Turning the concept of magnetocaloric cooling on its head

Exploit the hysteresis, not avoid

Smart design of materials

Computing power

Advanced laboratory equipment

Welcome to COOL INNOV

The outstanding research at the Functional Materials group of TU Darmstadt for the substitution of critical raw materials and materials for energy technologies has been recognized by honoring Prof. Dr. Oliver Gutfleisch with ERC Advanced Grant COOL INNOV.

COOL INNOV will attempt to achieve a breakthrough in caloric cooling based on magnetocaloric materials by rethinking the whole concept of this technology. Instead of the conventional idea of squeezing the best out of magnetostructural phase-change materials in relatively low magnetic fields, a second stimulus introduced in the form of pressure can help the COOL INNOV team to exploit, rather than avoid, the hysteresis that is inherent in these materials. It should lead to more efficient refrigeration, with a commercially viable technology that could satisfy the urgent global need.

COOL INNOV received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant no. 743116 - project Cool Innov).

COOL INNOV Research

Safe and efficient magnetic refrigeration
 
Safe and efficient magnetic refrigeration
Environmentally friendly and energy efficient alternative to the conventional cooling based on the magnetocaloric effect, taken one step further
Team
 
Team
The Cool Innov team consists of experienced scientists and young talented students working in experimental and theoretical physics
First principle calculations
 
First principle calculations
DFT-based high-throughput search for new compounds combined with detailed phase transitions calculations
Finite element method simulations
 
Finite element method simulations
FEM simulations including micromagnetics for calculating the magnetic properties and behavior of new magnetocaloric materials
Publications
 
Publications
Articles published in the framework of the project and other articles on the topic of multi-calorics and related physics
Additive manufacturing
 
Additive manufacturing
Implementing 3D printing for engineering heat exchangers with complex structures from magnetocaloric materials
Development of new materials
 
Development of new materials
Synthesis and modification using advanced processing routes of mechanically stable materials with the large magnetocaloric effect
Multi-stimuli concept
 
Multi-stimuli concept
Utilization of magnetic field and uniaxial mechanical stress for enhancing the efficiency of magnetocaloric devices
Devices and equipment
 
Devices and equipment
Modern techniques and versatile devices are available to characterise the magnetic and mechanical properties of new materials

Latest work

Maximum performance of an active magnetic regenerator

Magnetocaloric materials change their temperature when a magnetic field is applied or removed, which allows building a magnetic cooling device. We derive an analytical expression for the maximum heat that such a material can transfer in one cooling cycle by investigating the operation of a simplified active magnetic regenerator (AMR). The model largely only depends on the adiabatic temperature change, the specific entropy change, and the temperature span between the hot and cold reservoirs. While this expression overestimates the performance of a real AMR due to its simplification, it can predict an upper limit of any AMRs' performance independent of the implementation details. Based on this, we calculate the upper limit of the cooling power of magnetic cooling devices at any temperature span, frequency, mass, and material. This upper limit is used to predict how the thermal span is scaling with the applied magnetic field, and it can be utilized for the optimization of the magnetic field source. Additionally, we confirm that the product of isothermal entropy and adiabatic temperature change, already used in the literature, is a suitable figure of merit for magnetocaloric materials.

The article Maximum performance of an active magnetic regenerator by D. Benke, M. Fries, T. Gottschall, D. Ohmer, A. Taubel, K. Skokov, and O. Gutfleisch is published in Applied Physics Letters 119, 203901 (2021). See more of our activity in News
Microstructure engineering of metamagnetic Ni-Mn-based Heusler compounds by Fe-doping: A roadmap towards excellent cyclic stability combined with large elastocaloric and magnetocaloric effects

Ni-Mn-based metamagnetic shape-memory alloys are highly promising for solid-state caloric cooling applications but commonly exhibit structural and functional fatigue during cyclic operation. In this work, we present exemplarily for Ni-Mn-In a microstructure design which allows to achieve excellent cyclic stability together with large magnetocaloric and elastocaloric effects.

The article Microstructure engineering of metamagnetic Ni-Mn-based Heusler compounds by Fe-doping: A roadmap towards excellent cyclic stability combined with large elastocaloric and magnetocaloric effects by L. Pfeuffer, J. Lemke, N. Shayanfar, S. Riegg, D. Koch, A. Taubel, F. Scheibel, N. A. Kani, E. Adabifiroozjaei, L. Molina-Luna, K. P. Skokov and O. Gutfleisch is published in Acta Materialia 221 (2021) 117390. See more of our activity in News