Evaluation of magnetocaloric material optimization and magnetic field design for magnetic refrigeration systems
Magnetic refrigeration has emerged as a promising alternative to vapor-compression systems owing to its refrigerant-free operation and high theoretical efficiency based on the magnetocaloric effect (MCE). Recent research has focused on advancing both material-level and system-level aspects of the active magnetic regenerator (AMR) cycle. On the material side, multilayer AMRs composed of magnetocaloric materials with graded Curie temperatures have proven effective in extending the achievable temperature span. On the system side, various magnetic field configurations, including electromagnet-based, rotating permanent magnet, and reciprocating linear designs, exhibit distinct trade-offs in terms of field strength, controllability, compactness, and energy efficiency. While high magnetic fields maximize the intrinsic magnetocaloric response, systemlevel performance is increasingly constrained by mechanical losses, parasitic power consumption, and irreversible processes. Accordingly, this review emphasizes that future progress should prioritize efficient magnetic circuit design under moderate magnetic fields and the mitigation of irreversible losses such as heat transfer limitations and flow non-uniformity, rather than solely enhancing the reversible magnetocaloric effect. By synthesizing recent advances from a system-oriented perspective, this work highlights key design tradeoffs and outlines research directions critical for the scalable, high-COP commercialization of magnetic refrigeration technologies.