A furnace must be built with an inner layer of refractory brick (conductivity 1.27 Kcal/h mºC). This layer must be coated with a layer of insulating brick (conductivity 0.134 Kcal/hm ºC) 22 cm thick, in turn covered with a 15 cm layer of building brick (conductivity 0.75 Kcal/ hm°C). The inner surface of the refractory wall will operate at 1150ºC and the outside at 65ºC. How many centimeters of refractory brick would be required for the insulation not to exceed 930ºC (safety limit of the material in question)

A furnace must be built with an inner layer of refractory brick (conductivity 1.27 Kcal/h mºC). This layer must be coated with a layer of insulating brick (conductivity 0.134 Kcal/hm ºC) 22 cm thick, in turn covered with a 15 cm layer of building brick (conductivity 0.75 Kcal/ hm°C). The inner surface of the refractory wall will operate at 1150ºC and the outside at 65ºC. How many centimeters of refractory brick would be required for the insulation not to exceed 930ºC (safety limit of the material in question)

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.10P: 1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss...

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1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.
Wearing layers of clothing in cold weather is often recommended because dead-air spaces between the layers keep the body warm. The explanation for this is that the heat loss from the body is less. Compare the rate of heat loss for a single 2-cm-thick layer of wool [k=0.04W/(mK)] with three 0.67-cm layers separated by 1.5 mm air gaps. The thermal conductivity of air is 0.024 W(mK).
1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed to temperature of –5°C, while the inner surface is kept at 20°C. The thermal conductivity of the concrete is 1.2 W/m K. Determine the heat loss through the wall, which is 10-m long and 3-m high. Problem 1.1
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A furnace wall is constructed of an inner layer of 12.7 mm of refracter material, a middle layer of 101.6 mm of insulation material and outer layer of 76.2 mm of steel. The wall surface temperature is 1370 °C inside the refracter material (T0) and 37.8 °C at the outside surface of the steel (T3). Use thermal conductivity for refractor kref = 6.64 W/mK, for insulation, kins= 2.34 W/mK and for steel kste = 45 W/mK. Calculate the heat loss in W for 1 m2 (heat flux)? The temperature at the inter face between the insulation material and steel board?