Simulation investigation of room-temperature reciprocating packed bed magnetic refrigerator cycle: Comparison of magnetocaloric effect evaluated methods

Built-in method and straightforward adiabatic temperature change method have been widely used in the simulation investigation of Active Magnetic Regeneration Refrigeration (AMRR) cycle. Nevertheless, the difference between the abovementioned two approaches has rarely been discussed. In this regard, a simulation study on the reciprocating packed bed magnetic refrigeration cycle is presented with the special emphasis on the influence of the different magnetocaloric effect evaluated methods, where Gd and water working as magnetic material and heat transfer fluid. With the help of Finite Element Method (FEM), the numerical solutions of the thermodynamic equations of Gd and water can be obtained. Utilizing the FEM, the two methods can lead to same results when the time interval approaches zero. For a comparatively large time interval, the accurate heat expelled to the high-temperature reservoir can be achieved via the straightforward adiabatic temperature change method while the accurate heat absorbing from the low-temperature reservoir can be obtained via the built-in method. Moreover, calculated Coefficient of Performance (COP) via the straightforward adiabatic temperature change method is larger than that via the built-in method.