METHOD OF DETERMINATION OF HEAT-TRANSFER COEFFICIENT OF THERMOCOUPLE SENSOR Russian patent published in 1994 - IPC

FIELD: measurement technology. SUBSTANCE: sensor hot junction is brought in thermal contact with material or medium under test, DC current is passed through it, its temperature is raised above that of material or medium under test, then current is interrupted, and in time interval equal to four or five values of thermal time constant of sensor thermal emf is measured across sensor leads. Then current of same magnitude is passed in reverse direction and hot junction is cooled down to temperature lower than that of material or medium under test. Thermal emf is measured across leads in same time interval and heat-transfer coefficient is determined from equation α=2ПJE₂/[F(E₁-E₃)(T₁-T₀)], where E₁, E_2, E₃ are thermal emf values after heating, without heating, and after cooling-down of sensor junction, respectively; F is heating surface; P is Peltier coefficient depending on material of thermocouple wire; T₁ is temperature of material or medium under test; T₀ is temperature of wire leads. EFFECT: improved measurement accuracy due to elimination of effect of Loule heat and varying Seebeck coefficient of thermocouple electrodes. 1 dwg