Pyrometric Method Research Articles

Pyrometric Determination of Temperature in Rich Flames and Wavelength Dependence of Their Emissivity

A new experimental and theoretical method is described to determine the temperature of a rich flame from its luminosity in a time-resolved way. It differs from existing methods in supplying the wavelength dependence of the flame emissivity ϵ̂. The light emitted by the combustion is collected by a spectrograph and an image-intensifying streak-camera. Temperatures are derived from the spectral data. This pyrometric method is more precise and more meaningful than previous ones because it is free of any arbitrary assumptions on the wavelength dependence of ϵ̂. The experimental scheme is relatively simple and very well suited for various applications. It was tested by investigating a candle light, a butane gas burner, and a series production diesel engine. It yielded temperatures with a total error of about 4%.

Pyrometric sizing of high-temperature particles in flow reactors

A pyrometric method was developed earlier for the simultaneous in situ measurement of the temperature and the size of combusting fuel particles in entrained flow reactors. The temperature measurement is based on two-color pyrometry and the particle sizing on the proportionality of the measured radiative flux and the cross-sectional area of a particle at a known temperature. This particle-sizing method needs a discrimination procedure to confirm that the detected particle is valid for particle sizing. We report on a novel method for particle discrimination based on coaxial reference optics. The new method has several advantages compared with the method presented earlier, including the measurement in turbulent flow fields.

Pyrometric temperature measurement method and apparatus for measuring particle temperatures in hot furnaces: Application to reacting black liquor

A specialized two-color pyrometric method has been developed for the measurement of particle surface temperatures in hot, radiating environments. In this work, the method has been applied to the measurement of surface temperatures of single reacting black liquor char particles in an electrically heated muffle furnace. Black liquor was introduced into the hot furnace as wet droplets. After drying, the resulted particles were processed in different atmospheres corresponding to combustion, pyrolysis, and gasification at furnace temperatures of 700–900 °C. The pyrometric measurement is performed using two silicon photodiode detectors and 10 nm bandpass filters centered at 650 and 1050 nm. Thermal radiation is transferred using an uncooled fiberoptic probe brought into the vicinity of the char particle. The key features of the pyrometric apparatus and analysis method are: (1) Single particle temperature is resolved temporally at high speed. (2) The thermal radiation originating from the furnace and reflected by the particle is accounted for in the measurement of the surface temperature. (3) Particle temperatures above or below the furnace temperature can be measured without the need of a cooled background assisting the measurement in the hot furnace. To accomplish this, a minimum particle size is needed that is a function of the temperature difference between the particle and furnace. Particles cooler than the furnace can be measured if their diameter is more than 0.7 mm. Surface temperatures of 300–400 °C above the furnace temperature were measured during combustion of black liquor char particles in air. In atmospheres corresponding to gasification, endothermic reactions occurred, and char temperature remained typically 40° below the furnace temperature.

A simple non-invasive optical pyrometric method for plotting temperature—Time profiles of high temperature reactions in microwave ovens

A simple optical pyrometric method is described, based on a photocell with red and blue filters calibrated by the disappearing filament technique. The method, which is cheap, non-invasive and reproducible, is used for measurement of the rate of heating of solid materials such as coke, CuO or Fe3O4 in a microwave oven.

Measurement of the target surface temperature in the presence of a laser-induced plasma

A new pyrometric method was used to measure the evolution of the surface temperature of a metallic target at the end of a powerful laser pulse. The method uses the property of a metallic surface to polarize the reflected and emitted lights in different ways. Surface temperatures in the range 2000-5000 K were measured through the strongly radiative plasma.

Measurements of eutectic temperatures in the metal-rich regions of several M-C systems

The eutectic temperatures in the metal-rich regions of several M-C systems have been measured employing an optical pyrometric method known as the spot technique. The measured values are for Ni-C, 1319 ± 2 °C; Ru-C, 1958 ±5 °C; Rh-C, 1674 ± 4 °C; Pd-C, 1510 ± 3 °C; Ir-C, >2200 °C; Pt-C, 1738 ± 4 °C; Si-C, 1401 ± 2 °C; Ti-C, 1620 ± 3 °C; Zr-C, 1854 ± 5 °C; V-C, 1610 ± 3 °C; and Mo-C, 2174 ± 6 °C. These data have been found to be more precise than those reported earlier.

