Abstract
Heat receiver design is an essential portion of Concentrating Solar Power (CSP) plants, particularly within CSP systems that are particle based. Particle based CSP promises higher operating temperatures and more cost-effective thermal energy storage than existing systems. Two general types of Particle Heat Receivers (PHR) are under development, variations of the free-falling curtain concept being developed by Sandia National Labs and an obstructed flow concept being developed by King Saud University (KSU) and Georgia Institute of Technology (GIT)[1, 2]. The obstructed flow design utilizes specifically engineered obstacles placed in the flow path of the particles to remove momentum and kinetic energy and promote lateral and depthwise mixing. This design is named the discrete structure or DSPHR. This paper focuses on development and design work that has been done with the existing DS-PHR developed by GIT and KSU. Previous iterations of the DS-PHR have utilized obstruction materials that include simple metal meshes, and ceramic formed into an inverted V-shapes or chevrons. However, these previous designs have some shortfalls. The metallic mesh design has structural integrity issues under intense radiation, inherent in a DS-PHR. The ceramic chevrons have a disadvantageously thick leading edge, which may intercept too much radiation and overheat. Current development has continued with improvements to remedy the issues of the previous design work. Experience, modeling, and testing have shown that a cavity receiver is preferred to reduce heat and particle loss in the system. Recent work has been devoted to developing a Discrete Structure Refractory Particle Heat Receiver (DS-RPHR) suitable for cavity installation working with a north-located field. The simplest suitable configuration is 5 flat ceramic plates, or absorber panels, arranged in an arc, forming a 15 degrees angle of inclination, to improve particle retention in the system. To increase particle residence time, quartz rods are placed onto the back plane of the DS-PHR, in a hexagonal configuration. These serve as the momentum scrubbing obstructions as mentioned above. The performance of this design will be discussed in the following paper. This design has been extensively modeled using NREL's Solfrace to evaluate thermal and optical performance. Modeling has shown high thermal efficiency in the design, as well as promising heat flux profiles across the receiver. Currently at KSU, a 300 kW-thermal testing facility has been constructed and used for high temperature testing. The final proposed 6.6 MW-thermal design, called the pre-commercial demonstration, will be built at a site owned and operated by Saudi Electric Company, in Waad Al-Shamal, 20 kilometers east of Tuarif, Saudi Arabi.