Thin-filament pyrometry (TFP) is an optical method used to measure temperatures. It involves the placement of a thin filament in a hot gas stream. Radiative emissions from the filament can be correlated with filament temperature. Filaments are typically

silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal sin ...

(

SiC The Latin adverb ''sic'' (; "thus", "just as"; in full: , "thus was it written") inserted after a quoted word or passage indicates that the quoted matter has been transcribed or translated exactly as found in the source text, complete with any e ...

) fibers with a diameter of 15 micrometres. Temperatures of about 800–2500 K can be measured.

History

TFP in flames was first used by Vilimpoc et al. (1988). More recently, this was demonstrated by Pitts (1996), Blevins et al. (1999), and Maun et al. (2007).

Technique

The typical TFP apparatus consists of a

flame A flame (from Latin ''flamma'') is the visible, gaseous part of a fire. It is caused by a highly exothermic chemical reaction taking place in a thin zone. When flames are hot enough to have ionized gaseous components of sufficient density they ...

or other hot gas stream, a filament, and a camera.

Advantages

TFP has several advantages, including the ability to simultaneously measure temperatures along a line and minimal intrusiveness. Most other forms of

pyrometry A pyrometer is a type of remote-sensing thermometer used to measure the temperature of distant objects. Various forms of pyrometers have historically existed. In the modern usage, it is a device that from a distance determines the temperature of ...

are not capable of providing gas-phase temperatures.

Drawbacks

Calibration is required. Calibration typically is performed with a

thermocouple A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of the ...

. Both thermocouples and filaments require corrections in estimating gas temperatures from probe temperatures. Also, filaments are fragile and typically break after about an hour in a flame.

Applications

The primary application is to

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combusti ...

and

fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. At a certain point in the combustion reaction, called the ignition ...

research.

References