Materials Development

Micrograph of a PCM slurry based on an emulsion
© Fraunhofer ISE
Micrograph of a PCM slurry based on an emulsion.

Fraunhofer ISE places particular emphasis on the development of new materials for latent heat and cold storage and has an extensive R&D infrastructure and many years of experience in this field. The main aim of our research is to increase the storage density and long-term stability of storage materials. In addition to latent heat storage materials, we also develop and optimize sorption materials.

Our services include:

  • Material screening of heat storage materials, especially PCM and sorption materials
  • Development of formulations for the production of PCM emulsions (PCM slurries) on a liter scale
  • Upscaling the production of PCM emulsions up to the cubic meter scale
  • Microencapsulation of PCM
  • Thermal stabilization of PCM
  • Rheological characterization of heat transfer fluids and PCM
  • Determination of the specific heat capacity of materials
  • Determination of the heat of fusion and phase transition temperatures of phase change materials
  • Determination of the thermal conductivity of storage materials
  • Long-term stability studies of PCM and PCM composite materials
  • Determination of the crystal structure (XRD), phase analysis and conversion of sorption materials
  • Determination of reaction enthalpy and heat capacity by differential calorimetry of sorption storage tanks
  • Testing and characterization of PCM and PCM composite materials for the RAL-PCM quality seal
PMMA microcapsules with PCM as core material
© Fraunhofer ISE
PMMA microcapsules with PCM as core material.

Fraunhofer ISE has particularly broad expertise in the development of PCM slurries. These are high-performance heat transfer fluids, which, due to the high heat capacity of the fluid, make it possible to reduce the required storage volume. We disperse organic PCMs in water or water-glycol mixtures to produce a heat transfer fluid that has a storage density up to 4 times that of water in the melting range of the PCM.

The emulsification of PCM is the basis for microencapsulation. We encapsulate organic PCM in polymethyl methacrylate (PMMA) or melamine resin in a temperature range of about 10 to 50 °C. We further process these microencapsulated PCMs into composite materials for use in the building sector but also for technical applications such as cooling batteries and electronics. Microencapsulation allows PCMs to be distributed very finely in the composite material and creates a large surface area between the composite material and the PCM, which is beneficial for rapid charging and discharging.

PCM slurry
© Fraunhofer ISE
PCM slurry.

Within the framework of material investigations and development, we have extensive facilities for characterizing PCMs with regard to their thermal and rheological properties. An important aspect when using phase change materials is their thermal stability. Therefore we develop measures for the stabilization of PCMs and perform stability and degradation tests.