Fraunhofer researchers have made significant strides in the development of highly efficient, compressor-free solid-state heat pumps with the completion of the ElKaWe research project. This breakthrough brings us closer to cleaner and more efficient refrigeration and air conditioning systems, addressing the growing global demand for such technologies.
Currently, most heat pumps rely on compressors and chemical refrigerants, raising environmental concerns. The ElKaWe project, involving six Fraunhofer institutes, introduces a promising alternative: solid-state heat pumps powered by electrocaloric materials, which do not require harmful refrigerants and have the potential to outperform traditional compressor-based systems in efficiency.
Key developments include:
Electrocaloric Materials: Fraunhofer IAP’s team developed ultra-thin electrocaloric polymer films capable of forming multi-layer components, setting new international standards. Meanwhile, Fraunhofer IKTS created multilayer ceramic components based on PMN-PT (magnesium lead niobate/lead titanate), meeting stringent dielectric strength requirements.
Long-Term Stability: Materials tested during the project showed remarkable stability, with no changes in electrocaloric effect after 70 million cycles.
Heat Transfer Innovations: To address the challenge of rapid heat dissipation, Fraunhofer used active elastocaloric heat pipes (AEH) that employ ethanol and water, replacing traditional chemical refrigerants. This method allows efficient heat transfer through rapid fluid evaporation and condensation.
Advanced Electrical Control: Fraunhofer IAF designed a specific circuit for the electrocaloric heat pump, achieving a record-breaking electrical conversion efficiency of 99.74%, a significant improvement from previous technologies.
The team’s work on three demonstrator systems, each with up to four electrocaloric segments, has shown that these systems achieve the expected performance. Simulations suggest their efficiency is already comparable to compressor systems, with significant potential for further improvement.
With this project, Fraunhofer has demonstrated the disruptive potential of electrocaloric technology, advancing the development of more sustainable and efficient heat pumps.
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