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Measurement of the magnetization of materials in high magnetic fields under adiabatic conditions

Keywords:

E.T. Dilmieva – Post-graduate Student, Bauman MSTU. E-mail: kelvit@mail.ru A.P. Kamantsev – Post-graduate Student, Kotelnikov IRE RAS A.V. Mashirov – Trainee Researcher, Kotelnikov IRE RAS V.V. Koledov – Dr.Sc. (Phys.-Math.), Leading Researcher, Kotelnikov IRE RAS


We developed a system for measuring the magnetization of samples of materials in strong magnetic fields in the adiabatic regime. A method in-situ simultaneous measurement of the magnetization of the sample on the magnetic field in the quasi-adiabatic conditions and the magnetocaloric effect (MCE) is worked out. For a sample of Gd it is shown that due to the MCE, with increasing magnetic field up to 14 T, the sample temperature T increases from 24 0С to 38 0С (ΔT = 14 0C), and when the magnetic field decreases to 0 T decreases from 38 0С to 18 0С (ΔT = 20 0C). The resulting change in temperature for a series of ΔT = -6 0С is a consequence of the process of magnetic cooling. The dependence of the magnetization of the sample on the magnetic field exhibits hysteresis. Counting integral \"HdM\" in a closed circuit allows us to determine the work of the magnetic field in the loop and calculate the coefficient of efficiency of the process (CОP) magnetic cooling. He was as follows: at the maximum magnetic field 14 T CОР = 9 and by reducing the magnetic field of the CОP increases sharply for H = 2 T CОP = 92. We discuss the reasons for the CОP significantly below the fundamental limitations imposed by Carnot\'s theorem.
References:
  1. Sharma S., Dwivedi V.K., Pandit S.N.Exergy analysis of single-stage and multi stage thermoelectric cooler // Int. J. Energy Res. 2014. V. 38. R. 213–222.

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