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+clear;
+clc;
+disp('Example 8.15');
+
+//  aim : To determine
+//  (a) the mass of coal used per hour
+//  (b) the mass of air used per hour
+//  (c) the percentage analysis of the flue gases by mass
+
+//  given values
+m = 900;// mass of steam boiler generate/h, [kg]
+x = .96;// steam dryness fraction
+P = 1400;// steam pressure, [kN/m^2]
+Tf = 52;// feed water temperature, [C]
+BE = .71;// boiler efficiency
+CV = 33000;// calorific value  of coal, [kJkg[
+ea = .22;// excess air supply
+aO2 = .23;// oxygen composition in air
+c = 4.187;// specific heat capacity of water, [kJ/kg K]
+
+//  coal composition
+C = .83;// mass composition of carbon
+H2 = .05;// mass composition of hydrogen
+O2 = .03;// mass composition of oxygen
+ash = .09;// mass composition of ash
+
+// solution
+// from steam table at pressure P
+hf = 830.1;// specific enthalpy, [kJ/kg]
+hfg = 1957.1;// specific enthalpy, [kJ/kg]
+hg = 2728.8;// specific enthalpy, [kJ/kg]
+
+// (a)
+h = hf+x*hfg;// specific enthalpy of steam generated by boiler, [kJ/kg]
+hfw = c*Tf;// specific enthalpy of feed water, [kJ/kg]
+Q = m*(h-hfw);// energy to steam/h, [kJ]
+Qf = Q/BE;// energy required from fuel/h, [kJ]
+mc = Qf/CV;// mass of coal/h,[kg]
+mprintf('\n (a) The mass of coal used per hour is  =  %f kg\n',mc);
+
+// (b)
+// for one kg coal
+mO2 = 8/3*C+8*H2+-O2;// actual mass of O2 required, [kg]
+mta = mO2/aO2;// theoretical mass of air, [kg]
+ma = mta*(1+ea);// mass of air supplied, [kg]
+mas = ma*mc;// mass of air supplied/h, [kg]
+mprintf('\n (b) The mass of air supplied per hour is  =  %f kg\n',mas);
+
+ 
+// (c)
+// for one kg coal
+mCO2 = 11/3*C;// mass of CO2 produced, [kg]
+mH2O = 9*H2;// mass of H2O produced, [kg]
+mO2 = mO2*ea;// mass of excess O2 in flue gas, [kg]
+mN2 = ma*(1-aO2);// mass of N2 in flue gas, [kg]
+
+mt = mCO2+mH2O+mO2+mN2;// total mass of gas
+x1 = mCO2/mt*100;// mass percentage composition of CO2
+x2 = mH2O/mt*100;// mass percentage composition of H2O
+x3 = mO2/mt*100;// mass percentage composition of O2
+x4 = mN2/mt*100;// mass percentage composition of N2
+
+mprintf('\n (c) The mass percentage composition of CO2  =  %f,\n      The mass percentage composition of H2O  =  %f,\n      The mass percentage composition of O2  =  %f,\n      The mass percentage composition of N2  =  %f',x1,x2,x3,x4);
+
+//  mass of coal taken in part (b) is wrong so answer is not matching
+
+//  End
+
+
+