Francisco Fidelis Kisuka

[Display omitted] •Friction-induced heat generation and heat transfer models are developed.•Thermal behaviours of particles and walls are experimentally and numerically analysed.•Effects of rotation speed on temperature rises on both particles and walls are examined. In many granular material handling processes, heat generation, and subsequent temperature rise, due to contacts between particles and surfaces is common. Aiming to explore this phenomenon, friction-induced heat generation and heat transfer models are developed and implemented into a Discrete Element Method (DEM) in this paper. The DEM models are validated qualitatively for the temperature distribution pattern and quantitatively for the evolution of particle temperature rise using data obtained experimentally. Moreover, the temperature distribution of the drum end plates obtained in the simulations shows the same annulus pattern observed in experiments. It is also found that increasing the rotation speed of the drum leads to an increase in the annular heated region of drum and in the net heat that particles obtain. In addition, a higher rotation speed leads to higher absolute fluctuations and lower relative variability of particle temperature.

Granular flows are characterised by particle interactions that involve sliding and collisions. In such events, heat is generated from friction and plastic deformation. Despite the importance of such self-heating mechanisms, our understanding of the fundamental principles of heat generation from friction and plastic dissipation is still limited. This work explores this problem at the particle level for oblique impacts between a spherical particle and a rigid substrate. In the first part, theoretical models and a finite element method (FEM) model are used to predict the amount of heat generated and contact temperatures at various impact angles. The theoretical and the FEM models are in good agreement for all impact cases considered. A parametric study of the influence on heat generation and temperature distributions is also carried out. It is shown that the temperature profiles are dependent not only on the amount of the generated heat but also on the material's thermal properties, such as thermal conductivity and specific head capacity. Apart from a good insight into heat generation during oblique impacts, this study also identifies simple theoretical solutions that can be used in other numerical tools, such as discrete element methods, for studying heat generation problems in bulk granular flows.