Graphite thermal conductivity

If the AHTR-VT reactor vessel is built with the same dimensions as the 9.2-m-diam, 19.5-m-high S-PRISM reactor vessel, then the TBS will have an outside diameter of 8 m and a total surface area (including the bottom) of 500 m. For a t5 ical graphite thermal conductivity of 32 W/m°C, 0.64-m-thick graphite blocks would transfer 15 MW(t) at a TBS temperature difference of 600°C. At this temperature difference, a 6 1/s leakage flow through the blanket would also transfer 15 MW(t) across the blanket. 

Thermal conductivity of graphite Thermal conductivity of insulating alumina Equilibrium potential for reaction (2.93)... 

Irradiated nuclear graphite thermal conductivity data are usually presented as the reciprocal, which represents the thermal resistivity. The thermal resistivity is usually plotted as a function of fluence and irradiation temperature similar to other irradiated material properties. Thermal resistivity data for Gilsocarbon plotted as fractional change are given in Fig. 14.12. Thermal resistivity initially increases rapidly to a slightly rising plateau before a secondary increase at high fluence. 

Carbon—graphite materials do not gall or weld even when mbbed under excessive load and speed. Early carbon materials contained metal fillers to provide strength and high thermal conductivity, but these desirable properties can now be obtained ia tme carboa—graphite materials that completely eliminate the galling teadeacy and other disadvantages of metals. 

Carbon—graphite foam is a unique material that has yet to find a place among the various types of commercial specialty graphites. Its low thermal conductivity, mechanical stabiHty over a wide range of temperatures from room temperature to 3000°C, and light weight make it a prime candidate for thermal protection of new, emerging carbon—carbon aerospace reentry vehicles. 

Acetylene black is very pure with a carbon content of 99.7%. It has a surface area of about 65 m /g, an average particle diameter of 40 nm, and a very high but rather weak stmcture with a DBPA value of 250 mL/100 g. It is the most crystalline or graphitic of the commercial blacks. These unique features result in high electrical and thermal conductivity, low moisture absorption, and high Hquid absorption. 

All VGCF was graphitized prior to composite consolidation. Composites were molded in steel molds lined with fiberglass reinforced, non-porous Teflon release sheets. The finished composite panels were trimmed of resin flash and weighed to determine the fiber fraction. Thermal conductivity and thermal expansion measurements of the various polymer matrix composites are given in Table 6. Table 7 gives results from mechanical property measurements. 

Heremans J. and Beetz, C.P.,. Thermal conductivity and thermopower of vapor-grown graphite fibers J. Phys. Rev.B 32, 1985, p.l981... 

Recently, Dinwiddie et al. [14] reported the effects of short-time, high-temperatme exposures on the temperature dependence of the thermal conductivity of CBCF. Samples were exposed to temperatures ranging from 2673 to 3273 K, for periods of 10, 15, and 20 seconds, to examine the time dependent effects of graphitization on thermal conductivity measured over the temperature range from 673 to 2373 K. Typical experimental data are shown in Figs. 7 and 8 for exposure times of 10 and 20 seconds, respectively. The thermal conductivity was observed to increase with both heat treatment temperature and exposure time. 

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