Concentrated solar power (CSP) is a promising large-scale, renewable power generation and energy storage technology, yet limited by the material properties of the heat transfer fluid. Current CSP plants use molten salts, which degrade above 600˚C and freeze below 220˚C. A dry, particle-based heat transfer fluid (pHTF) can operate up to and above 1,200˚C, enabling high-efficiency power cycles. Demonstration of the flow and heat-transfer performance of the pHTF in a scalable process is critical to assess the feasibility for this technology.

In this study, we report on a first-of-a-kind pilot system to evaluate heat transfer to/from a densely flowing pHTF. This process unit circulates the pHTF at flowrates up to 1 tonne/h. Thermal energy is transferred to the pHTF as it flows through an electrically heated pipe. A fluidization gas in the heated zone enhances the wall-to-pHTF heat transfer. We found that the introduction of gas mixtures with thermal conductivities 4.5 times greater than air led to a 65% increase in the heat transfer coefficient. In addition to the fluidization gas, the particle size also plays a critical role in heat transfer performance. Particles with an average diameter of 270 µm contributed to heat transfer coefficients that were up to 25% greater than the performance of other particles of the same composition in size range of 65 to 350 µm. The fundamental mechanisms that we attribute to these findings and considerations for the design of an on-sun system will be discussed. Moreover, the collective work demonstrates the promise of this unique design in solar applications.


Pilot-Scale System With Particle-Based Heat Transfer Fluids for Concentrated Solar Power Applications

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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