Factors limiting the operation frequency of magnetic refrigerators

Simple calculations lead to a conclusion that there is an upper bound to the frequency at which magnetic refrigerators can operate, f(max)similar to 2x10(2) Hz. The principal factor limiting the operation frequency is a trade-off between thermal conductivity and viscous friction. The main events take place inside the magnetocaloric bed-the fundamental unit of any magnetic refrigerator-largely independently from the rest of the apparatus. (c) 2007 American Institute of Physics.