Breakthrough in Thermal Energy Storage: New Capsule Design Utilizes Phase Change Materials

Strategic Insights -

Researchers from the Changsha University of Science and Technology have designed a new type of encapsulated compacted capsule using cement-diatomite-based composite phase change materials. This innovative design has the potential to significantly enhance thermal energy storage capabilities, providing a new pathway for the practical application of shape-stable composite PCMs. The researchers have demonstrated that the fabricated capsule achieves an average latent heat of 58 J/g and a corresponding latent heat storage capacity of 1.305 kJ per capsule, while maintaining a stable shape and increasing the thermal storage capacity.

Key Takeaways:

  • The new encapsulated compacted capsule design utilizes cement-diatomite-based composite phase change materials (CPCMs) to enhance thermal energy storage capabilities.
  • The fabricated capsule achieves an average latent heat of 58 J/g and a corresponding latent heat storage capacity of 1.305 kJ per capsule.
  • The capsule maintains a stable shape while increasing the thermal storage capacity, making it a promising solution for packed bed thermal storage systems.
  • The compressive strength of the capsule was measured at 2.87 MPa, which is 21.53% higher than the unencapsulated counterparts.
  • The encapsulated capsule has a higher storage power than that of CPCM due to its higher thermal conductivity of 0.58 W/m-K.
  • The encapsulated capsule can complete the solid-liquid phase transition in the heat charging process in just 10 minutes, which is 1.4 times faster than its unencapsulated counterparts.

Statistics:

  • Average latent heat of the fabricated capsule: 58 J/g.
  • Corresponding latent heat storage capacity of the capsule: 1.305 kJ per capsule.
  • Density of the capsule: 1083 kg/m-3.
  • Compressive strength of the capsule: 2.87 MPa.
  • Increase in compressive strength when covered with an external cement shell: 21.53%.
  • Thermal conductivity of the encapsulated capsule: 0.58 W/m-K.
  • Time taken for solid-liquid phase transition in the heat charging process: 10 minutes.
  • Comparison of time taken for solid-liquid phase transition: 1.4 times faster than unencapsulated counterparts.

Sources:

  • Cement-diatomite Composite Phase Change Capsules for Thermal Energy Storage. Solar Energy Materials and Solar Cells, 2025; 289.
  • Solar Energy Materials and Solar Cells. Elsevier, Radarweg 29, 1043 Nx Amsterdam, Netherlands. (Elsevier - www.elsevier.com; Solar Energy Materials and Solar Cells - www.journals.elsevier.com/solar-energy-materials-and-solar-cells/)
  • NewsRx. Investigators at Changsha University of Science and Technology Report Findings in Phase Change Materials (Cement-diatomite Composite Phase Change Capsules for Thermal Energy Storage). Energy Weekly News. August 22, 2025; p 159.