Spectral emissivity and temperature of heated surfaces based on spectrometry and digital thermal imaging – Validation with thermocouple temperature measurements

Yan, Weijie; Panahi, Aidin; Levendis, Yiannis A.

doi:10.1016/j.expthermflusci.2019.110017

Cited by 33 publications

(24 citation statements)

References 59 publications

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“…Subsequently, the measured spectral emissivity can be used for correcting the temperature of the image method. 38,42,43 This improves the accuracy of the temperature measurement. In a previous study, the accuracy of this method was verified by using R-type platinum−rhodium filament thermocouples.…”

Section: Introductionmentioning

confidence: 95%

“…However, when measuring the flame, the ratio ε(λ 1 )/ε(λ 2 ) is an unknown parameter, and hence, it needs to be determined. For this purpose, the multispectral algorithm presented in a previous paper was used to measure the spectral emissivity ε(λ) of the soot flame in real time. , The spectral emissivity of the flame can be expressed by a polynomial function where m is the series of polynomial; a m is the polynomial coefficient; j is any of the number of measured effective wavelengths within the spectral response range of the spectrometer; and n is the number of measuring wavelengths of the spectrometer. Substitution of eqs into gives …”

Section: Measurement Principlementioning

confidence: 99%

“…The schematic of the experimental apparatus is shown in Figure . A Bunsen premixed burner was used to burn methane gas . The flow of methane (CH 4 ) was set to 0.40 L/min, the flow of air was set to 4.85 L/min, and the resulting equivalence ratio was φ = 0.786.…”

Section: Experimental Setupmentioning

confidence: 99%

“…Hence, if the radiation spectrum and radiation image of an object can be measured simultaneously in the same wavelength band, then the spectral emissivity of the object can be determined based on its radiation spectrum. Subsequently, the measured spectral emissivity can be used for correcting the temperature of the image method. ,, This improves the accuracy of the temperature measurement. In a previous study, the accuracy of this method was verified by using R-type platinum–rhodium filament thermocouples .…”

Section: Introductionmentioning

confidence: 99%

“…Subsequently, the measured spectral emissivity can be used for correcting the temperature of the image method. ,, This improves the accuracy of the temperature measurement. In a previous study, the accuracy of this method was verified by using R-type platinum–rhodium filament thermocouples . By comparison to the thermocouple temperature reading, the maximum relative error of the image temperature measurement was 0.62% under steady-state conditions, while the maximum relative error was 0.75% under nonsteady-state conditions.…”

Section: Introductionmentioning

confidence: 99%

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Determination of Flame Temperatures and Soot Volume Fractions during Combustion of Biomass Pellets

Yan

et al. 2021

Energy Fuels

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This article presents a method for real-time simultaneous measurements of the temperature and soot volume fraction distribution of volatile matter flames, forming during combustion of biomass pellets. This method uses flame radiation spectra, captured by a spectrometer, and images, captured by a digital camera, as inputs during combustion of three different types of biomass pellets (pine wood, rice straw, and corn straw). The pellets were ignited and burned in the post-combustion zone of methane gas at 1300 K. The radiation spectrum of the flame in the 500−800 nm wavelength band was selected for spectral analysis, combined with a spectral emissivity model based on polynomial fitting. The flame emissivity was measured at the response wavelengths of a dual band-pass filter (centered at 615 and 517 nm) fitted on the camera, and the resulting emissivity ratio showed the degree of departure from the gray radiation model. The measured emissivity ratio approached unity as the combustion intensity increased. The emissivity ratio of the spectrometer measurement was used to correct the flame temperature measurement obtained by the image method. Upon correction, the maximum relative error of the image temperature measurement was determined to be 2.7% by comparison to thermocouple readings. The experimental results showed that the maximum flame temperatures of pine wood, rice straw, and corn straw pellets were remarkably similar at 1876 ± 2 K. Moreover, the flame burnout durations and the peak soot volume fractions were both positively correlated with the volatile content of biomass pellets; the value of the latter was 1.19 ± 3 ppm. The experimental results measured in this article can provide data for models of the soot generation mechanism of biomass pellet combustion in industrial furnaces.

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Section: Introductionmentioning

confidence: 95%