Analysis of Particle Attrition and Material Abrasion at Varying Temperatures for Solar Energy Applications

Particles are one proposed heat transfer medium and thermal energy storage medium for high temperature solar energy applications. Particles come at a low cost and do not suffer from freezing as seen in molten salts, but the long-term durability of these particles and containment materials are largely unknown for operating conditions. This study primarily focuses on particle attrition and containment material abrasion. Particle attrition measures breakdown, which occurs when particles grind against themselves and surrounding surfaces. This breaks the particles into smaller and potentially sharper pieces. Particle attrition can be problematic as it changes the size distribution of the particles and can alter their thermal properties, which affects the overall efficiency of the system. Abrasion focuses on how containment materials degrade when particles slide across their surfaces. This is important for determining suitable materials to construct a particle transport and storage system. This experiment explores the effects of particle attrition and abrasion by measuring the change in mass of both the containment materials and the particles across a range of particle sizes. Results indicate that refractory composites experience five times the abrasion of typical metals. Particle attrition at low temperatures has been negligible after over 200 hours of testing.