MAGNETOCALORICS - Laboratory for refrigeration and district energy

Thermomagnetic conversion of low-grade waste heat: the role of permanent magnet selection

admin — Mon, 31 Aug 2026 08:39:29 +0000

A substantial amount of energy used in industrial and other thermal processes is ultimately released into the environment as low-grade waste heat. Recovering even a fraction of this energy and converting it into useful electricity could contribute to improved overall energy efficiency and a more sustainable use of energy resources. However, efficient conversion of heat available at relatively low temperatures remains a significant technological challenge.

Thermomagnetic energy conversion offers an alternative approach for harvesting low-grade waste heat. It exploits the strong temperature dependence of the magnetic properties of thermomagnetic materials. By cyclically heating and cooling the material around its magnetic transition temperature, changes in magnetization can be used to induce variations in magnetic flux and ultimately generate electrical power.

In our new study, published in iScience (Cell Press), we investigate an important component of a thermomagnetic generator (TMG) that has received comparatively little attention: the permanent magnets used as the magnetic-field source. Their properties directly influence the magnetic field available to the thermomagnetic material and therefore the performance of the complete energy-conversion system. At the same time, permanent-magnet selection also involves important considerations related to material availability, cost, thermal stability, and the use of critical raw materials.

A numerical model of the thermomagnetic generator was used to systematically compare configurations employing three technologically relevant permanent-magnet materials: neodymium-iron-boron (NdFeB), Alnico, and Ferrite. The analysis considers the interaction between the magnetic field source and the thermomagnetic material and evaluates the resulting electrical response of the generator, including output power, voltage, and current during cyclic operation.

The results demonstrate how strongly the choice of permanent magnet can influence the performance of a thermomagnetic generator. While high-performance permanent magnets can provide stronger magnetic fields and consequently higher electrical output, rare-earth-free alternatives such as Alnico and Ferrite offer different combinations of magnetic properties, temperature stability, material availability, and cost. The comparison therefore highlights that the optimal magnetic-field source cannot be selected solely on the basis of magnetic strength, but should be considered as part of the overall thermomagnetic-generator design.

The study contributes to the development of more efficient and practically viable thermomagnetic energy-harvesting systems and provides guidelines for selecting permanent magnets according to the requirements of a specific application. In the longer term, such systems could provide an additional pathway for converting currently unused low-temperature waste heat into electricity, particularly in applications where conventional heat-to-power technologies are difficult to implement.

The article is available in iScience: link to article.

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Direct Characterization of Electrocaloric and Magnetocaloric Responses in Multicaloric Composite Films

admin — Wed, 01 Jul 2026 05:57:47 +0000

Researchers from the Jožef Stefan Institute, the University of Ljubljana, the University of Barcelona, IFW-Dresden and collaborating institutions have published the article Direct observation of room-temperature electrocaloric and magnetocaloric responses in multicaloric composite films.

The study combines the electrocaloric ceramic PMN-10PT with the magnetocaloric La-Fe-Si-Co (LFSC) alloy. Using Powder Aerosol Deposition (PAD), the team fabricated dense multicaloric composite films approximately 5 μm thick. PAD enables the fabrication of functional thick films entirely at room temperature and offers an attractive route for integrating advanced caloric materials into future cooling devices.
A key achievement of the work is the direct characterization of both electrocaloric and magnetocaloric responses in the same multicaloric composite film at room temperature. The composite films exhibited an approximately 32 % higher electrocaloric temperature change compared to pure PMN-10PT films. The enhancement is attributed to Maxwell–Wagner polarization effects induced by the embedded magnetocaloric particles.
In addition, the magnetocaloric response was directly measured in the same composite films, experimentally confirming their multicaloric functionality and demonstrating the feasibility of combining electrocaloric and magnetocaloric effects within a single aerosol-deposited structure.
The results provide new insights into the development of multifunctional caloric materials and demonstrate the potential of multicaloric composite films for future solid-state cooling and micro-cooling technologies targeting electronics, sensors, and other miniaturized systems.

Link: https://www.sciencedirect.com/science/article/pii/S0955221926004607

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Thermag XI 2026: A successful gathering of the solid-state thermal community

admin — Tue, 16 Jun 2026 06:01:05 +0000

The 11th IIR Conference on Solid-State Cooling, Heating and Energy Harvesting – Thermag XI, held from 7-11 June in Ljubljana, Slovenia, has concluded successfully.

This milestone event brought together researchers, engineers, and industry experts from around the world to exchange the latest advances in solid-state cooling, heating, and energy harvesting. Thermag XI provided a unique forum for sharing cutting-edge research on functional materials, emerging concepts, and their integration into next-generation energy systems.

