Chapter 12 Radiation Heat Transfer12-81 A man wearing summer clothes feels comfortable in a room at 22°C. The room temperature at which this man would feel thermally comfortable when unclothed is to be determined. Assumptions1 Steady conditions exist. 2The latent heat loss from the person remains the same. 3 The heat transfer coefficients remain the same. 4 The air in the room is still (there are no winds or running fans). 5 The surface areas of the clothed and unclothed person are the same. AnalysisAt low air velocities, the convection heat transfer coefficient for a standing man is given in Table 12-3 to be 4.0 W/m2.°C. The radiation heat transfer coefficient at typical indoor conditions is 4.7 W/m2.°C. Therefore, the heat transfer coefficient for a standing person for combined convection and radiation is Troom= 20°C Clothed person Tskin= 33°Chhhcombinedconvrad2W/m . C=+=+=°40 47 87...The thermal resistance of the clothing is given to be Rcloth22clom . C / W = 0.109 m . C / W==×°°0707 0155..
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.