Thermometry application

The common feature of the schemes in this category is that the excitation light applied to the fluorescent material is a high intensity delta function pulse (e.g., a laser pulse or that from a flash lamp) or an rectangular pulse, and the measurement is derived from the observation of the fluorescence decay after the removal of the excitation light. The following are the outlines of some typical schemes which are of this type and have been used in thermometry applications. 

Recent research has shown that phosphor-based TSPs could be used for high temperature thermometry applications. Fluorescence from YAGiEu and YAG Ce could be detected through several thin YSZ samples. The average prompt fluorescence decay time for YAGiCe was measured to be 62.7 zb 2.9 ns, which is close to the accepted value of 65 ns. This result can be used directly to develop an operational high temperature heat flux gauge. 

D. P. DeW itt. Theory and Practice of Radiation Thermometry. New York John Wiley Sons, 1988. J. C. Richmond. Applications of Radiation Thermometry. ASTM Special Technical Publication. American Society for Testing and Materials, 1984. 

Perhaps the first detailed discussion of such a technique in fluorescent thermometry (shown in Figure 11.10) was given by Zhang et al. in their work(36) based on both mathematical analysis and experimental simulation. Examples of the electronic design of the corresponding system and the application of the technique in a ruby fluorescence-based fiber-optic sensor system are also listed. This shows that there is no difference in the measurement sensitivity between a system using square-wave modulation and one using sinusoidal modulation. However, the former performs a little better in terms of the measurement resolution. 

The work has shown the diversity of fluorescence-based thermometry schemes, materials, signal processing arrangements, and applications. In addition, a close agreement with theoretical predictions on material performance gives confidence to the assessment of new materials for such uses. Probe sizes are potentially smaller and more convenient due to optical source and detector developments. Thus the future for fluorescence thermometry is bright, with the expectation of a range of new ideas in the field in the future. 

K. A. Wickersheim, Application of fibre optic thermometry to the monitoring of winding temperatures in medium and large power transformers. SPIE Proc. 1584, 3-14 (1991). 

One of the main applications of hydrogen and oxygen isotope thermometry in geochemistry is the estimation of the reservoir temperatures of active geothermal systems or the evaluation of the ruling T conditions during deposition or alter-... 

Ehlers, T. A. and Farley, K. A. (2003) Apatite (U-Th)/He thermometry methods and applications to problems in tectonic and surface processes. Earth and Planetary Science Letters, 206, 1-14. 

The detection of contamination with mercury is a very serious issue due to the extreme toxicity and ease of reaction of this heavy metal. Mercury is commonly used in many everyday applications, such as thermometry, barometry or scientific apparatus. Therefore, it is important to note the development of a fluorescent IIP membrane for detection of mercury [63], This membrane was based on the combination of two fluorescent functional monomers, namely 4-vinyl pyridine and 9-vinylcarbazole. Binding of Hg2+ was proposed to be based on complexation of the metal ion with lone pairs of both pyridine and carbazole. The IIP membrane was capable of recognizing Hg2+in the linear range of concentrations from 5 x 10 7 to 1 x 10 4 M. Selectivity of the chemosensor was studied for a wide group of possible competitive ions and the chemosensor responded to all of them in the presence of a fixed amount of Hg2+ at 1 x 10 5 M. Nevertheless, the highest influence on recognition properties was observed in the presence of Cu2+ (4.87%) and Pb2+ (4.57%), which are still acceptable values for the successful detection of Hg2+. This progress stimulates further development of the MIP detection of ions. 

An acoustic sound source and a sound receiver can be located on the outside of opposing walls of a boiler or furnaces. Ultrasonic thermometry can be used at temperature extremes, in high electrical fields, or when the medium being measured is inaccessible. It is also useful for averaging the temperature of bulk materials or profiling furnace temperatures. Some of the applications are tabulated in Table 3.165. 

CARS appears ideally suited to thermometry and major species concentration measurements in both practical and clean flame environments. It should see widespread application in both practical combustors and fundamental flame investigations, particularly where soot levels are high. Saturated laser fluorescence has great potential for the measurement of selected species in low concentration (ppm) in both practical and clean flames. 

DISCUSSION By using a mixture of hydrogen and methane as the fuel, a case 2 (see above) experiment has been contrived, i.e., the effective Rayleigh scattering cross section of the fuel, air, and products are nearly ( < 2%) equal. It was then possible to make the first application of laser Rayleigh thermometry to non-premixed flames. 

Sulphur isotopes (32,33,34,36S) fractionate strongly in the earth s crust because (1) the element occurs in different oxidation states with differential preference for heavy isotopes, (2) the existence of volatile and easily soluble compounds favors kinetic separations, and (3) it is involved in biogenic cycles where the oxidation state is easily changed and kinetic processes are important. From theoretical calculations of Bigeleisen (1961) and data on the isotopic properties of sulphur compounds by Sakai (1957, 1968), the amount of S isotope fractionation and its temperature dependence is known. The information on experimental inorganic isotope fractionation in coexisting sulphide minerals which occur naturally was summarized by Thode (1970), who also discussed the application of S isotopes from sulphides for geo thermometry (cf. also Sakai, 1971). Analytical work on all types of sulphur compounds which occur in nature has been reviewed by Nielsen (1973). 

The original application of oxygen isotope thermometry. The thermal history (top) of the surroundings in South Carolina, USA, during the Cretaceous period as recorded by oxygen isotope changes (bottom) as a function of shell radius in the PeeDee belemnite (Urey et a/., 1951). 

Allison, S.W. Cates, M.R. Goedeke, S.M. Hollerman, W.A. Womack, F.N. Gillies, G.T. Remote thermometry with thermographic phosphors instrumentation and applications. Chapter 4. In Handbook of Luminescence, Display Materials, and Devices, Volume 2 Inorganic Display Materials, Nalwa, H.S., Rohwer, L.S., Eds. American Scientiflc Publishers, 2003 187-250. 

Phosphor thermometry has been used in a variety of applications from aerospace to manufacturing. The technique becomes indispensable in situations that have large blackbody background, such as combustion, and when the surface is in motion, such as in jet turbines. The technique is also very useful when the surface emissivity varies with time. This technique... 

Previous successful applications led to efforts aimed at measuring the temperatures of surfaces and structures inside turbine engines, particularly those of the rotating blades and the stationary vanes. The history of that research is documented in a series of papers, as shown in Refs. Several other groups have independently applied phosphor thermometry to turbomachinery, and in what follows we provide a synopsis of the work done in this held. 

Several others have also explored turbine engine and other aerospace applications of phosphor thermometry. For instance, Alaruri et al. exposed samples of Y2O3 Eu to the combustion flows in a burner rig. ° The gas velocities in the rig ranged from 245 to 407 m/sec at roughly atmospheric pressure. Data were taken over the range from 400° C to 1000°C with the overall accuracy of the measurements estimated to be 3%. They noted that the phosphor s fluorescence... 

In conclusion, the apparatus should be readily adaptable to other steel industry applications, such as slab heating, melt thermometry, roller thermometry. 

Allison, S.W. Gillies, G.T. Remote thermometry with thermographic phosphors instrumentation and applications. Rev. Sci. Instrum. 1997, (7),... 

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