The presentations reflected a wide range of research activities, from fundamental studies and materials development to device prototyping, modelling, and practical applications that contribute to more sustainable energy technologies. The conference proceedings will be published soon on the IIR website: https://iifiir.org/en/conference-proceedings.

We sincerely thank all authors for their submissions and the reviewers for their valuable contributions. Special appreciation goes to the keynote speakers, session chairs, scientific committee, and organizing team whose efforts made the event possible. We also gratefully acknowledge the support of the International Institute of Refrigeration (IIR), the Slovenian Energy Association (SZE), the Chinese Association of Refrigeration (CAR), the Faculty of Mechanical Engineering at the University of Ljubljana, and all sponsors and partners.

The following topics were presented:

THE CONVENTIONAL AND ROTATING MAGNETOCALORIC EFFECT OF A GADOLINIUM PARALLEL PLATE MAGNETIC REGENERATOR – INFLUENCE OF GEOMETRY (Rafael Almeida, Rodrigo Kiefe, Darja Gačnik, Ricardo M. C. Pinto, João O. Silva, Katja Klinar, Henrique Souza, Gonçalo Oliveira, João S. Amaral, Andrej Kitanovski, João H. Belo)

IMPLEMENTATION AND VALIDATION OF AN ACTIVE ELECTROCALORIC REGENERATOR COMPONENT IN TCC BUILDER (Grega Belšak, Izak Oberčkal Pluško, Katja Vozel, Andrej Kitanovski, Markys Cain, Katja Klinar)

NUMERICAL STUDY ON THE FREQUENCY DEPENDENCE OF THE DIRECT MAGNETOCALORIC EFFECT OF GADOLINIUM FILM (Zhonghao Chang, Jorge Revuelta-Losada, Erika Fontana, Nora Dempsey, Katja Klinar, Andrej Kitanovski, Jia Yan Law, Victorino Franco)

VALIDATION OF THE NUMERICAL SIMULATION OF A HIGH-FREQUENCY REGENERATIVE THERMOMAGNETIC GENERATOR HYPEREG (Kamyar Dobakhti, Katja Klinar, Urban Tomc, Jure Javornik, Andrej Kitanovski)

FINITE ELEMENT MODELING AND OPTIMIZATION OF A MAGNETIC FIELD SOURCE FOR THERMOMAGNETIC GENERATION (Radel Gimaev, Katja Klinar, Andrej Kitanovski)

NUMERICAL MODELING OF AN ACTIVE MAGNETIC REGENERATOR BASED ON THE ROTATIONAL MAGNETOCALORIC EFFECT (Radel Gimaev, Darja Gačnika, Urban Tomc, Rafael Almeida, Rodrigo Kiefe, João H. Belo, João S. Amaral, Katja Klinar, Andrej Kitanovski)

PHASE-CHANGE MATERIAL THERMAL DIODES FOR CALORIC REFRIGERATOR (Karl Joulain, Katja Klinar, Katja Vozel, Andrej Kitanovski, Younès Ezzahri)

A GENERALIZED MODELLING APPROACH FOR ACTIVE ELECTROCALORIC REGENERATORS (Matija Kalin, Darja Gačnik, Katja Klinar, Andrej Kitanovski)

HYPEREG: HIGH-FREQUENCY MAGNETOCALORIC REGENERATOR (Andrej Kitanovski, Katja Klinar, Jure Javornik, Simon Nosan, Jakob Perne, Simon Bogić, Blaž Jagodic, Urban Tomc)

THE PERSPECTIVES OF ULTRA-HIGH-TEMPERATURE SOLID-STATE HEAT PUMPS (Katja Klinar, Darja Gačnik, Radel Gimaev, Andrej Kitanovski)

BRIDGING THE THERMAL GAP: THE ROLE OF FLUIDIC AND MECHANICAL THERMAL CONTROL DEVICES IN ADVANCING CALORIC TECHNOLOGIES (Katja Klinar, Urban Tomc, Katja Vozel, Andrej Kitanovski)

THERMAL CONDUCTIVITY OF CELLULOSE-BASED COMPOSITE FILMS (Vanja Kokol, Vera Vivod, Katja Klinar)

MODELING OF THERMOACOUSTIC GENERATOR IN TCCBUILDER (Izak Oberčkal Pluško, Harini Nivetha Raja, Grega Belšak, Jingyuan Xu, Katja Vozel, Andrej Kitanovski, Katja Klinar)

EVALUATION OF CURIE TEMPERATURE EFFECTS IN THE PERFORMANCE OF ACTIVE MAGNETIC REGENERATORS – PART I: SECOND ORDER PHASE TRANSITION (Urban Tomc, Guilherme F. Peixer, Chistian R. H. Bahl, Kaspar K. Nielsen, Jaime A. Lozano, Jader R. Barbosa Jr., Andrej Kitanovski)

