Design of Particle-Based Thermal Energy Storage for a Concentrating Solar Power System

2017 ◽  
Author(s):  
Zhiwen Ma ◽  
Ruichong Zhang ◽  
Fadi Sawaged
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Performance ◽  
High Efficiency ◽  
Solar Power ◽  
Solid Particles ◽  
Concentrating Solar Power ◽  
Hot Particles ◽  
Power Cycle

Solid particles can operate at higher temperature than current molten salt or oil, and they can be a heat-transfer and storage medium in a concentrating solar power (CSP) system. By using inexpensive solid particles and containment material for thermal energy storage (TES), the particle-TES cost can be significantly lower than other TES methods such as a nitrate-salt system. The particle-TES system can hold hot particles at more than 800°C with high thermal performance. The high particle temperatures increase the temperature difference between the hot and cold particles, and they improve the TES capacity. The particle-based CSP system is able to support high-efficiency power generation, such as the supercritical carbon-dioxide Brayton power cycle, to achieve >50% thermal-electric conversion efficiency. This paper describes a solid particle-TES system that integrates into a CSP plant. The hot particles discharge to a heat exchanger to drive the power cycle. The returning cold particles circulate through a particle receiver to absorb solar heat and charge the TES. This paper shows the design of a particle-TES system including containment silos, foundation, silo insulation, and particle materials. The analysis provides results for four TES capacities and two silo configurations. The design analysis indicates that the system can achieve high thermal efficiency, storage effectiveness (i.e., percentage usage of the hot particles), and exergetic efficiency. An insulation method for the hot silo was considered. The particle-TES system can achieve high performance and low cost, and it holds potential for next-generation CSP technology.

Supercritical Carbon Dioxide Power Cycle Configurations for Use in Concentrating Solar Power Systems

2012 ◽  
Author(s):  
Craig S. Turchi ◽  
Zhiwen Ma ◽  
John Dyreby
Keyword(s):  
Carbon Dioxide ◽  
Energy Storage ◽  
Molten Salt ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Power ◽  
Brayton Cycle ◽  
Concentrating Solar Power ◽  
Power Cycle ◽  
Cycle Efficiency

Concentrating Solar Power (CSP) plants utilize oil, molten salt or steam as the heat transfer fluid (HTF) to transfer solar energy to the power block. These fluids have properties that limit plant performance; for example, the synthetic oil and molten salt have upper temperature limits of approximately 390°C and 565°C, respectively. While direct steam generation has been tested, it requires complex controls and has limited options for integration of thermal energy storage. Use of carbon dioxide as the HTF and power cycle working fluid offers the potential to increase thermal cycle efficiency while maintaining simplicity of operation and thermal storage options. Supercritical CO2 (s-CO2) operated in a closed-loop recompression Brayton cycle offers the potential of higher cycle efficiency versus superheated or supercritical steam cycles at temperatures relevant for CSP applications. Brayton-cycle systems using s-CO2 have smaller weight and volume, lower thermal mass, and less complex power blocks versus Rankine cycles due to the higher density of the fluid and simpler cycle design. Many s-CO2 Brayton power cycle configurations have been proposed and studied for nuclear applications; the most promising candidates include recompression, precompression, and partial cooling cycles. Three factors are important for incorporating s-CO2 into CSP plants: superior performance vs. steam Rankine cycles, ability to integrate thermal energy storage, and dry-cooling. This paper will present air-cooled s-CO2 cycle configurations specifically selected for a CSP application. The systems will consider 10-MW power blocks that are tower-mounted with an s-CO2 HTF and 100-MW, ground-mounted s-CO2 power blocks designed to receive molten salt HTF from a power tower.

Fluidized Bed Technology for Concentrating Solar Power With Thermal Energy Storage

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Zhiwen Ma ◽  
Greg Glatzmaier ◽  
Mark Mehos
Keyword(s):  
Energy Storage ◽  
Fluidized Bed ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Performance Metrics ◽  
Solar Power ◽  
Solid Particles ◽  
Thermal System ◽  
Concentrating Solar Power ◽  
And Storage

A generalized modeling method is introduced and used to evaluate thermal energy storage (TES) performance. The method describes TES performance metrics in terms of three efficiencies: first-law efficiency, second-law efficiency, and storage effectiveness. By capturing all efficiencies in a systematic way, various TES technologies can be compared on an equal footing before more detailed simulations of the components and concentrating solar power (CSP) system are performed. The generalized performance metrics are applied to the particle-TES concept in a novel CSP thermal system design. The CSP thermal system has an integrated particle receiver and fluidized-bed heat exchanger, which uses gas/solid two-phase flow as the heat-transfer fluid, and solid particles as the heat carrier and storage medium. The TES method can potentially achieve high temperatures (>800 °C) and high thermal efficiency economically.

Numerical Analysis of Latent Thermal Energy Storage System With Embedded Thermosyphons

2012 ◽  
Author(s):  
Karthik Nithyanandam ◽  
Ranga Pitchumani
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Power ◽  
Storage System ◽  
High Energy ◽  
Concentrating Solar Power ◽  
Discharge Performance ◽  
Low Thermal Conductivity

Latent thermal energy storage (LTES) system offers high energy storage density and nearly isothermal operation for concentrating solar power generation. However, the low thermal conductivity possessed by the phase change material (PCM) used in LTES system limits the heat transfer rates. Utilizing thermosyphons to charge or discharge a LTES system offers a promising engineering solution to compensate for the low thermal conductivity of the PCM. The present work numerically investigates the enhancement in the thermal performance of charging and discharging process of LTES system by embedding thermosyphons. A transient, computational analysis of the LTES system with embedded thermosyphons is performed for both charging and discharging cycles. The influence of the design configuration of the system and the arrangement of the thermosyphons on the charge and discharge performance of the LTES installed in a concentrating solar power plant (CSP) is analyzed to identify configurations that lead to improved effectiveness.

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