Achimney of height 32m is used for producing a draught of 16mm of water. the temperatures of ambient air and flue gases are 27°c and 300°c respectively. the coal burned in the combustion chamber contains 81% c, 5% moisture and remaining ash. neglecting losses and assuming the value of burnt products equivalent to the volúme of air supplied and complete combustion of fuel find the percentage of excess air supplied.

At steady state, air enters an insulated duct of varying cross-sectional area (similar to a nozzle or diffuser) at 200 kpa, 52°c with a mass flow rate of 0.5 kg/s. at the duct exit, the pressure of the air is 100 kpa, the velocity is 255 m/s, and the cross-sectional area is 2 x 10-3 m^2. assuming an ideal gas model, determine: a)-find the specific volume of the air at the exit, in m3/kg. b)- the temperature of the air at the exit, in k. c)-the velocity of the air at the inlet, in m/s. d)-the inlet cross-sectional area, in m^2.