Mathematical Modeling of Magnetic Regenerator Refrigeration Systems

ABSTRACT: Active magnetic regenerative refrigeration (AMRR) systems are designed based on magnetocaloric effect of some special solid materials, such as Gadolinium-Silicon-Germanium, Ferrum-Rhodium, etc. During the last three decades, a variety of cooling systems have been proposed using magnetic materials at room temperature. In this thesis, an AMRR system using FeRh as refrigerant is studied. For the simulation, a one-dimensional, time-varying mathematical model is developed. This model consists of two energy equations for the heat transfer fluid and the regenerator which are descritized by finite difference method. The simulation begins at an initial temperature distribution in the regenerator and fluid and takes time steps forward in time and space until the steady state is attained. On the other hand, in order to simulate the system, it was necessary to obtain and code the properties of the FeRh alloy, especially the entropy. The entropy of the alloy was calculated by using the specific heat experimental data. The coding procedure of properties was done by surface fitting and additional interpolation. To verify the developed model, the temperature distribution in the regenerator was obtained for all stages using Gadolinium as the refrigerant validated with some published results. At last, the performance of the refrigerator was optimized in terms of refrigerant porosity, mass flow rate, and type of the heat transfer fluid. The capability to give acceptable results of the performance of the system proves that the model is a powerful tool to predict the performance of AMRR systems. Besides, the high performance of the AMRR gained in this study, shows that this upcoming technology will be a suitable alternative for space cooling in the near future. ……………………………………………………………………………………………………………………………………………………………………………………………………………………