Lighthouse project ElKaWe

Electrocaloric heat pumps

In the lighthouse project »ElKaWe«, six Fraunhofer Institutes under the direction of Fraunhofer IPM are working on the development of electrocaloric heat pumps for heating and cooling. Today, heat pumps work almost exclusively based on compressor technology. Electrocaloric heat pumps promise significantly higher efficiency and do not require harmful refrigerants. As part of the project, the scientists are developing ceramic and polymer-based electrocaloric materials and are working on an innovative system concept that enables particularly efficient heat dissipation.

Work in the project is intended to demonstrate that electrocaloric heat pumps have the potential to replace compressors in the long term. Heat pumps are an important component of the energy revolution, as they ensure optimized space heating and hot water generation. Powered by electricity generated from renewable sources, they form the missing link between electricity and heat generation. However, the number of heat pumps for air conditioning in buildings is growing slowly because compressor-based heat pumps are economically inefficient. In cooling technology, the gradual ban on refrigerants within the framework of the European »F-gas Regulation«, which aims at reducing fluorinated greenhouse gases, also makes alternative technologies desirable.

How does an electrocaloric heat pump work?

If an electric field is applied to electrocaloric materials, the electric dipole moments in the field are aligned. This additional order is accompanied by heating of the material according to the laws of thermodynamics. The resulting heat is dissipated via a heat sink so that the material cools down again to the initial temperature. If the electric field is removed, the order is reduced and the material cools down to a temperature below the initial temperature  – again in accordance with the laws of thermodynamics. Now it can absorb thermal energy from a heat source. The effect is reversible. In this way, a cycle can be set up that functions as an efficient heat pump for cooling or heating.

 

Press release Fraunhofer FEP / 15.8.2024

Thin films for more efficient heat transfer in electrocaloric heat pumps

Fraunhofer FEP has made significant progress in the development of thin films to improve heat transfer in electrocaloric heat pumps. The latest research results will be presented at PSE 2024, September 2 – 5, 2024, in Erfurt, Germany.

IEE Power Electronics Society / 19.8.2024

Best Paper Award

 

As part of the ElKaWe project, Fraunhofer researchers developed ultra-efficient power electronics for electrocaloric heat pumps. A publication on this subject published in April 2023 has now been recognized by the IEEE Journal of Emerging and Selected Topics in Power Electronics (JESTPE) as the best paper of 2023.

Congratulations to the authors!

 

 

 

Presse release Fraunhofer IAF / 20.7.2023

Power electronics for novel heat pumps achieve efficiency of over 99.7 percent

As part of the ElKaWe project, researchers at Fraunhofer IAF have successfully realized a circuit topology for voltage converters with over 99.74 percent electrical efficiency. The power electronics are intended for use in electrocaloric heat pumps.

 

 

Green ICT Award 2023 of the Research Fab Microelectronics Germany (FMD)

Award-winning Master's thesis

Kareem Mansour, Master's student at Fraunhofer IAF and at the University of Freiburg's INATECH, has been awarded the Green ICT Award 2023 for his Master's thesis

"Design and Implementation of a Highly Efficient Bidirectional DC-DC Converter for Multi-Phase Control of Capacitive Loads".

The thesis was part of the ElKaWe project.

Congratulations from the entire ElKaWe team!

