On the Theoretical Analysis of a Dynamic Thermocouple: 2—The Continuous Area Interface

The dynamic thermocouple formed by the moving junctions of two dissimilar metals is analyzed for the case of two semi-infinite bodies of dissimilar metals having continuous contact and nonuniform temperature distribution over a circular area. A procedure is given for determining the potential measured by the thermocouple leads placed in the two respective bodies at an infinite distance away from the contact area in terms of the Seebeck emf corresponding to the contact-area temperature distribution. This thermocouple potential at infinity is solved completely for a circular contact area, and numerical examples are given for the case of radial symmetry. It is found that the potential at infinity is not in general equal to the area average Seebeck emf. Instead, it is shown that the potential at infinity is equal to the average Seebeck emf weighted by the area divided by its distance from the perimeter of the circle. This result together with comparison with the results of a previous paper leads to the conclusion that the temperature near the perimeter of a contact area has a greater influence on the thermocouple emf than the temperature in the interior of the contact area.