Problem $2\mathrm{.}4($a$)($to be done in class$)$

A certain natural gas of composition:

$90$ mole $\%C{H}_4$

$5$ mole $\%C_2{H}_6$

$5$ mole $\%N_2$

is burned with air $(79\%N2$ plus $21\%O2$ in stoichiometric amounts.

Assuming the fuel and air are fed to the combustion zone at $25C,$ calculat the adiabatic flame temperature $($AFT$).$

Addenda to this problem....$($to be attempted by the student after part a has been done in class. See the end of this section

for comments and answers$).$

Problem $2\mathrm{.}4($b$)$ If the same fuel is burned with only $80\%$ of stoichiometric air $($i$.$e$.20\%$ of the fuel is unburnt$)$ recalculate the

composition of the products and the AFT.

Problem $2\mathrm{.}4($c$)$ Repeat the calculation for $120\%$ of stoichiometric air $($i$.$e$.20\%$ more air than that needed for stoichiometric

reaction; this does not mean that $20\%$ of the original oxygen is left at the end$).$

Problem $2\mathrm{.}4($d$)$ Compare the AFT for the three cases $($i$.$e$.80,100$ and $120\%).$ What do you conclude?

Problem $2\mathrm{.}4($e$)$ Calculate the AFT if$,$ in the original case, oxygen is used in place of air.

Just part $($a$)$ please!