Unformatted text preview: Chapter 9 Natural Convection 948 A room is to be heated by a cylindrical coalburning stove. The surface temperature of the stove and the amount of coal burned during a 30dayperiod are to be determined. Assumptions 1 Steady operating conditions exist. 2 Air is an ideal gas with constant properties. 3 The local atmospheric pressure is 1 atm. 4 The temperature of the outer surface of the stove is constant. 5 The heat transfer from the bottom surface is negligible. 6 The heat transfer coefficient at the top surface is the same as that on the side surface. Properties The properties of air at 1 atm and the anticipated film temperature of ( T s + T ∞ )/2 = (130+24)/2 = 77 ° C are (Table A1) 1 2 5 K 002857 . K ) 273 77 ( 1 1 7161 . Pr /s m 10 066 . 2 C W/m. 02931 . = + = = = × = ° = − f T k β υ Analysis The characteristic length in this case is the height of the cylindir, Air T ∞ = 24 ° C Stove T s ε = 0.85 L =0.7 m D = 0.32 m m. 7 . = = L L c Then, 9 2 2 5 31 2 2 3 10 387 .....
View
Full Document
 Fall '10
 Dr.DanielArenas
 Thermodynamics, Convection, Mass, Heat, Heat Transfer, Nusselt number, Steady operating conditions, cylindrical coalburning stove

Click to edit the document details