DOI: 10.1615/ICHMT.2004.RAD-4
ISBN Print: 978-1-56700-207-2
ISSN Online: 2642-5629
ISSN Flash Drive: 2642-5661
ON THE MEASUREMENT OF FLAME TEMPERATURES USING THERMOCOUPLES
要約
The flame temperature is an important parameter in flame chemical structure calculations and for decades it has been a challenge to make such measurements accurately. Several methods have been developed for this purpose using probes, acoustic, pneumatic or optical instruments, and all have their advantages and disadvantages. Temperature measurements using thermocouples are among the simplest and most affordable methods for determining a flame's temperature profile, but they involve uncertainties, including corrections for heat losses. To avoid such uncertainties a method was devised in the past by Nichols [1], according to which the temperature at a location in a flame is recorded with a series of thermocouples of various diameter beads. The individual measurements are plotted against the bead diameter and they are linearly extrapolated to zero-bead size (the location where the line intersects the temperature- axis). This is presumably the true temperature of the flame as a zero-bead size thermocouple is not subjected radiative heat losses. This manuscript presents an investigation on this technique and shows that a third order polynomial extrapolation of the data on the aforementioned plot provides a rather accurate way to infer flame temperatures. It also illustrates the entire axial temperature profile of a premixed ethyl-benzene flame and presents parametric studies on involved uncertainties.