(633g) Quantitative analysis of heat transfer in a rotary drum

Heat transfer in granular processing and handling is commonly encountered in material manufacturing. Granular processing consumes roughly ten percent of the world’s energy [1]. Approximately 1–3% of the world's energy is utilized in cement industries alone [2]. Since most of these processes are energy-intensive, the handling of granular materials is tightly connected to a high-energy demand. The flow properties of granules alone are governed by their intrinsic material properties (e.g., cohesion, the coefficient of friction and yield stress) and particle properties (e.g., size distribution, morphology, porosity, and roughness), which makes predicting the heat transfer behavior of dynamic granular processes even more complex. Over the last five decades, there has been a continued interest in understanding the role of system parameters and the mechanisms of heat transfer between granular media and the boundary surfaces. The thermal behavior of the granules may change dramatically during processing, introducing variability into the process and affecting final product quality and characteristics. It is, therefore, important to understand the heat transfer mechanism in process specific granular systems.

This work focuses on understanding the heat transfer mechanism in the granular bed inside a rotary drum, one of the most commonly used process equipment. Experiments are performed using silica particles to investigate the granular flow and heat transfer mechanism inside a stainless-steel rotary drum. All the modes of heat transfer are quantified under varying operation conditions to establish a strong understanding of the heat transport. For this, both experiments and CFD-DEM (using MFIX-DEM, an open source multi-solver suite) simulation techniques are used to analyze the thermal behavior. The experimental setup is designed to handle up to 1000⁰C, making it possible to study all modes of heat transfer via conduction, convection, and radiation. Omega thermocouples and a mid-wave infrared (MWIR) camera were used to record the temperature profile. The digital image analysis (DIA) and the particle image velocimetry (PIV) are combined with IR thermography (DIA/PIV/IR technique [3]) to obtain combined quantitative hydrodynamic and thermal data sets.

Reference:

• Duran, Jacques. "Introduction."Sands, Powders, and Grains. Springer New York, 2000. 1-18.
• Engin, T., Ari, V., 2005. Energy auditing and recovery for dry type cement rotary kiln systems – a case study. Energy Convers. Manag. 46, 551–562.
• Patil, A. V, Peters, E. A. J. F., Sutkar, V. S., Deen, N. G., & Kuipers, J. A. M. (2015). A study of heat transfer in fluidized beds using an integrated DIA / PIV / IR technique. Chemical Engineering Journal, 259, 90–106.