A method for determining the thermal conductivity k and the specific heat c p of a material is illustrated in the sketch. Initially the two identical samples of diameter D = 60 mm and thickness L = 10 mm and the thin heater are at a uniform temperature of T_i = 23.00°C, while surrounded by an insulating powder. Suddenly the heater is energized to provide a uniform heat flux q₀; on each of the sample interfaces, and the heat flux is maintained constant for a period of time, ∆t_o . A short time after sudden heating is initiated the temperature at this interface T_o is related to the heat flux as

For a particular test run, the electrical heater dissipates 15.0W for a period of ∆t_o = 120 s and the temperature at the interface is T o (30 s) = 24.57°C after 30 s of heating. A long time after the heater is deenergized, t >> ∆t_o' the samples reach the uniform temperature of T_o (∞) = 33.50°C. The density of the sample materials, determined by measurement of volume and mass, is p = 3965 kg/m³.

Determine the specific heat and thermal conductivity of the test material. By looking at values of the thermo-physical properties in Table A.1 or A.2, identify the test sample material.

1/2 T.(1) T = 24 Tpc,k, -Sample 1, D, Lp CHeater leads Sample 2, D, Lp