Development of High-Temperature Blackbodies and Furnaces for Radiation Thermometry

Abstract

Two high-temperature blackbodies were developed and tested. The first one is a graphite blackbody with a maximum temperature of 2000 • C, an opening of 40 mm, and an emissivity of 0.995. It is intended for the routine calibration of pyrometers. The second one is a small version of a pyrolytic graphite (PG) blackbody with a cavity diameter of 15 mm, an opening of 10 mm, and an emissivity of 0.9996. The blackbody has two options with maximum temperatures of 2500 • C and 3000 • C, respectively. With these, the list of high-temperature blackbodies developed at VNIIOFI consists of five PG types and one graphite type, which can be used in radiation thermometry as precision Planckian sources or furnaces for fixed-point applications. The article also describes modifications to the PG furnace, where PG heater rings are replaced partly or totally by graphite elements. Such modifications extend the lifetime of the heater, reduce the cost for some applications and, for some cases, improve the temperature uniformity.

Flexible Graphene–Graphene Composites of Superior Thermal and Electrical Transport Properties

“…Under the assumption of the specific heat being unchanged, which is a common practice in the literature, thermal conductivities of the annealed GN–GN films should be in the range of 220–390 W/m·K. Therefore, the thermal transport performance of these obviously flexible films is close to that found in some commercially supplied pyrolytic graphite materials (which are generally brittle with little mechanical flexibility). − …”

“…The concept and practice on graphene-based composites go beyond the polymeric systems, including also the development of all-carbon nanocomposites from GNs and their derived precursors. − In targeted thermal transport applications, these nanocomposites are often pursued as an alternative to the highly ordered pyrolytic graphite materials of ultimate performance (the in-plane thermal conductivity of 400–1800 W/m·K, for example). ,− However, the ordered graphite materials are sometimes limited by other properties, such as their brittle nature not suitable for applications that require flexible structures, and they are generally very high in cost. − There have been a number of reported strategies on the development of flexible graphene composites with nanoscale structural features. ,− For example, Xiang and Drzal prepared papers of neat graphite nanoplatelets through mechanical pressing for high thermal transport performance . Further improvements in the performance were achieved by processing the papers in a combination of thermal-annealing and hot-press treatment, reaching an in-plane thermal conductivity of 313 W/m·K .…”

Simultaneous Determination of Na Concentration and Temperature during Zhundong Coal Combustion using the Radiation Spectrum

“…39 The blackbody furnace calibration can be used to convert the original intensity (counts) output by the spectrometer into radiation intensity. 55,56 Figure 13 presents the variations of the I Na 589 with time in the coal pellet combustion process, which first increased and decreased during the devolatilization phase, slowly increased again in the char phase, and then slowly decreased after entering the ash phase, exhibiting a bimodal shape. In the devolatilization phase, the I Na 589 of the raw coal was the highest (7.5218 × 10 9 W/m 3 •sr), followed by that of the 40 °C water-washed It can be seen from Figure 14 that the change in C Na in the raw coal pellet combustion process exhibits a bimodal shape.…”

“…The spectra demonstrated in Figure are the sum of the continuous and characteristic spectra, which were separated by the spectral separation algorithm . The blackbody furnace calibration can be used to convert the original intensity (counts) output by the spectrometer into radiation intensity. , Figure presents the variations of the I Na 589 with time in the coal pellet combustion process, which first increased and decreased during the devolatilization phase, slowly increased again in the char phase, and then slowly decreased after entering the ash phase, exhibiting a bimodal shape. In the devolatilization phase, the I Na 589 of the raw coal was the highest (7.5218 × 10 9 W/m 3 ·sr), followed by that of the 40 °C water-washed coal (3.7727 × 10 9 W/m 3 ·sr), and that of the 80 °C water-washed coal, which was the least (3.0013 × 10 9 W/m 3 ·sr).…”