Chapter 12 Radiation Heat Transfer 12-72 The temperature, pressure, and composition of combustion gases flowing inside long tubes are given. The rate of heat transfer from combustion gases to tube wall is to be determined. Assumptions All the gases in the mixture are ideal gases. Analysis The mean beam length for an infinite cicrcular cylinder is, from Table 12-4, L = 0.95(0.10 m) = 0.095 m Then, atm ft 0.056 atm m 0171 .0 m) atm)(0.095 18 .0 ( atm ft .0370 atm m 0114 .0 m) atm)(0.095 12 .0 ( ⋅ = ⋅ = = ⋅ = ⋅ = = L P L P w c The emissivities of CO 2 and H 2 O corresponding to these values at the gas temperature of T g = 800 K and 1atm are, from Fig. 12-36, T s = 500 K D = 10 cm Combustion gases, 1 atm T g = 800 K 055 .0 atm 1 , = ε c and 050 .0 atm 1 , = ε w Both CO 2 and H 2 O are present in the same mixture, and we need to correct for the overlap of emission bands. The emissivity correction factor at T = T g = 800 K is, from Fig. 12-38, 0.0 6
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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.