(380ab) Conduction and Convection Heat Transfer in a Rotary Drum Using Simulations and Experiments
Granular material subjected to agitation is encountered in many practical applications of material processing. Furthermore, many of these applications also involve heat transfer whereby solids face cold or hot surfaces and heat is exchanged not only between individual particles but also between the particles and external surfaces via the particleâparticle, particleâwall, particle-fluid, and particle-environment contacts. This work focuses on understanding the conduction and convection heat transfer in the granular bed inside a rotary drum, one of the most commonly used process equipment. Experiments are performed using silica gel beads inside a 3-inch radius and 3-inch long stainless-steel rotary drum. One side of the drum is closed with a transparent quartz window, which can handle high temperatures. Another side of the drum is closed with a sapphire window, compatible with an IR camera, specifically chosen to give a high transmittance to the infrared light. The setup is designed to handle up to 1000 Â°C, making it possible to study all modes of heat transfer at a wide range of temperatures. The wall of the drum is maintained at a desired high temperature using heat guns placed around the drum. Heat transfer is quantified under varying operation conditions to establish a strong understanding of the heat transport. For this, both experiments and CFD-DEM simulation techniques are used to analyze the thermal behavior. Experiments are conducted to validate the CFD-DEM code in the first phase. In the second phase, the validated code is used to study the effect of rotation rate, fill level, particle size, and particle size distribution on the wall-particle bed heat transfer.