A proposed magnetic heat pump would contain flow diverters for suppression of undesired flows. If left unchecked, these undesired flows would mix substantial amounts of partially heated and partially cooled portions of a working fluid, effectively causing leakage of heat from the heated side to the cooled side. By reducing the leakage of heat, the flow diverters would increase the energy efficiency of the magnetic heat pump, which potentially offers an efficiency greater than that of a compressor-driven refrigerator.
In a magnetic heat pump of the type in question, a magnetic rotor would play a role analogous to that of the compressor in a compressor-driven heat pump. The outer surface of the rotor would include circumferential channels lined with and separated by walls and partitions containing a magnetic material. Pumps would circulate the working fluid between the heated-side and cooled-side heat exchangers. These pumped flows would be coupled into and out of the circumferential channels of the rotor via stationary ports in a housing in which the rotor turned.
The direction of rotation of the rotor would be opposite the intended direction of the pumped flows. At one location in its circumferential travel (between points 4 and 3 in the figure), the magnetic material would pass through a magnetic field, which would align magnetic moments of electrons in the magnetic material and, thereby, heat the electrons. The heat thus generated would be transferred to the rest of the magnetic material and then to the working fluid flowing toward the heated-side heat exchanger. The heated-side heat exchanger would transfer heat to the environment on that side.
When the magnetic material left the magnetic field at point 3, the freeing of the magnetic moments of the electrons would cool the magnetic material. Because this magnetic cooling would occur immediately after the transfer of heat to the fluid during travel through the magnetic field, the magnetic material would emerge from the magnetic field cooler than it was before it entered the magnetic field. Con-tinued rotation would carry the cooled magnetic material through the region between points 2 and 1, where it would cool the working fluid flowing toward the cooled-side heat exchanger. In the cooled-side heat exchanger, the working fluid would absorb heat from the environment on that side. From there, the fluid would flow into the rotor at point 3, then enter the portion of the rotor in the magnetic field, completing the magnetic heat-pump cycle.
In the absence of flow diverters, there would be spurious flows along two paths through the rotor: from point 2 to point 3, bypassing the cooled-side heat exchanger; and from point 1 to point 4, as part of a short circuit through the heated-side heat exchanger. Accordingly, two flow diverters would be mounted at diametrically opposite points. Each flow diverter would be a comblike object with tangs that would fill most of the cross sections of the circumferential channels in the rotor. The gaps between the flow diverters and the walls of the channels would be just large enough to allow the rotor to turn freely and small enough that there would be very little flow through them.
Thus, the flow diverters would almost completely block the undesired flow paths, forcing most of the fluid to follow the desired long path through both heat exchangers and the rotor.
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Contact: F.S. Howard, DM-ASD, (321) 867-3748