Use of unidirectional flow modes of magnetic cooling systems

A combination magnetic refrigerator-freezer apparatus, comprising:

• a refrigerator compartment that is maintained above 0 C;
• a freezer compartment that is maintained below 0 C;
• a controller;
• one or more magnets configured to generate one or more time-varying magnetic fields;
• a first magnetic refrigeration system for the refrigerator compartment comprising:
• a first set of one or more beds of magnetocaloric material;
• a first heat transfer fluid (HTF);
• a first pump to drive flow of the first heat transfer fluid;
• a hot side heat exchanger (HHEX);
• a first cold side heat exchanger (CHEX);
• a first section of an inter-stage heat exchanger (IHEX);
• one or more first valves to direct flow of the first heat transfer fluid;
• and
• wherein the controller is configured to control the periodic switching of the one or more valves to direct the first HTF to a cold end of the first set of one or more beds through the first set of one or more beds to a hot end of the first set of one or more beds and through the HHEX when the time-varying magnetic field applied to the first set of one or more beds is high, and to the hot end of the first set of one or more beds through the first set of one or more beds to the cold end of the first set of one or more beds and through the first CHEX and the first section of the IHEX when the time-varying magnetic field applied to the first set of one or more beds is low, in order to transfer heat from the first CHEX and the first section of the IHEX to the HHEX;
• and
• a second magnetic refrigeration system for the freezer compartment comprising:
• a second set of one or more beds of magnetocaloric material;
• a second heat transfer fluid;
• a second pump to drive flow of the second heat transfer fluid;
• a second CHEX;
• a second section of the IHEX;
• one or more second valves to direct flow of the second heat transfer fluid;
• and
• wherein the controller is configured to control the periodic switching of the one or more valves to direct the second HTF to a cold end of the second set of one or more beds through the second set of one or more beds to a hot end of the second set of one or more beds and through the second section of the IHEX when the time-varying magnetic field applied to the one or more beds is high, and to the hot end of the second set of one or more beds through the second set of one or more beds to the cold end of the second set of one or more beds and through the second CHEX when the time-varying magnetic field applied to the second set of one or more beds is low, in order to transfer heat from the second CHEX via the second section of the IHEX to the first section of the IHEX.