Date of Award

Spring 5-7-2021

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Advisor

Justin Lapp

Second Committee Member

Andrew J. Goupee

Third Committee Member

Olivier Putzeys

Abstract

High-temperature solid particle receivers have been widely studied for use in concentrated solar power systems to absorb concentrated solar radiation. Many efforts have been made to select a particle that can increase the performance of these systems. In this experimental study, available coating technology for particles is used to examine whether it could enhance heat transfer. A packed bed setup is designed and validated to assess the heat transfer of these particles. The validated packed bed opens the scope in which a packed bed can be used as a primary experiment for the prediction of suitable alternative particles and reduce the cost of large-scale experiments for solar energy. A solar simulator, consisting of one 7 kW xenon arc lamp, is used to heat the particles.

Alumina is selected as the primary material of particles, and AMA (Al2O3–Mo–Al2O3) is selected as the coating of particles. Axial and radial temperature profiles are measured to compare the heat transfer rate through coated particles and uncoated particles. The comparison was made over the temperature range from room temperature to 1100 °C for different sizes of particles from 176 μm to 1023 μm. Furthermore, the thermal stability and durability of the particles in high-temperature conditions caused by the radiative heat transfer of a solar simulator are investigated qualitatively. Although the AMA coating was not stable over 1031 °C for materials that contain more alumina, the results include the relative benefit of the coating for those materials. Comparing the temperature profiles of coated and uncoated particles showed that coating would cause more heat absorption for MES976 particles. But the coating did not affect the heat absorption for CP368 particles. The described procedure is presented as a means to efficient thermal testing of new candidate particles for solar receivers.

A numerical approach is applied to calculate the effective thermal conductivity of each particle from experimental results. The results showed the effective thermal conductivity was higher for particles with larger average pore sizes. Moreover, the effective thermal conductivity of the MES976 increased on average 6% due to AMA coating. However, it decreased for CP368 on average 8%. Finally, a two-dimensional cylindrical packed bed example is solved analytically. This analytical method can be applied to various geometries, boundary conditions, and assumptions to achieve a basic design of packed beds.

Available for download on Tuesday, December 20, 2022

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