes, such as the fouling of bacteria and milk proteins in microscale milk pasteurization units.