1. Air at 7°C enters a turbojet engine at a rate of 16 kg/s and at a velocity of 300 m/s (relative to the engine). Air is heated in the combustion chamber at a rate 15,000 kJ/s and it leaves the engine at 427°C. Determine the thrust produced by this turbojet engine.
2. Determine the total exergy destruction associated with the Otto cycle described in Problem 9-33, assuming a source temperature of 2000 K and a sink temperature of 300 K. Also, determine the energy at the end of the power stroke.
Problem 9-33:
An ideal Otto cycle has a compression ratio of 8. At the beginning of the compression process, air is at 95 kPa and 27°C, and 750 kJ/kg of heat is transferred to air during the constant-volume heat-addition process. Taking into account the variation of specific heats with temperature, determine
(a) the pressure and temperature at the end of the heat- addition process,
(b) the net work output,
(c) the thermal efficiency, and
(d) the mean effective pressure for the cycle.