On the systematic error associated with the measurement of temperature using acoustic pyrometry in combustion products of unknown mixture

Abstract

The measurement of internal gas temperature by the technique of acoustic pyrometry potentially offers excellent resolution due to its dependence on the measurement of time. The accuracy of the technique in combustion applications, however, must be questioned given its dependence on the acoustic constant, C a . In a typical combustion application, where the exact composition of the gas along the measuring path may not be known, this is of particular concern. Systematic errors arise due to the deviations of the actual gas properties from those assumed.Analysis of the variation of the acoustic constant for the products of combustion of typical fuels is reported as a function of temperature, mixture ratio and oxidant composition. From this it is possible to quantify the level of systematic error and hence the accuracy of the technique for a general case.A strong dependence of C a is observed with temperature but this may easily be taken into account in the measurement using correction factors. A far lesser dependence is observed on combustion mixture ratio, moisture and air humidity for a wide range of fuels and oxidant compositions. The systematic error resulting from ignoring these factors over an extensive range of values is better than ±2% for most applications.

A New Algorithm for Reconstructing Two-Dimensional Temperature Distribution by Ultrasonic Thermometry

“…Information about temperature distribution is helpful for detecting and correcting hot spots which may cause safety accidents like explosions and spontaneous ignitions; meanwhile, it also contributes to designing combustion systems of low , as presence of hot spots always increases generation [3,4]. Furthermore, temperature distribution always immediately influences the combustion efficiency of pulverized coal, the structure and state of reaction, and the safety of operation [4][5][6]. Apart from these applications of industrial furnaces, temperature distribution and its reconstruction during combustion are of great interest in automotive and aerospace industries as well, because engine properties need to be monitored via studying flame dynamics [7,8].…”

Experimental investigation on simultaneous measurement of temperature distributions and radiative properties in an oil-fired tunnel furnace by radiation analysis

“…But due to the large dimensions of a furnace and the limited power of a laser, these methods are unsuitable for industrial furnaces and boiler furnaces. Acoustic thermography has been adopted into measure two-dimensional (2-D) cross-section distributions of temperature in furnaces [3,4]. However, this method is limited by the propagating velocity of acoustic waves and the inadequacy of the measurements provided by the transducers, so it is hard to achieve high temporal and high spatial resolutions.…”

Acoustic Pyrometry using an Off-the-Shelf Range Finding System

“…Tomography has been coupled with many nondestructive examination (NDE) techniques, such as X-ray, shearography, and ultrasound to gather data to produce a 3-D image. The data collection used to make the tomography possible can be done in two basic ways [2][3][4][5][6][7].…”

“…Although this method is more expensive due to the greater amount of equipment necessary, it allows the user to collect data for many points at a common time [6,7]. This method finds transient hot-spots and cold-spots within the fire.…”