(721c) Microvascular Carbon-Carbon Composite for Concentrated Solar Power Gas Receivers

Concentrated solar power systems offer a sustainable energy source by integrating it with thermal energy storage systems to produce electricity on demand. The technology uses mirrors to concentrate sunlight into a central receiver, which is used to heat a working fluid. The state-of-the-art approach to constructing gas receivers is the use of nickel-alloy modules with microchannels, showing promise by achieving nearly 90% global receiver efficiency based on simulated solar testing with super-critical carbon dioxide as working fluid (sCO₂) [1]. While the initial achievements of this technology are impressive, these receiver designs do, however, suffer from technical challenges that must be overcome before adoption. An alternative to these metallic systems is the use of high-temperature carbon-carbon (c-c) composites with novel microvascular (microVasc) composites technology [3]. In this work, these composites are made by first preparing prepregs with sheets of PAN-based carbon fibers and phenolic resin with the sacrificial polymer micro-channel (Polyacrylonitrile - PLA) between them, which is later removed by heat treatment under vacuum. The prepreg are then carbonized under an inert atmosphere (N₂) at 1000 °C. Due to gas evolution, this process lowers density and increases porosity. Therefore, to obtain the desirable mechanical and heat transfer properties, the composite is densified using phenolic resin under the same conditions. The c-c composites will then be evaluated for their mechanical and heat transfer properties. In addition, multiple densification cycles will be necessary in order to obtain the desired properties. Lastly, hydraulic and leakage testing of the channels will be necessary to prove their efficacy with flowing of sCO₂.

References

[1] Zada, K. R., Hyder, M. B., Drost, M. K. & Fronk, B. M. J. Sol. Energy Eng. 138, 61007 (2016).

[2] Chung, Deborah DL. Carbon fiber composites. Elsevier, (2016).

[3] Esser‐Kahn, A. P. et al. Adv. Mater. 23, 3654–3658 (2011).