The air temperature in a room is maintained at 20°C year-round, but the wall temperature is approximately 27°C in the summer and 14°C in the winter. Determine the total (convection + radiation) rates of heat transfer from a person in this room in both winter and summer if the exposed surface area, emissivity, convection coefficient, and the average outer surface temperature of the person are 1.8 m², 0.8, 4 W/m²-K, and 31°C, respectively.

Elements Of Electromagnetics
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4. The air temperature in a room is maintained at 20°C year-round, but the wall temperature
is approximately 27°C in the summer and 14°C in the winter. Determine the total
(convection + radiation) rates of heat transfer from a person in this room in both winter and
summer if the exposed surface area, emissivity, convection coefficient, and the average
outer surface temperature of the person are 1.8 m², 0.8, 4 W/m²-K, and 31°C, respectively.
Transcribed Image Text:4. The air temperature in a room is maintained at 20°C year-round, but the wall temperature is approximately 27°C in the summer and 14°C in the winter. Determine the total (convection + radiation) rates of heat transfer from a person in this room in both winter and summer if the exposed surface area, emissivity, convection coefficient, and the average outer surface temperature of the person are 1.8 m², 0.8, 4 W/m²-K, and 31°C, respectively.
3. Both convection and radiation heat transfer can be important in situations where the heat
transfer coefficient is relatively low. A steam pipe running through a factory is 30 m long
and has a diameter of 15 cm. The steam maintains the outside surface temperature of the
pipe at 165°C, and the emissivity of the pipe's surface is = 0.8. The natural convection
heat transfer coefficient is 8 W/m²-K. Determine the heat loss rate from the pipe to the
surrounding air and walls, both of which are at a temperature of 25°C.
Transcribed Image Text:3. Both convection and radiation heat transfer can be important in situations where the heat transfer coefficient is relatively low. A steam pipe running through a factory is 30 m long and has a diameter of 15 cm. The steam maintains the outside surface temperature of the pipe at 165°C, and the emissivity of the pipe's surface is = 0.8. The natural convection heat transfer coefficient is 8 W/m²-K. Determine the heat loss rate from the pipe to the surrounding air and walls, both of which are at a temperature of 25°C.
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