A steam boiler heats liquid water at 200oC to superheated steam at 4 MPa and 400oC. Methane fuel (CH4) is burned at atmospheric pressure with 50 percent excess air. The fuel and air enter the boiler at 25oC and the products of combustion leave at 227oC. Calculate
(a) The amount of steam generated per unit of fuel mass burned
(b) The change in the exergy of the combustion streams, in kJ/kg fuel
(c) The change in the exergy of the steam stream, in kJ/kg steam
(d) The lost work potential, in kJ/kg fuel. Take T0 = 25oC.