Radiation Pyrometry

Figure 4.25. Experimental configuration for optical pyrometry of shock temperatures induced in transparent minerals. Upon impact of projectile with driver plate, a shock wave is driven into the driver plate and then into the sample. Optical radiation from the sample is detected via six lens/interference filter channels and an array of six photodiodes. Signals from photodiode circuits are recorded on oscilloscopes operating in single sweep model. (After Ahrens et al. (1982).)...

Cross-Referencing of Fluorescence Thermometry with Blackbody Radiation Pyrometry... 

Nd YAG and the lifetime measurement is made by the use of the phase-locked detection of fluorescence lifetime (PLD) scheme. By reference to the use of the fluorescence lifetime measurement, the problems, in pyrometry, of emissivity, and sight path factor in the blackbody radiation measurement could be corrected in such a scheme having an internal self-calibration. ... 

Harrison, T. R. Radiation Pyrometry, John Wiley and Sons, Inc., New York 1960... 

Because the spatial area with higher temperature on the catalyst surface of one of the samples of the library is very small the detection of catalytic activities through temperature measurement cannot be carried out by direct temperature measurements but only by non-contact methods such as pyrometry or IRT. The IR video camera used here measures the emission at every point of the library in parallel. The detector consists of a 256x256 pixel array of Pt-silicide-IR-sensors. Each pixel delivers a voltage-signal that depends on the infrared radiation and the sensitivity of that pixel (fixed pattern noise). 

Cox and Macosko (19) have reported experimental results on measurements of the melt-surface temperature upon exit from the capillary using infrared pyrometry, which senses the radiation emitted by the hot polymer melt surface. Their work also included the numerical simulation of viscous heating in a capillary, a slit, and an annular die, using a method resembling that of Gerrard et al. (13). They used a boundary condition at the die wall in between the isothermal and adiabatic case, —k(dT/dr) = h T — To) at the wall, where 7o is the die temperature far from the melt-die interface as well as the inlet melt... 

The transport of thermal energy can be broken down into one or more of three mechanisms conduction--heat transfer via atomic vibrations in solids or kinetic interaction amongst atoms in gases1 convection - - heat rapidly removed from a surface by a mobile fluid or gas and radiation—heat transferred through a vacuum by electromagnetic waves. The discussion will begin with brief explanations of each. These concepts are important background in the optical measurement of temperature (optical pyrometry) and in experimental measurement of the thermally conductive behavior of materials. 

A significant concern in the use of total radiation pyrometry is that it must be calibrated at the distance it will be from the source because of the influence of the atmosphere. Normal atmosphere contains a small fraction of carbon dioxide and water vapor (the latter dependent on the relative humidity, which varies with the day). When combustion is used for furnace heating (e.g. CH4+2O2 = 2H2O+CO2), water vapor and carbon dioxide are the predominant, atmospheric constituents. As... 

R. R. Harrison, Radiation Pyrometry and Its Underlying Principles of Heat Transfer, John Wiley and Sons, NY, 1960. 

Soot samples were obtained by use of a nitrogen-quench, porous-walled probe and Nucleopore filters (7). Gas phase hydrocarbons were collected by the porous probe as batch samples and analyzed by standard FID gas chromatography. Thermal measurements included gas temperature by radiation-corrected bare wire thermocouple, and soot temperature by Kurlbaum reversal (9, 10) and two color pyrometry (11). 

The latter relation is especially useful in radiation pyrometry where true wall temperatures must be computed from wallradiosities. 

Example 9 demonstrates classical zoning calculations for radiation pyrometry in furnace applications. Example 10 is a classical furnace design calculation via zoning an enclosure with a diathermanous atmosphere and M = 4. The latter calculation can only be addressed with die matrix method. The results of Example 10 demonstrate the relative insensitivity of zoning to M > 3 and the engineering utility of the SSR model. 

Equation (5) states that the total radiation of all wave lengths emitted by a black body is proportional to These two laws which form the basis of optical and radiation pyrometry respectively are in agreement with the temperature scale defined by the gas thermometer up to 1,550°C., the upper limit at which a gas thermometer has been used satisfactorily. Above this range to 2,500°C. the scales defined by these two laws have been found, experimentally, to be in mutual agreement, and it is believed that they correctly represent the thermodynamic scale for all temperatures. 

Recording Pyrometry.—The pyrometers which can be made to record automatically fall under the following classifications (1) Gas, saturated vapor, and liquid thermometers (2) resistance thermometers (3) thermoelectric pyrometers (4) radiation pyrometers. 

Burgess and Foote, Radiation Pyrometry, Bureau of Standards, Sci, Paper 250, 1915. Burgess and Foote, Pyrometry, Standard Handbook for Electrical Engineers," McGraw-Hill, 1922. 

Any device or system that has one or more physical properties (e.g., electrical resistance, electrical potential, length, pressure at constant volume, or volume at constant pressure) that vary monotonically and repro-ducibly with temperature may be used to measure temperature. The science of the measurement of temperature is called thermometry. In the past, the measurement of high temperature was known as pyrometry but now that term usually refers to radiation thermometry at any temperature. Although the accuracy of a measurement refers to the difference between the measured value and the true value of the quantity being measured, and the precision of measurement refers to the degree of agreement among repeated measurements of the same quantity, it follows that a set of measurements of the same quantity, it follows that a set of measurements may be very precise but terribly inaccurate. Since in many instances the word accuracy is used when inaccuracy is meant and the word precision is used when imprecision is meant, perhaps it would be better always to refer to uncertainties of measurement, statistical and systematic, rather than to accuracy and precision. 

Pyrometry is thought to be the most feasible method to extract quantitative information from radiation spontaneously emitted from flames. Temperature distributions over large regions of the flame can be derived by applying the Plank law to every pixel of a CCD sensor. Two-color techniques are usually applied, due to its reduced sensitivity to uncertainties in emissivity or attenuation. Infrared cameras are used in most cases, as radiation levels are highest in this region of the spectrum [4-7]. Two channels of RGB video cameras have been also used in some works [8] although less accurate, this has the... 

Svet DYa (1968) Objective methods of high temperature pyrometry for continuum radiation. Nauka, Moscow (in Russian)... 

The definite integral can be evaluated to give a purely numerical quantity, so that the total radiation density is seen to be proportional to the fourth power of the absolute temperature. This is Stefan s law, also a well-known result of experiment and the basis of high-tempera-ture pyrometry. 

Temperature is undeniably the most important property for all calorimetric measurements, because it is the common denominator. Two different techniques for temperature measurements are used for pulse calorimetry contact thermometry (e.g. thermocouples) and radiation thermometry or pyrometry. Because pulse calorimetry is often used to handle and measure liquid materials, non-contact radiation thermometry is far more common in pulse-heating than contact thermometry. Other reasons for non-contact temperature measurement methods include the fast heating rates and temperature gradients (inertia of the thermocouples), difficulties mounting the contact thermometers (good thermal contact needed), and stray pick-up in the thermocouple signal because the sample is electrically self-heated. 

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