Preparation of Thermoelements and Construction of Cooling Units
The performance of a cooling unit is usually calculated on the basis of the assumption that all the positive or negative thermoelements have the same dimensions and thermoelectric properties. In practice, of course, it is impossible to manufacture a batch of thermoelements with identical properties, and this must usually lead to some deterioration in performance. Thus, if the nominal electrical conductivity has the optimum value, any other value for the electrical conductivity must reduce the figure of merit. Moreover, a departure of the thermoelectric properties or of the dimensions from their nominal values implies that the optimum current for a thermoelement with the nominal design parameters will no longer lead to the best performance. Before discussing the preparation of thermoelements, some consideration will therefore be given to the tolerances that can be allowed in their manufacture. Ioffe(41) has calculated some of the effects of departure from the optimum conditions; we shall make use of his calculations and extend them to the situation where the parameters show a Gaussian distribution about some nominal value.
KeywordsNickel Furnace Anisotropy Graphite Foam
Unable to display preview. Download preview PDF.