A jet propulsion unit working with the Joule cycle uses an air/fuel ratio of 100:1, the calorific value of the fuel being 4.184 x 104(kJ/kg). Air is taken in at pressure 1 bar and temperature 300 (degree K), and is compressed to pressure 3.5 bar. The fuel is then injected in the burner at constant pressure after which it is expanded adiabatically to pressure 1 bar. The air is then cooled back to its initial state. Find: (1) the ideal efficiency of the cycle, (2) the compression ratio, (3) the temperature at the beginning and end of the adiabatic expansion. Neglect the effect of friction.
- Joules Cycle for Jet Propulsion
- Air/fuel = 100:1
- Calorific value CVf = 41840 kJ/kg
- Pressure at entrance P1 = 1 bar
- Temperature at entrance T1 = 300 K
- Pressure at end of adiabatic compression P2 = 3.5 bar
- Pressure at end of adiabatic expansion P4 = 1 bar
Ideal Efficiency ηideal , Compression ratio rp , Temperature at start and end of adiabatic expansion i.e. T3 and T4 respectively.