3 The methane (CH4) gas at 25C is fed into a furnace with 100% excess air at 100C. (a) Taking a basis of 1 mole of methane gas feed and assuming complete combustion, use the values of heat of formation to calculate the value of heat of reaction at 1000C in kJ/mol. [5 marks] CH4(g)+2O2(g)CO2(g)+2H2O(v) (b) Calculate the Higher Heating Value (HHV) and Lower Heating Value (LHV) of pure methane in kJ/mol. [10 marks] (c) Calculate again the HHV and LHV of a methane mixture with 4% by volume of noncombustible nitrogen as impurity in kJ/kg. [5 marks] Physical property data: For CH4(g),Hfo=74.85(kJ/mol) Cp=34.31103+5.469105T+0.3661106T211.01012T3(kJ//molC) where T is in C For CO2(g),Hfo=393.5(kJ/mol) Cp=36.11103+4.233105T2.887106T2+7.4641012T3(kJ/molC) where T is in C For H2O,Hfo(v)=241.83(kJ/mol) Hv=40.656kJ/mol at 100C Cp(v)=33.46103+0.6880105T+0.7604108T23.5931012T3(kJ/molC) where T is in C Cp(l)=75.4103(kJ/molC) For O2(g), Cp=29.10103+1.158105T0.6076108T2+1.3111012T3(kJ/molC) where T is in C For N2(g). Cp=29.00103+0.2199105T+0.5723108T22.8711012T3(kJ//molC) where T is in C Atomic weights of H,C,N, and O are respectively, 1, 12, 14, and 16 . Page 4 of 5 Turn the page over