A Modified Two-sensor-method for the Measurement of High Gas Temperature Facing Surroundings with Different Surface Temperatures

With an adequate correction, thermocouples can be used for the measurement of high gas temperatures within enclosing walls of different temperatures. Considering heat radiation between thermocouple and surroundings, Fischer developed a two-sensor method for the case with only one unique surrounding surface temperature, which is widely used for this kind of correction. The modified two-sensor method derived in this paper is applicable to the case with different surface temperatures of the surroundings, if inter-reflections between the surrounding surfaces may be neglected. Fischer's correction may thus be considered as a special case of this modified two-sensor method. In the case of an infrared radiation burner for example, results of the calculations concerning the temperature profile near to a burner plate show that both correction methods give obviously higher temperatures than those measured. Under the measurement conditions, Fischer's correction gives a slightly lower gas temperature profile than the real one corrected according to the authors' modified method. A greater difference between these two correction methods may be expected in case of a bigger participation of the sensor surface which faces the burner plate and/or at a greater difference in surface temperatures of the surroundings.