An efficient numerical scheme for the simulation of parallel-plate active magnetic regenerators

A one-dimensional model of a parallel-plate active magnetic regenerator (AMR) is presented in this work. The model is based on an efficient numerical scheme which has been developed after analysing the heat transfer mechanisms in the regenerator bed. The new finite difference scheme optimally combines explicit and implicit techniques in order to solve the one-dimensional conjugate heat transfer problem in an accurate and fast manner while ensuring energy conservation. The present model has been thoroughly validated against passive regenerator cases with an analytical solution. Compared to the fully implicit scheme, the proposed scheme achieves more accurate results, prevents numerical errors and requires less computational effort. In AMR simulations the new scheme can reduce the computational time by 89%.B. Torregrosa-Jaime acknowledges the Spanish Ministry of Education, Culture and Sport (Ministerio de Educacion, Cultura y Deporte) for receiving the Research Fellowship FPU ref. AP2010-2160.Torregrosa Jaime, B.; Corberán Salvador, JM.; Payá Herrero, J.; Engelbrecht, K. (2015). An efficient numerical scheme for the simulation of parallel-plate active magnetic regenerators. International Journal of Refrigeration. 58:121-130. https://doi.org/10.1016/j.ijrefrig.2015.06.007S1211305

Application of magnetic cooling in electric vehicles

The features of an active magnetic regenerator refrigerator (AMRR) are determined for its application in mobile air-conditioning (MAC) systems. The thermal requirements of an electric vehicle have been firstly obtained and result in a cooling demand of 3.03 kW at a temperature span of 29.3 K. A comprehensive parametric study has been conducted in order to find the AMRR design and working parameters that fulfill the vehicle needs with a minimum electric consumption and device mass. Specifically, a permanent-magnet parallel-plate AMRR made of Gd-like materials is considered. According to the possibilities of current prototypes, in the study the cycle frequencies have been limited to 10 Hz and the applied magnetic fields, to 1.4 T. The results show that an AMRR made of plates between 30 and 40 µm thick and channels between 20 and 40 µm high could meet the vehicle demand with a COP between 2 and 4 and a total mass between 20 and 50 kg. Compared to vapor-compression devices for MAC systems (COP=2.5 and mass 12 to 15 kg), the AMRR works optimally with fluid flow rates at least 3 times larger. In order to integrate AMRRs into MAC systems, the hydraulic loops should be consequently redesigned.Barbara Torregrosa-Jaime acknowledges the Spanish Ministry of Education, Culture, and Sport (Ministerio de Educacion, Cultura y Deporte) for the Research Fellowship FPU ref. AP2010-2160.Torregrosa Jaime, B.; Payá Herrero, J.; Corberán Salvador, JM. (2016). Application of magnetic cooling in electric vehicles. Science and Technology for the Built Environment. 22(5):544-555. doi:10.1080/23744731.2016.1186459S54455522