Direct Measurement of the Magnetocaloric Effect in Gd Based Alloy

A magnetocaloric refrigeration test setup for adiabatic cooling near room temperature has been designed. This setup enables the magnetization (adiabatic heating) and demagnetization processes (adiabatic cooling) of magnetocaloric material fast. We have measured adiabatic temperature change (Delta T-ad) for bulk gadolinium during magnetization and demagnetization processes under 1 T magnetic field over the temperature range 4 to 34 degrees C. The Delta T-ad vs temperature curve shows asymmetric nature around the peak temperature. The fall in Delta T-ad is more gradual above the peak temperature, whereas it falls relatively fast below the peak temperature. The existence of domains even after removal of magnetic field (below peak temperature) could be responsible for the observed behavior. The present setup can be used to optimize the magnetization or demagnetization process as well as heat exchange with the hot and cold heat exchangers, which will enable us to improve the efficiency of the magnetic refrigerator device.