Bricks, measuring thermal conductivity

Figure 9.3 Schematic of the calorimeter method of measuring thermal conductivity [2]. Specimen sizes are approximately three bricks of dimensions 23 x 11.4 x 6.4 cm3.

Figure 2 Collection of test pieces made of unshaped refractories. Description from left to right (Top) Two bricks for measuring thermal conductivity (230 x 114 x 76 mm) Shape A according to EN cup for slag tests (100 x 100 x 100 mm, hole 50 mm in diameter and depth). (Middle) Test piece for measuring abrasion resistance according to ASTM C 704 (114 x 114 x 40 mm) test piece according to special specifications for petrochemical industry (230 x 50 x 50 mm) drilled 50 mm cylinders out of a shape B (one with 12.5 mm hole for determination of Refractoriness Under Load or Creep Under Compression). (Bottom) Shape B according to EN 3 cubes for petrochemical specifications (50 x 50 x 50 mm) Shape C according to EN.

Example 1.8 A brick wall, 225 mm thick and having a thermal conductivity of 0.60 W/(m K), measures 10 m long by 3 m high, and has a temperature difference between the inside and outside faces of 25 K. What is the rate of heat conduction ... 

Consider a 3-m-high, 6-m-wide, and 0.3-m-lhick brick wall whose thermal conductivity is ik = 0.8 W/m C. On a certain day, the temperatures of the inner and the outer surfaces of the wall are measured to be 14°C and 2 C, respectively. Determine the rate of heat loss through the wall on that day. 

Hot-topping Tile. Refractory insulating tiles performing the function of a MOULD BRICK (q.v.), i.e. delaying solidification of the melt in a hot-top. Hot-wire method. A dynamic method for the measurement of thermal CONDUCTIVITY (q.v.) applied to refractories up to 1500°C (PRE/R32 1978). A linear heat source embedded in the test piece gives a power output constant along its length and in time. 

Materials such as clay brick have a low thermal conductivity and the temperature distribution through the section is curvilinear [33]. Should be noted that, in some trials, measurements of thermal conductivity as a function of temperature shows a decrease thereof to T=1000 °C, where the radiative component compensates and sometimes reverses the decreasing tendency [23]. While, from the Debye temperature conductivity begins to slow down, at very high temperatures contributions by radiation again cause an increase in the value of the conductivity. 

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