The paper presents magnetic parameters of LaFexCoySi1.1 bulk specimens proving strong magnetocaloric eect. The main research work was oriented on measurements of the alloy's power losses according to IEC 60404 standards and validated with unbalanced bridge method and other methods. The measurements of the LaFe10.8Co1.1Si1.1 specimens were determined in the range of temperatures near the Curie temperature where the magnetocaloric eect is the strongest. Power losses were taken into account mainly for the evaluation of usefulness and eciency in the magnetic refrigeration applications. The results of presented measurements testify that the most suitable range of temperature and the best operational conditions are very close to the point of magnetic phase transition and slightly above it. It indicates that the magnetic state between the T∆Smax and Tc is more eective for the magnetic refrigeration applications due to lower power losses and high level of the isothermal changes of entropy. Operating temperature below the T∆Smax in ferromagnetic state is improper because of the increasing power losses which achieve the level of 130 mJ/kg for main frequency and decrease to 20 mJ/kg for the value of 0.1 Hz.
The topic of this paper is modeling based on Hamiltonian spin interactions. Preliminary studies on the identification of quasi-static magnetizing field in a magnetic system were presented. The random-field Ising model was then used to simulate the simplified ferromagnetic structure. The validation of algorithms and simulation tests were carried out for the 2D and the 3D model spaces containing at least 106 unit cells. The research showed that the response of a slowly driven magnetic system did not depend on the external field sweep rate. Changes in the spatial magnetization of the lattice were very similar below a certain rate of the external field change known as the quasi-static boundary. The observed differences in obtained magnetization curves under quasi-static conditions stemmed from the random nature of the molecular field and the avalanche-like magnetization process
The paper concerns the design and development of large electric energy storage systems made of lithium cells. Most research advances in the development of lithium-ion battery management systems focus solely on safety, functionality, and improvement of the procedures for assessing the performance of systems without considering their energy efficiency. The paper presents an alternative approach to the design and analysis of large modular battery management systems. A modular battery management system and the dedicated wireless communication system were designed to analyze and optimize energy consumption. The algorithms for assembly, reporting, management, and communication procedures described in the paper are a robust design tool for further developing large and scalable battery systems. The conducted analysis of energy efficiency for the exemplary 100S15P system shows that the energy used to power the developed battery management system is comparable to the energy dissipated due to the intrinsic self-discharge of lithium-ion cells.
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