Invention Reference Number
ORNL has developed a new thermal energy storage design utilizing low conductivity organic phase change materials. The new design offers low costs along with charge/discharge times appropriate for building thermal mass—even when there is a small temperature difference between the heat transfer fluid and the material’s phase change temperature.
Description
Thermal energy storage is an essential part of reducing a building’s energy consumption during peak hours, which are often up to four hours long. Thermal energy is typically stored in materials with high energy density. Phase change materials have a very high energy density, but heat transfer is complex in these materials because the melting and freezing fronts change with time and location. Prior attempts to use these materials as heat exchangers have been largely unsuccessful because the materials were thought to require complex geometries for optimal heat transfer, which are expensive and difficult to construct.
ORNL’s design makes use of commercially available phase change materials with low conductivity after finding that these materials have four- to five-hour charge/discharge times. Furthermore, the fin-and-tube design is far more cost-effective than the fractal geometries of prior attempts at using phase change materials. The design is also able to use aluminum tubes instead of copper ones, offering further price reduction through material costs.
Benefits
- Low material costs and efficient discharge
- Design is consistent with current heat exchange manufacturing processes
Applications and Industries
- Suitable for building space heating and cooling
- Heat exchanger manufacturers
Contact
To learn more about this technology, email partnerships@ornl.gov or call 865-574-1051.
