Question

1) In an air-standard Brayton cycle, the air enters the compressor at 0.1 MPa and 15?C. The pressure leaving the compressor is 1.0 MPa, and the maximum temperature in the cycle is 1100?C. Determine The pressure and temperature at each point in the cycle. The compressor work, turbine work, and cycle efficiency. For each control volume analysed, the model is ideal gas with constant specific heat at 300 K, and each process is steady state with no kinetic or potential energy changes.

2) A utility runs a Rankine cycle with a water boiler at 3MPa, and the highest and lowest temperatures of the cycle are 450?C and 45?C, respectively. Find the plant efficiency and the efficiency of a Carnot cycle with the same temperatures.

3) A single stage air compressor running at 80 RPM, compress air from a pressure of 1 bar and temperature of 15oC to a pressure of 5 bar. The clearance volume is 5 % of swept volume which is 0.42 m3 . Assuming that the compression and expansion to follow the law, PV(1.3)= constant. Determine volumetric efficiency, mass of air delivered in kg/sec, exit temperature of air and the power required to drive the compressor in KW.

4) The velocity of steam at inlet to a simple impulse turbine is 1000 m/s, and the nozzle angle is 20o. The blade speed is 400 m/s and the blades are symmetrical. Determine the blade angle if the steam is to enter the blade without shock. If the relative velocity at exit is reduced by friction to 80% of that at inlet, what are then the diagram power and the axial thrust for a mass flow of 0.75 kg/s? Calculate also the diagram efficiency in this case.

5) The nozzle of the impulse stage of a turbine receives steam at 15 bar and 300oC and discharges at 10 bar. The nozzle efficiency is 95% and the nozzle angle is 20 o . The blade speed is that required for maximum work and the inlet angle of the blades is that required for entry of the steam without shock. The blade exit angle is 5o less than the inlet angle. The blade velocity coefficient is 0.9. Calculate for a steam flow of 1350 kg/h: The diagram power; The diagram efficiency.

Answer 1