Use of a ferrofluid as the heat‐exchange fluid in a magnetic refrigerator

The use of a ferrofluid is proposed as the heat‐exchange fluid in a wheel‐type magnetic refrigerator in order to avoid flow‐control problems. An equivalent‐circuit analysis of the ferrofluid flow path with several different magnetic field profiles indicates that it is possible to obtain the desired flow control in at least one case. Sample design calculations for the revised wheel‐type refrigerator are presented. In addition, the results of heat‐transfer measurements from kerosene to a stainless‐steel screen and from a kerosene‐base ferrofluid to the same screen in and out of an 8‐T magnetic field are described.