Thermal management is one of the crucial issues in the development of magnetocaloric refrigeration technology for application. In order to ensure optimal exploitation of the materials “primary” properties, such as entropy change and temperature lift, thermal properties (and other “secondary” properties) play an important role. In magnetocaloric composites, which show an increased cycling stability in comparison to their bulk counterparts, thermal properties are strongly determined by the geometric arrangement of the corresponding components. In the first part of this paper, the inner structure of a polymer-bonded La(Fe, Co, Si)13-composite was studied by X-ray computed tomography. Based on this 3D data, a numerical study along all three spatial directions revealed anisotropic thermal conductivity of the composite: Due to the preparation process, the long-axis of the magnetocaloric particles is aligned along the xy plane which is why the in-plane thermal conductivity is larger than the thermal conductivity along the z-axis. Further, the study is expanded to a second aspect devoted to the influence of particle distribution and alignment within the polymer matrix. Based on an equivalent ellipsoids model to describe the inner structure of the composite, numerical simulation of the thermal conductivity in different particle arrangements and orientation distributions were performed. This paper evaluates the possibilities of microstructural design for inducing and adjusting anisotropic thermal conductivity in magnetocaloric composites.

No abstract

No abstract

<p>PASTRI will be a joint pilot study of ConstellR, GFZ Potsdam and FU Berlin for airborne based aerial surface temperature retrieval. The mission is planned as a preparation and demonstrator mission for the upcoming spaceborne thermal satellite microsatellites of ConstellR. ConstellR will provide a land surface temperature (LST) monitoring service with an initial focus on companies in the precision farming industry. The initial minimal viable constellation (MVC) of four microsatellites will offer global, daily LST monitoring at 50 m spatial resolution with 1.5 K radiometric accuracy for a monitoring area capacity comparable to the size of Germany’s agricultural area.</p><p>The authors intend to use a six-week airborne campaign in May/June 2021 as a data delivery pilot to develop and validate the provision of an LST product. In total 18 flights are planned (3 flights/week every second week, 2 flights/day) with the FU Berlin Cessna T207A. On the technical side, the project includes the payload development and adaptation to the mechanical interface of the airplane, the actual (airborne) recording or imagery, as well as setting up the data processing pipeline. The aircraft will be instrumented with an adapted ConstellR Sensor and a thermal hyperspectral Telops HyperCam. This enables a performance evaluation of the microsatellite sensor performance against a hyperspectral reference instrument. Based on that results, final adaptions could be made for the spaceborne sensors. The flights will be performed in Central Germany at agricultural sites and will be supplemented by in-situ reference measurements.</p><p>The concept and the status of preparation of the campaign will be presented.</p>