Structure of equations specifying operating characteristics of energy converters constructed of anisotropic materials

Abstract

The expressions for efficiency and coefficient of performance of galvano-thermomagnetic energy converters have been re-examined to determine what mathematical constraints are needed to guarantee that these quantities remain real, non-negative, and subject to the Carnot requirement. These constraints lead to conditions that must be satisfied by the anisotropy parameters, the transport coefficients, and the temperature differences within the device arms. Conditions for operating the devices at Carnot efficiency are also spelled out. In the appendix it is proved mathematically that no more than one device arm is needed for optimal operation of thermomagnetic converters and refrigerators.