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Surface Temperature Measurements (surface + temperature_measurement)
Selected AbstractsSurface temperature measurements on burning materials using an infrared pyrometer: accounting for emissivity and reflection of external radiationFIRE AND MATERIALS, Issue 1 2004Joe Urbas Abstract This paper demonstrates the successful use of an infrared pyrometer, operating in the 8,10 µm wavelength band, to measure the surface temperature of combustible specimens in a heat release calorimeter. The temperature histories of ten different materials were measured in the ICAL (intermediate scale calorimeter). The set of materials comprised four wood products, gypsum board, polyisocyanurate foam, PVC floor tile, PMMA and two non-combustible boards. A small-diameter bare thermocouple was installed on each specimen in order to determine an accurate temperature for comparison. The spectral emissivity and the spectral flux reflected from the surface were measured simultaneously and used to correct the apparent temperature measured by the pyrometer. The spectral emissivity and reflected spectral flux were both constant prior to ignition for all the combustible materials. During the burning phase all the combustible materials had a spectral emissivity very close to unity. The agreement between the temperatures measured with the pyrometer and thermocouple was not affected by the flame. The wood products, the polyisocyanurate foam and the calcium silicate board required no correction for reflected spectral flux over the whole temperature range. Copyright © 2004 John Wiley & Sons, Ltd. [source] A quantitative identification technique for a two-dimensional subsurface defect based on surface temperature measurementHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 4 2009Chunli Fan Abstract The inverse identification of a subsurface defect boundary is an important part of an inverse heat conduction problem, and is also the basis for the quantitative development of a nondestructive thermographic inspection technique. For the commonly encountered quantitative thermographic defect identification problem when the test piece is heated from one part of the outer boundary, our previous study showed that some parts of the defect boundary are sensitive to the initial defect boundary prediction of the conjugate gradient method. In this paper, the heat transfer mechanism inside a test piece with this problem is analyzed by building a two-dimensional model. A new method, the multiple measurements combination method (MMCM), is also presented which combines the identification algorithm study with the optimization of the thermographic detection technique to solve the problem. Numerical experiments certified the effectiveness of the present method. The temperature measurement error and the initial prediction of the defect boundary shape have little effect on the identification result. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20251 [source] Particle surface temperature measurements with multicolor band pyrometryAICHE JOURNAL, Issue 1 2009Hong Lu Abstract A noncontact, color-band pyrometer, based on widely available, inexpensive digital imaging devices, such as commercial color cameras, and capable of pixel-by-pixel resolution of particle-surface temperature and emissivity is demonstrated and described. This diagnostic instrument is ideally suited to many combustion environments. The devices used in this method include color charge-coupled device (CCD), or complementary metal oxide semiconductor (CMOS) digital camera, or any other color-rendering camera. The color camera provides spectrally resolved light intensity data of the image, most commonly for three color bands (Red, Green, and Blue,), but in some cases for four or more bands or for a different set of colors. The CCD or CMOS sensor-mask combination has a specific spectral response curve for each of these color bands that spans the visible and often near infrared spectral range. A theory is developed, based on radiative heat transfer and camera responsivity that allows quantitative surface temperature distribution calculation, based on a photograph of an object in emitted light. Particle surface temperature calculation is corrected by heat transfer analysis with reflection between the particle and reactor wall for particles located in furnace environments, but such corrections lead to useful results only when the particle temperature is near or below the wall temperatures. Wood particle-surface temperatures were measured with this color-band pyrometry during pyrolysis and combustion processes, which agree well with thermocouple measured data. Particle-surface temperature data simultaneously measured from three orthogonal directions were also mapped onto the surface of a computer generated 3-D (three-dimensional) particle model. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] Permafrost distribution in talus slopes located within the alpine periglacial belt, Swiss AlpsPERMAFROST AND PERIGLACIAL PROCESSES, Issue 3 2008Christophe Lambiel Abstract The extent of permafrost in nine talus slopes located within the alpine periglacial belt in the western Swiss Alps was investigated using ground surface temperature measurements and one- dimensional geoelectrical profiles. Based on the thermal data, permafrost appears likely in the lower parts of the slopes. At the same locations, an electrically resistive layer, interpreted as frozen sediments, was identified beneath 3,5,m of surface materials. Further upslope, resistivities were lower and ground surface temperatures were warmer, suggesting that permafrost was absent. The cooling of the ground in the lower parts of some of the talus slopes investigated was apparently due to the chimney effect. It is inferred that this mechanism plays an important role in permafrost development in the lower half of talus slopes located within the discontinuous mountain permafrost belt. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||