1) A low pressure air compressor develops a pressure of 0.147 bars. If the initial and final states of air are p1 = 1.02 bar, T1 = 300 k and T2 = 315 K. Compute the compressor and the infinitesimal stage efficiency. Another compressor changes the state of air from p1 = 1.02 bar, T1 = 300 K to p2 = 2.5 bars with an efficiency of 75%. Find the infinitesimal efficiency of this compressor.
2) With velocity triangles for R<1, deduce an equation for axial fan stage with downstream guide vanes.
3) A centrifugal blower with a radial impeller generates a pressure equivalent to 100 cm column of water. The temperature and pressure at its entry are 0.98 bars and 310 K. The electric motor driving the blower runs at 3000 rpm. The efficiencies of the fan and drive are 82% and 88% respectively. The radial velocity remains constant and has a value of 0.2u2. The velocity at the inlet eye is 0.4u2. If the blower handles 200 m3 entry Conditions, compute
a) Power needed by the electric motor.
b) Impeller diameter.
c) Inner diameter of blade ring.
d) Air angle at entry.
e) Impeller widths and at entry and exit.
4) The initial pressure and temperature of steam entering a multistage turbine are 10 Mpa and 773K respectively. The steam flow rate is 100 kg/s and exit angle of the first stage nozzle blade is 70°, diameter 0.1m and speed 3000 rpm. Assuming maximum/min of air at the utilization factor, determine the rotor blade angles, blade heights, power developed and the final state of steam after expansion for the two stage Curtis wheel ηst=0.65.