Lab News

AMR experimental
The Permanent Magnet Magnetic Refrigerator (PMMR) is in the testing phase. Currently only gadolinium as refrigerant has been used. The refrigerator recorded temperature spans up to 30C, cooling power up to 50W (with 10C temperature span), and efficiencies (including all mechanical losses) with a COP up to 1.6.

The Passive Regenerator Test Apparatus (PRTA) has been completed and it is now operative. Heat transfer correlations and friction factor have been evaluated using the experimental data for 1mm diameter ss spheres.

Large temperature span and cooling power have been obtained with Gadolinium-GadoliniumTurbium-GadoliniumErbium layering. Temperature spans up to 85 K and up to 30 W cooling have been achieved with a two regenerator array, of 135 g each and 5 T field. For the first time data is unquestionably proving that material layering is the path to pursue. GdSiGe alloy is currently tested for cryogenic cooling (below 85 K).

AMR modeling
A one dimension numerical model has been developed and validated against experimental results. Further model refinement is in progress. A first attempt to regenerator layering optimization has been conducted. The model also explored regenerator performance in a range of operating parameters beyond the experimental apparatus capabilities. Demagnetization effects are also being studied through a 2D model for low field (<2 T) applications.