A Technique for Measuring the Apparent Thermal Conductivity of Flat Insulations

Abstract

A technique for measuring the apparent thermal conductivity, λ a, of flat insu lations (either batt or loose) is described. This technique consists of an elec trically heated flat Nichrome-screen wire sandwiched between a pair of samples. Results from a limited experimental test are described and compared with results from a pipe insulation tester. Thermal modeling of this system shows that accurate measurements with λ a down to 0.01 W/m·K** and insula tion thicknesses below 0.089 m (3½ in.) should be straightforward. Measure ment of λ a for material as thick as 0.305 m (12 in.) should also be possible with a lateral guard scheme to reduce heat flow along the screen wire heater.