DIGITAL MICROFLUIDIC THERMAL SWITCH CAPACITORS FOR MAGNETOCALORIC COOLING (Blaž Velkavrh, Hana Uršič, Urška Erjavec Nagode, Andrej Kitanovski, Lukas Beyer, Jens Freudenberger, Klara Lünser, Enric Stern-Taulats, Lluis Mañosa, Urban Tomc)

ENHANCING SOLID-STATE THERMAL RECTIFICATION VIA TEMPERATURE-DEPENDENT THERMAL CONTACT RESISTANCE (Katja Vozel, Andrej Kitanovski)

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Cool BatMan featured as M-ERA.NET Success Story

admin — Tue, 10 Feb 2026 13:40:49 +0000

The Cool BatMan project has been recognized as a Success Story by M-ERA.NET.

The project aimed to build a fundamental understanding of the dynamic thermal behavior of a compact cooling concept. It combines magnetocaloric materials, exploiting the magnetocaloric effect, with electrowetting-on-dielectric (EWOD) digital microfluidics. The work included advanced microfabrication and new characterization approaches.

A key outcome is the demonstration that digital microfluidics, widely used in bioanalytical lab-on-a-chip systems, also has strong potential for thermal management at the mini- and microscale.

We thank our consortium partners: Jožef Stefan Institute, Leibniz Institute for Solid State and Materials Research Dresden, and the University of Barcelona. We also thank M-ERA.NET for the recognition.

Read the full success story here:
https://www.m-era.net/news/successtory_coolbatman

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A completed research secondment at the Bundesanstalt für Materialforschung und -prüfung (BAM)

admin — Tue, 13 Jan 2026 11:16:20 +0000

Our PhD student Kamyar Dobakhti recently completed a research secondment at the Bundesanstalt für Materialforschung und -prüfung (BAM). This secondment provided valuable hands-on experience in X-ray tomography and Life Cycle Assessment (LCA) methodologies relevant to thermomagnetic heat exchanger development.

During his stay at BAM, Kamyar visited several X-ray tomography facilities and a mechanical testing setup, gaining in-depth insight into tomography procedures for structural characterization and defect analysis. Close collaboration with experts in the field enabled a detailed understanding of how these techniques can be applied to optimize manufacturing parameters and material design.

Furthermore, precise geometrical parameters extracted from the X-ray tomography data were directly incorporated into numerical simulations. The primary focus of the secondment was the development of a numerical model to evaluate the heat transfer characteristics of different heat exchanger geometries, supporting the optimization of thermomagnetic heat exchanger performance.

A heartfelt thank you to Dr.-Ing. Anja Waske, Heike Q. and Savvina Papaioannou from BAM for their warm welcome and support. I also want to express my gratitude to our group leaders, the Laboratory for Refrigeration and District Energy, and the entire team for providing me with this incredible opportunity.

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Emerging opportunities for high-temperature solid-state and gas-cycle heat pumps

admin — Sun, 21 Dec 2025 12:51:38 +0000

Researchers from the Laboratory for Refrigeration and District Energy (LAHDE), together with an international team, have published a study in Nature Energy (Springer Nature), the world’s leading scientific journal in the field of energy. The paper offers the first comprehensive assessment of an often-overlooked opportunity: alternative high-temperature heat-pump technologies that could replace inefficient fossil-fuel combustion and direct electric heating in industry and the energy sector. Doing so could significantly reduce energy use, greenhouse-gas emissions, and thermal pollution.

Heat lies at the core of the energy challenge. Around 50% of final energy consumption is used for heating and cooling, and roughly 50% of final energy is ultimately released as waste heat—heat that is frequently discharged into the environment via cooling towers, the warming of rivers or seawater, and other outlets. The study shows that high-temperature heat pumps can capture this waste heat and upgrade it efficiently to much higher temperature levels, suitable for demanding industrial processes.

Today’s commercial high-temperature heat pumps are typically limited to about 250 °C, whereas many industrial processes require higher temperatures—up to, or even beyond, 1000 °C. The newly published research therefore systematically presents and compares alternative approaches that could enable a step change: caloric, thermoelectric and thermoacoustic technologies, as well as mechanical processes based on Stirling and Brayton cycles.

Link: https://www.nature.com/articles/s41560-025-01908-4

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Delft days on magnetocaloric 2025

admin — Wed, 26 Nov 2025 14:30:08 +0000

On November 20 and 21, the 6th DDMC Conference took place in Delft, Netherlands, organized by the Technical University of Delft.

