A superheater is to be designed using metallic coils (heat flux 150 kW/m2) of inside diameter 50 mm and wall thickness 5mm. The steam leaving the superheater coils is at 60 bars, 500 0C and flows at a velocity of 10 m/s. If the steam mass flow rate is 90 kg/s, find the number and length of coils.
For steam at 60 bars, take the following values – dry saturated steam h = 2784.3 kJ/kg, at 500 0C superheated steam temperature husp = 3422.2 kJ/kg and specific volume Vsup = 0.05665 m3/kg. The steam enters the superheater as dry and saturated.