Heated air required for a food-drying process is generated by passing ambient air at 20°C through long, circular tubes (D = 50 mm, L = 5 m) housed in a steam condenser. Saturated steam at atmospheric pres- sure condenses on the outer surface of the tubes, maintaining a uniform surface temperature of 100°C.
(a) If an airflow rate of 0.01 kg/s is maintained in each tube, determine the air outlet temperature Tm,o and the total heat rate q for the tube.
(b) The air outlet temperature may be controlled by adjusting the tube mass flow rate. Compute and a more appropriate temperature. plot Tm,o as a function of m for 0.005 m
A range of tube lengths from 4 to 7 m is available to the engineer designing this condenser.
Generate a plot to show what coolant mean velocities are possible if the water outlet temperature is to remain at the value found for part (b). All other conditions remain the same.