Fundamental investigation of heat transfer mechanisms between a rolling sphere and a plate in OpenFOAM® for laminar flow regime

Abstract

The heat transfer between particles and walls has been topic of research for several decades. In most cases existing correlations were developed empirically for special conditions and applications like fluidized beds or rotary kilns. With a deeper fundamental understanding of the occurring heat transfer mechanisms both design of existing and development of innovative apparatuses, could be more straightforward since the mentioned existing correlations cannot be applied flawlessly to other conditions, due to specific simplifications and assumptions. The aim of this work is to investigate the fundamental heat transfer mechanisms between spherical particles rolling on a plate on the microscale with the lowest level of simplifications. For the identification of the dominating heat transfer mechanisms an approach with Computational Fluid Dynamics (CFD) simulations is chosen. The fundamental investigations are carried out using a basic geometry of a moving sphere on a plate. Due to the lack of a solver which is able to describe the system of a moving sphere on a plate, a new solver is developed in OpenFOAM®. The solver is validated against an existing model as well as own experimental results. Simulations in the laminar flow region show good agreement. Analogically to literature the main transport resistance is identified in the gap between plate and sphere. The heat conduction through the gas layer between sphere and plate is identified as the dominating mechanism.