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Magnetocaloric refrigeration is based on solid-state refrigerants exhibiting magnetocaloric effect, detected in a temperature change of the materials due to the adiabatic variation of the intensity of a magnetic field applied to it. Magnetocaloric refrigeration could represent potentially an alternative to vapor compression since the former is more environmentally-friendly. The reference thermodynamical cycle is AMR cycle, applied to a solid-state structure made by the magnetocaloric material, placed between a cold and a hot heat exchanger and subjected to alternative magnetization/demagnetization cycles. To vehiculate the fluxes between cold and hot heat exchangers, a heat-transfer fluid is used: it usually is water or a water-ethylene mixture for sub-zero applications, but innovative solutions could be adopted, such as nanofluids in order to enhance the thermal conductivity of the resulting fluid. In this paper we report the results of an investigation conducted on a parallel-plate AMR refrigerator, employing nanofluids (Al2O3 and CuO) as heat-transfer medium. The analysis was perpetuated changing both the nanofluid volume concentration and the magnetocaloric material. The results are reported in terms of cooling power and coefficients-of-performance and we detect that the effect of using a water-based nanofluid is always positive in terms of the energy performances of the AMR refrigerator.
nanofluids, magnetic refrigeration, magnetocaloric, AMR, heat transfer fluid, CuO
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