The spherical shell method of determining the thermal conductivity of a thermal insulator

Abstract

The spherical shell method of determining thermal conductivity has been applied to a thermal insulator in a system of comparatively small dimensions, the outer diameter of each of the shells employed being roughly 10 cm. Sulphur was selected as the material under test, and the spherical shells were cast in a brass mould. The supply of heat to the centre of the system was maintained electrically, a power-supply of 2 watts producing a temperature-drop of approximately 10°C. across the specimen. The range of temperature covered by the experiments was from 5°C. to 85°C. The results obtained are compared with those derived for sulphur by other observers.