Exergoeconomic analysis of potential magnet configurations of a magnetic refrigerator operating at 4.2 K

Abstract

This article compares the exergetic cost of cooling of an Adiabatic Demagnetization Refrigerator (ADR) providing 1W of refrigeration at 4.2 K, with two different magnetic field sources: a Nb3Sn superconducting (SC) magnet and a NdFeB permanent magnet (PM) Halbach cylinder. The total cost of the system is assumed to be comprised of two components: the cost of the magnetocaloric material (MCM), which is a function of the total volume of the MCM, and the cost of the magnetic system, which depends on the MCM volume and the peak magnetic field. The exergetic cost of cooling for different values of mass (volume) of MCM and hot source temperatures are shown in the article, assuming a specific cost of the SCwire of 890$/kg, 3500$/kg for the MCM, and 100$/kg for the PM. The SC appear to be the most cost-effective solution for the system. However, if large temperatures spans are required between the hot source and the cold source PMs emerge as a better option.