During the conference, our student Kamyar Dobakhti presented his poster on the Numerical simulation of a high-frequency regenerative thermomagnetic generator, which attracted significant interest from attendees.

Additionally, Professor Dr. Andrej Kitanovski delivered an invited talk titled Magnetocaloric Cooling and Heat Pump Technologies: Competitive Outlook, which was highly regarded.

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Heat4Energy School “Simulations, data mining and artificial intelligence”

admin — Wed, 26 Nov 2025 14:20:29 +0000

From November 17th to 19th, the school “Simulations, data mining and artificial intelligence” took place in Delft, Netherlands, for PhD students participating in the HEAT4ENERGY project. The event was hosted by partners at the Technical University of Delft (TUD).

Over the course of this intensive two-day program, students attended lectures on:

Basics of phase field simulations
Modeling of active magnetocaloric regenerators for heat pump applications
Developing multiphysics software using finite elements
First-principles theory of magnetic materials
AI in computational Molecules and Materials research

In the practical sessions, participants engaged in hands-on exercises in finite elements, and the first-principles theory method.

In addition, students received insightful presentations on Science Communication and Commercializing magnetocaloric materials by Magneto. The program also included visits to Magneto and the Yes!Delft startup incubator.

Overall, the workshop was highly productive and sparked strong interest and engagement among all participants.

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MAGCCINE – 1st annual meeting in Grenoble

admin — Thu, 23 Oct 2025 13:19:37 +0000

The first annual meeting of the MAGCCINE consortium took place on 17 October 2025 in Grenoble. The event was hosted by the Institut Néel (CNRS), which, together with MagREEsource, provided excellent organization and a warm welcome to all participants.

The meeting offered an exceptional opportunity for project partners to present the achievements of the first year of collaboration, exchange ideas, and outline the next steps in the development of a vaccine cooler prototype based on the rotating magnetocaloric effect. At the heart of the event was collaboration: exchanging ideas, reviewing progress, and planning future activities between academic and industrial partners. The discussions were enriched by in-depth scientific exchanges on cooling, magnetism, and related innovations.

The meeting was further enhanced by contributions from Advisory Board members, including representatives of the International Institute of Refrigeration (IIR) and Tecnea – Cemafroid, who provided valuable insights into key issues related to innovation and standardisation in the field of cooling technologies.

The programme also included a visit to MagREEsource, a company specialising in sustainable development and the recycling of used magnets. Their production capacities, scientific approach to designing the entire recycling value chain, and their clear sustainability vision left a strong impression on all participants.

The first annual MAGCCINE consortium meeting inspired everyone involved and strengthened the shared sense of responsibility for further developing technologies with the potential to significantly contribute to more sustainable solutions for global cold chains.

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AI-Driven Monte Carlo Uncertainty Analysis of Curie Temperature Effects on Active Magnetic Regenerator Performance

admin — Mon, 06 Oct 2025 08:51:19 +0000

In the paper AI-Driven Monte Carlo Uncertainty Analysis of Curie Temperature Effects on Active Magnetic Regenerator Performance, published in the International Journal of Refrigeration (IF = 3.8), researchers from the Laboratory for Refrigeration and District Energy revisited the methodology for analyzing the impact of statistical variations in Curie temperature on the performance of multilayer magnetocaloric regenerators, as previously established in a recent publication [link].

The study was conducted in collaboration with colleagues from the Federal University of Santa Catarina (Brazil), this time using their numerical model of a multilayer active magnetic regenerator (AMR) combined with machine learning. Instead of second-order materials, the study focused on first-order LaFeSiH magnetocaloric materials, which are even more sensitive to Curie temperature distributions.

Once again, the study revealed that Curie temperature deviations above 1 K drastically reduce the probability of achieving the target cooling power. Given current margins provided by MCM suppliers (standard deviations between 1.5 and 2 K) and a typical AMR layer count (10 to 15), the cooling power would need to be oversized by 30% to 80% to ensure a 90–95% probability of meeting performance targets. In practice, this would require oversized magnets and regenerators, significantly increasing production costs.

Thus, large-scale production of magnetic refrigeration devices with current LaFeSiH materials is unfeasible, as quality assurance standards would require much tighter control over Curie temperature uncertainty than currently offered by manufacturers. For a successful market deployment of magnetocaloric technology, MCM manufacturers will need to prioritize reducing Curie temperature variability in their materials.

Figure: a) Schematic representation of a multilayer AMR and the Curie temperature deviation. Solid lines represent the original curves and dashed lines represent the ones achieved by the manufacturing process, b) Effect of the uncertainty of the Curie Temperature on the performance of the 10 layer AMR, c) Cumulative Distribution Function for the 10 layer AMR, d) Effect of the certainty level on the achieved performance of the 10 layer AMR.

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