Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer. Consider a room whose air temperature is maintained at 22°C throughout the year, while the walls of the room are nominally at 24°C and 12°C in the summer and winter, respectively. The exposed surface of a person in the room may be assumed to be at a temperature of 32°C throughout the year and to have an emissivity of 0.90. The coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 W/m2-K. Calculate the following. Heat flux due to convection: qCony = i W/m? Heat flux due to radiation in the summer: Tad W/m2 i Heat flux due to radiation in the winter: Trad W/m2 %3D

Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer. Consider a room whose air temperature is maintained at 22°C throughout the year, while the walls of the room are nominally at 24°C and 12°C in the summer and winter, respectively. The exposed surface of a person in the room may be assumed to be at a temperature of 32°C throughout the year and to have an emissivity of 0.90. The coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 W/m2-K. Calculate the following. Heat flux due to convection: qCony = i W/m? Heat flux due to radiation in the summer: Tad W/m2 i Heat flux due to radiation in the winter: Trad W/m2 %3D

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 1.48P: A horizontal, 3-mm-thick flat-copper plate, 1-m long and 0.5-m wide, is exposed in air at 27C to...

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1.19 A cryogenic fluid is stored in a 0.3-m-diameter spherical container is still air. If the convection heat transfer coefficient between the outer surface of the container and the air is 6.8 , the temperature of the air is 27°C, and the temperature of the surface of the sphere is –183°C, determine the rate of heat transfer by convection.
Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer.Consider a room whose air temperature is maintained at 18ºC throughout the year, while the walls of the room are nominally at 24°C and 14°C in the summer and winter, respectively. The exposed surface of a person in the room may be assumed to be at a temperature of 32°C throughout the year and to have an emissivity of 0.90. The coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 W/m2·K. Calculate the following. a. heat flux due to convection in W / m^2 b. Heat flux due to radiation in the summer in W / m^2 c. Heat flux due to radiation in the winter in W / m^2
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