Numerical analysis of the effects of particle-particle interactions and particle size on the performance of an electrodynamic dust shield
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© 2019 Elsevier B.V. Performance loss due to dust accumulation on solar energy collection surfaces has garnered increasing research interest in recent years. The electrodynamic dust shield (EDS) has been proposed to clean solar devices, the design of which can benefit from understanding of the microscopic interactions of individual dust particles with each other and the electric field in the system. Consequently, the objective of this work was to determine the effects of particle sizes and particle interactions on the performance and power utilization of an EDS through a discrete element simulation of the transport, collision, and adhesion of charged dust particles subject to a four-phase traveling wave on a horizontal EDS. Over a thousand monodisperse particles with diameters from 10 to 200 μm were simulated. In the presence of all types of particle-particle interactions, particles with diameters greater than 10 μm were transported in the direction of the wave with a larger average transport distance as diameter decreased. This result was due to, in general, smaller particles remaining closer to the surface to travel more closely along electric field lines toward the positive electrode, while larger particles exhibited more disordered motion. Meanwhile, 10-μm particles were transported slightly in the direction opposite to the wave due to lack of particle-particle collisions and the presence of van der Waals adhesion, which had a relatively larger effect on smaller particles than larger particles. Electrodynamic particle-particle interactions and particle images were identified to be the main interactions responsible for a reduction in the efficiency of 50-μm and 100-μm particles to travel with the wave. The average power applied to a particle while it was lifted off the surface increased as particle diameter increased in most cases, due to increased particle momentum at lifting. This power was reduced with the absence of at least one type of particle-particle interaction due to reduced velocity and distance traveled immediately after lifting from the surface. Our study identified additional important factors in EDS dust mitigation that were not suggested by previous experimental studies, namely, particle-particle collisions and large particle charge. As well, our work indicated that intermittent operation of the EDS may aid in cleaning of small particles and that the use of the lowest possible voltage that still lifts large particles may aid in cleaning of large particles.
author list (cited authors)
Chesnutt, J., Guo, B., & Wu, C.