A Measurement of Thermodynamic Temperatures Between 683 K and 933 K by an Infrared Pyrometer

A pyrometric method and appropriate black bodies are described for the accurate measurement of thermodynamic temperature above 683 K (410 °C). The pyrometer employs unbiased low-noise silicon detectors of linear response and a dielectric multi-cavity interference filter of 40 nm halfwidth with a sharply-edged band pass. The effective wavelength equals about 974 nm. Special emphasis has been given to determine and to minimize the errors due to temperature gradients inside a black body that is controlled to a very stable temperature T68 utilizing platinum resistance thermometers.The difference ΔT = T - T68 between thermodynamic and practical temperatures at the antimony point (630.74 °C) was measured to be - 0.150 K ± 22 mK. From 683 K to 903 K the difference ΔT is expressed by the empirical least-squares fit ΔT = T - T68 = a1 + a2 T68; a1 = 0.2154 K; a2 = - 0.4038 × 10-3. The thermodynamic temperature of the aluminium point has been determined as 933.452 K ± 24 mK. The overall uncertainties are given at the 99% confidence level.

Détermination radiométrique des températures thermodynamiques comprises entre 904 et 1338 K

The thermodynamic temperatures of the freezing points of silver and gold are determined by comparison with 903.89 K, a temperature which is regarded as exact; we are using the monochromatic optical pyrometric method (with a wavelength close to 1 μm) based on Planck's radiation law, taking c2 = 0.014388 m.K. The values obtained for Ag (1235.16 K ± 0.13 K) and Au (1337.53 K ± 0.16 K) are in good agreement with the values of the IPTS-68 (1235.08 K and 1337.58 K), but the scale of the standard thermocouple is not satisfactory between 904 K and 1235 K.

Pyrometric method of measuring instantaneous velocities in nonisothermal gas flows

Pyrometric method of measuring instantaneous velocities in nonisothermal gas flows

Method of Measuring Target Temperature in a Solar Furnace

A pyrometric method of measuring the surface temperature of a target in a solar furnace has been developed by using 1.38-μ wavelength radiation which is absent in solar radiation. The measured temperature distribution of irradiated graphite together with the theoretical consideration of the performance is presented.

Visible Radiation Characteristics of Incandescent Oxides

Energy radiated in the visible part of the spectrum of various oxides and their mixtures when heated to red brightness temperatures between 1400\ifmmode^\circ\else\textdegree\fi{} and 2000\ifmmode^\circ\else\textdegree\fi{}K by means of cathode-ray bombardment, and gas-air and oxy-gas flames was measured by an optical pyrometric method. The oxides investigated were urania, ceria, lanthana, neodymia, erbia, yttria, zirconia, thoria, alumina, beryllia, magnesia, and mixtures of thoria with one percent ceria (the Welsbach mantle mixture), one percent and less of urania, one percent neodymia, and one percent manganese oxide. These were either pressed or fused to insure good surface conditions. In general, linear relations were found between the logarithm of the red-blue intensity ratio and the reciprocal of the brightness temperature, and between the logarithm of the candles emitted per unit surface area and the logarithm of the brightness temperature. Different modes of heating gave different radiation curves for the same oxide. Tables are given of the candles per square centimeter and the relative blue brightness for red brightness temperatures of 1400, 1500, 1600, 1700, 1800, 1900, and 2000\ifmmode^\circ\else\textdegree\fi{}K.

Visible radiation characteristics of incandescent oxides

Energy radiated in the visible part of the spectrum of various oxides and their mixtures when heated to red brightness temperatures between 1400\ifmmode^\circ\else\textdegree\fi{} and 2000\ifmmode^\circ\else\textdegree\fi{}K by means of cathode-ray bombardment, and gas-air and oxy-gas flames was measured by an optical pyrometric method. The oxides investigated were urania, ceria, lanthana, neodymia, erbia, yttria, zirconia, thoria, alumina, beryllia, magnesia, and mixtures of thoria with one percent ceria (the Welsbach mantle mixture), one percent and less of urania, one percent neodymia, and one percent manganese oxide. These were either pressed or fused to insure good surface conditions. In general, linear relations were found between the logarithm of the red-blue intensity ratio and the reciprocal of the brightness temperature, and between the logarithm of the candles emitted per unit surface area and the logarithm of the brightness temperature. Different modes of heating gave different radiation curves for the same oxide. Tables are given of the candles per square centimeter and the relative blue brightness for red brightness temperatures of 1400, 1500, 1600, 1700, 1800, 1900, and 2000\ifmmode^\circ\else\textdegree\fi{}K.

Societies and Academies

Societies and Academies