Download AS1300 TUTORIAL3 2023

Thermodynamics for Aerospace Engineers (AS1300)
TUTORIAL-3, 11/04/2023 DUE ON 18/04/23 by 9 PM
First law of Thermodynamics
A. First law of Thermodynamics applied to a closed system
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B. First Law applied to Control volume
7. Air enters compressor operating at steady state at a pressure of 1 bar, a temperature of 290K, and a
velocity of 6 m/s through an inlet with an area of 0.1 m 2. At exit, the pressure is 7 bar, the
temperature is 450 K and the velocity is 2 m/s. Heat transfer from the compressor to the
surroundings occurs at the rate of 180 kJ/min. Employing the ideal gas model, calculate the power
input to the compressor. Take cp= 1.005 kJ/kgK.
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Wcv= ?
2
8. In a gas turbine the gas enters at the rate of 5kg/s with a velocity of 50 m/s and enthalpy of 900
kJ/kg leaves the turbine with a velocity of 150 m/s and enthalpy of 400 kJ/kg. The loss of heat from
the gases to the surroundings is 25 kJ/kg. Assume for gas R= 0.285 kJ/kgK and c p = 1.004 kJ/kgK
and inlet conditions to be at 100 kPa and 27°C. Determine the power output of the turbine.
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Wcv= ?
Q
2
9. The air speed of a turbojet engine in flight is 270 m/s. Ambient air temperature is -15°C. Gas
temperature of outlet of nozzle is 600°C. Corresponding enthalpy values for air and gas are
respectively 260 and 912kJ/kg. Fuel-air ratio is 0.0190. Chemical energy of the fuel is 44.5 MJ/kg.
Owing to incomplete combustion 5% of the chemical energy is not released in the reaction. Heat
loss from the engine is 21 kJ/kg of air. Calculate the velocity of the exhaust jet.
10. A tank of volume 0.3 m3 is initially filled with air at a pressure and temperature of 3.5 MPa and
400°C. The air is now allowed to discharge slowly through a turbine into the atmosphere until the
pressure in the tank falls to the atmospheric pressure of 0.1 MPa. Determine the work developed by
the turbine. Neglect friction, heat loss, KE & PE changes.