Kochan O. Methods and means for improving the accuracy of temperature measurement by thermoelectric transducers with inhomogeneous thermocouples

Scientific novelty is: 1) For the first time there is proposed a new concept of in situ calibration of the TC, for its implementation it is necessary and sufficient to determine the section on its TC which undergoes no degradation of Seebeck coefficient, which allows using this section by purposefully moving the temperature gradient zone towards the reference junction. 2)There is further developed a model describing changes of thermo-emf of inhomogeneous TC versus changes in temperature distribution along its electrodes, which allows establishing the relationship between the current and maximum values of errors due to drift and due to inhomogeneity. 3) For the first time there is proposed an operative method for in-situ determining error due to the TC drift by the means of a reference section and a purposeful shift of the temperature gradient zone so that this gradient applied only to the TC reference section. 4) For the first time there is proposed an operative method of in situ diagnosing the state of the TC legs is proposed, which, due to purposeful changes of temperature field along TC, allows determining, by solving a system of linear equations by the method of aggregate measurements, Seebeck coefficients of sections which the TC is split into and determine the degree of their degradation to make a justified decision about the suitability of the TC for further operation. 5) For the first time there is proposed, a stable method to control the temperature field using an artificial neural network, which reduces the duration of setting a preset temperature field to one or two iterations by implementing an open control system and training the neural network directly on the object of control. 6) There is further developed a model of TC error, which describes the dependence of TC error on temperature and duration of operation, and temperature difference between the current and operation temperatures after changing the temperature field, which allows predicting the future time of operation of the TC. 7) For the first time there is proposed a structure of a two-contour temperature measurement system, which, due to alternate changes of contour functions (measurement and control of object’s temperature or error correction and diagnostics of thermocouple legs) provides temperature measurement error of 1.3°C for the type K TC. 8) For the first time there is proposed a method for setting the conversion characteristic of the TC by introducing two additional wires, which allows confirming experimentally the effeciency of the proposed methods.