Scientific publications within the project

Jahr
Year
Titel/Autor:in
Title/Author
Publikationstyp
Publication Type
2024 Influence of Grain-Growth Inhibitors on Modified (Ba,Sr)(Sn,Ti)O3 for Electrocaloric Application
Li, Zhenglyu; Molin, Christian; Gebhardt, Sylvia
Zeitschriftenaufsatz
Journal Article
2024 Voltage-Sensorless Control and GaN Multilevel Converter for Charging Non-Linear and Lossy Electrocaloric Capacitors
Mönch, Stefan; Reiner, Richard; Basler, Michael; Waltereit, Patrick; Quay, Rüdiger; Bartholome, Kilian
Konferenzbeitrag
Conference Paper
2024 Over 99.7% Efficient GaN-based 6-Level Capacitive-Load Power Converter
Mönch, Stefan; Reiner, Richard; Basler, Michael; Bartholome, Kilian; Waltereit, Patrick; Quay, Rüdiger
Konferenzbeitrag
Conference Paper
2024 Introduction of novel method of cyclic self-heating for the experimental quantification of the efficiency of caloric materials shown for LaFe11,4Mn0,35Si1,26Hx
Schipper, Jan; Melchin, Stefan; Metzdorf, Julius; Bach, David; Fehrenbach, Miriam; Löwe, Konrad; Vieyra Avilés, Víctor Hugo; Kühnemann, Frank; Wöllenstein, Jürgen; Bartholome, Kilian
Zeitschriftenaufsatz
Journal Article
2024 Magnetron-Sputtered Long-Term Superhydrophilic Thin Films for Use in Solid-State Cooling Devices
Barrera Marin, Maria Isabel; Zywitzki, Olaf; Modes, Thomas; Fietzke, Fred
Zeitschriftenaufsatz
Journal Article
2024 Electrocaloric cooling system utilizing latent heat transfer for high power density
Metzdorf, Julius; Corhan, Patrick; Bach, David; Hirose, Sakyo; Lellinger, Dirk; Mönch, Stefan; Kühnemann, Frank; Schäfer-Welsen, Olaf; Bartholome, Kilian
Zeitschriftenaufsatz
Journal Article
2024 Field dependence of the electrocaloric effect in BaTiO3 and Ba(Zr0.12Ti0.88)O3: High-resolution measurements around the phase transition
Fischer, Jonas; Molin, Christian; Gebhardt, Sylvia; Hägele, Daniel; Rudolph, Joseph
Zeitschriftenaufsatz
Journal Article
2023 A 99.74% Efficient Capacitor-Charging Converter using Partial Power Processing for Electrocalorics
Mönch, Stefan; Reiner, Richard; Mansour, Kareem; Waltereit, Patrick; Basler, Michael; Quay, Rüdiger; Molin, Christian; Gebhardt, Sylvia; Bach, David; Binninger, Roland; Bartholome, Kilian
Zeitschriftenaufsatz
Journal Article
2023 GaN-HEMT with a Back-Gated Segment for High Voltage Cascodes
Reiner, Richard; Mönch, Stefan; Waltereit, Patrick; Basler, Michael; Müller, Stefan; Mikulla, Michael; Quay, Rüdiger
Konferenzbeitrag
Conference Paper
2023 Influence of Sintering Additives on Modified (Ba,Sr)(Sn,Ti)O3 for Electrocaloric Application
Li, Zhenglyu; Molin, Christian; Gebhardt, Sylvia
Zeitschriftenaufsatz
Journal Article
2023 On the efficiency of caloric materials in direct comparison with exergetic grades of compressors
Schipper, Jan; Bach, David; Mönch, Stefan; Molin, Christian; Gebhardt, Sylvia; Wöllenstein, Jürgen; Schäfer-Welsen, Olaf; Vogel, Christian; Langebach, Robin; Bartholome, Kilian
Zeitschriftenaufsatz
Journal Article
2023 Simultaneous direct measurement of the electrocaloric and dielectric dynamics of ferroelectrics with microsecond temporal resolution
Fischer, Jonas; Döntgen, Jago; Molin, Christian; Gebhardt, Sylvia; Hambal, Yusra; Shvartsman, Vladimir; Lupascu, Doru; Hägele, Daniel; Rudolph, Jörg
Zeitschriftenaufsatz
Journal Article
2023 Phenomenological Material Model for First-Order Electrocaloric Material
Unmüßig, Sabrina; Bach, David; Nouchokgwe Kamgue, Youri Dilan; Defay, Emmanuel; Bartholome, Kilian
Zeitschriftenaufsatz
Journal Article
2023 Modified (Ba,Sr)(Sn,Ti)O3 via hydrothermal synthesis for electrocaloric application
Li, Zhenglyu; Molin, Christian; Michaelis, Alexander; Gebhardt, Sylvia
Zeitschriftenaufsatz
Journal Article
2023 Spatio-temporal solid-state electrocaloric effect exceeding twice the adiabatic temperature change
Mönch, Stefan; Bartholome, Kilian
Zeitschriftenaufsatz
Journal Article
