In the quest to optimize energy systems, a recent study published in the journal *Nature Scientific Reports* has shed light on the often-overlooked role of particle shape and size in the flowability of bauxite, a critical material in concentrated solar power (CSP) applications. The research, led by Aidana Boribayeva of the Chemical and Materials Engineering Department at Nazarbayev University, offers a nuanced understanding of how granular materials behave, with significant implications for industrial efficiency and energy storage.
Bauxite, a primary source of aluminum, is also a key component in moving bed heat exchangers (MBHEs) used in CSP systems. These systems rely on the efficient flow of bauxite particles to store and transfer thermal energy. However, the flowability of these particles can vary greatly depending on their shape and size, a factor that has not been thoroughly explored until now.
Boribayeva and her team conducted a series of experiments and simulations to investigate this phenomenon. They found that non-spherical bauxite particles exhibited higher angles of repose (AoR) and greater flow resistance compared to their spherical counterparts. The AoR is a measure of the steepness of a stable slope formed by granular material, with higher angles indicating poorer flowability.
“Our static angle of repose tests revealed that non-spherical particles tend to interlock and resist flow more than spherical ones,” Boribayeva explained. “This is because their irregular shapes create more contact points and friction between particles.”
The team also discovered that particle size played a crucial role in flow behavior. Smaller non-spherical particles showed reduced interlocking and frictional resistance compared to larger ones, while spherical particles demonstrated flow characteristics that were largely independent of size.
To validate their experimental findings, the researchers used the Discrete Element Method (DEM), a computational technique that simulates the behavior of granular materials. The DEM simulations accurately reflected the shape-dependent behavior observed in the experiments, providing a valuable tool for predicting and optimizing particle flow in industrial settings.
One of the most intriguing findings was the differing sensitivity of cylindrical (non-spherical) and spherical particles to rolling friction parameters. “Cylindrical particles exhibited a mild sensitivity to these parameters, while spherical particles were more significantly affected,” Boribayeva noted. “This suggests that the shape of the particles can influence the way they interact with each other and their surrounding environment.”
The implications of this research are far-reaching for the energy sector. By understanding and controlling the flow behavior of bauxite particles, engineers can enhance the performance of MBHEs and other industrial systems that rely on granular materials. This, in turn, can lead to more efficient energy storage and transfer, reducing costs and improving the overall viability of CSP and other renewable energy technologies.
Moreover, the validated DEM framework developed in this study offers a powerful tool for simulating and optimizing particle flow in a wide range of applications. As Boribayeva and her team continue to refine their models, they hope to unlock new insights into the behavior of granular materials and pave the way for innovative solutions in the energy sector and beyond.
In the ever-evolving landscape of energy technology, this research serves as a reminder that even the smallest details—like the shape and size of a particle—can have a profound impact on the big picture. As we strive to create a more sustainable and efficient energy future, studies like this one will be instrumental in guiding our efforts and shaping our understanding of the world around us.