US Patent 9746214 Use of unidirectional flow modes of magnetic cooling systems

A dual-mode magnetic refrigeration apparatus includes beds of magnetocaloric material, a magnet to apply a time-varying magnetic field to the beds, a heat transfer fluid (HTF), a pump to circulate the HTF, a hot side heat exchanger (HHEX), a cold side heat exchanger (CHEX), valves to direct flow of the HTF, and a controller configured to control periodic switching of the valves to allow the apparatus to operate in a first mode and in a second mode. The first mode transfers heat from the CHEX to the HHEX. In the second mode of operation, the periodic switching of the valves is suspended to allow unidirectional flow of the HTF through the HHEX, the beds, and the CHEX such that heat is transferred from the HHEX to the CHEX.