ASSESSMENT OF THE TEMPERATURE MEASUREMENTS IN COMBUSTION ENGINEERING.

The temperature measurements by thermocouples are evaluated via the comparison between four different thermocouple wire diameters and three different constructions of suction pyrometers. In each pyrometer the suction velocity, which had been ranged from 20 to 320 m/s, was used to increase the heat convection from the hot gases to the thermocouple junction and thus to compensate for the radiation lost from the junction to the walls and for conduction through the thermocouple wires. Different temperature levels which ranged from 950 degree C to 1250 degree C were covered. The measurements were conducted in a cylindrical water cooled horizontal flame tube of 0. 6 m diameter and 3. 75 m length fired with liquid fuel. The results confirmed a minimum value for suction velocity over the junction to attain the correct temperature reading. It showed also that this suction velocity increases with the increase in the measured temperature level.