Rock wool thermal insulation

Insulation. Impure sdiceous limestone and blast-furnace slag are the main raw materials for making rock-wool insulation bats and peUets (see Insulation, thermal). 

Steam at a temperature of 1 = 600 °C flows in a tube of inner diameter d = 0.25m and outer diameter d2 = 0.27m made of a steel alloy (Ai = 16 W/Km). The heat transfer coefficient is cq = 425W/m2K. The tube is insulated with a rock wool layer of thickness 82 = 0.05 m, on whose outer surface a hull of mineral fibres of thickness 83 = 0.02 m is attached. The heat transfer coefficient between the hull and the air at temperature tf0 = 25°Cis ao = 30W/m2 K. The thermal conductivity of the rock wool varies according to the temperature ... 

A flat incinerator wall with a surface area of 480 consists of 6 in. of firebrick with a thermal conductivity of 0.61 Btu/(h ft °F) and an 8-in. outer layer of rock wool insulation with a thermal conductivity of 0.023 Btu/(h ft °F). If the temperature of the insulation of the inside face of the firebrick and the outside surface of the rock wool insulation are 1900 and 140°F, respectively, calculate the following ... 

Solids. The thermal conductivity of homogeneous solids varies quite widely, as may be seen for some typical values in Table- 4.1-1. The metallic solids of copper and aluminum have very high thermal conductivities, and some insulating nonmetallic materials such as rock wool and corkboard have very low conductivities. 

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