a) A house walls that are 19 cm thick and have an average thermal conductivity four times that of glass wool. Assume there are no windows or doors. The walls' surface area is 1250000 cm² and their inside surface is at 20°C, while their outside surface is at 7°C. (Thermal conductivity of glass wool is 0.042 W/m°C) O Calculate the rate of heat conduction through house walls? (i) How many 150W room heaters would be needed to balance the heat transfer due to conduction? (approximate number)

Elements Of Electromagnetics
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Author:Sadiku, Matthew N. O.
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a) A house walls that are 19 cm thick and have an average thermal conductivity four times that of glass
wool. Assume there are no windows or doors. The walls' surface area is 1250000 cm² and their inside
surface is at 20°C, while their outside surface is at 7°C. (Thermal conductivity of glass wool is 0.042
W/m°C)
) Calculate the rate of heat conduction through house walls?
(ii) How many 150W room heaters would be needed to balance the heat transfer due to conduction?
(approximate number)
b) A spherical infrared heater of radius 6.25 cm has an emissivity of 0.79. What temperature must it run
at if the required power is 0.58 kW? Neglect the temperature of the environment. (Stefan's constant =
5.67*10-8 Wm-2K)
The temperature of the heater in Celsius =
Transcribed Image Text:a) A house walls that are 19 cm thick and have an average thermal conductivity four times that of glass wool. Assume there are no windows or doors. The walls' surface area is 1250000 cm² and their inside surface is at 20°C, while their outside surface is at 7°C. (Thermal conductivity of glass wool is 0.042 W/m°C) ) Calculate the rate of heat conduction through house walls? (ii) How many 150W room heaters would be needed to balance the heat transfer due to conduction? (approximate number) b) A spherical infrared heater of radius 6.25 cm has an emissivity of 0.79. What temperature must it run at if the required power is 0.58 kW? Neglect the temperature of the environment. (Stefan's constant = 5.67*10-8 Wm-2K) The temperature of the heater in Celsius =
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