Octane (C8H18) at 25C is burned in the combustion chamber of a steam boiler with 20 percent excess air that also enters at 25C. The products leave the combustion chamber at 500 K. Assuming combustion is complete, determine

(a) the percent exhaust losses and

(b) the boiler efficiency if other losses (such as incomplete com n and heat losses) amount to 2.5 percent.. Use Eq. (5-17) with the molar enthalpies of product gases from the ideal gas tables (Tables A-11 through A-16).

-This question need to be solved by balance the chemical equation then doing the Calculations of (q exhaust ) and boiler efficiency by the equations in the below photos

Note the chemical equation after balancing will be:

C₈H₁₈+15(O₂+3.76N₂) 8CO₂+9H₂O+2.5O₂+56.4N₂

boiler=100 Exhaust losses - Other losses Qexhaust=Qsensible+Qlatent=NCO2(hh)CO2+NN2(hh)N2+NO2(hh)O2+NH2O(hh)H2O+NH2O[hf(g)hf(l)]H2O boiler=100 Exhaust losses - Other losses Qexhaust=Qsensible+Qlatent=NCO2(hh)CO2+NN2(hh)N2+NO2(hh)O2+NH2O(hh)H2O+NH2O[hf(g)hf(l)]H2O