Air enters a hand held hair dryer with a velocity of 3 m/s at a temperature of 20°C and a pressure of 101 kPa. Internal resistance heaters warm the air and it exits through an area of 20 cm 2 with a velocity of 10 m/s at a temperature of 80°C. Assume that internal obstructions do not appreciably affect the pressure between inlet and exit and that heat transfer to the surroundings are negligible.
Determine the power in kW needed to operate the hair dryer at steady state.