1. Air enters a horizontal, constant-diameter heating duct operating at steady state at 290 K, 1 bar, with a volumetric flow rate of 0.25 m3/s, and exits at 325 K, 0.95 bar. The flow area is 0.04 m2. Assuming the ideal gas model with k 5 1.4 for the air, determine (a) the mass flow rate, in kg/s, (b) the velocity at the inlet and exit, each in m/s, and (c) the rate of heat transfer, in kW.
2. Air at 600 kPa, 330 K enters a well-insulated, horizontal pipe having a diameter of 1.2 cm and exits at 120 kPa, 300 K. Applying the ideal gas model for air, determine at steady state (a) the inlet and exit velocities, each in m/s, and (b) the mass flow rate, in kg/s.
3. At steady state, air at 200 kPa, 528C and a mass flow rate of 0.5 kg/s enters an insulated duct having differing inlet and exit cross-sectional areas. 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 3 1023 m2. Assuming the ideal gas model, determine
(a) the temperature of the air at the exit, in 8C.
10 m/s. Assuming ideal gas behavior for the methane, plot the temperature of the gas exiting the nozzle, in 8C, versus the exit velocity ranging from 500 to 600 m/s.