... 61 4 Modeling of Combustion Systems: A Practical Approach Usually, one defines a reaction coordinate known as the conversion (xk),having the property that for species k the reaction starts at ... is a constantand Nk is a variable. We may also write(G .6) For constant density, we have, where [k] is the concentration of species k, and [k0] is the starting concentra-tion. We may ... $110112022,,⎡⎣⎤⎦⎛⎝⎜⎞⎠⎟=⎡⎣⎤⎦⎛⎝⎜⎞⎠⎟=pxpxPPP$xrrxRRRRPR120101221010=⎡⎣⎤⎦⎡⎣⎤⎦==⎡⎣⎤⎦⎡,,,,$⎣⎣⎤⎦=⎡⎣⎤⎦⎡⎣⎤⎦=rpxrpx1112010122PPPR,,$© 20 06 by Taylor & Francis Group, LLCKinetics Primer 61 5We may also substitute mole fractions for concentrations using(G.11)For combustion in furnaces, the ideal gas law applies:(G.12)where...