PELTIER EFFECTS IN ELECTRODE CARBON

The thermoelectric power of a cell with platinum electrodes and a carb on conductor was determined. The electromotive force (emf) was measure d as a function of the temperature difference between the electrodes a t temperatures varying from 310 degrees C to 970 degrees C. From these measurements, the transported entropy of electric charge in carbon wa s found to vary from -1.7 to -1.9 J/(K mole) at temperatures around 30 0 degrees C, from -2.0 to -2.3 J/(K mole) at temperatures around 550 d egrees C, and from -3.4 to -3.7 J/(K mole) at temperatures around 950 degrees C. This transported entropy had not before been determined for temperatures above 550 degrees C. Also, it is shown how the previousl y neglected surface properties can be taken into account to interpret the measurements. In the Hall-Heroult cell, the anode is made of a sim ilar kind of carbon. Hence, the transported entropy found above can be used to describe the often neglected coupling between transport of he at and electric charge in this electrode. It is shown that the calcula ted electric potential profile through a coal sample will change signi ficantly if the coupling is neglected, but the calculated temperature profile is independent of whether the coupling is neglected. New equat ions are also developed that can be used to evaluate the importance of the coupling in other systems.