11.8 Cylindrical Shell Method
Thermal conductivity of bad conductors may also be determined by cylindrical shell method. Here, the space between two hollow cylinders of radius r1 and r2 is filled with the bad conducting material (saw dust, sand, fire clay, rock) (Fig. 11.13).
Fig. 11.13 Schematic representation of cylindrical shell method
The source of heat lies along the axis of the cylinder so that the heat flows radially along the surface of the cylinder as the cylinder is symmetrical about its axis where the source of heat is kept. The temperatures of the cylindrical surfaces of radii r1 and r2 are measured by thermocouples. Let the ...