{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

MulticomponentDiffusionEPSolnLect12ME525SP2011

# MulticomponentDiffusionEPSolnLect12ME525SP2011 - 1 Example...

This preview shows pages 1–4. Sign up to view the full content.

1 Example Problem Multicomponent Diffusion Lecture 12 ME 525 SP2011 Prof. Lucht The table below lists flame properties calculated using the CHEMKIN PREMIX code for a burner-stabilized H 2 -air flame. The flame temperature (K) and the mole fractions of H 2 , O 2 , H 2 O, and N 2 are listed as a function of distance z (in cm) from the burner surface. The mole fractions of all other species in the flame gases total less than 1% and can be neglected in calculating MW mix . The pressure of 1 atm is uniform throughout the flowfield. Assume that the multi - component diffusion coefficient D i,mix for a species i in the mixture is approximately equal to the binary diffusion coefficient for species i and N 2 , D i,N2 . Use the Chapman-Enskog formula and the Lennard-Jones parameters, both given in the equation sheets, to calculate the binary diffusion coefficients. The atomic hydrogen (H) mole fraction profile and the polynomial fit to the data are shown in the plot on the next page. (a) Calculate the diffusive velocity, the total species velocity, the diffusive mass flux, and the total species mass flux for atomic hydrogen (H) at the axial flame position z = 0.0094 cm. Assume that the molecular weight of the mixture is approximately constant as a function of axial position at z = 0.0094 cm. z (cm) T (K) V (cm/s) Density (g/cm 3 ) H 2 Mole Frac O 2 Mole Frac H 2 O Mole Frac N 2 Mole Frac 0.0000 373.70 49.280 0.0008117 0.11230 0.1459 0.07832 0.6621 0.0006 414.70 54.620 0.0007323 0.10870 0.1434 0.08390 0.6624 0.0012 454.10 59.760 0.0006694 0.10520 0.1410 0.08932 0.6628 0.0018 492.30 64.720 0.0006180 0.10190 0.1386 0.09461 0.6631 0.0023 529.30 69.530 0.0005753 0.09872 0.1362 0.09979 0.6634 0.0035 599.90 78.710 0.0005082 0.09258 0.1315 0.1098 0.6640 0.0047 666.00 87.290 0.0004582 0.08678 0.1268 0.1195 0.6646 0.0059 727.70 95.300 0.0004197 0.08128 0.1223 0.1288 0.6651 0.0070 785.20 102.70 0.0003893 0.07604 0.1178 0.1376 0.6655 0.0094 889.00 116.20 0.0003442 0.06625 0.1091 0.1544 0.6664 0.0117 979.60 128.00 0.0003126 0.05730 0.1007 0.1699 0.6671 0.0141 1059.0 138.20 0.0002893 0.04918 0.09266 0.1841 0.6678 0.0164 1128.0 147.20 0.0002717 0.04189 0.08518 0.1970 0.6684 0.0187 1188.0 155.10 0.0002580 0.03548 0.07838 0.2083 0.6621 0.0234 1284.0 167.70 0.0002385 0.02528 0.06709 0.2267 0.6624

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document