1D models of an active magnetic regeneration cycle for cryogenic applications

In investigation of an active magnetic regenerator (AMR) cycle operating at room temperatures, 1D models have been extensively used to accurately computing its performance metrics. However, extending these models to simulate an AMR cycle at cryogenic temperatures introduces inherent complexities and challenges. The broad temperature span and low operating temperatures required for cryogenic applications, such as hydrogen liquefaction, lead to significant density variations of the working fluid within the AMR that cannot be overlooked. In this work, two 1D AMR models assuming a compressible working fluid operating at cryogenic temperatures are demonstrated which address the large density variations and the numerical stiffness of the equations. The models exhibit good agreement with experimental and 2D numerical results of an AMR configuration designed for hydrogen liquefaction. A comparative study is conducted between the developed models and an incompressible AMR model at cryogenic temperatures shows that the incompressible model predicts cooling powers that are higher by a factor of up to 10 at high values of utilization, highlighting the error of assuming an incompressible fluid on estimating the performance metrics.