PhD defence: Designing optimal magnets for magnetocaloric heat pumps

Wednesday 02 Nov 16

On November 1, 2016 Andrea Roberto Insinga from DTU Energy successfully defended his PhD thesis with the title “Optimising Magnetostatic Assemblies”.

Permanent magnets are used in many different technical and scientific contexts, e.g. in motors, gears, generators and in medical and scientific instruments. The stronger the magnetic field required, the more expensive the magnets become. This makes it important to find the optimal use of them.

For the past three years Andrea Roberto Insinga has investigated the best way of combining individual magnets to achieve a magnetic field with the required properties for a given application. In this case his object has been to develop a magnet system for a magnetocaloric heat pump. His work was done within the project ENOVHEAT which will ultimately result in a prototype heat pump for a single-family house, based on magnetocaloric materials which change temperature in a magnetic field.

“The goal of my thesis was to find the best arrangement of both permanent magnets and electromagnets to obtain a magnetic field with the most desirable features, depending on the application. In ENOVHEAT we are creating a new heat pump design based on the magnetocaloric effect. The magnet system is a crucial component of the device. My part in the project was to find the optimal shape of the permanent magnets to get the desired effect”, Andrea says.

"Instead of figuring out what arrangement of magnet blocks could produce the desired effect and trying to improve from there, you start with the field you want and then you directly calculate the optimal shapes"
Andrea Roberto Insinga, DTU Energy

The magnets are combined to create a magnetic field with adjacent regions of high and low intensity. As the device rotates, the magnetocaloric material experiences alternately a high field and a low field which makes it become colder and hotter by turns.  This allows one to use it in a heat pump. The technique can also be used for cooling. To find the optimal arrangement of magnets, Andrea uses an algorithm he has developed during his project.

“Instead of figuring out what arrangement of magnet blocks could produce the desired effect and trying to improve from there, you start with the field you want and then you directly calculate the optimal shapes”, says Andrea.

Andrea Roberto Insinga came to DTU Energy knowing a lot about quantum physics but little about magnets, so he had to learn a lot about magnet systems and their properties during his PhD.

“It was a new topic, so I had to learn a lot. That is the best part of studying: to learn new things, to get to know a new area of research, and most of all to get to know and work with amazing people, and I had the good fortune to experience that here at DTU Energy. I love working here”, Andrea says.

Even though his PhD study at DTU Energy has come to an end, Andrea is not finished with magnetocalorics, as he is currently working on a related postdoc project in the department.

Read more about research in magnetic cooling and heating at DTU Energy