Thermal Conductivity
*Most from Young, Hugh D., University Physics, 7th Ed. Table 15-5. Values for diamond and silica aerogel from CRC Handbook of Chemistry and Physics. Note that 1 (cal/sec)/(cm2 C/cm) = 419 W/m K. With this in mind, the two columns above are not always consistent. All values are from published tables, but can't be taken as authoritative. The value of 0.02 W/mK for polyurethane can be taken as a nominal figure which establishes polyurethane foam as one of the best insulators. NIST published a numerical approximation routine for calculating the thermal conductivity of polyurethane at http://cryogenics.nist.gov/NewFiles/Polyurethane.html . Their calculation for freon filled polyurethane of density 1.99 lb/ft3 at 20°C gives a thermal conductivity of 0.022 W/mK. The calculation for CO2 filled polyurethane of density 2.00 lb/ft3 gives 0.035 W/mK .
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Index Tables Reference Young Ch 15. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Wiedemann-Franz RatioThe ratio between thermal and electrical conductivities of metals can be expressed in terms of the ratio: which may be called the Wiedemann-Franz Ratio or the Lorenz constant.
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Index Tables Reference Blatt Section 13.2 | |||||||||||||||||||||||
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