A fuel oil is burned with air in a boiler furnace. The combustion produces 813kW of thermal energy; of which 65% is transferred as heat to boiler tubes that pass through the furnace. The combustion products pass from the furnace to a stack at 650°C. Water enters the boiler tubes as a liquid at 20°C and leaves the tubes as saturated steam at 20bar absolute.

(a) Calculate the rate (kg/h) at which steam is produced.

(b) Use the steam tables to estimate the volumetric flow rate of the steam produced.

(c) Repeat the calculation of part (b), only assume ideal gas behavior instead of using the steam tables. Would you have more confidence in the estimate of part (b) or part (c)? Explain.

(d) What happened to the 35% of the thermal energy released by the combustion that did not go to produce the steam?