Thermal storage system using hexagonal-packed, tube-encapsulated PCM and a method for specifying encapsulation tube parameters

Physical Sciences : Mechanical

Available for licensing


  • Atila Novoselac, Ph.D. , Civil, Architectural and Environmental Engineering
  • Stephen Bourne, M.S. , Energy and Environmental Resources

Background/unmet need

High-density thermal storage is needed to shift HVAC cooling loads to off-peak periods. Common methods utilizing chilled water are large and bulky and do not integrate well into structures that need thermal storage; e.g., residential and small commercial buildings. Latent thermal storage systems have higher density than chilled water systems, but a method is needed to optimize these designs with respect to performance and storage density to enable retrofit into these existing structures. 

Invention Description

Researchers at The University of Texas at Austin presented an optimal design of an encapsulated PCM-based latent thermal energy storage system. It identifies the thermal and physical parameters of the encapsulation and packing system for any given heat transfer fluid and phase change material such that the highest density and recovery rates are possible. Such a system provides 3 to 7 times the thermal storage density of conventional chilled water thermal storage systems, particularly when flow rates are high and return temperatures low (as in high-demand periods).


  • Highest possible density of PCM thermal storage
  • Acceptable energy recovery rates for this thermal store design


    This method and design permit the specification of encapsulation material and dimensional parameters to optimize thermal storage density and performance.  

Market potential/applications

Residential and small commercial HVAC system providers who wish to incorporate thermal storage into their products. 

Development Stage

Lab/bench prototype