Analysis of radiative and solid conduction components of the total thermal conductivity of an evacuated glass fiber insulation measurements with a 700 x 700 sq mm variable load guarded hot plate device

Stationary calorimetric measurements of the total thermal conductivity of powder and glass fiber insulations in a vacuum, at high temperatures, and in dependence of an applied external mechanical load, are reported. LOLA I, a 700 x 700 sq mm guarded hot-plate device suitable for the measurement of the thermal conductivity of insulations under a variable external pressure load up to 100,000 Pa is described. Another guarded hot-plate apparatus, LOLA II, is used to extend the external pressure load to 5,000,000 Pa. The analysis in terms of a simple thermal resistor model, of separated solid conduction components of glass-fiber insulations at a temperature of 500 K, is discussed.