Stabilization of reactive bed particles for thermochemical energy storage with fiber reinforcement

Thermochemical energy storage (TCES) is an emerging technology harnessing chemical reactions for storage of thermal energy. Among the primary challenges for TCES based on crystal-to-crystal chemical transformations is the design and manufacturing of macroscopic reactive particles that are resistant to mechanical changes over multiple cycles of operation. Such changes often lead to an increase in the pressure drop over a packed bed, thereby adversely affecting the performance of TCES. This work explores the effect of polymeric fibers on reactive TCES particles as a potential route for mechanical stabilization of both the particles and the bed. The salt hydrate K₂CO₃·1.5H₂O was used as a model thermochemical material and polyacrylonitrile fibers (PAN) were selected as a reinforcing additive. The stabilization effect of fibers for composite tablets of (K₂CO₃·1.5H₂O)#PAN with respect to crushing behavior, salt deliquescence and deformation after 50 cycles was demonstrated and attributed to the shape-stable structures formed by the internal fiber networks. The increase of a pressure drop at a reactive bed of fiber-reinforced particles was found to be smaller by a factor of 1.5–3 as compared to a bed of pure K₂CO₃ tablets, while the reaction rate was unaffected. Thus, the proposed approach may be an inexpensive and efficient route to stable macroscopic reactive particles for TCES reactors.