2023 Lateral GaN Power Devices and Integrated GaN Power Circuits: Status and Recent Progress
Reiner, Richard; Basler, Michael; Mönch, Stefan; Waltereit, Patrick; Benkhelifa, Fouad; Mikulla, Michael; Quay, Rüdiger
Konferenzbeitrag
Conference Paper
2023 Integrated Multi-Stage Cascode Structure for Lateral High-Voltage GaN Power Transistors
Reiner, Richard; Mönch, Stefan; Basler, Michael; Waltereit, Patrick; Müller, Stefan; Mikulla, Michael; Quay, Rüdiger
Konferenzbeitrag
Conference Paper
2023 How highly efficient power electronics transfers high electrocaloric material performance to heat pump systems
Mönch, Stefan; Reiner, Richard; Waltereit, Patrick; Basler, Michael; Quay, Rüdiger; Gebhardt, Sylvia; Molin, Christian; Bach, David; Binninger, Roland; Bartholome, Kilian
Zeitschriftenaufsatz
Journal Article
2023 GaN power converter and high-side IC substrate issues on Si, p-n junction, or SOI
Mönch, Stefan; Basler, Michael; Reiner, Richard; Benkhelifa, Fouad; Döring, Philipp; Sinnwell, Matthias; Müller, Stefan; Mikulla, Michael; Waltereit, Patrick; Quay, Rüdiger
Zeitschriftenaufsatz
Journal Article
2022 Tailoring electrocaloric properties of Ba1-xSrxSnyTi1-yO3 ceramics by compositional modification
Molin, Christian; Richter, Tony; Gebhardt, Sylvia
Zeitschriftenaufsatz
Journal Article
2022 GaN Power Converter Applied to Electrocaloric Heat Pump Prototype and Carnot Cycle
Mönch, Stefan; Reiner, Richard; Mansour, Kareem; Basler, Michael; Waltereit, Patrick; Quay, Rüdiger; Bartholome, Kilian
Konferenzbeitrag
Conference Paper
2022 Electrocaloric temperature changes in epitaxial Ba1-xSrxTiO3 films
Magalhaes, Bruno; Engelhardt, Stefan; Molin, Christian; Gebhardt, Sylvia; Nielsch, Kornelius; Hühne, Ruben
Zeitschriftenaufsatz
Journal Article
2022 Enhancing Electrocaloric Heat Pump Performance by Over 99% Efficient Power Converters and Offset Fields
Mönch, Stefan; Reiner, Richard; Waltereit, Patrick; Molin, Christian; Gebhardt, Sylvia; Bach, David; Binninger, Roland; Bartholome, Kilian
Zeitschriftenaufsatz
Journal Article
2022 A GaN-based DC-DC Converter with Zero Voltage Switching and Hysteretic Current Control for 99% Efficient Bidirectional Charging of Electrocaloric Capacitive Loads
Mönch, Stefan; Mansour, Kareem; Reiner, Richard; Basler, Michael; Waltereit, Patrick; Quay, Rüdiger; Molin, Christian; Gebhardt, Sylvia; Bach, David; Binninger, Roland; Bartholome, Kilian
Konferenzbeitrag
Conference Paper
2021 Structural and Electric Properties of Epitaxial Na0.5Bi0.5TiO3-Based Thin Films
Magalhaes, Bruno; Engelhardt, Stefan; Molin, Christian; Gebhardt, Sylvia; Nielsch, Kornelius; Hühne, Ruben
Zeitschriftenaufsatz
Journal Article
Diese Liste ist ein Auszug aus der Publikationsplattform Fraunhofer-Publica

This list has been generated from the publication platform Fraunhofer-Publica

Sub projects

Overall system and simulation

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  

Projekt ElKaWe: Experimentier-Plattform für den Aufbau elektrokalorischer Wärmepumpen
© Fraunhofer IPM
Measurement platform for the characterization of electrocaloric segments.
ElKaWe project: Laboratory platform for the construction of electrocaloric heat pumps
© Fraunhofer IPM
Electrocaloric segment integregrated into a measurement platform.
ElKaWe project: Laboratory platform for the construction of electrocaloric heat pumps
© Fraunhofer IPM
Electrocaloric segment

Ceramic materials and components

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.

Hybrid materials

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.

Coatings

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).

Electrical control

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.

System Reliability and durability

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.

 

Further information

Caloric Systems

We are conducting research into magnetocaloric, elastocaloric and electrocaloric systems for cooling and heating.