Lighthouse project ElKaWe

As part of the project, Fraunhofer IPM is developing a system design for an efficient electrocaloric heat pump. The heat transfer between the electrocaloric material and the heat transfer unit is realized according to the principle of a heat pipe via a combination of evaporation and condensation of a fluid (e.g. water) and a thermal diode. No harmful refrigerants are used in the process. This novel, patented approach ensures heat transfer rates that are many times higher than those of previously known solid-state-based heat pumps.

Experimental platform for setting up an electrocaloric heatpump  

As part of the project, Fraunhofer IKTS is developing electrocaloric materials and components based on ceramic materials and technologies. The focus is on the synthesis and targeted modification of functional ceramic materials for high reversible temperature changes in the range of the application temperature. Robust electrocaloric components with high dielectric strength are manufactured via film casting and ceramic multilayer technology. The manufacturing process of multilayer ceramic capacitors (MLCC), which is well established in microelectronics, allows components to be manufactured for integration into solid-state heat pumps that are suitable for series production.

During this project, Fraunhofer IAP is developing electrocaloric materials and components based on polymers and, in cooperation with Fraunhofer IKTS, also on hybrid materials. As part of the development of electrocaloric-active polymers, Fraunhofer IAP is investigating the processing of various terpolymers with relaxor-ferroelectric properties in different layer thicknesses. In addition, the optimization of intrinsic material properties with regard to high electrocaloric effects is to be researched. On the basis of these optimized polymer materials, electrocaloric-active components will then be developed using, among other things, layering or stacking processes and made available for integration into the overall system. Alternatively, electrocaloric-active ceramic particles dispersed in an electrocaloric polymer matrix are used to develop hybrid materials that also have an electrocaloric effect.

Fraunhofer FEP develops and applies all surface coatings required for the function of the electrocaloric heat pump. Regardless of their thickness of only a few micrometers, they are capable of fundamentally changing the property profile of the component surface in question and adapting it to the application. Specifically, these are layers for electrical insulation of the active components, for adjusting the wetting behavior of the surfaces in contact with the working fluid, and for protecting the materials used from the ingress of foreign gases and from corrosion. All layers are applied by means of vacuum-based processes (PVD, CVD).

Fraunhofer IAF develops power electronics of the electrocaloric cells. For this purpose, the dielectric loss properties of the cells are first comprehensively measured as a function of voltage, temperature and frequency and a simulation model is created. Based on this, the control of the cells is designed to be as energy-efficient as possible in a second step. Tailor-made innovative semiconductor components are to maximize the efficiency.

Fraunhofer LBF is contributing its many years of experience in materials research of polymer-based electroactive materials to the project. The characterization and reliability analysis of these materials, the simulation of their behavior and the development of system-theoretical reliability models of the components and the overall system are the focus of the research.