Preliminary Design Development, Laboratory Testing, and Optimization of a 6.6 MW-Thermal All-Refractory Particle Heating Receiver

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 depth-wise mixing. This design is named the discrete structure or DS-PHR. 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° 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 Soltrace 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.

Analyses of Thermal Performance of Solar Power Tower Station Based on a Supercritical CO2 Brayton Cycle

Concentrating solar power (CSP) technology, possessing an inherent capacity to couple with energy storage ideally, attracts a great deal of attention nowadays. However, these power plants with various types of CSP system still cannot compete with the traditional thermal power plants in terms of levelized cost of electricity (LCOE), and their potential for utilizing clear and renewable solar energy cannot be overestimated. To improve the total efficiency of the solar power tower (SPT) plant is the key factor for its development. In this present paper, a SPT plant based on an S-CO2 Brayton cycle (with S-CO2 serving as heat transfer and working fluid) is proposed. A numerical simulation is carried out to calculate the effects of key operating parameters, including power cycle and subsystem parameters, on the overall performance of the SPT plant. The results show that there is an optimum value for the compression ratio for the SPT plant. For the heat receiver, the trends of exergy and thermal efficiency varying with turbine inlet temperature are reversed, because of the significant energy loss caused by high temperature of the surface of the heat receiver. As for the overall performance, the SPT plant proposed in this paper is better than other SPT plants based on a steam Rankine system and an S-CO2 Brayton system with molten salt serving as heat transfer fluid (HTF) operating under the similar condition. Its overall thermal efficiency is 1.04% and 3.42% higher than that of two other SPT plants, respectively.

POSSIBILITIES OF INCREASING THE EFFICIENCY OF THE HEAT RECEIVER OF ICS FROM METAL SHAVINGS

The article considers a solar air heater with a heat sink of metal shavings and the possibility of increasing efficiency by changing the location of the heat sink inside the structure. And also considered to improve the efficiency of the corrugated surface of the heat sink due to the angle of the corrugations. An analytical formula for calculating the radiation transmittance through the form of metal shavings is proposed.