A two-thermocouples probe for radiation corrections of measured temperatures in compartment fires

Bare-bead thermocouples are widely used for measuring temperature fields in compartment fires. It is well-known that temperature readings using such a device call be significantly affected by radiation errors, the apparent thermocouple junction temperature being thus different from the true gas temperature. However, a probe consisting of two thermocouples of unequal diameters, but made of the same material can be used for estimating the gas temperature in a fire environment. Using a steady-state heat transfer model applicable to a bare-bead thermocouple, a very simple rule is proposed for the estimation of radiation errors when temperatures are measured by use of two thermocouples of different diameters. Radiation errors obtained from this simple rule are compared and discussed with experimental results involving a compartment fire with pyridine as the fuel. (C) 2004 Published by Elsevier Ltd.